May 28, 2018

Subtropical Storm Alberto Makes Landfall on Florida Panhandle

Subtropical Storm Alberto made landfall near Laguna Beach, Florida, around 5:00 PM on Monday, with maximum sustained winds of 45 MPH. Laguna Beach is about halfway between Fort Walton Beach and Panama City. The storm will continue to produce heavy rain, gusty winds, and the chance for isolated tornadoes as it pushes inland and moves toward the Great Lakes over the next couple of days.

An additional two to three inches of rain are possible across the Mid-Atlantic and Southeast as Alberto and its remnants move north toward the Great Lakes through Thursday. The heaviest rain will follow the core near the center of the storm as it tracks north through Alabama and Tennessee. There's an elevated risk for flash flooding across areas expecting the heaviest precipitation totals—the greatest risk for flash flooding beyond today will exist in the Appalachian Mountains of Georgia and the Carolinas on Tuesday.

There's also a risk for isolated tornadoes in the southeast on the eastern half of the system. Some of the stronger discrete thunderstorms that develop will have the opportunity to produce small, quick tornadoes. Small tornadoes are dangerous nonetheless, and the quick nature of tropical tornadoes can reduce warning lead time to just a few minutes.

The forecasts for Alberto were decent considering the nature of the storm. Alberto did max-out with winds of 65 MPH on Sunday evening before weakening before landfall. The landfall point has been within the cone of uncertainty since Friday morning. Several inches of rain have fallen across the southeast over the past few days and the rain is continuing north as it comes ashore.

Alberto never made the expected transition from subtropical to tropical. A subtropical storm is a cyclone that has both tropical and extratropical characteristics, a sort of hybrid between the two. Subtropical storms derive some of their energy from upper-level winds rather than thunderstorms around the center of circulation. The storm's maximum winds were also displaced from the center for most of its life. The storm also wasn't totally warm from top to bottom, a requirement of tropical systems.

The storm remained an organized mess for its entire life, more closely resembling a nor'easter than a tropical storm. The above satellite image shows Alberto's interesting appearance late on Sunday night. It's not clear whether or not that technical designation confused people in the path of the storm's rain and wind—meteorologists and weather reporters did a pretty good job explaining "subtropical" and hammering away at the risks rather than the name.

Unfortunately, social media is packed this weekend with photos and videos of people ignoring the red flags and beach patrol warning people to stay out of the water. Drowning from flooding is the number one cause of death in tropical cyclones, but people routinely drown in rip currents even when storms are hundreds of miles offshore. They just don't listen to the warnings. They think they know better and they think it won't happen to them.

There's not much we can do to get people to heed the warnings other than constant education and pounding away the message that it's too dangerous to swim in the ocean. I wrote for Forbes a few years ago that meteorologists can't help people who don't want to be warned. I wrote the post in the context of people driving through flooded roads despite signs, warnings, and common sense, but it could just as easily apply to rip currents. 

June 1 marks the beginning of hurricane season in the Atlantic Ocean. Storms commonly form closer to land during the early part of the season and start forming farther out in the Atlantic as the summer wears on. The historical peak of hurricane season's activity is the second week of September.

[Maps: Dennis Mersereau | Infrared Satellite: College of DuPage]

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May 27, 2018

Soaking Rains for Southeast as Florida Prepares for Strengthening Tropical Storm

Subtropical Storm Alberto is looking more organized tonight as it moves into the southeastern Gulf of Mexico. The storm's outer bands are overspreading the Florida peninsula this evening and bringing heavy rain, gusty winds, and the chance for tornadoes to the southern part of the state. Tropical storm warnings are in effect for coastal parts of Florida and Alabama ahead of Alberto's expected landfall on Monday.

The National Hurricane Center still expects Alberto to strengthen into a strong tropical storm before it comes ashore on the Florida panhandle near Pensacola in the afternoon or evening hours on Monday. The latest forecast shows the storm reaching maximum sustained winds of around 65 MPH by landfall.

Alberto is still a subtropical storm due to its interaction with upper-level winds; thunderstorms aren't completely driving the storm's development yet. The center has reformed a couple of times over the past day or so as new thunderstorms pop up near the center. This has caused the storm's minimum central pressure to fluctuate every couple of hours. The storm went from 1005 mb on Saturday morning to 999 mb in the afternoon before coming back up to 1001 millibars when the center relocated yet again on Saturday evening.

The storm certainly looks healthier tonight than it did last night. Infrared satellite imagery around 11:30 PM EDT shows deep thunderstorm activity near the center of the storm and a big, curved outflow of cirrus clouds stretching east into the Atlantic Ocean. It's getting the "look" you'd expect of a tropical system rather than an amorphous blob of clouds that even experienced weather enthusiasts would have a hard time picking out of a lineup.

Thunderstorms should root themselves over the center of circulation as the environment becomes more favorable for tropical development, helping Alberto become a fully-tropical storm and allowing it to gradually strengthen through landfall.

Alberto is lopsided and it'll likely remain asymmetrical through the rest of its life. This will affect the distribution of heavy rain over the next couple of days. The greatest threat with this storm remains flooding from heavy rain.

The Weather Prediction Center predicts a widespread area of 2-4" of rain across the southeast with more than 7" possible where the storm makes landfall. I overlaid the storm's predicted track over the rainfall forecast to show the uneven distribution of rain—the cutoff between flooding rains and a nuisance will be just a few dozen miles.

While rain is the greatest threat, we can't ignore the potential for wind damage. Downed trees and power lines will likely cause power outages in some spots. There's also the possibility of trees falling on buildings and cars. The greatest risk of bodily harm during Alberto will be due to flooding, rip currents, and falling trees.

A storm surge is possible as Alberto makes landfall. The above map shows the National Hurricane Center's "reasonable worst case scenario" for storm surge along the coast.

Most of the surge will be focused east of Alberto's center where the strongest winds are pushing water against the coastline. Here's a zoomed-in view of the part of Florida's Gulf Coast where the greatest surge is expected:

A storm surge of 2-4 feet above ground level is possible along the coast at high tide, especially in the Big Bend region of Florida. Thankfully, this is one of the least-populated stretches of coast in Florida, but people still live there and storm surge flooding is dangerous even if it's a handful of homes at risk.

In addition to the rain, wind, and storm surge, tornadoes are a concern across Florida on Sunday and Monday. The tornado threat will stretch into Alabama and Georgia as Alberto comes inland on Monday and Tuesday.

Small, quick tornadoes are common in the outer bands of tropical cyclones as they interact with land. These tornadoes can happen so quickly that they afford forecasters little or no time to issue tornado warnings for the affected areas. It's extremely important to have a reliable way to receive severe weather warnings as Alberto approaches over the next couple of days.

[Maps: Dennis Mersereau]

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May 25, 2018

Tropical Storm Watches Issued for Northern Gulf Coast Ahead of Alberto

Tropical storm watches are now in effect for portions of the northern Gulf Coast ahead of Subtropical Storm Alberto's expected arrival on Monday. Forecasters expect the system to be a strong tropical storm by the time it makes landfall. While there's a chance that the storm could be near hurricane strength around landfall, the biggest story with this storm will be the rain.

The 5:00 PM EDT advisory from the National Hurricane Center doesn't make many changes to the forecast beyond some fine-tuning of the track and the issuance of tropical storm watches. The watches are now in effect from Grand Isle, Louisiana, to Indian Pass, Florida, including the cities of New Orleans, Gulfport, Mobile, and Pensacola. These watches will likely be upgraded to warnings later this weekend.

A tropical storm watch means that tropical storm conditions (sustained winds between 39 and 73 MPH) are possible within the next 48 hours. The onset of wind and rain will precede Alberto's landfall by a day or so. Rain from this system will begin across Florida tomorrow and Sunday, reaching inland parts of the southeast late Sunday through the first half of next week.

A storm surge watch is also in effect from the mouth of the Mississippi River in Louisiana to Horseshoe Beach, Florida. A storm surge is water sea water pushed inland by strong, persistent winds. Storm surge inundation of 2-4 feet is possible in areas currently under the watch.

Alberto has that just-rolled-out-of-bed look to it on satellite imagery. The storm is quite disheveled as it battles wind shear and it has a ways to go before it organizes into a respectable-looking system. An Air Force Reserve Hurricane Hunter aircraft investigated the storm this afternoon and found that it remains a weak subtropical storm.

A subtropical storm is one that contains characteristics of both a tropical and extratropical storm. In Alberto's case, the storm is pulling some of its energy from an upper-level trough rather than solely through thunderstorm activity around the low-pressure center at the surface. It should become fully tropical as it grows more organized over the next day or so.

The storm is lopsided and it will likely remain that way for much of its life. The majority of the wind and heavy rain will occur along and to the east of the path of the center of circulation. The track is important in determining who sees the heaviest rain and the worst winds. Alberto is also a sizeable system and it will have widespread impacts across the southeast.

The Weather Prediction Center's updated rainfall forecast for the next seven days continues to show at least 3" of rain is possible across most of the southeastern United States, with the heaviest rain focused on Florida, Alabama, and Mississippi. There's now an area of 7"+ of rainfall predicted right around where the National Hurricane Center expects Alberto to make landfall. This bullseye will change as future forecasts adjust the predicted track as needed. Flooding is likely across the southeast where heavy rains have fallen for the past couple of weeks. Flash flooding will be a problem with persistent bands of thunderstorms.

While the rain is by far the greatest threat with Alberto, we can't discount the potential for wind damage, especially since the storm is expected be within shouting distance of hurricane strength by the time it makes landfall.

Water in the northern Gulf of Mexico is abnormally warm for this time of the year, running between 79°F and 82°F. The combination of warm waters and lower wind shear should allow Alberto to strengthen as it slows down in the northern Gulf on Sunday and Monday. The only saving grace is that it looks like dry air will impinge on the storm's ability to organize and ramp itself up. If that doesn't happen, though, there's a chance Alberto could flirt with hurricane status if everything comes together just right.

What can you do to prepare? The most important thing to do is to make sure you're prepared for power outages. Take stock of your ready-to-eat food—stuff like canned ravioli, Spam, breakfast bars, those tasty little cups of fruit—and keep some bottled water on hand in case there's a boil water advisory issued for your area and you can't, well, boil water. Batteries and battery-operated flashlights are a must. Your cell phone's flashlight is great in a pinch but keeping your phone charged is a must.

Take a look around outside and tie up or bring in anything that could fall over or blow around in high winds. Trim tree branches and limbs away from your home if possible. If you have to drive during high winds or heavy rain, search out some alternate routes in case roads are covered by water or downed trees and power lines.

It's the little things—easy food, a reliable flashlight, knowing an alternate route—that really help when you're faced with a storm and you haven't had much time to think and prepare for the season.

The next full update from the NHC comes out at 11:00 PM. We'll know more about exactly who will see the worst of the storm tomorrow and certainly by Sunday.

[Maps: Dennis Mersereau | SST Map: NOAA/ESRL/PSD]

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Alberto Will Likely Threaten the Northern Gulf Coast as a Strong Tropical Storm Next Week

And so it begins. The National Hurricane Center has issued its first advisory on newly-minted Subtropical Storm Alberto in the western Caribbean. The storm could intensify into a strong tropical storm as it approaches the northern Gulf Coast early next week. Heavy rains, flooding, and rip currents are likely across the southeast through next week, an especially tricky situation given the influx of tourists for the holiday weekend.

The first advisory from the NHC on Alberto shows the storm making landfall somewhere between New Orleans and Mobile during the day on Monday. Everyone from central Louisiana to the Florida Peninsula is within the cone of uncertainty. The cone is the historical track error in the previous forecasts for a storm. The center of a storm historically stays within the cone 66% of the time. The wind, rain, and storm surge can extend hundreds of miles from the center of a storm, however, and that's why the entire southeast is in play for foul weather from this storm.


Don't let the term "Subtropical Storm Alberto" trip you up. A subtropical storm is a cyclone that has both tropical and extratropical characteristics. Tropical cyclones are driven by thunderstorms around a low-pressure center at the surface and their wind field is usually compact. Subtropical storms derive some of their energy from upper-level winds and their surface wind fields are usually more spread out or detached from the center of circulation.

The difference between a tropical storm and subtropical storm is technical and has little practical use for people in the path of the storm. It's the NHC's job to adhere to the "well, technically" aspect of storms like this. Don't focus on the name. Alberto will likely transition to a fully-tropical system this weekend and it'll still have the same threats and hazards no matter what you call it.


Heavy rain is the greatest concern with this storm as Alberto taps into deep, tropical moisture flowing across the southeastern United States. The Weather Prediction Center's latest rainfall forecast (issued early Friday morning) shows a slug of 3-5" of rain covering most of the southeast.

Rain associated with Alberto will start this weekend in Florida and gradually work its way inland as the storm pushes inland early next week.

The heaviest rain will likely be focused on the eastern side of Alberto when it makes landfall. The storm will likely slow down when it approaches the coast, exacerbating the heavy rain in areas where rain bands start training (repeatedly moving over the same areas). Some spots caught under training bands could see rainfall totals approach double digits by the middle of next week.

I talked a bit yesterday about how the southeast has already been soaked by heavy rain over the past couple of weeks. Most of us have seen several inches of rain and some areas have seen more than half a foot of rain from recent thunderstorms. The ground is already saturated and it won't take much of a downpour from Alberto to cause flooding concerns in low-lying areas.


The threat for wind damage is a growing concern along the northern Gulf Coast where Alberto makes landfall. Alberto is expected to be a high-end tropical storm when it makes landfall on Monday with sustained winds somewhere around 65 MPH. Forecasters will fine-tune the storm's intensity as we get closer to landfall and models get a better handle on the storm.

It's important to point out that the NHC's forecast discussion with the first advisory calls this forecast "conservative" in its intensity as the storm approaches landfall on Monday. The storm will slow down as it enters an environment favorable for strengthening once it reaches the northern Gulf of Mexico on Monday. There's an outside chance that Alberto could push hurricane strength at landfall if current forecasts hold true.

The risk for power outages will grow as the storm grows stronger. That sounds like an unnecessarily obvious thing to say, but all the rain over the past few weeks has loosened the soil enough that it won't take much for trees and power lines to start falling down. Widespread power outages are possible. It's a good idea to make sure you're prepared with batteries, battery-operated flashlights, food that doesn't need to be cooked (ravioli and Pop Tarts are your BFFs in the dark), and bottled water. Even a little bit of cash wouldn't hurt if you're lucky enough to have it—your credit/debit card does no good when the power's out.

Storm Surge

A storm surge is possible at the coast when Alberto makes landfall. The threat for a deeper surge will grow as the storm slows down and grows stronger near landfall. The northern Gulf Coast is an especially sensitive spot for storm surge. New Orleans is firmly within the cone of uncertainty and it would only take a small nudge to the west in Alberto's track to make flooding in New Orleans a serious concern.

The National Hurricane Center started issuing storm surge watches and warnings last year to make residents aware of the threat for coastal flooding independent of the storm's intensity. There aren't any watches or warnings in effect for the United States right now, but they'll almost certainly be issued this weekend as the storm draws closer.

Surf/Rip Currents

It's a holiday weekend and thousands of people are heading to the beach to mark the beginning of the summer season. There will be lots of people at the beaches even as the storm approaches, and many of them will still go in the water even though the risks of rough waves and rip currents will be well advertised.

I'll crib what I wrote yesterday about the threat for rip currents and how to deal with them:

Rip currents will be a growing threat as the winds pick up ahead of Alberto. Rip currents are fast currents of water that pull water away from the beach. Rip currents occur when waves crash directly on the beach rather than at an angle—you can sometimes spot these currents by looking for calm spots mixed in with the waves.

Don't go in the water if you're at the coast for the holiday weekend and there are red flags flying at the beach. Rip currents don't suck you under like they show in the movies. People drown in rip currents because they can't swim, panic, or can't tread water anymore due to exhaustion or waves. If you're ever caught in a rip current, either tread water and calmly signal for help or swim parallel to the shore until the pull stops, and then swim back to the beach.


Tornadoes are a common part of landfalling tropical cyclones. The greatest threat for tornadoes exists in the right-front quadrant of a landfalling storm—in Alberto's case, this will be the eastern side of the storm. Tornadoes in tropical cyclones happen quickly but they're dangerous because they can touch down without much warning at all.

The Storm Prediction Center has issued a marginal risk for severe weather in Florida on Saturday as Alberto passes into the Gulf of Mexico and its rain bands start overspreading the peninsula. The tornado threat will continue early next week farther north when Alberto makes landfall.


The National Hurricane Center issues full forecasts every six hours (5 AM/PM and 11 AM/PM Eastern Time) and will issue intermediate updates every three hours (2 AM/PM and 8 AM/PM Eastern Time) as long as there are watches and warnings in effect.

As always, I'll keep you updated with maps and analysis here on DAMWeather and on Twitter @wxdam. Thank you as always for your continued support.

[Maps: Dennis Mersereau | Satellite: NOAA | Wind Prob. Map: National Hurricane Center]

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May 24, 2018

Flooding Rains, Gusty Winds Likely as Tropical Disturbance Approaches the Gulf of Mexico

This weekend marks the unofficial start of the summer season, so of course it's going to be absolutely miserable at some of the country's most popular vacation spots. The National Hurricane Center has given a tropical disturbance in the western Caribbean a 90% chance of developing into a tropical cyclone in the Gulf over the next couple of days. The summery weather pattern we've seen over the past two weeks will continue right into next week, and that means more tropical downpours for a region already drenched from recent heavy rains.

We're going to see heavy rain from this pattern regardless of this disturbance's development into a named system. If it feels like you've read this same post twice, it's because we went through this very ordeal just last week. The tropical disturbance in the Gulf of Mexico last week had a much lower chance of developing than the one we're watching this weekend, however, and it looks like the next five days could bring significant rainfall to parts of the southeast.

Tropical Threat

The tropical disturbance off the coast of Belize—officially called Invest 90L for now—briefly started to look more impressive on satellite imagery on Thursday. A large burst of convection developed over the tropical wave early Thursday morning and the convection sustained itself for most of the day before waning with the loss of daytime heating.

Thursday's 8:00 PM EDT outlook from the National Hurricane Center gives the system a 70% chance of developing into an organized system by Saturday evening and a 90% chance of developing within the next five days.

There's a decent chance that the NHC could start issuing advisories on this disturbance tomorrow if a surface low is able to develop near or beneath that burst of convection off the Yucatan Peninsula. If and when the system develops into an organized system, it's not out of the question for it to reach at least tropical storm strength once it makes it to the Gulf of Mexico this weekend.

The system will be named Alberto if it manages to reach tropical (or subtropical) storm strength. What will possible Alberto (possAlberto?) look like when it reaches the Gulf? Rain. Rain rain rain. Lots of rain. Tons of rain. Enough rain to cause flooding whether or not the storm gets a shiny new name or not.

It's Gonna Rain

It's been raining for a while and it's gonna rain even more. The latest rainfall forecast from the Weather Prediction Center for the next seven days—extending through May 31—calls for up to 7" of rain along the northern Gulf Coast and a widespread area of 3-4" of rain from New Orleans to Wilmington and everywhere in between. Rainfall totals will be higher in spots if persistent heavy rain and thunderstorms are able to train over the same areas for an extended period of time. And trust me, that probably will happen somewhere. It almost always does in a situation like this.

The stagnant weather pattern has already brought lots of rain to the southeast and Mid-Atlantic. Take a look at these totals over the past 14 days:

If you can overlook the horrendous color table I created for observed rainfall in my mapping software (it looks like a box of crayons effervesced!), the overall point is that there's been a ton of rain over the past two weeks and you can easily see the areas that have seen persistent thunderstorm activity. Many areas from Florida to Pennsylvania saw more than five inches of rain between May 10 and May 24, and parts of the Mid-Atlantic and southern Florida saw totals approaching (and in some spots exceeding) double digits.

Flooding is a serious concern as the disturbance moves closer to the United States, especially in areas that have seen many inches of rain. The ground is saturated and waterways are full. It won't take much of a downpour to cause issues in areas where natural and man-made water systems are taxed to begin with. Keep an eye on severe weather alerts over the next week and take a look at your smartphone to see if your wireless emergency alerts are activated.

The Wind and Waves May Be Problematic

Make sure you're ready for power outages. Trees and power lines usually don't handle gusty winds well when the ground is saturated. Lingering sogginess and upcoming rain will enhance the potential for downed trees and power lines in gusty winds. The risk for wind-driven power outages will increase if the system approaches the coast as an organized storm.

Rip currents will be a growing threat as the winds pick up ahead of the disturbance. Rip currents are fast currents of water that pull water away from the beach. Rip currents occur when waves crash directly on the beach rather than at an angle—you can sometimes spot these currents by looking for calm spots mixed in with the waves.

Don't go in the water if you're at the beach for the holiday weekend and there are red flag warnings in effect. Rip currents don't suck you under like they show in the movies. People drown in rip currents because they can't swim, panic, or get tired and can't tread water anymore. If you're ever caught in a rip current, either tread water and calmly signal for help or swim parallel to the shore until the pull stops, and then swim back to the beach.

It's also worth keeping in mind the risk for tornadoes. Tornadoes are common in the bands of tropical systems that come ashore. These tornadoes are small but they're especially dangerous because they can happen very quickly with a reduced (or even no) tornado warning lead time.

May Storms

I sure feel like I jinxed it by talking about how we might just make it through May without any named storms for the first time in a few years. Here's what I wrote last week:

It looks like we might make it to the end of May without a named system for the first time since 2014. It's not too unusual to see a named system develop before the official start of the Atlantic Hurricane Season on June 1. It happens once every couple of years. In fact, the past three years have all seen storms develop early.
My bad!

But really, if and when this thing gets a name, you're going to see sites and news networks make a huge deal about how A STORM FORMED BEFORE THE START OF HURRICANE SEASON! Here's the deal. Storms form before June 1 every couple of years. It happened to happen in 2014, 2015, and 2016. And we'll make it four years in a row if this thing develops.

It's not that unusual to see a sorry excuse for a tropical storm develop in May. They usually form in the western Atlantic or the Gulf of Mexico. What would be unusual, though, would be for this storm to gain any significant strength beyond sustained winds of maybe 50 MPH, but we'll cross that bridge if we ever get there. 

While there is evidence that the date of a season's first named storm has grown earlier over time, the streak of seeing named storms in April or May will be noteworthy if that trend keeps up for another couple of years. For now, it's probably safe to consider it a novelty statistic.

[Images: Dennis Mersereau]

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May 23, 2018

NOAA's Newest Weather Satellite Isn't Working Properly

One of GOES-17's most important instruments can't cool off properly. NOAA broke the bad news today concerning the new weather satellite the United States launched into orbit back on March 1 of this year. The news comes not long after the first test products from the new satellite were released, sending back information about space weather and showing vivid lightning in thunderstorms across the United States earlier this month.

The press release on the agency's blog is enough to put a lump in the throat of weather enthusiasts:
The GOES-R Program is currently addressing a performance issue with the cooling system encountered during commissioning of the GOES-17 Advanced Baseline Imager (ABI) instrument.  The cooling system is an integral part of the ABI and did not start up properly during the on-orbit checkout.

A team of experts from NOAA, NASA, the ABI contractor team and industry are investigating the issue and pursuing multiple courses of possible corrective actions. The issue affects the infrared and near-infrared channels on the instrument. The visible channels of the ABI are not impacted.

NOAA’s operational geostationary constellation -- GOES-16, operating as GOES-East, GOES-15, operating as GOES-West and GOES-14, operating as the on-orbit spare -- is healthy and monitoring weather across the nation each day, so there is no immediate impact from this performance issue.

If efforts to restore the cooling system are unsuccessful, alternative concepts and modes will be considered to maximize the operational utility of the ABI for NOAA's National Weather Service and other customers.  An update will be provided as new information becomes available.
The GOES-R family of satellites contains a number of cool scientific instruments to help folks back on Earth monitor different aspects of our planet and the Sun. The Advanced Baseline Imager (ABI) is the instrument that gives us the visible, infrared, and water vapor satellite images we see on a daily basis.

Mechanical issues in space are...not good!, to say the least. There's no fixing it if something mechanical breaks on a satellite. Engineers only have technical and software tricks and workarounds to try to resolve issues like this. 

Satellites get hot and they need cooling systems in order to operate. If technicians can't get the ABI's cooling system to work properly, NOAA says they'll have to work with what they've got. Visible imagery is great, but meteorologists need all 16 bands made available by the ABI to fully analyze the atmosphere.

GOES-17 is scheduled to be the western counterpart to GOES-16, the satellite launched in November 2016 and put into regular service this past December to keep a watchful eye over the Atlantic Ocean and eastern North and South Americas. The satellite was scheduled to go into operational service later this year, but it's unclear when or even if  that will happen given these latest developments.

The additional wavelengths and dramatically improved spatial and temporal resolution of the new GOES family of satellites puts the old satellites to shame. Meteorologists can now watch thunderstorms, hurricanes, and even wildfires with sharp imagery that updates almost in real-time. Hopefully they're able to troubleshoot the cooling system on the new satellite so we can have this kind of coverage across the entire western hemisphere.

[Image: Scientists install the ABI on GOES-17 at Lockheed Martin's Gateway Center near Denver, Colorado, via NOAA/NASA]

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May 17, 2018

Spring Was a Lovely Week and Now It's Time to Deal With Summer

Did you enjoy spring? I had a pretty good week, too. The patterns quickly shifted gears late last week and it looks like we've started on June's greatest hits a little early this year. We're talking tropical weather outlooks, severe storms influenced by a ridge of high pressure, and an unrelenting slog of warm, wet weather. Lovely.

The Tropical Cyclone Thing That Wasn't

The National Hurricane Center kept watch over a sad sack of clouds over the eastern Gulf of Mexico for signs of tropical development earlier this week. The system had the chance to organize itself into a subtropical or tropical entity, but it couldn't take advantage of marginally-favorable conditions in time to develop into much of anything.

Even without the name and shiny cone of uncertainty, the disturbance has brought heavy rain to the southeast and the rain will keep falling up the coast through the weekend. The system's impacts would've been the same with or without a name.

It looks like we might make it to the end of May without a named system for the first time since 2014. It's not too unusual to see a named system develop before the official start of the Atlantic Hurricane Season on June 1. It happens once every couple of years. In fact, the past three years have all seen storms develop early.

2017's Tropical Storm Andrea formed in May. A freak hurricane formed in January 2016 and the year's second named storm (Bonnie) came around in May. Tropical Storm Ana formed in May 2015. These early-season storms are usually on the weaker side, but they can produce prolific rainfall if they form near the coast.

(*"S.T.S" on the above map stands for subtropical storm. The distinction between "tropical" and "subtropical" is interesting if you're into that sort of thing.)

Bermuda High

The polar jet stream has mostly retreated to northern Canada for the time being, which means that the majority of our weather in the United States over the past few days has been driven by smaller-scale features like the Bermuda High and the subtropical jet stream over the southern United States and Mexico.

The Bermuda High, a strong high-pressure system over the western Atlantic, opened the pipeline for warm, moist air from the Caribbean and Gulf to overspread much of the eastern and central United States. The heat we saw last weekend broke in favor of a cooler but muggier and wetter pattern. It's positively swampy out there in the southeast right now.

The animation above from Tropical Tidbits shows an analysis of surface dew points beginning on the evening of Sunday, May 13, and ends with the model's forecast for dew points on Friday, May 18. The wind barbs and isobars show the high over the western Atlantic and trough over the Gulf pumping a steady stream of tropical air over the eastern half of the country.

Showers and thunderstorms associated with the aforementioned tropical disturbance and small disturbances approaching from the west will continue to be a regular feature over the next couple of days.

The storms are widespread but hit-or-miss in their nature. It's hard to say in advance who will get poured on and who will be spared. If you get caught under one of those pop-up storms, high precipitable water values (a measure of the moisture in the atmosphere) will mean that heavy rain that sticks around over one spot for too long could lead to flash flooding.


Flooding has been a serious issue. Forecasters had to issue a flash flood emergency in Frederick, Maryland, on Tuesday night due to storms that dropped up to five inches of rain in a short period of time. The same squall line that blasted the Northeast with wind gusts up to 80 MPH on Tuesday afternoon kept going into the Mid-Atlantic after sunset. Thunderstorms associated with the squall line began training over northern Maryland, leading to life-threatening flash flooding that required several high-water rescues.

More heavy rain will overspread the Mid-Atlantic through the end of the week, leading to the potential for more flash flooding. The latest from the Weather Prediction Center indicates the potential for five or more additional inches of rain across the Mid-Atlantic—centered on the D.C. area—over the next seven days.

You can keep track of the threat for flash flooding by checking in with your local National Weather Service office and the Weather Prediction Center.

Severe Thunderstorms

The Mid-Atlantic and Northeast have taken the brunt of the nation's severe weather since last Thursday. There were more than 1,500 reports of severe weather between the morning of May 10 and the morning of May 16. A rather sharp stationary front across the Ohio Valley and Mid-Atlantic often served as the focus for the severe weather across the east.

In fact, you can even see the influence of the ridge of high pressure just by looking at the pattern of severe weather reports over the past week. Most of the storms occurred around the periphery of the ridge while those under the high were mostly spared save for a few rogue storms.

The threat for severe weather through the end of this week will move back to the Plains, where places like western Nebraska and northeastern Colorado could see severe thunderstorms produce damaging winds, large hail, and possibly a tornado or two. That doesn't rule out the potential for an occasional damaging wind gust or round of hail in the more vigorous storms that form out east.

[Maps: Dennis Mersereau | Model Animation: Tropical Tidbits]

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May 14, 2018

Severe Thunderstorms Likely in the D.C. Area This Evening

A line of severe thunderstorms is making its way toward the Washington D.C. and Baltimore metro areas and should arrive in the area around the end of rush hour on Monday, May 14. There is an enhanced risk for severe weather across much of the Mid-Atlantic ahead of the squall line moving southeast out of the Ohio Valley. The greatest threat this evening will be damaging straight-line winds.

The severe weather over the past few days has been the result of a stubborn stationary front that's hung around the area since the end of last week. The front has moved back and forth over the past few days, but it's been remarkably stationary even for a stationary front. This boundary served as the focus for several rounds of severe thunderstorms this weekend and it's set the stage for yet another burst of activity this afternoon.

An enhanced risk for severe weather—a three on a scale from one to five—exists across much of the Mid-Atlantic on Monday evening. The greatest hazard within the significant risk area is damaging straight-line winds. There's also a risk for tornadoes and isolated instances of large hail.

A severe thunderstorm watch is in effect ahead of the squall line. The watch mentions the chance for straight-line wind gusts up to 75 MPH, isolated large hail, and possibly a few tornadoes. Straight-line winds can cause as much damage as a weak tornado, downing trees and power lines and damaging roof, winds, and siding on homes and businesses.

While this system won't be a repeat of the derecho of 2012—that day saw the perfect mix of ingredients during a brutal heat wave—it's important to treat any threat for severe weather seriously. If you're under the threat for severe weather, it's a good idea to make sure you don't have anything loose outside that can become a projectile in high winds. It's also wise to stay away from parts of the house where tall trees or big limbs could pose a threat to your safety if they fall.

Stay aware of your surroundings this evening and make sure you always have a way to get warnings the moment they're issued.

[Satellite: NOAA | Maps: Dennis Mersereau]

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May 11, 2018

A Wildfire Likely Spawned a Severe Thunderstorm in Texas

The ground can influence the weather in ways we don't always realize are happening. Cities warm up the atmosphere around them. Air lifting over the sides of mountains can create rain and snow. Wildfires can cause billowing cumulonimbus clouds. And some of those fires can even trigger thunderstorms like the supercell that popped up over the Texas Panhandle on Friday afternoon.

Satellite and radar imagery showed smoke rising from a large wildfire southeast of Amarillo, Texas, on Friday afternoon. The fire grew in size through the afternoon and the heat generated by the fire spawned a rather hefty pyrocumulonimbus cloud.

There was enough instability over Texas and Oklahoma on Friday to support the development of thunderstorms, but only if the cap broke. A "cap" is a nickname for an inversion layer, or a layer of warmer air sitting atop a layer of colder air. An inversion layer can prevent air from freely rising through the atmosphere, stifling the development of showers and thunderstorms. Stronger caps are harder to erode.

Something needs to break the cap in order for a storm to form. Strong surface heating during the day can raise low-level temperatures enough that rising air can reach a speed at which it breaks through the cap like cheap aluminum foil. Sometimes it takes forcing from a feature like a cold front or a sea breeze to give rising air the extra oomph it needs to break through the inversion.

Today, the force that helped break the cap was the heat from the fire.

You can follow the progress of the wildfire using GOES-East's shortwave infrared product. The heat generated by the fire makes the affected area southeast of Amarillo show up as a black splotch on satellite imagery. Smoke billowing northeast of the fire starts off a darker shade of gray at first, but the smoke eventually becomes obscured by the pyrocumulonimbus clouds as the afternoon wears on.

The thunderstorm developed in the late afternoon. The storm was able to tap into the instability already present and organize into a supercell, complete with at least one report of quarter-size hail and a beautiful overshooting top and expansive anvil that shows up well on visible satellite imagery.

You can even track the smoke and thunderstorm on radar imagery out of Amarillo. The smoke appears on radar as the steady stream of returns flowing northeast on the eastern side of the radar. The thunderstorm develops around 5:00 PM CDT and continues to grow as it approaches the Oklahoma border as it feeds off of instability in the atmosphere.

While fire-induced thunderstorms are rare, it's not out of the question when there's a large fire in the right environment. The devastating fires in and around Fort McMurray, Alberta, back in May 2016 were strong enough to spawn pyrocumulonimbus clouds that caused lightning, which, in turn, started even more fires.

[Vis/IR Combo: Dennis Mersereau (data via AllisonHouse) | Radar/Sat.: College of DuPage | Model Image: PivotalWeather]

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May 4, 2018

Damaging Winds and Tornadoes Are Possible in the Northeast on Friday Afternoon

There's a moderate risk for severe thunderstorms on Friday across interior parts of the Northeast as intense storms develop during the afternoon and evening hours. A moderate risk is a 4 on a scale that runs from 1 to 5. Any thunderstorms that develop in the risk areas will form in an environment capable of sustaining destructive straight-line wind gusts, tornadoes, and some large hail.

Thunderstorms are already firing up ahead of a cold front extending off of a low-pressure system moving through southern Ontario and Quebec today. Temperatures in the upper 70s and some low 80s across the Northeast, combined with dew points in the low 60s, will provide the instability and moisture necessary to sustain the storms once they develop.

Severe thunderstorm watches are in effect from eastern Ohio to eastern New York ahead of the storms this afternoon. A tornado watch covers northern New York and much of Vermont through this evening. Thunderstorms are starting to pop up near Lakes Erie and Ontario as of the publication of this post, and storms will continue to develop and push east through the evening hours. The severe weather should clear out after sunset.

The latest forecast from the Storm Prediction Center shows an enhanced risk for severe thunderstorms across interior parts of the Northeast, with the greatest threat for damaging winds and tornadoes focused on New York, Vermont, and New Hampshire.

Wind is the greatest threat on Friday. Winds are racing just a few thousand feet above the surface. It won't take much for thunderstorms to mix some of those intense winds down to the surface.

The SPC's latest forecast shows an area of significant damaging winds possible; both the severe thunderstorm and tornado watches mention thunderstorm wind gusts up to 80 MPH possible. The black hatching on the map above shows the risk for significant damaging winds. Winds that strong will easily blow down trees and power lines and possibly cause some damage to roofs and windows.

The environment here is also capable of supporting tornadoes in any discrete thunderstorms or along the leading edge of squall lines that move through the region. The latest SPC forecast denotes a 10% risk for tornadoes near the Canadian border in New York, Vermont, and New Hampshire, with a lower risk radiating southward from there.

Such an elevated risk for severe weather in an SPC forecast is uncommon so far north in New England, occurring only once every couple of years on average. This is only the second 10% tornado probability for Burlington, Vermont since the IEM's records begin back in March 2002. The point is that the risk for severe weather today is much higher than normal for a part of the country that typically doesn't see much in the way of bad storms.

Weather doesn't stop at the border. (Wouldn't that be wild, though?) The risk for severe weather extends into the southern parts of Ontario and Quebec. Environment Canada has issued severe thunderstorm watches for parts of southern Ontario as the line of storms sweeps through this afternoon.

If you're in the affected areas, make sure you're close to safe shelter when storms threaten your area. It's a good idea to take mental note of supplies you have just in case the power goes out. An extended power outage around dinner time isn't the best if you don't have any ready-to-eat food and local restaurants are closed. Stay away from parts of your home where large trees or limbs may fall in high winds. Straight-line winds can cause as much damage as a tornado, just over a wider area.

If a tornado warning is issued, seek shelter on the lowest possible floor and in an interior room, putting as many walls between you and the outdoors as possible. You won't be able to see a tornado before it hits. Tornadoes in this part of the country are usually obstructed by terrain and trees, and tornadoes in the kind of storms we'll see today will likely be obscured by heavy rain—you won't see it until it's on top of you.

UPDATE: This post was updated at 4:30 PM EDT to reflect the latest forecast from the Storm Prediction Center, which upgraded some areas to a moderate risk and expanded the enhanced risk area.

[Maps: Dennis Mersereau]

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May 3, 2018

Living With Storm Anxiety as a Weather Geek

I get nervous before thunderstorms. Well, I get nervous before bad thunderstorms. For a couple of years now I've talked openly about my newfound struggle with storm anxiety. It's a weird thing to have to deal with when you love weather as much as I do and talk about it pretty much every day for a living. Publicly dealing with my storm anxiety has given me an interesting insight into how everyday people deal with thunderstorms and how meteorologists and weather enthusiasts have a giant blind spot when it comes to something they love.

I'm fine during run-of-the-mill thunderstorms. It's the wind—heck, even just the threat of wind—that gets to me. I've seen too many pictures of destroyed buildings. I've seen pictures of destroyed apartments that looked exactly like mine with a gaping hole where my bedroom would be. I've seen pictures of tornado victims. A few years ago I watched a warehouse's roof peel off across the street from me during a strong storm. I've seen tornado debris fall from the sky. Lightning and thunder and hail are unnerving but they don't bother me too much.

The wind bothers me.

I’ve had a love-hate relationship with storms all my life. I used to sit in the window as a toddler and watch lightning zap across the sky without so much of a twinge of fear. Storms started to terrify me in elementary school. I’m not sure if it was the movies Twister or Night of the Twisters (especially the latter), or the scary beeps and alerts that flew across the TV screen, but whatever spooked me as a kid grew into storm anxiety.

My storm anxiety got better once I hit high school. The fear eventually turned into a healthy obsession. I still got nervous ahead of tornadoes or bad squall lines but it was manageable. I was still excited to see storms. Going to college in Mobile, Alabama, intensified my love for storms. Even a few close calls with lightning strikes weren’t enough to completely shake me of my love for storms.

Starting in the summer of 2016, it seemed like every thunderstorm that passed through my town in central North Carolina reached its convective apogee directly over my apartment. Gone were the days of listening to the rain and rolling thunder and standing in the window for hours taking pictures of lightning. Almost every storm was severe and its worst attributes unfolded right over me.

I dubbed it #Rockinghaming on Twitter. That was my way of making light of the endless stream of sky-rage that seemed to inflict its pain specifically on our county and nowhere else in the area. Over the course of a year and a half, we've had two destructive microbursts, numerous extended power outages, a couple of hailstorms, lightning that destroyed a clock radio, two rounds of flash flooding, and a tornado that passed within a couple of miles of where I live and dropped a significant amount of debris on our apartment complex.

I know that my renewed fear of bad thunderstorms stems from living on the top floor of a wood-framed apartment building. It's the wind. I'm afraid that the roof is going to peel away or a tornado will scrub away everything I know. Even if I know that's probably not going to happen, the nervousness still takes hold.

I’ve always been an anxious person. Most of my fears have been and still are totally ridiculous. They all relate to emergencies in one way or another. I was terrified of the Emergency Alert System as a kid. I would have nightmares about the sound and the unnecessarily-apocalyptic screen Comcast chose to flash on every channel during an alert. I got over it (though the sound can still induce chills).

A fear of fire alarms that developed in elementary school has stuck with me the longest. (I know, right?) The best way I’ve found to describe it is an intense fear of being startled. A fear about fear! How odd. I learned to manage it a bit as I've gotten older, but I still struggle with it.

It makes my renewed storm anxiety feel like one of the more normal things about me. It’s also made me hyper-aware of how many other people get nervous when thunderstorms are in the forecast. I have a relative who sometimes sits in the bathroom during a bad lightning storm. I have friends on Facebook who can only bring themselves to post a worried emoji with a copy of the Storm Prediction Center’s latest outlook.

When we were under a risk for tornadoes a couple of weeks ago, I jokingly tweeted that my anxiety kept telling me that a delayed forecast by the SPC was the forecasters painting the highest tornado risk over me. Later that day, as I watched a confirmed tornado roll toward me on radar, I forgot all about being nervous and became laser-focused on staying safe. That’s not to say that I won’t be nervous during the next storms. But knowing that my mind switches into safety mode when I’m in actual danger feels like a positive step.

Blind Spots

My newfound (re-found?) storm anxiety informs the way I talk and think about the weather now. It makes storms more of a human event than a natural event for me. It's disappointing to see folks in weather speak about storm anxiety with derision or indifference.

Viewers and readers with storm anxiety are an enormous blind spot for meteorologists and weather reporters. It's more than just the jitters. Why would someone be nervous over something so cool? I get it.

I used to get a little excited when I saw a big severe weather outbreak on the horizon or a picture-perfect hurricane buzzsawing its way across the Atlantic. It’s instinctively thrilling for a weather enthusiast to witness the most furious conditions nature can produce. Nature is a beautiful force. But there's a human cost.

It’s upsetting to see weather enthusiasts cheer for tornadoes. Tornadoes are photogenic and tornadoes over open fields with a beautiful backdrop are gorgeous images. They’re still tornadoes. Openly hoping for a tornado outbreak isn’t the best optics for a field whose pitch to gain the public trust is predicated on serving and helping people. How are we serving or helping when we’re expressing delight over an event that could destroy homes and cost people their lives?

I'm well aware that people who get excited over bad weather aren't hoping that people die or lose their homes. But imagine being someone who actually lost a loved one or lost their home in a tornado or someone who lives with storm anxiety and follows a bunch of meteorologists to calm their nerves only to see a steady stream of posts excitedly hoping for big tornadoes or massive squall lines.

I’m also well aware that people who root for bad storms aren't jinxing it. The weather is going to happen whether or not those people cheer it or ignore it or even if those people didn’t exist.

It’s a matter of sensitivity and professionalism. Whether it's intended or not, they're actively conveying to people in the path of the storm—who may very well be looking to those professionals for information—that it's more a matter of personal entertainment and fascination than an issue of life or death seriousness.

The effect is more pronounced when someone in harm's way suffers from storm anxiety. Lots of people with storm anxiety follow lots of meteorologists and weather enthusiasts to keep up with weather and assuage their concerns by staying in-the-know.

What we say and do in public has an effect on other people and it reflects poorly on ourselves and our field when we express glee over something that could ultimately exact a human cost. We can’t and shouldn’t police people’s thoughts and emotions. At the same time, it's important to carefully measure our words when dangerous weather is on the horizon. It's a matter of what should and shouldn't be kept to ourselves.

It's natural for someone who loves the weather to stand in awe of a storm and gawk at radar and satellite. That shines through and everyone understands it. When we get eager for a severe weather outbreak and express delight at the chance for tornadoes, though, that negates so much of the seriousness and solemnity of the work we try to convince people is worth paying attention to.

I have no doubt that the folks who would benefit from heeding this advice the most are going to be the first to brush off my concerns and mock them. I can only hope that it's enough to give pause and maybe even some hesitation during the next severe weather outbreak.

Help Is Available

One of the most prominent meteorologists to discuss storm anxiety online is Rick Smith, the Warning Coordination Meteorologist for the NWS office in Norman, Oklahoma. Central Oklahoma is one of the most storm-prone regions of the country. The area has seen multiple devastating tornadoes in the past 20 years. Hail larger than baseballs and wind gusts stronger than 80 MPH aren't uncommon here.

The efforts of Smith and his office to help residents in central Oklahoma deal with their storm anxiety were recently covered in a fantastic article written by Nomin Ujiyediin for Oklahoma City's NPR station KGOU. The interview drives home just how many people are affected by storm anxiety:

Some people call several times a day, asking the same questions over and over. Others message the National Weather Service on Twitter and Facebook every few minutes for hours at a time.

“People are very clearly disturbed and bothered and upset by just the forecast of a severe storm. It’s not that they’re scared of the storm, they’re scared seven days before the storm ever gets here, and that’s prevalent,” Smith said.

These interactions happen so frequently that Smith and others in the Norman office decided they needed to address storm anxiety in the community. The Weather Service has begun posting mental health resources on its social media to a warm reception from followers. And the Norman office has reached out to specialists who see the effects of disasters on mental health, both immediately and over the long term.

There is help available for people who struggle with storm anxiety. You're not alone. Staying aware of the situation is the most important thing any of us can do. Completely ignoring the threat just puts you at risk of missing a critical warning. Talking about it helps. People who genuinely care about you will listen. Finding distractions helps. I listen to music to deal with bad storms. (Smooth jazz is a favorite, but it's a little on the nose.)

The Substance Abuse and Mental Health Services Administration (SAMHSA) is a federal agency that offers assistance and services for people who have storm anxiety or issues coping with the aftermath of a disaster.

If you're struggling to deal with storm anxiety or the aftermath of a disaster, you can reach SAMHSA's disaster distress helpline day or night by calling 1-800-985-5990. You can also text TalkWithUs to 66746 to speak with a counselor.

The agency's website has extensive resources available for folks who have trouble dealing with storms or other disasters, including warning signs and coping tips.

[both photos taken by me]

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