September 30, 2024

Helene's Floods: When catastrophe comes to pass


Western North Carolina and eastern Tennessee are reeling this week from the onslaught of historic floods associated with Hurricane Helene.

Entire neighborhoods washed away in the immense flooding. Major highways are severed. Dozens, if not hundreds, of roads no longer exist. Public utilities like water, electricity, and phone services are hanging by a thread if they're connected at all. The death toll, which just climbed above 100 as of this post, will almost certainly rise higher as officials finally make their way into the hardest-hit communities. 

By all accounts, this is the new flood of record for western North Carolina. The previous benchmark event was the Great Flood of 1916, the result of two tropical storms that hit the region one after the other. 


Hurricane Helene's rains were also a one-two punch that overwhelmed the region with more water than it could handle. I wrote more about it for The Weather Network over the weekend.

A predecessor rain event (PRE) brought 8-10+ inches of rain in the days before Hurricane Helene ever made landfall. Saturated soils and swollen waterways were already a major problem by the time Helene's core reached the region, dropping the final push of torrential rains that turned a dangerous situation into pure chaos. 

It was a well-predicted fiasco. The words "catastrophic," "devastating," and "life-threatening" filled the forecasts for days before the floods.
The southern Blue Ridge remains under a high risk for excessive rainfall through Friday, which signals extreme confidence among meteorologists that major flash flooding will occur throughout the region. Flash flooding is possible across areas that may not typically flood. Landslides and road washouts are likely in vulnerable areas. 
It doesn't matter how accurate the forecasts were. Flash flood warnings were timely and plentiful. Meteorologists used phrases like "flash flood emergency" to convey the severity of the situation.

But it's impossible to adequately prepare for 30 inches of rain. You can do everything right—have a plan, buy insurance, monitor the forecasts, heed alerts—and still nothing can prepare you for the aftermath of nearly a year's worth of rain falling in a couple of days.

There are natural catastrophes, and then there are catastrophes made even worse by human failures. Last week's flooding raised comparisons to Hurricane Katrina, the flooding from which killed more than one thousand people. This is not Katrina because Katrina's aftermath was made far worse by a cascade of human failures. Human-made levees failed. The response was slow and botched to a shameful extent. Katrina was a natural catastrophe that coincided with a societal catastrophe.


The flooding that devastated dozens of communities throughout the southern Appalachians was a natural catastrophe through and through. No amount of planning or preparation can contain the runoff from a year's worth of rain falling in mere days. Streams turned to rivers, rivers turned to oceans, and the valleys bore the brunt of nature's impersonal destruction.

Anger is fresh in the wake of a calamitous storm. People want to blame something, someone, anyone, anything, for the havoc that befell a vast swath of our fellow Americans. There's lots of anger aimed at state and federal officials for the seemingly slow response to communities no longer connected to the outside world.

Some of that anger is righteous, but much of it is contrived by outsiders looking to score points off the dripping ruins of their neighbors in need.

Bridges washed out and ravines carved into the earth where roads once existed. How are supplies supposed to instantly hustle into towns now severed from society? Helicopters need somewhere safe to land and rubble-strewn communities are nestled on rugged terrain in tree-lined valleys. Air drops require coordination with people on the ground—people who can't easily drive to where their help is needed the most, and where communication links are tenuous at best.

It's going to be days and possibly weeks before the full scope of Helene's human toll is known to the outside world. Recovery will be measured in months and years. Some residents are almost certainly never going to return; some communities will never rebuild to the way they were before the rain started.

We can shout accurate forecasts from the rooftops. Adequate warnings can make phones sing like slot machines. But when catastrophe comes to pass—a true, generational catastrophe—there's little even our modern conveniences can do to stave off heartbreaking levels of devastation. 



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September 25, 2024

Hurricane Helene will bring extensive inland flash flooding, power outages


Hurricane Helene remains on track to bring widespread and significant flash flooding and wind damage to large swath of the southeastern United States over the next couple of days.

The storm is intensifying as expected as it enters the southern Gulf of Mexico. A sharp upper-level trough digging over the southern U.S. is picking up the storm and forcing it to turn north-northeast and accelerate toward the Florida Panhandle.
  • 100+ mph winds will hit the Florida Panhandle as Helene makes landfall, with long-lasting power outages and a life-threatening storm surge across the region
  • Damaging winds will push toward Atlanta, Greenville, and Charlotte, with a threat for widespread power outages
  • Extensive flooding rains will continue into Friday, especially through northern Georgia, upstate South Carolina, and western North Carolina
  • Tornadoes are possible in the storm's outer rainbands through Friday
Here's the latest on the storm and its predicted impacts.

Helene Strengthening


Helene is quickly strengthening as it encounters a very favorable environment around the storm. Sea surface temperatures in the southern Gulf of Mexico are on the order of 88-90°F. That upper-level trough is also helping to vent air up and away from the storm; this kind of efficient outflow can help storms thrive.

It can't be overstated that this is a large hurricane. Helene's minimum central pressure is 978 mb, which is very low for a hurricane of this strength. Storms can translate some of that energy into growing their size—exactly what Helene is doing now. 

As of 5:00 p.m. EDT on Wednesday, tropical storm force winds extended 345 miles from the center of the storm. This broad size will continue to grow and exacerbate the storm's impacts across the southeast as it pushes inland through the end of the week.

Landfall on Thursday Evening


Forecasters with the National Hurricane Center continue to expect Helene to strengthen into a major category four hurricane as it powers toward the Florida Panhandle over the next 24 hours, where the storm will likely make landfall on Thursday evening. A life-threatening storm surge of 15-20 feet is possible across Florida's Big Bend if the storm arrives at high tide—an exceptional potential that's due both to the storm's intensity and sheer size.


Sustained winds of 100+ mph will buffet a large swath of the Florida Panhandle as Helene's eyewall pushes ashore. These winds could bring significant structural, tree, and power line damage to the Tallahassee area. Communities affected by the eyewall could go a week or longer without electricity.

Major Inland Wind Impacts Expected

From there, the large storm will push into Georgia and the western Carolinas overnight Thursday and into the day Friday.


Helene's enormity and swift forward speed will prevent the storm from quickly weakening after it makes landfall. Sustained winds of 75+ mph are likely well into southern Georgia, where hurricane warnings are in effect.

The system will likely remain a potent tropical storm into the day Friday as it makes its way into northern Georgia. A tropical storm warning is in effect for the cities of Atlanta, Greenville, and Charlotte ahead of Helene's arrival.

Sustained winds of 40-60 mph, with higher gusts, could bring widespread tree damage and long-lasting power outages to northern Georgia—including the Atlanta metro area—as well as upstate South Carolina and western North Carolina.

Life-Threatening Flash Flooding Likely


We'll have to deal with prolific rains on top of the threat for widespread wind damage. Heavy rain will start Wednesday night, well in advance of the storm's arrival. Significant flash flooding is likely throughout Georgia, western South Carolina, and western North Carolina for the duration of this storm, where 7-10+ inches of rain could fall through Friday.

The southern Blue Ridge remains under a high risk for excessive rainfall through Friday, which signals extreme confidence among meteorologists that major flash flooding will occur throughout the region. Flash flooding is possible across areas that may not typically flood. Landslides and road washouts are likely in vulnerable areas. 

Tornado Threat


On top of all the other hazards, we have to remain alert for the risk for tornadoes on the eastern half of the storm. Strong wind shear in the eastern half of landfalling tropical cyclones can produce a risk for tornadoes. Tropical tornadoes can happen quickly with reduced tornado warning lead time. 

The greatest risk for tornadoes on Thursday will fall across northern Florida and eastern sections of Georgia and South Carolina. We'll see the threat for tornadoes focus on North Carolina and portions of South Carolina and Virginia heading into the day Friday.

NHC Updates

The National Hurricane Center releases full forecast packages—including updated cones and wind forecasts every six hours, at 11:00 a.m./p.m. and 5:00 a.m./p.m.

When there are watches and warnings in effect, the agency also releases intermediate updates every three hours in between. These advisories provide status updates on the storm's current location and conditions, as well as any changes to watches and warnings that are in effect.



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September 24, 2024

Helene's damaging winds, flooding rain will extend hundreds of miles inland


Hurricane warnings are now in place for parts of the Gulf Coast as Tropical Storm Helene steadily marches toward the region over the next couple of days. The system could reach major hurricane strength before slamming into the Florida coast on Thursday.

Helene's dangerous weather conditions will extend hundreds of miles inland from the point of landfall, exposing a vast swath of the southeastern U.S. to dangerous winds, flooding rains, and a risk for tornadoes.

Current Status & Predicted Path


The storm rapidly organized into Tropical Storm Helene during the day on Tuesday as it moved over the warm waters of the western Caribbean Sea. Forecasters expect the storm to thread the needle between the Yucatan Peninsula and the western tip of Cuba over the next day, coming very close to Cancun on Wednesday.

A sharp upper-level trough over the southern U.S. will pick up the storm and force it to turn on a north-northeasterly track toward Florida's Gulf Coast. 

Things will happen quickly once Helene enters the Gulf late Wednesday.


Extremely warm waters and favorable environmental conditions should allow the storm to rapidly intensify into a major hurricane by Thursday. The latest forecast from the National Hurricane Center brings Helene into the Florida Panhandle or the state's Big Bend region as a major hurricane on Thursday evening.

This is going to be a large hurricane with a sprawling footprint as it hits the southeastern U.S. Damaging winds, storm surge flooding, freshwater flooding from heavy rain, and a threat for tornadoes will extend hundreds of miles away from the center of the storm.

Flooding Rains


Widespread flooding rains will pose the greatest threat to the most people as Helene pushes inland. A wide swath of 5-10+ inches of rain will follow the storm from Florida into the Carolinas.

This much heavy rain falling in such a short period of time will lead to significant flash flooding across vulnerable areas, and we may see flooding in areas that typically don't experience it during heavy rainfall.

Flash flooding and landslides will be a particular concern across the southern Blue Ridge as orographic lift—winds flowing up the sides of the mountains—will enhance rainfall totals across the western Carolinas and northern Georgia. Some areas may see double-digit rainfall totals by this weekend.

Please remember and spread the word: it's never safe to drive across a flooded roadway. It's impossible to tell how deep the water is until it's too late, and the road may be washed out beneath the floodwaters. It only takes a few inches of moving water to lift up a vehicle and carry it downstream.

Damaging Winds & Storm Surge Flooding

While rain will be the biggest threat from this storm, we can't ignore the looming impact of damaging winds as this soon-to-be-hurricane approaches land.


Communities near the point of landfall could see destructive sustained winds in excess of 115 mph, which will cause structural damage in addition to a massive blowdown of trees and power lines. Power outages near the point of landfall could last for weeks.

Helene's winds won't stop at the coast. Sustained winds of 70+ mph will follow the core of the storm as it pushes across the Florida Panhandle and into southern Georgia. Major tree damage and downed power lines are likely throughout cities like Tallahassee, Valdosta, Albany, and possibly even up toward Macon.

Based on the storm's current projected path, wind gusts of 40-60+ mph are possible into northern Georgia, including metro Atlanta, as well as into the western Carolinas, which may include Greenville, Spartanburg, and the Charlotte metro area. This will lead to downed trees and power outages throughout the region.

SOURCE: NHC

Helene's intense winds will push a destructive, life-threatening storm surge into the coast. Storm surge flooding could rise 10-15 feet above ground level near the point of landfall if the surge coincides with high tide. We can only hope that the worst surge inundates unpopulated areas of the swampy Florida coast.

The storm's growing size will make a storm surge of 5-8 feet possible across Florida's west coast, including the Tampa Bay area. This much storm surge flooding will easily inundate neighborhoods near the coast. Please heed all evacuation orders issued by local officials.

Tornado Risk


Tornadoes are an ever-present hazard when a tropical system rolls ashore. Strong wind shear within the storm can cause spin-up tornadoes to occur within the storm's outer rain bands. These tornadoes can happen very quickly with reduced tornado warning lead times. 

Tornadoes are most likely on the eastern side of a landfalling storm, which places the greatest risk for tornadoes across large portions of Florida and Georgia, as well as eastern sections of the Carolinas.

Make sure you've got emergency alerts activated on your phone so you can get warnings the moment they're issued for your location. These free push alerts are a proven lifesaver in the critical moments ahead of a tornado—especially when your reaction time is reduced.

NHC Updates

The National Hurricane Center releases full forecast packages—including updated cones and wind forecasts every six hours, at 11:00 a.m./p.m. and 5:00 a.m./p.m.

When there are watches and warnings in effect, the agency also releases intermediate updates every three hours in between. These advisories provide status updates on the storm's current location and conditions, as well as any changes to watches and warnings that are in effect.



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September 23, 2024

Prepare now: A hurricane is likely in the Gulf of Mexico this week


A disturbance in the western Caribbean has a very high likelihood of rapidly intensifying into a hurricane over the next couple of days as it closes in on the Gulf Coast. 

This isn't the kind of storm we get to watch for a week and a half before anyone has to take action. This is going to be a very fast developing storm, and we could be less than 72 hours away from dangerous winds and flooding rains beginning to sweep over the southeastern United States. 

A Budding Hurricane Is Likely

The National Hurricane Center began issuing forecasts on soon-to-be-Helene on Monday afternoon. The agency's opening bid calls for the storm to rapidly intensify into a hurricane as it enters the Gulf of Mexico over the next 36 hours. The storm could approach major hurricane intensity by the time it makes landfall during the day on Thursday.

A complex pattern of upper-level winds over the United States will affect future-Helene's path over the next few days. The storm will start to curve northeast once it enters the Gulf of Mexico, likely taking it on a path toward the Florida Panhandle or the state's Big Bend region.


It's worth noting that everyone from Tampa to Pensacola is currently in the cone of uncertainty, which is the historical margin of error in the NHC's track forecasts.

There are several key factors that meteorologists are still struggling with right now. The biggest is that the storm hasn't actually developed yet. This disturbance is still a disorganized cluster of thunderstorms over the Caribbean. Forecasters and weather models both will have a clearer idea of the storm's future once it actually develops.

Here are a few potential scenarios we could see over the next few days.

Potential #1: Worst-Case Scenario

The worst-case scenario is that future-Helene will rapidly intensify as it approaches land, strengthening into a major hurricane before it makes landfall on Thursday.


Sea surface temperatures across the Gulf of Mexico are extremely warm, running several degrees above average for the end of September. Warm waters are like rocket fuel to a budding storm.

These warm waters and a favorable environment around the storm could allow future-Helene to rapidly intensify up through landfall on Thursday.

Potential #2: A Dangerous But Weaker Storm

A second realistic scenario is that future-Helene will struggle to get its act together. Any delay in the storm's ability to organize would be good news for coastal residents. A delayed hurricane means it's likely that a slightly weaker storm would make landfall.

We'd still see damaging winds and storm surge flooding at the coast, as well as prolific heavy rains far inland, but it wouldn't be the high-end system those steamy ocean waters are capable of supporting.

Potential #3: Best-Case Scenario

The best-case scenario is actually two different potential hiccups in the storm's future.

Some otherwise-promising disturbances never manage to get their act together. It's not out of the question that this disturbance will struggle for its entire life, reaching shore as a relatively weak and disheveled system that's more of a flood threat than a multi-faceted disaster.


A second point of failure may be Hurricane John over in the eastern Pacific Ocean. That storm is close enough to the western coast of Mexico that it could throw off upper-level wind shear that travels east over the Caribbean and southern Gulf of Mexico.

Wind shear disrupts the updrafts in thunderstorms trying to form around the center of a system. If the Pacific hurricane throws off enough wind shear—which isn't out of the question—it could be an unexpected wild card in future-Helene's ultimate development.

Prepare For Significant Impacts—Even Far Inland

Folks who live along the northern and eastern Gulf Coast should prepare for this storm's arrival no matter what happens over the next couple of days. 


Widespread flash flooding from heavy rain is likely for hundreds of miles inland across the southeastern United States after the system makes landfall later this week. Rainfall totals of 3-5+ inches are expected all the way into portions of the Midwest. Extensive heavy rain could lead to major flooding issues throughout the southern Blue Ridge region.

If the storm intensifies as expected, widespread and long-lasting power outages could follow the center of the storm inland and affect communities throughout northern Florida, eastern Alabama, and much of southern and central Georgia. Make sure you're prepared for power outages even if you're hundreds of miles away from the coast.

Tornadoes are always a concern with landfalling storms. Communities on the eastern side of the storm will be most vulnerable to spin-up tornadoes, including across Florida, Georgia, and possibly into portions of Tennessee and the Carolinas. 


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How to get accurate weather information in the era of internet junk


A hurricane is likely going to develop and rapidly intensify before making landfall on the Gulf Coast this week. Meteorologists are in a rush against time to warn folks in harm's way of the brewing storm to their south. 

This is one of the hair-raising scenarios that experts have long feared—not the beast we can watch swirl over the ocean for two weeks, but the sneaky storm that blows up so fast that people hardly have time to blink before it's threatening our shores.

How do you keep up with all the posts and articles competing for your attention? Here are a few helpful hints to sift out the useful from the harmful.

Follow People Worthy Of Your Trust

The internet is full of junk. It's been full of junk forever, but the amount of factoid flotsam now bobbing aimlessly through cyberspace has long surpassed the point of manageability.

Content creators on social media have to compete against The Algorithm in order to boost views and engagement. It's tough to make it on Facebook, Twitter, Threads, Instagram, or YouTube by being thoughtful.

Hyperbole rules the roost alongside the rush to be first. The scariest weather models shared with fifty-cent adjectives are the key to success. It's also the key to confusing the heck out of average people. 

Uncertainty Isn't Ignorance

Forecasts are great, but look for someone who's also willing to tell you what they don't know.

There are plenty of thoughtful meteorologists, experts, and enthusiasts out there who are more interested in you than they are in themselves. It's just a matter of finding the right people and places. Articles and posts sent out by the big news outlets are solid resources during a storm. (Full disclosure: I'm also a digital writer for The Weather Network.)

Smaller blogs (hi!) are also a fantastic resource if you follow the right ones. The Eyewall is an amazing outlet for tropical news with a level head. Folks like Kim WoodTomer Burg, Eric Webb, and Philip Klotzbach are experts in their field and excellent follows on social media when bad weather is brewing. 

Please Use Forecasts Over Weather Models

Seeking weather information from a weather model is like using WebMD to diagnose your own maladies—everything turns out to be fatal if you don't know what you're doing.

Computer models guide forecasters to create their forecasts. Every weather model has its own flaws and biases. No model is ever 100% correct. It takes knowledge and experience to blend model guidance together in order to create a forecast. 

Hurricane season is second only to nor'easter season for weather model imagery making the rounds on social media. Meteorologists themselves are pretty guilty of posting model guidance these days (please use more care, y'all!), but pages like Local Weather Doppler Expert Force 3000 tend to go mega-viral when they post the most outlandish model to get people whipped up.

The National Hurricane Center issues forecasts every six hours with intermediate updates every three hours when there are watches or warnings in effect. Please seek out their official forecasts, as well as guidance from local meteorologists and emergency management officials, when you're looking for critical information to protect life and property. 

If nothing else, please remember that good and accurate information is out there. Whether it's weather or politics or any of the other pressing issues we deal with, it's on each of us to search out trustworthy sources and ignore the junk. Meteorologists can only do so much to help us keep ourselves safe.


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September 10, 2024

We're at the peak of Atlantic hurricane season. What's next?


September 10 is the climatological peak of hurricane season in the Atlantic Ocean. This is the day with the greatest odds of having at least one named storm somewhere in the Atlantic basin—and, true to form, we've got a hurricane brewing in the Gulf of Mexico.

It's clear that this year isn't going to live up to expectations of a hyperactive hurricane season. But that doesn't mean we should let our guard down. Here's what we could expect from the second half of hurricane season ahead.

All signs pointed toward a bustling basin


The field's leading experts almost unanimously called for an extremely active hurricane season this year.

An average Atlantic hurricane season would see 14 named storms, seven of which would strengthen into hurricanes, and three of those turning into major hurricanes. NOAA called for 17-25 named storms this season, while the good folks over at Colorado State University expected about 23 named storms this year. 


Why so bullish? Everything seemed to be aligning just right. We're in between El Niño and La Niña right now. An active monsoon season across sub-Saharan Africa should've led to more disturbances that could seed the development of tropical systems.

On top of all that, sea surface temperatures across the Atlantic have been near historic highs for over a year now. Those sultry ocean waters helped power an above-normal hurricane season last year despite the odds against it

Things haven't panned out as expected

The atmosphere is complicated. Meteorology, for all its incredible advances over the years, is still an inexact science. There's plenty that even the leading minds in the field are still working to understand about the intricate links between every aspect of our skies above.


Despite all the ingredients seemingly coming together for a blockbuster hurricane season, it's been...well, not that. Hurricane Beryl showed us what those hot sea surface temperatures are capable of when it roared into a category five storm in early July. Since then, though, we've only seen a smattering of named storms.

Francine, which is gathering strength in the Gulf as of this post, is only the season's sixth named storm. If projections remained on track, we should've seen twice as many storms form by the peak of the season.

Lots of factors contributed to this unexpected lull in hurricane activity. I wrote a bit about it for The Weather Network a couple of weeks ago:
[...] You can’t bake a sweet cake with just flour. Water temperatures are just one part of the equation that plays into the formation of a vigorous tropical cyclone. This precise mix of ingredients includes moist air, calm wind shear, and vigorous thunderstorms that serve as the seed from which a hurricane grows.
Those ingredients have been a little bit out of step this season. Monsoon rains in sub-Saharan Africa have been travelling farther north than usual—bringing rare rains to the desert while missing key windows to seed tropical disturbances over the Atlantic. We've also seen intrusions of dry, dusty air puffing off the desert itself, as well as a general lack of instability over the tropical Atlantic.

The dangers of a "quiet" season

If you follow any meteorologists on social media, you've probably seen a lot of this introspective chatter over the past week. But Francine highlights the danger of banging away at this being a supposedly quiet season: it only takes one storm to make a mess.

An example I frequently use is the 1992 hurricane season. That was a below-normal hurricane season that didn't produce its first named storm until the end of August. That storm was Hurricane Andrew. That's not to say we're going to see anything close to a repeat. But this season has already proven what it's capable of in Hurricane Beryl's rapid intensification over the Caribbean.


Storms toward the latter half of hurricane season tend to form closer to land, reducing the amount of time residents have to react and prepare for a storm's arrival. Look at Francine in the Gulf—if anyone in Louisiana tuned out the weather over the weekend, they were probably shocked by the hurricane warning that hit their phone last night.

Folks throughout the southern and eastern United States need to remain prepared for dangerous storms well into November. Even though this season isn't going as expected, we've got a long way to go before the basin shuts down for the winter. September and October have a long history of nasty storms swirling ashore. 

Make plans to deal with dangerous weather, including potential evacuations, flooding from heavy rainfall, and even tornadoes as storms push inland. Make sure you've got an emergency kit ready for power outages that could last days—even far inland from where a storm might make landfall.

[Satellite image of Beryl courtesy of RAMMB/CIRA]


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September 9, 2024

Francine expected to hit the northern Gulf Coast as a hurricane Wednesday


A dangerous storm developing in the southwestern Gulf of Mexico will make landfall as a hurricane Wednesday along the Louisiana coast.

Tropical Storm Francine spent Monday rapidly getting its act together off the eastern shores of Mexico.

The latest advisory from the National Hurricane Center (NHC) says that Francine has maximum sustained winds of 65 mph. The storm even appears to be developing an eye based on satellite and radar imagery, which is a sign the storm could soon close in on hurricane intensity.


Sea surface temperatures are a few degrees warmer than normal across the western Gulf, partially a result of having next to no storm activity over the region so far this year. (Tropical systems churn up cooler waters from below, even if briefly.)

Given the warm ocean temperatures and favorable environmental conditions around the storm, forecasters expect Francine to strengthen into a hurricane before making landfall on the central Louisiana coast during the day Wednesday.

Wind and Storm Surge

The NHC expects Francine to be near peak strength by the time it makes landfall in Louisiana on Wednesday. 


Widespread tree damage and long-lasting power outages are possible where Francine's eyewall makes landfall. Hopefully the worst winds remain over the relatively unpopulated bayous, but Lafayette—home to more than 100,000 people—could find itself in or close to the eyewall based on the current projected track.

Damaging winds are possible as far east as New Orleans and as far west as Beaumont, Texas. The outer edges of the storm could bring winds high enough to cause some downed trees and sporadic power outages.

A life-threatening storm surge is likely along the coast where Francine makes landfall. The latest advisory calls for a storm surge of 5-10 feet where the eye crosses the coastline if landfall coincides with high tide. This is some of the most surge-vulnerable land in the United States. Storm surge flooding can extend many miles inland across southern Louisiana's flat, marshy terrain. 

Any eastward jog in the storm could bring more dangerous wind and storm surge closer to New Orleans.

Heavy Rainfall

Tropical downpours are a certainty along Francine's track inland. The majority of deaths associated with landfalling tropical storms are the result of flash flooding from heavy rainfall. 


The Weather Prediction Center calls for 5-7+ inches of rain along Francine's track inland, which will pretty closely follow the Mississippi River north of Baton Rouge. Several inches of rain could fall as far west as Little Rock and as far east as Birmingham through the end of the week.

It's also worth noting that little bullseye over upstate South Carolina and adjacent areas. Southerly winds and enhanced moisture associated with Francine flowing up the foothills could produce 3-5 inches of rain over the region, leading to a localized flash flood threat. 

Almost all flash flood injuries and deaths are preventable. Never drive across a flooded roadway. It's impossible to tell how deep the water is until you're in it, and the road itself could be washed out beneath the water. It's not worth the risk to your life or those who have to rescue you or recover your body.


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September 3, 2024

Hot and humid nights drove another summer of record heat across the U.S.


This was one of the hottest summers—if not the hottest summer—ever recorded for large portions of the United States, another data point on the undeniable trend toward warmer days and even warmer nights as our climate steadily changes.

Meteorological summer began on June 1 and ended on August 31. This clean division of months more closely tracks temperatures than dividing the year up based on astronomical solstices and equinoxes.

The overall pattern we saw this summer featured persistent ridges of high pressure over the western and eastern ends of the U.S., with troughing in the center of the country.

Ridges foster sinking air, which warms up as it compresses on descent toward the ground. Troughs force air to rise, leading to unsettled weather and generally below-seasonal temperatures.

Source: IEM

We can see this divide in a map showing how much average daily temperatures departed from normal. A day's average temperature is the daytime high and nighttime low averaged together. Troughing in the center of the country led to somewhat seasonable temperatures, while folks west of the Rockies and east of the Appalachians dealt with warmer-than-normal conditions.

What really stands out is the desert southwest.


Folks in Phoenix, Arizona, just lived through their hottest summer on record. The daily average temperature there was a whopping 98.9°F this summer, which beat the previous record (set last year!) by nearly two degrees.

This summer's daytime highs in Phoenix were absolutely blazing hot—as of this post, the city is in the midst of a 100-day streak of daytime highs at 100°F or hotter, exceeding the previous record 100-degree streak by nearly three weeks.

Source: IEM

But it was the nighttime lows that really stood out.

Every single day this summer saw a warmer-than-normal low temperature, with those departures often coming in 10 or more degrees above normal. That's no small thing when midsummer nights don't cool off much in the desert. The city's low temperature in July only dipped below 88°F five times, and it remained 90°F or warmer at night 19 days throughout the month.


While not as unbelievably hot, the story of nighttime lows driving near-record summertime temperatures is constant up and down the East Coast.

Take a look at interior New England, where Caribou, Maine, just saw its warmest summer since records began there back in 1939. Repeated intrusions of muggy air in late June, mid-July, and in early August made low temperatures above 65°F a common sight in this small community near the Canadian border. For reference, Caribou's average low on July 16—summer's midpoint—is about 57°F.

This summer's noteworthy heat and humidity follows the pattern you'd expect to see as the climate changes.

Source: Climate Central

As I wrote back in July: "Climate change sets a new baseline for extreme heat throughout the United States and around the world. As the entire frame of reference moves toward a hotter climate, warm temperature extremes are far more likely that cold temperature extremes. Excessive heat will come in hotter than what we grew used to just one or two generations ago."

A warmer atmosphere can also hold more moisture. This increase in humidity makes it harder for nights to cool off as much as they used to, which is a significant factor driving warmer-than-normal summer low temperatures.


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