June 12, 2019

Parts Of Southern Georgia Saw 7 Inches Of Rain In Just Three Hours On Tuesday

A large cluster of thunderstorms that popped up in southern Georgia on Tuesday evening produced more than 7.00 inches of rain in just a couple of hours, prompting a flash flood warning as local waterways and storm sewers were inundated by the abrupt surge of water. The sudden nature of the storms highlights the flooding risk that summertime thunderstorms can pose in the moisture-laden southeastern United States.

Folks who live in the southeast are no strangers to a drenching afternoon thunderstorm. It's not uncommon for a thunderstorm to pop up and drop a quick inch or two of rain before moving on an hour later. The storms north of Valdosta, Georgia, however, are an example of how quickly things can get serious when your run-of-the-mill summertime thunderstorms sit in the same spot for too long.


The cluster of thunderstorms that put down the torrential rain were the result of converging outflow boundaries. An outflow boundary is the rush of cool air that descends out and away from a thunderstorm. Outflow boundaries often act like little cold fronts that scoop up unstable air ahead of them and trigger the development of more thunderstorms as the afternoon wears on. This domino effect can continue until the unstable air is exhausted—usually around sunset.

Outflow boundaries were responsible for the flooding rains over southern Georgia on Tuesday. Imagery from the Valdosta radar showed multiple outflow boundaries colliding almost head-on across the counties north of Valdosta. A cluster of thunderstorms bloomed when the boundaries collided and the unstable air had nowhere to go but straight up.
Radar-estimated rainfall amounts on Tuesday evening. Source: GREarth/AllisonHouse

Since there weren't any prevailing boundaries or strong steering currents to drive the storms out of the area, they just sat and poured over the same communities for several hours at a time as they very slowly drifted toward the south. A weather spotter near Weber, Georgia, reported 5.81 inches of rain between 5:54 PM and 7:54 PM. NWS Tallahassee reported on Twitter that one community—possibly that same weather spotter—saw more than 7.00 inches of rain by the time the storm wound down. Radar estimates indicate that several counties saw 5-7 inches of rain during the storm.

The Weather Prediction Center warns that there's a chance for more flash flooding across coastal sections of Georgia, South Carolina, and southeastern North Carolina on Wednesday. It's hard to say who will see the heaviest rains, but any thunderstorms that pop up in the region have the potential to produce lots of heavy rain in a short period of time.

[Radar Imagery: GR2A/Gibson Ridge]


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June 11, 2019

Typically-Comfy San Francisco Hits 100°F As West Coast Heat Wave Continues This Week


Hoowee. It hit 100°F at San Francisco International Airport on Tuesday, the warmest temperature ever recorded so early in the year. The heat wave baking the West Coast with unusually toasty temperatures for early June will continue through the end of the week, forcing some residents to deal with almost unbearable indoor temperatures.

Temperatures easily soared into the 100s as far north as northern California's Central Valley on Monday and Tuesday, with 90s at lower elevations through eastern Washington. Temperatures at 4:00 PM PDT on Monday are shown in the map at the top of this post. Even downtown San Francisco, which is typically rather cool given the influence of the chilly Pacific waters, made it all the way up to 97°F on Monday, breaking the station's record for June 10 by one degree.

Things didn't cool down much on Tuesday. Portland, Oregon, hit 95°F at 3:00 PM PDT on Tuesday, and temperatures were right up around 100°F again in the San Francisco Bay area. 

San Francisco's high on Monday was one of only seven times SFO Airport's temperature reached 100°F or warmer, and the earliest it's ever done so. Every other triple-digit reading at the city's airport occurred during the month of September, according to data pulled from xmACIS2 and professionally compiled on the lovely PowerPoint chart above.

Other record highs on Monday include 113°F in Thermal, CA; 105°F at Salinas Airport in Monterrey County, CA; 105°F in Stockton, CA; 104°F in El Cajon, CA; and 101°F in Redwood City, CA; and 101°F in Santa Rosa, CA. Many of the records broken in California, especially around the San Francisco area, have stood since at least 1994.

500mb height anomalies on Monday afternoon. Source: Tropical Tidbits

A large ridge of high pressure parked over western North America is responsible for the prolonged heat wave. Ridges tend to foster calm, hot weather—stronger and more anomalous ridges can bring about stronger and more anomalous heat waves. Models show the ridge sticking around for at least a couple more days, which means temperatures will be slow to cool down through the end of the week.

An animated loop of expected high temperatures across the western U.S. between Tuesday, June 11, and Friday, June 14.
The National Weather Service's forecast on Tuesday afternoon called for high temperatures at or near 100°F to persist across most of California's Central Valley through Friday. Things will progressively start to cool down at the coast in places like San Francisco and Los Angeles—the high in downtown San Francisco will only hit the mid-60s by the end of the week, but even inland the warmth won't be anywhere near as brutal as we saw on Monday.

It's bad enough to have to deal with hot temperatures when you're not used to them, but many homes and businesses in the western United States—especially near the coast—aren't equipped with air conditioning, which makes a days-long heat wave an uncomfortable and potentially dangerous prospect.

Heat is a compounding hazard. Enduring a successive period of extremely warm days and nights prevents the indoor temperature (and, back east, the humidity) from rebounding to a livable level. The longer a heat wave lasts, the more unlivable it becomes indoors. That's why so many people fall ill or die during long heat waves in low-income communities or climates where air conditioning isn't a standard in homes and businesses.


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June 7, 2019

A Rare Tornado Hit A Small Town In Northern Canada, One Of Only 4 Recorded So Far North



A tornado struck a tiny town in northern Canada’s vast wilderness on June 2. The tornado damaged homes and businesses in Fort Smith, Northwest Territories, leaving residents shocked by the storm that just hit them. Tornadoes are rare at such a high latitude, and it’s even more rare that the tornado managed to hit such an isolated community.

Environment Canada confirmed that an EF-1 tornado touched down in Fort Smith on the afternoon of June 2, causing some structural damage and bringing down trees and power lines. Photos obtained and posted by CBC North show significant tree damage, crushed vehicles, and what appears to be a metal shed that was tossed and smashed in someone’s yard.

Residents in this part of the country have no reliable way to know a tornado is coming unless they see it for themselves. Environment Canada only has 31 weather radar sites set up across the country, centered on population centers near the southern border and in parts of the tornado-prone Prairie provinces. The nearest weather radar to Fort Smith is more than 350 miles away—that’s like using the radar at Washington’s Dulles Airport to see a storm over Providence, Rhode Island. This leaves folks up north to rely on satellite imagery or old-fashioned sky watching to stay ahead of an approaching thunderstorm.

Folks in Fort Smith probably never thought they'd see a tornado there. Tornadoes are extremely rare this far north. This is reportedly only the fourth tornado on record to strike Northwest Territories. It’s possible there are more tornadoes than we realize in interior and far-northern Canada, but communities are so few and far between that it takes a direct strike like we saw in Fort Smith for a tornado confirmation.

Tornado data maintained by Environment Canada shows more than 1,800 confirmed tornadoes across the country between 1980 and 2009, mostly focused around populated areas where people are actually around to witness tornadoes. Most tornadoes in Canada are relatively weak, though some tornadoes on the Prairies and in southern Ontario have been quite strong. The strongest tornado in Canadian history was an EF-5 that hit Elie, Manitoba, on June 22, 2007.


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June 5, 2019

Tropical Downpours Could Lead To Flash Flooding In Parts Of The Southeast This Week



Heavy downpours could lead to localized flash flooding across parts of the southeastern United States this week as a deep plume of tropical moisture spreads over the region. Forecasts on Tuesday night called for a widespread drenching across the southeast through early next week, with some areas potentially seeing more than five inches of rain by the end of the period.

Last week, we started watching a tropical disturbance in the Bay of Campeche for signs of tropical development. The National Hurricane Center had given the system a 60 percent chance of developing into a tropical system at its beefiest, but the disturbance was never able to take root and grow. The disturbance ran out of room to develop on Tuesday as it approached eastern Mexico.

Source: Tropical Tidbits


Nothing ever really goes away in the weather, of course. Even though the soon-to-be-erstwhile disturbance is no longer a thing of interest on weather maps, the remnant moisture from the system will continue spreading across the southeast. The above chart from Tuesday night's run of the GFS model shows precipitable water (PWAT) values through the weekend.

Precipitable water is a great way to visualize how much moisture shower and thunderstorms can work with. PWAT tells us how much rain would fall if you could wring all the moisture out of that part of the atmosphere. Higher PWAT values indicate a greater potential for showers and thunderstorms to produce heavy downpours that could lead to flooding. A PWAT value over 2.00" is considered delightfully soupy and tropical, a ripe environment for drenching rains.

As a result of all that evaporated paradise moving over land, it won't be hard for a hefty thunderstorm to put down a quick inch or two of rain if it sits over one spot for too long. It's important to note that not everybody covered under, say, the five-inch rainfall contour in the Weather Prediction Center's forecast will definitely see five inches of rain. Storms are hit-or-miss during the summer. Most everyone will see rain, but some could see a whole lot more than others.

Stay alert for flash flood watches and warnings over the next couple of days. It's always wise to memorize or program multiple safe routes to get home, to work, or wherever you need to go, just in case your normal route is covered in water and you need to turn around. It only takes a few inches of moving water to pick up a vehicle and carry it away, and it's impossible to tell how much water is covering a roadway—or if the road is even still there under the water.


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May 22, 2019

Strong, Long-Track Tornadoes Possible in Okla., Kansas, and Missouri on Wednesday



Talk about things ramping up in a hurry. Conditions have quickly grown favorable across the southern and central Plains for severe thunderstorms capable of producing strong, long-track tornadoes. The quick ramp-up and lingering feelings from Monday's severe weather threat means that today's threat for severe weather could catch people off guard.

GREarth/AllisonHouse


At 3:30 PM CDT, the Storm Prediction Center had issued two PDS Tornado Watches covering a vast swath of the central United States from southern Oklahoma to central Missouri. The watches include Wichita Falls, Oklahoma City, Tulsa, and Joplin. "PDS" stands for "Particularly Dangerous Situation," enhanced wording added to a tornado watch when conditions are favorable for the development of strong, long-track tornadoes.

The environment seems primed for the development of supercell thunderstorms capable of producing strong, long-track tornadoes, as well as damaging wind gusts in excess of 70 MPH and hailstones the size of baseballs or larger. There may not be a large number of storms, but the storms that do form could get ugly in a hurry.




There's a moderate risk for severe weather beginning in northeastern Oklahoma and stretching through central Missouri, including the Tulsa metro area, Joplin, and stopping just short of Columbia and Jefferson City, Mo. A heightened tornado threat exists from the PDS Watch in Oklahoma through central Missouri. The black hatching on the tornado probability map above shows where the conditions are most favorable for thunderstorms to produce strong, long-track tornadoes.

Much of the severe weather expected this evening may occur after nightfall, which, combined with heavy rain, may make tornadoes impossible to see before they're on top of you. Don't wait to see a tornado before you take action if you're put under a tornado warning.


The parameters in place aren't as intense as they were on Monday—where we could have seen a very ugly situation had thunderstorms been able to develop—but that was an extreme risk, and the high-end is the high-end for a reason. Monday's risk saw all the ingredients, but few thunderstorms formed to tap into that highly favorable environment.

Today, however, thunderstorms are developing along the Red River (the Texas/Okla. border) with more on the way. Thunderstorms that develop will soon move into a position where they can tap into those favorable ingredients and begin rotating.

Pay close attention to severe weather warnings today and stay close to safe shelter if you have to take quick action. Don't let a false sense of security set in because we got lucky on Monday. The SPC doesn't include PDS wording in watches lightly.

Here's a pure and shameless copy/paste of the safety advice I included in my post on Monday morning. Folks in this part of the country are always prepared for severe weather in late May, but it's important to make sure you're ready to go if you're under a warning.

Plan your day accordingly. Don't run to Walmart or another big box store when storms are on the way. Mentally map out your home, work, or school to scout out the safest place to go if a tornado warning is issued. Do you have a safe building to pull off the road if you have to go out? If you have to be in a big box store, do you know the safest place within the store? Ask the manager. Seriously. They have to have a plan for that kind of stuff in this part of the country.

Leave mobile/prefabricated homes. Spend the whole day somewhere safer—a friend's house, the library, anywhere but home. Mobile homes can start to roll and break apart in winds as low at 70 MPH. Even a small tornado can heavily damage or destroy a mobile or prefabricated home and leave you in a life-threatening situation. Hell, the bathroom in a McDonald's provides you with more protection than a mobile or prefab home.

Consider the flooding risk when seeking shelter from a tornado. If your home is in a flood-prone area, consider leaving and going somewhere safer for the day. You don't want to be put in the impossible situation of deciding whether to go to the basement—and possibly drown—or stay at ground level and possibly risk a direct strike from a tornado.

Wear a helmet, jeans, and closed-toe shoes if you have to take cover from a tornado. The most vulnerable part of your body in a tornado is your head and a helmet will spare you from at least some debris if the worst happens. Jeans and closed-toe shoes will protect your feet and legs if you have to walk over debris.

Make sure wireless emergency alerts are activated on your cell phone. These alerts have saved countless lives over the past couple of years. Some folks disabled these alerts ahead of a nationwide test last year. Keep them on! I often receive my emergency alert within a minute of my weather radio going off.

Use a weather radio. Many people in this part of the country already have weather radios. Modern weather radios are like smoke detectors for the weather. You can program them with your county's unique code so they sound a loud siren when you're placed under a watch or a warning. Most devices even flip on the weather radio feed and read the warning out loud.

Don't rely on tornado sirens for warnings. These systems are outdoor warning systems and they are not meant to be heard indoors. Tornado sirens are also vulnerable to technical failures, power outages, and wind shifts that affect where they can be heard.

Don't hide from a tornado under a bridge or overpass. It is not safe. Strong winds grow even stronger when they press under a bridge. Three people died under three separate bridges during the 1999 Bridge Creek-Moore tornado in central Oklahoma. Bridges will not protect you. Get to a sturdy building and take shelter there.

Don't hide from large hail under an overpass, either. Drivers trying to protect their vehicles from hail damage often wind up creating a traffic jam, stranding hundreds (possibly thousands) of people and emergency crews behind them. This is especially dangerous since large hail often precedes a tornado in a classic supercell, which could leave all those people trapped in the path of a tornado with nowhere to go.

Don't go storm chasing. Wednesday's storms are expected to form in a bad part of the country for storm chasing. Trees, hills, and a limited road network will combine with ongoing widespread flooding to make keeping up with, and staying ahead of, dangerous thunderstorms a risky gamble. Leave chasing to the experts...and, based on what we've seen lately, even some of them shouldn't be out there.

Keep up with the Storm Prediction Center's website through the day. The SPC issues severe thunderstorm and tornado watches, as well as short-term forecast discussions that can give you a heads-up of what's coming over the next couple of hours. Stay proactive on a day like this. You should know about the threat for storms an hour or two before they arrive. Don't simply wait for a warning to act.

(Post updated at 4:35 PM EDT to include the new PDS watch stretching through central Missouri.)


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May 21, 2019

Oklahoma Is Extremely Lucky That Monday's Severe Weather Didn't Live Up To Its Potential



The parameters existed on Monday for an intense tornado outbreak on the southern Plains had thunderstorms managed to develop in the warm sector. That didn't happen. Even though there was plenty of severe weather from western Texas to southwestern Missouri, it's safe to say that Oklahoma got extremely lucky compared to what could have been.

It's admittedly a little tough to say Oklahoma got "lucky" when there were still damaging tornadoes there and in Texas—some of which likely rated as a significant EF-2 or stronger—and major flash flooding across Oklahoma and parts of Kansas and Missouri. But the overall situation wasn't as bad as it could have been given the potential that existed. Something—possibly unexpected subsidence in the mid-levels of the atmosphere or rising air not rising fast enough near the surface—prevented thunderstorms from blowing up in the most favorable area for tornadoes. That was truly the best outcome given how dire the situation looked going into Monday afternoon.



The above tweet from NOAA's Hazardous Weather Testbed shows the significant tornado parameter on May 31, 2013—the day of the 2.6-mile wide tornado in El Reno, Oklahoma—compared to what we saw on Monday, when the parameter was twice as high as it was on that awful day six years ago. The environment over the region on Monday was about as favorable for tornadoes as it gets. The atmosphere was ready to spin anything that managed to root itself in central Oklahoma, but nothing really got going until later on when approaching storms had coalesced and the tornado threat began to wane.

The weather doesn't suddenly veer from a predetermined path. Thunderstorms were never going to develop in central Oklahoma when conditions were most favorable for tornadoes. We just didn't know that ahead of time, and that's a failure. The search for answers as to why that wasn't detected and accounted for ahead of time—and how to catch it the next time—will come through plenty of research in the coming months and years. Meteorologists have gotten really good at tornado forecasting over the years, but there's still a lot left to learn.

Rare and memorable severe weather outbreaks are rare and memorable for a reason. It's really hard for all the ingredients to come together at the same time to produce a high-end tornado outbreak. I made note of that going into the day on Monday:

It appears the environment will be capable of supporting a high-end severe weather outbreak. It's hard for big severe weather outbreaks to occur. Lots of things have to go right and it's easy for storms to morph into a sloppy mess on a day like this. Even if the storms on Monday don't reach maximum capacity—and many likely won't!—one storm breaking through to produce one bad tornado is still a big deal.

I won't pretend to have had any special intuition that made me include that blurb. I thought it would be ugly just the same as everyone else. But we've seen lots of seemingly high-end severe weather outbreaks in recent years turn into a sloppy mess. Sloppy clusters of storms and the lack of a sufficient trigger in the warm sector mostly stifled the extreme tornado threat away from the dry line farther west. The setup still produced plenty of tornadoes in parts of the Texas panhandle and western Oklahoma, but it wasn't nearly as bad as it could have been given the dynamics in place.

The most important part of a forecast is getting it right. Messaging is a close second, though—and I'm not convinced (at least not yet) that the high risk yesterday was unwarranted given the extreme parameters in place had a storm been able to form and take advantage of that kind of environment. Can you imagine if it had gone the other way and supercells had blown up around the Oklahoma City area after forecasts downplayed the threat?

Sounding the alarm for a big day that doesn't quite pan out will hurt trust in weather forecasting at least a little bit. You know how averse I am to hype, and yesterday will probably hurt some readers' trust in me. The atmosphere pointed a loaded gun at central Oklahoma on Monday. We're very lucky nothing pulled the trigger.

Thankfully, instead of mourning, today we have an internet full of part-defensive and part-introspective weather folks, storm chasers ticked they didn't see the best day of their lives, residents peeved that they worried over nothing, and officials left explaining why they cancelled classes and moved armies (well, just some planes) based on a potential that went unfulfilled.

It's a good thing that people took the threat seriously. Every live shot of Oklahoma City on television yesterday showed the streets virtually empty for most of the day. Yesterday's response shows that people really do trust the forecasts and they really do prepare when things get scary. I hope they still choose to take action the next time.


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May 20, 2019

Subtropical Storm Forms Near Bermuda, 2019 Hurricane Season Starts in May. (Again.)

Subtropical Storm Andrea formed southwest of Bermuda on Monday. The appearance of a named storm in the Atlantic means this basin's hurricane season has started before June 1 for the seventh time in the last decade. Andrea will be weak and short-lived, posing no threat to land.


This storm forming while everyone is paying attention to the severe weather over the Plains is the atmospheric equivalent of a Friday night news dump. Most people will never know it existed, and the rest will forget about it soon enough. Subtropical Storm Andrea will probably dissipate by early Wednesday morning without affecting land. The storm's remnants could bring showers to Bermuda by the middle of the week, but that's about it as far as impacts are concerned.

A subtropical storm is a low-pressure system that shares both tropical and extratropical characteristics. It's tropical-like. It forms and acts like a tropical cyclone, and carries the same impacts as a tropical cyclone, but it's not fully warm throughout the system and it derives some of its energy from upper-level winds. A fully tropical cyclone would be warm from top to bottom and the thunderstorms near the center of the storm would completely drive its formation and maintenance.



We're almost to the point where you can wager money on a named storm forming before June 1 and wind up winning the bet. This is the seventh hurricane season since 2009, and the fifth season in a row, that we've seen at least one named storm form in the "pre-season."

I argued a few weeks ago that we should move the beginning of the Atlantic hurricane season up a few weeks into May. Not only would moving up the start of the season to, say, May 15, which would sync it up with eastern Pacific's season, but it would start the awareness campaigns a little earlier than they run right now. That'd be helpful for coastal residents, seeing as several of these "pre-season" storms, like Alberto in 2018, wound up making landfall in the United States.

The tropics should fall quiet again for a while after Andrea dissipates.

[Top Image: RAMMB/CIRA]



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Here's Why the Atmosphere Is Primed for a High-End Tornado Outbreak on the Plains



A rare high risk for severe weather is in effect Monday for a large chunk of Texas and Oklahoma, now including the Oklahoma City metro area, ahead of what could be a high-end severe weather event for the region. It's been a long time since conditions have been this ripe for severe weather on the southern Plains. Today's forecast—and stern warnings from meteorologists—are the weather equivalent to red lights flashing and alarm bells ringing. Here's a quick look at why the environment is so primed for dangerous thunderstorms today.

(See my post earlier today for a detailed look at today's threat and some safety advice.)



The high risk is in effect because of the high risk for potentially violent and long-track tornadoes—and that's the SPC's words, not mine. There's a 45% risk for tornadoes across parts of Texas and Oklahoma, which is an extreme probability when you consider your daily risk of seeing a tornado, even on the Plains, is down around 0%. The tornado threat isn't confined to the high risk. Just about everyone in Oklahoma, a large chunk of Texas, and parts of Arkansas, Missouri, and Kansas, are under an elevated threat for tornadoes today. For some perspective, we really start to get concerned when the probability for tornadoes ticks up to 10% or higher.

Here's why this is happening today.

Modeled upper-level winds at 3:00 PM CDT Monday. (NOAA/SPC)


A powerful jet stream—unusually powerful for this far south in late May—moving across the southern Rockies will set the stage for dangerous thunderstorms across the southern Plains on Monday. The trough generated a low-pressure system at the surface in northeastern New Mexico, which is allowing strong southerly winds to drag deeply unstable air north from the Gulf of Mexico.

Modeled surface Theta-E at 4:00 PM CDT Monday. (TwisterData)


The above image shows "Theta-E" at the surface this afternoon, according to the latest run of the GFS weather model. Theta-E is a great way to visualize an unstable air mass in this kind of severe weather setup because it combines temperature and moisture. The reds and purples over Texas and Oklahoma show warm temperature and high moisture, which act as the fuel that powers thunderstorms.

Severe thunderstorms will develop in a hurry today in that warm sector over Texas and Oklahoma. Storms will likely start firing along the dry line, which is the sharp gradient between high moisture and low moisture located over the Texas Panhandle, and grow eastward from there through the afternoon and evening hours.

A diagram of wind shear (left) and a diagram showing how a thunderstorm updraft tilts that rotation into the vertical, leading to a supercell thunderstorm (right). NOAA/NWS


Any thunderstorm that develops has the potential to turn into a tornadic supercell in this kind of environment. A supercell is a thunderstorm with a rotating updraft. The updraft begins rotating due to strong wind shear through the atmosphere. We've got strong southeasterly winds near the surface and strong southwesterly winds at the upper-levels of the atmosphere. The rapid increase in wind speed and sharp change in wind direction with height creates horizontal rotation in the atmosphere. The updraft in a developing thunderstorm can push that horizontal rotation into a vertical position, which causes the updraft (and the storm itself) to begin rotating.

Modeled Significant Tornado Parameter (STP) at 3:00 PM CDT Monday. NOAA/SPC


You can neatly summarize the threat by looking at composite indices, which take into account factors such as wind shear and instability to determine the threat for features like supercells and significant tornadoes. The above image is a model-generated image of the much-advertised "significant tornado parameter," which shows how favorable the environment is for significant (EF-2+) tornadoes. STP values around 1 or 2 are typically cause for concern, so when we're seeing models spit out a large field of values greater than 6 where we know dangerous thunderstorms will likely develop, the alarm bells start going off.

I mentioned in my last post that not every storm will reach its maximum potential, but there's a really, really good chance that some storms will:

It appears the environment will be capable of supporting a high-end severe weather outbreak. It's hard for big severe weather outbreaks to occur. Lots of things have to go right and it's easy for storms to morph into a sloppy mess on a day like this. Even if the storms on Monday don't reach maximum capacity—and many likely won't!—one storm breaking through to produce one bad tornado is still a big deal.

I keep flashing on the Lee County, AL, tornado from a couple of months ago. The storms that day were largely sloppy, but one supercell broke loose and put down an EF-4. It's cliche, sure, but it really does only take one. Please take the threat seriously and prepare even if it doesn't turn into a classic tornado outbreak.
Even the storms that don't produce significant tornadoes will be dangerous. This severe weather outbreak will occur in several rounds. Supercells will eventually grow and merge into large clusters and lines of thunderstorms, which could produce damaging rain and very heavy rain that leads to significant flash flooding.

Keep following updates from the Storm Prediction Center and your local National Weather Service office throughout the day.


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