September 24, 2018

Severe Thunderstorms Are Possible in the Northern U.S. This Week


Pumpkin spice, cooler air, and angry election ads proclaiming the end of the world—it sure feels like fall, but the weather doesn't always agree. A potent cold front will sweep across the northern United States and southern Canada through the middle of the week, potentially triggering severe thunderstorms along its path.

The Storm Prediction Center's forecasts on Monday showed a slight risk for severe thunderstorms in the Great Lakes and Midwest during the day on Tuesday, with the severe threat moving into the Northeast on Wednesday. The maps stop at the border—there are sovereignty and tax-dollar issues preventing most government weather maps from extending into Canada—but you can use your imagination to fill in the missing lines that extend into southern parts of Ontario and Quebec.

The pattern is a classic fall severe weather setup. A strengthening low-pressure system will cross the Great Lakes into eastern Canada over the next couple of days, dragging down cooler and less-humid air behind it. The cold front, digging into warm-ish and muggy-ish air to the south, will trigger lines of severe thunderstorms, some of which could be severe with damaging wind gusts, large hail, and isolated tornadoes.

The SPC mentioned in its afternoon update on Monday that the risk in some areas on Tuesday could be upgraded to an enhanced risk—a three out of five on the scale measuring the severe weather risk—if it looks like some storms could tap into enhanced instability and wind shear.

Even though the threat for severe storms isn't as high as you would see in the spring, any risk for severe thunderstorms is a big deal if you're in the path of one. It's worth paying attention to watches and warnings this week, particularly since folks don't normally expect severe thunderstorms now that we've been able to wear our coats a few times, and since there are lots of outdoor events now that schools are back in session.


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September 17, 2018

Trump Isn't 'Taking Over' Your Cell Phone and This Conspiracy Theory Could Kill You One Day

Warning people about dangerous weather is a matter of life or death. Meteorologists need all the help they can get when it's time to get the word out about severe weather. The federal government is about to test one of those important warning systems in a few weeks. As we approach the test on October 3, I have one thing to say: Y'all are out of your got-danged, ever-lovin', conspiracy-addled minds if you think Donald J. Trump is planning to take your cell phone to make you read his angry rants while he watches television. Seriously? Come on now! Get a grip.

Stealing a page from Alex Jones' Little Black Book of Big Black Helicopters, the #resist side of Twitter has firmly latched on to the news that FEMA will conduct a nationwide test of the Emergency Alert System on Wednesday, October 3 as proof that Donald Trump is planning take over everyone's cell phones on command. The unbelievable hyperventilation over the test—which was also pushed about Obama by the Alex Joneses of the world seven years ago—came about thanks to several news sites and big-name viral Tweeters screaming misleading headlines at their millions of readers. Even Time's article on the tests opened with the line "you may be getting text messages from President Donald Trump soon."

Emergency Alerts Can Save Your Life

An example of what a Wireless Emergency Alert looks like on an Android smartphone.
Here's what's going on. FEMA will conduct a nationwide test of the Emergency Alert System on Wednesday, October 3. (The test was originally scheduled for September 20, but was rescheduled due to Hurricane Florence.) The test will be pushed to cell phones at 2:18 PM EDT and transmitted to television and radio stations at 2:20 PM EDT. The federal government has conducted these nationwide EAS tests a couple of times in recent years—to varying degrees of success—but this will be the first time that the test includes the Wireless Emergency Alert capability on cell phones.

Starting in 2012, all modern smartphones gained the ability to receive Wireless Emergency Alerts. These alerts are sent to your device based on your location. If you're within an alert—say, a tornado warning—you'll instantly see a push notification on your device that's accompanied by a loud, EAS-like tone. These WEAs are proven life-savers, transmitting alerts like tornado warnings to people who might not otherwise have been paying attention to the weather.

That's all it is. Really.

Wireless Emergency Alerts on your smartphone can save your life. The system has only been in place for a couple of years, but there are documented cases of people saving their lives by acting on alerts sent to their phone just minutes before their homes were destroyed in a tornado or flood.

The catch is that you can't disable presidential alerts. Those are the only alerts you can't shut off. You can shut off tests, severe weather alerts, and AMBER Alerts, however, which is what I fear many people will do if they're afraid "the president is taking over their cell phone." Do not shut off the weather alerts on your phone to spite the president. Tampering with your weather alert settings does nothing to stop the presidential alerts and could jeopardize your safety one day.

Presidential Alerts Are A Relic of the Cold War


It's easy to forget that the Emergency Alert System exists for reasons other than giving you chills. The EAS is the successor to the Emergency Broadcast System and CONELRAD, systems developed to allow the president to quickly address Americans in the event of a nuclear war or invasion. Due to the relative lack of nuclear wars or foreign invasions in the decades since the alert systems were developed, the ever-present feature on television and radio is mostly used to transmit severe weather warnings and child abduction alerts.

Every president since Harry S. Truman has had the ability to activate the EAS (or its predecessors) and quickly address Americans in the event of an emergency. The presidential purpose of the EAS didn't become widespread knowledge until FEMA conducted its first nationwide test of the system on November 9, 2011.

That test was pretty glitchy. Some stations never repeated the alert. Some never shut the alert off. Folks watching DirecTV heard pop music during the test. But finding those glitches was the whole point of the test. They've repeated that nationwide test a couple of times in recent years, but this will be the first to include test alerts on cell phones as well.

The Same Conspiracies Were Pushed About Obama

Similar conspiracy theories ran wild in the lead-up to the 2011 test, but from the other side of the spectrum. Alex Jones' site, InfoWars, ran news of the test with the headline "OBAMA LAUNCHES TOTAL TAKEOVER OF MEDIA SYSTEM."

Here's how they freaked out about it at the time:

Even the Washington Post describes it like something out of Orwell’s 1984. The FCC has approved a presidential alert system. Obama may soon appear on your television or call your cell phone to warn you about the next specious al-Qaeda underwear bombing event.

[...]

Once again, the government has imposed an unreasonable and absurd mandate on business and the American people


Sound familiar? Right-wing blogs and commentators, ever-wary of the government's power and seething with rage over Obama's presidency, latched on to these nationwide television and radio alerts as evidence that the president was going to use the system to take over the airwaves and indoctrinate Americans with propaganda.

That didn't happen, of course. No president has ever used the Emergency Alert System (or its predecessors) to address the country. The government didn't even use the system on September 11, 2001, as the events of the day were immediately carried live on every television network in the country.

The system is there, though, just in case they need to use it one day. You can argue that the central premise of the Emergency Alert System is less necessary today than it was back in the days when television and radio were our only means of instant mass communication. If North Korea launched a nuclear missile at the United States, we're likely going to hear about it before Trump or anyone in Washington can go through the steps of activating the EAS.

It's improbable that even the most attention-craving president would abuse the slow, bureaucratic process it takes to activate the Emergency Alert System as their own personal megaphone. It doesn't take long for a Trump tweet to make its rounds. A screenshot of every tweet is blasted on cable news within a minute of its issuance.

This system isn't there to let Trump send you text messages while he angrily watches Fox News. The system is there to warn you in case of a missile launch, foreign invasion, or natural disaster. You'll probably only ever see these alerts before tornadoes and flash floods. Please don't disable these alerts on your cell phone because of what you read online. The alerts could save your life one day.

*This post was corrected to reflect that the test was postponed from September 20 to October 3 due to the lingering effects of Hurricane Florence.

[CONELRAD advertisement via Wikimedia Commons]


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September 13, 2018

Hurricane Florence Is a Slow-Motion Disaster With Historic Rains, Deadly Storm Surge

Hurricane Florence is making a slow-motion landfall along the North Carolina coast this evening. The storm is moving painfully slow—just 5 MPH as of 11:00 PM Thursday. The storm's creeping track toward North Carolina and South Carolina will expose a vast swath of land to an extended period of intense winds, historic rains, and exacerbate the life-threatening storm surge already inundating the coast.



The National Hurricane Center expects Florence to eventually make landfall near Wilmington, North Carolina, during the day on Friday. It will begin pushing inland through the weekend before a trough picks it up and causes it to race toward the Northeast early next week.

Hurricane Florence is going to be a long-duration event, and we can't stress the hazard posed by water with this storm. Most fatalities in a landfalling tropical cyclone are caused by drowning. Freshwater flooding from prolonged heavy rain and a storm surge at the coast will likely cause damage from this hurricane to rise into the billions of dollars. This was a well-warned event, and hopefully most folks in the path of flooding and surge were able to get out before the storm made escape all but impossible.

RAIN

The latest forecast from NOAA's Weather Prediction Center shows an eye-popping swath of 20"+ of rain expected by the end of the storm. This would exceed the devastating rainfall totals seen in 1999's Hurricane Floyd and the remnants of Hurricane Matthew in 2016. This kind of rain will lead to unprecedented flooding in this part of the Carolinas. I've never seen a rainfall map like this before outside of Texas during Hurricane Harvey last year.

Adding insult to injury, the WPC notes that some areas in that 20"+ swath may see final totals up near 40". That's more than three feet of rain. That would make this the wettest tropical cyclone in the southeastern United States and one of the wettest in the country's history. Rainfall will taper off—a relative term, in this case—farther inland, but totals of 6-12 inches (higher in some spots) will still lead to flash flooding as far inland and north as the Virginia mountains.

Forecasts of excessive rain are already verifying where Florence's rain shield is ashore. A rain gauge near Morehead City has reported a foot of rain since the storm started earlier on Thursday. Given the storm's slow movement, that total will easily double by this time tomorrow.

STORM SURGE

Expected storm surge from Hurricane Florence. SOURCE: National Hurricane Center
It's not just the rain causing life-threatening flooding. A storm surge of 10 feet above normal water levels was reported at the Cherry Branch Ferry Terminal, located near the mouth of the Neuse River southeast of New Bern, North Carolina. The storm surge along the coast in North Carolina is enough to inundate the first level of homes and businesses near the shore. This will kill people who elected to stay behind and can't evacuate to a higher level or the roof.

The surge will continue to build along north- and east-facing coasts as the storm nears landfall. This was one of the problems with focusing on Florence's maximum wind speeds. As I wrote yesterday, the storm started translating its energy into expanding the wind field rather than focusing it all in an intense sting of winds in the eyewall. Large, strong storms lead to devastating storm surges. We've seen it time and time again in past storms, and it's playing out right now in Florence.

WIND



While flooding is the headline story from this hurricane, the wind can't be ignored. Winds are already gusting around 100 MPH as the core of the storm starts dragging over land. A 105 MPH wind gust was reported at Fort Macon, N.C., just after 8:00 PM on Thursday. Between 9:00 PM and 10:30 PM, Fort Macon saw another gust up to 99 MPH, a 96 MPH gust occurred at Cape Lookout, and the NWS office in Newport, N.C., saw an 82 MPH gust.

The wind is already causing severe and widespread power outages. This trend will continue down the coast and inland as the ground softens due to heavy rain and flooding. Millions of people will spend a long time in the dark because of this storm. Downed trees will also likely block roadways, damage homes, and potentially crush cars.

There's some discussion about how folks in harm's way reacted to the storm "only" packing category two winds as it approaches land. Even without the extreme winds, the biggest story with Florence was always going to be the water. The categories of the Saffir-Simpson Scale only apply to winds. It says nothing of the storm surge or rain that accompanies the storm. Many of the most destructive storms we've seen in the past couple of decades packed hazards far greater than their category.

Even so, it's easy to lose sight of how much wind damage can be caused by a low-end hurricane. Severe thunderstorms are warned for 60 MPH wind gusts and many of the memorable derechos of years past had maximum winds of 80 to 90 MPH. Those winds only lasted for a few minutes. These are lasting for many hours without relenting.

Hurricane Florence Set to Bring Intense Flooding and Storm Surge to Carolinas


Don't let the headlines proclaiming that "Hurricane Florence has weakened" fool you. It's still an intense storm tonight as it lumbers toward the Carolinas. Florence's winds have dropped below major hurricane status as the storm struggles against wind shear and turmoil within its own structure. While the winds aren't as ferocious as they once were, Florence is still a large and dangerous storm. Coastal communities will likely suffer a life-threatening storm surge as sustained winds of 100 MPH or more batter the coast for hours on end. After landfall, many areas even hundreds of miles from the coast will be exposed to the threat for flash flooding from potentially-historic amounts of rain.



Hurricane Florence had 110 MPH winds as of Wednesday's 11:00 PM EDT advisory. Florence is much more ragged looking tonight than it was on Tuesday. The eye is poorly defined and the eyewall is struggling to stay closed due to westerly wind shear disrupting the storm's structure. Even so, Florence is expected to remain a strong storm through landfall.

RELATED: You Should Prepare for Hurricane Florence Even Hundreds of Miles Inland 

It's not terribly uncommon for a storm like Florence to see its winds start to weaken at this stage in its life cycle. First of all, it's hard for scale-topping storms to survive this far outside of the tropics. That's why it was such an eye-popping prospect that Florence could have been the farthest north such a strong storm has made landfall on record in the United States.

The other reason Florence's maximum winds were prone to falling is the storm's natural structure. A tropical cyclone's winds are generated by the extreme pressure gradient between the core of the storm and the environment around it. Weather is nature trying to balance itself out—the intense winds exist because air is rushing in to fill the void at the center of the storm. This usually leads to a tight core of strong winds in the right-front quadrant of the eyewall.

Sometimes, though, a hurricane can translate its deep air pressure into widening the wind field rather than packing all that energy into a tiny part of the eyewall, and that—along with disruption from wind shear—appears to be what's happening with Hurricane Florence. The hurricane is using its strength to bulk-up rather than sting one particular area.



This storm has a very large wind field. The wind swath map above shows how the footprint of Florence's winds has grown since it strengthened back into a hurricane last week. I hate using this as an example because it may give anyone speed-reading the wrong idea, but the "deep pressure widening the wind field" scenario is one of the reasons Sandy touched such an enormous area of the East Coast. The storm had the minimum pressure of a major hurricane, but only had maximum winds of 80 MPH at landfall—the storm's wind field at landfall, however, measured about 1,000 miles across. (For comparison, Florence's wind field measures more than 350 miles across.)

Models seem to have neatly converged on a nightmarish scenario for the southern N.C. and northern S.C. coasts. The storm is now expected slow to a crawl near the coast or just after crossing the shore, subjecting areas to the north of the eye to a prolonged period of destructive winds, storm surge, and potentially-historic amounts of rain. In addition to the damage caused by hours of winds in excess of 100 MPH, the storm surge could exceed nine feet above ground level in the worst-hit areas, completely inundating and likely destroying buildings near the coast.

Once the storm moves inland, meteorologists now expect the center of the storm to dip into South Carolina through the weekend jutting north into the Ohio Valley on Monday. The storm is so large that the exact track of the center of the system only matters in determining who will see the heaviest rain, strongest winds, and the greatest chance for tornadoes through early next week.



The rain will be Florence's lasting legacy. There's a chance that some communities are about to have the wettest couple of days they've ever recorded. Unprecedented amounts of rain will lead to widespread flooding, even in areas that don't typically flood. The flooding threat will stretch hundreds of miles inland. Flash flooding is likely near the track of the storm and landslides/mudslides are possible in the mountains as the storm and its remnants move through the area.

This afternoon's forecast from the Weather Prediction Center showed the chance for more than 20 inches of rain near the coast. Some areas could see more than three feet of rain by the time the storm is over. This could easily be one of the wettest tropical cyclones ever seen in this part of the United States. Rainfall totals of up to a foot are possible inland through parts of North Carolina and South Carolina.

We also can't ignore the risk for tornadoes. Tornadoes are always a possibility in the right-front quadrant of a landfalling storm—in this case, to the north of the storm's expected track. Tornadoes that occur in landfalling tropical storms are usually weak and don't last very long, but they can happen quickly. The tornado warning lead time can be reduced to just a few minutes in a situation like this.


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September 11, 2018

The Case for Preparing for Hurricane Florence Even If You're Hundreds of Miles Inland

Hurricane warnings are in effect for the North Carolina and South Carolina coasts ahead of Hurricane Florence, a powerful category four storm that's expected to make landfall on Friday. The hurricane will slow to a crawl near the coast, producing historic rainfall totals that will likely lead to catastrophic flooding across parts of North Carolina, South Carolina, and Virginia.

If you've followed my writing for a while, you know that I'm averse to hype. Hyping up "normal" bad weather sucks because it takes the punch out of truly disastrous storms. It's the Crying Wolf Effect in action. This is not one of those storms. If the current forecasts pan out, Hurricane Florence is on track to become a generational storm in North Carolina. This could be the storm to which all future storms are compared for decades to come, much like Hurricane Hazel in 1954 or Hurricane Floyd in 1999.





Sustained winds greater than 100 MPH and a destructive storm surge exceeding nine feet above ground level in spots would lead to widespread damage in coastal communities where the center of the storm makes landfall. The storm's size would allow damaging winds and a life-threatening storm surge to extend far up and down the coast from the point of landfall. This will be a large storm when it approaches land and its size will bring hazardous conditions to an area hundreds of miles wide.

This hurricane won't only be a coastal disaster. Florence's flooding rain and wind could extend far inland away from the coast. Flooding is possible hundreds of miles away from where the hurricane makes landfall. You need to prepare for the wind and rain from the storm even if you live as far inland as the mountains.

The water section at my Walmart was mostly wiped out by 3:00 PM Monday.


I do not live on the coast. I do not live anywhere near the coast. It would be an all-day production to drive from where I live to the coast. But I've spent the past two days in and out of grocery stores getting ready for Hurricane Florence. We make a mistake when we think of hurricanes as purely a nuisance for people who built their homes 100 feet from the water. Hurricanes—and this hurricane in particular—won't begin to unleash its full potential until the storm is inland.

But while we always focus on the point of landfall (for good reason!), it's just the beginning of Florence's story. I wrote an article for Popular Science  on Monday detailing why Hurricane Florence could be such a big deal for inland areas far beyond the coast:
Weather models generally agree that the storm is likely to make landfall in North Carolina during the day on Thursday. The storm is also likely to slow to a crawl once it moves inland. The hurricane is moving into the bottom of a strong ridge of high pressure over the eastern United States and Canada. Ridges usually foster calm weather, but that calm environment will force Florence to sit and spin over the same areas for days on end. Without any other weather systems to push Florence along, some models don’t see Florence moving out of the region until early next week.
In fact, you'd be forgiven for thinking you've seen this entire storm before and this is some protracted fever dream. We went through a slightly similar event last year with Hurricane Harvey. That hurricane made landfall as a category four, stalled out over land, and dumped historic amounts of rain over coastal parts of Texas and Louisiana.

The amount of rain that could fall in Hurricane Florence may be unlike anything recorded from a tropical cyclone in this part of the country. Our country's recent history with horrendous flash flooding caused by landfalling tropical systems should inform the actions of anyone in the Carolinas and Mid-Atlantic this week. If forecasts hold true, Florence looks likely to break the record for most rain ever produced by a tropical cyclone in North Carolina, a spot currently held by the two feet of rain dropped during Hurricane Floyd.

The heaviest rain and strongest winds will be determined by the exact track of the hurricane. But don't just focus on a couple of points on a map. The NHC's track forecasts—like the one at the top of this post—only apply to the center of the storm. The heavy rain, wind, and storm surge can extend hundreds of miles from the center of the storm, and that will certainly be the case with Florence.

Not only that, but the center of a storm historically stays within the cone of uncertainty 66% of the time. The average error for NHC track forecasts is more than 100 miles after 4 or 5 days.  The window of possible tracks for this hurricane could take it anywhere from South Carolina to the Virginia Tidewater.

The meteorologists at the NHC are experts in their field, and they use their experience with the preponderance of evidence to come up with their forecasts. They believe that their current forecast is the most likely scenario based on the evidence before them. Models will refine their guidance and meteorologists will improve their forecasts as we get closer to landfall on Friday.

Monday afternoon's rainfall forecast from NOAA'S Weather Prediction Center.


According to current forecasts, intense rainfall is likely along coastal regions of North Carolina. Wilmington, N.C., could see several feet of rain by the end of the weekend if the storm does indeed make landfall there. Flooding rain is most likely in eastern and central parts of North Carolina, South Carolina, and Virginia.

The bullseye for the heaviest rain will keep moving around as forecasters refine their track predictions as we draw closer to landfall and they can figure out how the storm is going to meander once it gets near or over land.

Inland flash flooding is the silent killer in storms like this. Many people believe that they're safe from a hurricane's ill effects because they're nowhere near the coast. That wasn't the case in Louisiana in 2016, Texas in 2017, and it won't be the case this week with Florence.

Some communities may set all-time rainfall records. The record for the most rain ever recorded in a three-day period in Roanoke, VA, is 8.99" set in 1987. That record was 6.99" in Danville, VA, set in 2008. The most rain recorded at Raleigh-Durham Airport in a three-day stretch was 10.05", and 19.66" is the top three-day total in Wilmington, N.C. Unfortunately, all of those records could be broken this weekend.

If you live inland, please do not ignore this storm. Areas that don't typically flood—and areas outside of designated flood zones—may flood with unprecedented rainfall. Incredibly heavy rain can easily wash out roads and cut off your routes around town. Water that looks shallow may not be. Even if you're unaffected at home, your ability to get around town may be severely hampered or impossible due to flooded roadways.

There's also the issue of power outages. I drive home this point a lot because the power grids in my county—and in many rural areas—are fragile. We lose power during an obnoxious summertime thunderstorm. The potential for sustained winds of 20-40 MPH (with higher gusts) reaching far inland, along with rain-soaked ground, could easily bring down trees and power lines. Power companies will have a hard time keeping up with all of the power outages. It may take longer than normal for crews to restore power to your neighborhood.

FOOD: I say it over and over again, but you don't realize how much you use electricity until you really need it. How much food do you have in your house that you can eat without having to cook it or keep it cold? Would you be able to feed yourself and your family for several days without cooking, refrigeration, or getting food from a restaurant? We laugh at people for rushing to the store to stock up before a snowstorm, but it really is necessary under threat from a hurricane.

WATER: Stocking up on water—bottled or stored from the tap—is important. You've got pretty good odds of the water staying on even if the power goes out. But if you're in an area that experiences an exceptional power outage or bad flooding, municipal pumping stations or treatment plants may be compromised. Under normal circumstances, officials would issue a boil water advisory and you'd be fine, but it's usually impossible to boil water at home during a storm when you have no electricity.

LIGHTS: Batteries and flashlights are another important but overlooked supply. Many folks probably use the flashlight feature on their cell phone these days and may not have an actual flashlight in their house. If the power goes out, you'll need to conserve every precious bit of battery you've got in your cell phone. "Power Outage Dark" is one of the darkest darks you'll experience outside of camping in the wilderness or sailing with the lights off. The moon's phase during the hurricane will be a waxing crescent—not much help to those without power, and even less so with thick clouds overhead.

CELL PHONE: Think about your cell phone, too. A portable battery pack is a good investment to make. Most are good for at least one full charge of your cell phone, if not more. You can also charge your cell phone in the car, but you run the risk of wasting precious gas or draining your car's battery. If you have no way to charge your phone in a power outage, shut it off and use it with your battery saving settings turned to max. (Some phones also have an "emergency" setting that disables almost all features to conserve battery life.)

MEDS/CASH/ETC.: Think about all the other things you'd need if the power goes out or you're cut off from getting around town for several days. Do you have enough prescription meds to get you through to next week? How about toilet paper? It's a cliché that goes without saying, but fill up your gas tank. After all, gas stations will likely shut down without power. That brings up another issue—if the power goes out, your credit/debit card does you no good. If you can afford to have some cash on hand, it'll help if you need to buy things and retailers around town are open and cash-only.


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September 7, 2018

From Guam to Africa, We're Tracking Seven Different Tropical Systems Right Now


True to form, the tropics are wide awake as reach the much-dreaded peak of hurricane season. The world's tropical tracking agencies have their hands full with seven systems right now that could all pose a threat to land over the next week or so. The National Hurricane Center's map for the Atlantic is lit up like Christmas with five—count 'em, five!—areas of interest, including a storm threatening Hawaii in the eastern Pacific and a significant typhoon approaching Guam in the western Pacific.

The sudden breakneck pace of tropical activity kind of feels like a Billy Joel song.

Random invest off the coast, that one just might be a ghost
Gordon hit Mississippi, 'nother one's in Cabo Verde
Slow to form? That's okay, it's no matter anyway
It'll be a fish and just go north and swirl away

Twitter, yeah, we have a bone, conspiracies are all that's known
Facebook models going viral, grandma's on the phone
Reporter asks you what went wrong, you claim it came right from the blue
What's that storm? Florence? No! We haven't got a clue.

WE DIDN'T START THE FIRE

See? It kinda works.

Tropical Storm Florence


Tropical Storm Florence is still out in the middle of the Atlantic Ocean this afternoon. A shadow of its former self, the once-improbably intense hurricane got knocked down from its former stature by the persistent force of wind shear acting against the storm. The system is essentially in maintenance mode right now as it drifts west through the windy chaos over the Atlantic.

The environment that will determine Florence's future strength and future track is in question right now. I published an article at Popular Science yesterday detailing the ways in which the environment will determine whether Florence gets pushed out to sea or shunted into the United States. The longer Florence keeps moving west, the greater the odds are that the East Coast will feel some sort of effects from this storm, if not an outright landfall.

We're still six or seven days away from whatever happens, so you have ample time to prepare if you live along or near the East Coast. It's a good idea to prepare for hazards like power outages and flooding even if you're hundreds of miles away from the coast. I keep using this line over and over, but you don't realize how unprepared you are for a power outage until the lights go out and you're stuck without dinner or working flashlights.

Invest 94L


There's an area of interest a few hundred miles off the coast of North Carolina this evening. Some models completely ignore it and others try to turn it into a named storm. The National Hurricane Center only gives it a 20 percent chance of development. The system is in Florence's path, so that could be another wrench in trying to predict Florence's future if the invest turns into a legitimate Thing.

Tropical Depression Eight and Tropical Depression Nine


Tropical Depressions Eight and Nine are in a race to see which one becomes Helene and which one becomes Isaac. The two systems are far out in the eastern Atlantic Ocean right now. T.D. Eight just swirled off the African coast, prompting tropical storm warnings for the Cabo Verde Islands. T.D. Nine is stationary as it sits about halfway between Africa and the Leeward Islands.

Tropical Depression Eight will start heading toward the central Atlantic through next week. It shouldn't be anything we have to worry about in the United States—it's likely to remain a fish out at sea—but as always, it's worth close monitoring just in case it starts tracking west.

Tropical Depression Nine could be more of a headache next week as we're dealing with whatever happens along the East Coast, Hawaii, and Guam. The National Hurricane Center expects Nine to track toward the Caribbean as a hurricane by early next week. The storm will follow a concerning path for this time of year. It's hard to say what will happen once the system reaches the Caribbean, but it's safe to say that it's important to keep your guard up even if Florence won't affect you. There's more to worry about behind it.

Hurricane Olivia


Hawaii has another tropical threat worth watching this evening. This threat comes just two weeks after Hurricane Lane dropped the most rain ever seen from a tropical cyclone in the Hawaiian Islands and second-highest tropical cyclone rainfall total anywhere in the U.S.

The National Hurricane Center currently predicts that Olivia will approach the islands as a tropical storm early next week. The arcing path the storm is expected to take toward the islands is concerning because it might not have much of an "out" for its heavy rain or strong winds to miss the islands. The storm could be a significant flooding and mudslide threat even as it weakens on approach.

Tropical Storm Mangkhut

Source: Joint Typhoon Warning Center


Both Guam and the Northern Mariana Islands, which are territories of the United States and matter  very much to us even if we don't write as often as we should, are also in the path of a developing storm. Tropical Storm Mangkhut could be quite strong when it approaches Guam—current forecasts show it nearing the islands on Monday (local time) as the equivalent of a category four on the Saffir-Simpson Scale with sustained winds around 130 MPH.

The Joint Typhoon Warning Center's current forecast takes the worst winds directly over Guam, but Tinian, Rota, and Saipan are very much in the cone of uncertainty. If it approaches the islands as forecast, Mangkhut could be one of the worst storms in these territories in decades.

Tropical Depression Gordon



Remember the strong tropical storm that hit Mississippi a hundred and fifty news cycles ago? It's still clinging to life over central Arkansas as a tropical depression with...10...MPH winds. (No, really!) The system is mostly bringing squally weather to the Mid-South, but flash flooding is possible where storms start training. Even though Gordon made landfall on Tuesday night, it's not uncommon for tropical cyclones to maintain their tropical characteristics for several days after making landfall, especially when it's as wet and humid as it has been in the southern part of the country.



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September 3, 2018

What You Need to Know About Tropical Storm Gordon Before Going to Bed

Tropical Storm Gordon is gathering strength in the eastern Gulf of Mexico as it heads toward landfall on the northern Gulf Coast on Tuesday evening. The storm will likely make landfall on the Mississippi coast, exposing Biloxi, Pascagoula, and Mobile to the strongest winds, roughest surf, and deepest storm surge. Gordon could reach hurricane strength by landfall. Here's what you need to know about the storm before you go to bed tonight.

  • WINDS: Gordon's internal structure has improved since the storm moved off the Florida Peninsula on Monday afternoon. While it's not all that impressive on satellite imagery, aircraft flying recon through the storm found 60 MPH winds late Monday evening. The storm is forecast to be a category one hurricane at landfall. It will have similar impacts whether it reaches land as a strong tropical storm or a hurricane.

  • ARRIVAL: The NHC says that the "earliest reasonable arrival time" of tropical storm force winds (39+ MPH) is 8:00 AM CDT on Tuesday along the Florida Panhandle near Panama City Beach and around mid-afternoon closer to Mobile. The storm is expected to approach landfall near Pascagoula, Mississippi, just after sunset, but that could change by an hour or two if the storm speeds up or slows down a bit.

  • HEAVY RAIN: The greatest threat posed by Gordon is flooding from heavy rain. A swath of three to six inches of rain is possible along the storm's path from landfall in Mississippi through dissipation in Oklahoma. Higher totals are likely in any training bands and thunderstorms.

  • NO LOITERING: Gordon is moving quickly. It won't be a prolonged storm. The storm will keep moving rather than stall-out like so many other Gulf storms in recent years, limiting the length of time heavy rain affects any one area. Training thunderstorms could lead to more rainfall than forecast, increasing the chances of flash flooding in these areas.

  • STORM SURGE: A storm surge is possible along and to the east of the track of the storm. An inundation of three or more feet is possible in some areas. The potential for a deeper surge increases with the storm's size and strength.

  • TORNADOES: Tornadoes are possible to the right of the storm's forward motion, which will include Mississippi, Alabama, and the Florida Panhandle. Tropical tornadoes happen quickly, affording forecasters less time than normal to issue tornado warnings. It's important to closely watch the radar and listen to warnings. Act quickly if you're under a warning.

  • GO JAGS: I went to college in Mobile. I know the area and I know how well-prepared the area is for a storm like this. But I also know how hard-headed people can be about storms that aren't scale-topping monsters. The region is susceptible to flash flooding from heavy rain. Gordon shouldn't be that big of a deal as far as landfalling tropical cyclones go, but any one storm is a threat if you encounter flooding, a tornado, falling and flying debris, or an extended power outage.

  • BE PROACTIVE: You can keep track of updates on Gordon (and all tropical cyclones) by checking the National Hurricane Center's website. The agency issues official forecasts every six hours with intermediate updates every three hours when watches and warnings are in effect.

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September 2, 2018

Developing Tropical System Likely to Bring Heavy Rain to the Gulf Coast This Week


Appearances aren't everything. The satellite image at the top of this post shows two interesting features approaching the United States. The system that looks most like a tropical cyclone isn't, while the system that looks less impressive is the feature that's expected to become Tropical Storm Gordon in a couple of days. Both systems will bring heavy rain to the Gulf Coast through the middle of the week.


Potential Tropical Cyclone Seven over The Bahamas isn't yet a tropical depression or tropical storm, but it's expected to become one soon. The National Hurricane Center calls systems "potential tropical cyclones" if they're developing near land and forecasters need to issue watches and warnings before the storm has officially formed. This gives people enough advanced notice to prepare without getting lost in the technical weeds.

The latest NHC forecast shows that possible-Gordon could pack winds of 60 MPH when it approaches landfall on the southeastern Louisiana coast on Tuesday. While Gordon's biggest threat is heavy rainfall, winds that strong could bring down trees and power lines, especially on soggy ground.

Several inches of rain are likely along the path of this storm as well as the disturbance currently drenching parts of Texas and Louisiana. The tropical system's forward speed—it's expected to keep moving!—should limit excessive rainfall totals, but there's a widespread potential for 3-6" of rain where the storm makes landfall, and even higher totals in areas stuck under training thunderstorms. Any slowdown in the storm's motion could result in heavier rain than anticipated.

We have several tropical interests in the Atlantic right now. The peak of the season is next week and it sure shows—Tropical Storm Florence is out in the middle of the ocean and there's another wave coming off Africa behind it. Conditions are favorable for systems to develop in the Atlantic, so we'll have to keep an eye on what's behind possible-Gordon over the next week or two.

[Satellite: RAMMB/CIRA]

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