Forecast for Helene continues to escalate in a bad way for Florida’s Big Bend region and for inland locations (UPDATED: 11 PM ET Wed)

(11 PM ET update): The 11 PM ET advisory is out with few changes. No forecast changes have been made, and no intensity changes have been made.

Helene is still mixing out some dry air, and it’s large size is slowing the intensification process somewhat. We should see the system better organize overnight and on Thursday morning. (Tropical Tidbits)

Helene is still organizing, and it seems that the size of Helene is acting to keep that intensification steady for now. As the system hits the ultra warm water in the Gulf and a more favorable environment internally, it will likely strengthen at a steady, faster pace tomorrow before making landfall tomorrow night.

There have been no notable changes to the surge or rainfall forecasts unfortunately. We’ll have an update in the morning.

Previous post follows…

Changes since this morning

  • Storm surge forecasts have been increased on the Florida coast with a surge as high as 20 feet expected between Carrabelle and the Suwannee River.
  • Helene is expected to be a category 4 storm at landfall.
  • The high risk of flooding has been expanded tomorrow in both the Carolinas and in Georgia/Florida.
  • Tropical Storm Warnings are now posted for the rest of Georgia, all of South Carolina, and portions of western North Carolina and Tennessee.
  • Helene is likely to be the modern storm of record for Florida’s Big Bend Region and possibly some other areas.

This blog is committed to no-hype because of storms like Helene. This one merits your full attention and full preparedness if you are anywhere in the area that will be affected by the storm. This includes all of Florida except the far western Panhandle, all of Georgia, eastern Alabama, almost all of South Carolina, western North Carolina, and Tennessee. We cannot stress this enough. Follow the advice of local officials. This is almost certainly going to be a major storm, and most of the data suggests that this will be a catastrophic storm in several places.

There’s no way we can cover all the elements of this storm, but we’ll try.

Storm surge

The storm surge forecast is, frankly, hideous. The forecast surge values, should they verify, will be worse than any modern storm has brought to the area between Tampa Bay and Apalachee Bay.

An absolutely catastrophic surge event is forecast for the areas north of Pasco County, FL. A historic surge event is likely south of there into Tampa Bay with substantial surge also in southwest Florida. (NOAA NHC)

The surge will be worse than Idalia all across the Big Bend Region, Apalachee Bay, the Nature Coast, and Tampa Bay. It will probably be the new benchmark for modern storms in this region. The surge will drop off dramatically to the west of where the center comes ashore, so folks in Panama City and Mexico Beach will only see a minor surge from this, with a huge escalation near and to the east of where the eye comes ashore. If these forecasts verify, this will be unsurvivable type surge in the region east of Carrabelle through about Cedar Key. I cannot stress enough how serious the storm surge from Helene may be.

Wind

Obviously with a cat 4 hurricane expected, there will be catastrophic wind at the immediate coast. But with Helene’s acceleration north, the wind will spread far inland.

Tropical storm force winds will extend into the Carolinas. Hurricane force winds will extend deep into Georgia. Catastrophic hurricane winds may get as far north as Tallahassee or Valdosta depending on the exact track. (NOAA/Google Earth)

We expect hurricane force winds to get deep into Georgia. The exact track will be critical in determining if Tallahassee sees catastrophic damaging winds or something more manageable. It will be close. It will probably be less close in Valdosta, GA which could see gusts in excess of 100 mph. Those winds will slowly decelerate deeper into Georgia, but hurricane force winds could get as far north as Macon. Strong tropical storm winds will impact metro Atlanta, especially on the south side and perhaps creeping close to Athens. Tropical storm force winds will be an issue deep into South Carolina and western North Carolina, as well as eastern Tennessee. There will be widespread wind damage and widespread, likely significant power disruption. This is a very bad looking storm.

Rain & flooding

We continue to see a high risk of excessive rain leading to flash flooding, possibly catastrophic flash flooding in two areas tomorrow. First is where Helene comes ashore in Florida, which will see substantial rain — what you would expect from a landfalling category 4 storm.

Thursday’s excessive rainfall outlook for south Georgia and the Florida Panhandle. (NOAA WPC)

The storm will dump heavy rain and produce widespread flash flooding across Georgia, eastern Alabama and portions of South Carolina as well. But when the storm interacts with the Appalachians, that’s when severe flooding issues could creep up. The high risk was expanded south into metro Atlanta, especially north and east of the city. And it continues through Asheville, NC, including much of Upstate South Carolina north and west of Greenville-Spartanburg. Portions of the Smokeys will also be impacted.

High risk of flash flooding between about Gwinnett County, GA and Smokeys and southern Blue Ridge on Thursday (NOAA WPC)

The interaction of terrain with a hurricane can produce copious amounts of rain leading to destructive flooding and landslides, and that’s the concern in Appalachia. Again, I cannot stress enough how serious an event this may be in those areas. It’s a much different hazard than storm surge but extremely dangerous just the same.

Tornadoes

Isolated tornadoes are likely anywhere east of Helene’s center, so be aware of that risk in the Florida Peninsula, the Jacksonville area, and much of eastern Georgia and the Carolinas.

Again, we strongly encourage you to follow local officials, follow local media, and do everything possible to get out of harm’s way. This is not a storm you want to roll the dice on. We’ll update this post later this evening with any relevant new info. Look for a full post again in the morning.

Helene likely to become a hurricane today, delivering complex, damaging impacts for Florida and much of the Southeast (UPDATED: 2:25 PM ET)

(2:25 PM ET Update): The storm surge forecast has been increased to 12 to 18 feet in the Big Bend, now well above the levels set during Idalia last year. This has potential to be the benchmark event for this region historically.

Storm surge forecast for Florida has increased. (NOAA NHC)

(1:20 ET Update): Hurricane Helene is here, as it has strengthened enough to cross the threshold to hurricane intensity. Winds are 80 mph, and strengthening into a borderline Category 3 or 4 hurricane is expected up to landfall tomorrow night.

Hurricane Helene avoided landfall on the Yucatan and is now set to traverse very, very warm water up to landfall. Helene is a sprawling, large storm. (Weathernerds.org)

Helene will rapidly intensify into a major hurricane tonight or tomorrow. SHIPS model guidance shows a 10 times greater than normal chance of Helene adding 50 mph to its intensity over the next 36 hours, which would place the storm on the cusp of category 4 intensity.

Whatever it becomes at this point may matter little, as the impacts now seem set: Catastrophic storm surge, worse than Idalia for the Big Bend and Nature Coast, severe storm surge in Tampa Bay, significant wind damage from the Big Bend and Panhandle deep into Georgia, and potentially catastrophic flooding in North Georgia and the Carolinas. Among other impacts. For the U.S., Helene appears to be the most significant threat of the 2024 hurricane season.

The surge forecast has changed little from this morning, though the 10 to 15 foot values were nudged a bit west to Carrabelle, FL. Again, this is likely to be much worse than Idalia and over a larger area.

The landfall forecast continues to hold steady. Expected landfall is in or very near Apalachee Bay.

Inland tropical storm watches and warnings have been expanded today and now cover parts of Alabama, all of Georgia, much of South Carolina, and western North Carolina.

Watches and warnings cover a huge swath of the Southeast from the coast to hundreds of miles inland. (Pivotal Weather)

We continue to watch the rainfall outlook very closely. Unfortunately, many areas will be drenched today by a predecessor rain event (PRE) that will exacerbate flooding as Helene itself comes inland tomorrow night. As much as 2 to 5 inches of rain are expected today and tonight across Georgia and into North Carolina.

Heavy rain will fall today from west-central Georgia into western North Carolina, with a high risk of flash flooding. Flooding will worsen tomorrow and tomorrow night as Helene approaches and winds kick up. (Pivotal Weather)

With more rain tomorrow and the storm itself not arriving until tomorrow night and Friday, conditions will steadily deteriorate into Friday in those areas, and the severity of flash flooding will worsen. This will be a prolonged, extremely serious flooding event for North Georgia, Upstate South Carolina, and western North Carolina. Landslides, at least moderate river flooding, and possibly major river flooding is a safe bet in those areas. Current forecasts indicate perhaps as much as 20 inches of rain in some southeast facing mountains in western North Carolina.

We will update again later today.

What’s changed since yesterday

  • Helene’s forecast intensity as it approaches Florida has been increased a bit, with risk for further increase in the intensity forecast today. Folks between Port St. Joe and Cedar Key should be preparing for major hurricane impacts.
  • Hurricane Warnings extend into Georgia, a good bit beyond Valdosta. Tropical Storm Warnings now cover virtually the entire Florida Peninsula. Tropical Storm Watches extend into central Georgia and much of southeastern South Carolina.
  • Helene’s track and surge forecast is relatively unchanged.
  • The interior rainfall forecast has escalated, and there is growing risk of a potentially damaging, catastrophic flash flooding event from northeast Georgia into western North Carolina, including Asheville.
Helene’s forecast to come ashore near Apalachee Bay as a major hurricane. (NOAA NHC)

Not a whole lot has changed since yesterday. It’s nice to have a consistent forecast, but this is certainly turning into quite a serious situation for the eastern Florida Panhandle and Big Bend. Again, the minimum you should expect right now is an Idalia-type impact. For many, if not most places between Apalachee Bay and Tampa, this will probably be a worse impact than Idalia. Current surge forecasts continue to suggest impacts at or above Idalia. This surge forecast is virtually unchanged from 12 hours ago.

Potential max storm surge forecasts are as bad or worse than Idalia and unchanged since yesterday. (NOAA NHC)

There’s honestly not a whole lot that needs to be said here with respect to the Florida coast between Cedar Key and Apalachee Bay: This has a decent chance to be worse than Idalia was and you should be closely following the advice of local officials.

The track forecast isn’t entirely locked down, but it’s close to it right now. There are still a handful of model data points suggesting a track slightly farther east than currently shown by the majority of tropical models and the official NHC forecast. This won’t hit Tampa directly, but a track closer to Cedar Key or Steinhatchee is possible, a Nature Coast/Big Bend hit more than an Apalachee Bay hit. This is why we encourage everyone from Port St. Joe to Homosassa or Clearwater to prepare for a significant hurricane hit, be it via surge, wind, or both.

Hurricane force winds are expected to extend deep into Georgia, perhaps north of Tifton and near Albany. Tropical storm force winds will extend possibly into Metro Atlanta and much of South Carolina. (NOAA NWS)

It’s also important to note how deep into Georgia hurricane-force winds are expected to go. That takes them close to Albany, GA and about halfway to Macon. Tropical storm force winds are expected to extend north of Macon to metro Atlanta and into South Carolina. This will almost certainly cause widespread power outages, and folks should be prepared to be without power for at least a few days.

Here is a list of major cities and their maximum wind gust forecasts from the NWS Point and Click forecasts as of Wednesday morning. These are likely to change:

(Editor’s Note: We will update these later today with slightly better data than point & click forecasts)

Florida
Tallahassee: 63 mph
Cedar Key: 80 mph
Apalachicola: 77 mph
Panama City: 54 mph
Clearwater: 60 mph
Tampa: 59 mph
Sarasota: 72 mph
Fort Myers: 57 mph
Naples: 56 mph
Orlando: 49 mph
Jacksonville: 63 mph
Gainesville: 56 mph
Key West: 44 mph

Elsewhere
Valdosta: 57 mph
Albany, GA: 68 mph
Macon: 92 mph
Atlanta: 56 mph
Savannah: 39 mph
Athens: 75 mph
Augusta: 46 mph
Charleston: 37 mph
Columbia: 41 mph
Greenville: 48 mph
Spartanburg: 43 mph
Charlotte: 41 mph
Asheville: 51 mph

A major, potentially catastrophic flooding event possible in the Appalachians

I want to focus on one element of this storm that is now coming into focus and becoming very serious: The risk of significant, possibly catastrophic flash flooding in the Appalachians from north Georgia into North Carolina.

Widespread flash flooding is expected in north Florida and Georgia, but a major, potentially catastrophic flood event is becoming more plausible from northeast Georgia into the western North Carolina mountains, where over a foot of rain is now possible. (NOAA WPC)

A high risk of flooding has been issued for some of those areas by the Weather Prediction Center, which historically has correlated to extensive, significant damage.

A high risk (level 4/4) of flash flooding exists tomorrow north of Metro Atlanta into much of western North Carolina and portions of upstate South Carolina. (NOAA WPC)

This is a historically favorable setup for major rainfall in this region, and there’s no reason to believe this forecast is incorrect. So for anyone in those affected areas and even in the red moderate risk areas surrounding the high risk, it is important to be prepared to take immediate action in the case of flooding or landslides. Please heed the advice of local officials. It is possible that the damage and problems from the inland flooding will be equally as bad as the surge issues at the coast.

Helene is going to be a complex, very difficult storm with multiple different concerns along the way. We’ll keep you posted as best we can through the event, but please also stick with trusted local sources for the latest and most relevant information for your neighborhood. We’ll update this post through the day.

Tropical Storm Helene is beginning to steadily organize in the northwest Caribbean with little forecast change

Changes since this morning

  • PTC 9 became Tropical Storm Helene and its satellite presentation has improved markedly since earlier today.
  • Hurricane Warnings have been issued between Anclote River just north of Clearwater and Mexico Beach in Florida.
  • Storm Surge Warnings have been issued from Flamingo to Indian Pass in Florida, including Tampa Bay and Charlotte Harbor.
  • Tropical Storm Warnings have been issued for the Lower & Middle Florida Keys and the west coast of Florida between Flamingo and the Anclote River, which includes Tampa Bay.
  • Tropical Storm Watches are now posted on the East Coast of Florida and Georgia between the Palm Beach and Martin County line and Savannah River.
(NOAA NHC)

Tropical Storm Helene is slowly getting organized now, as it appears that the wind shear impacting it earlier has leveled off, and it’s feeling the heat of the warm water underneath it. Expect a steady, if not rapid strengthening process to start unfolding soon. SHIPS model guidance indicates rapid intensification risk that is about 8 times climatology over the next 48 hours, not the biggest number we’ve seen in recent years but a very healthy signal that says Helene is going to take off eventually.

Helene’s satellite presentation has improved pretty dramatically today.

The evolution of Helene today from nascent tropical cyclone to organized tropical storm. (College of DuPage)

It now “looks the part” much more than it did earlier. One thing to note is the size of Helene. This is a pretty sprawling storm already, and as it comes north, it will continue to maintain that size, with tropical storm and hurricane force winds extending out farther than we’ve seen with recent Big Bend storms in Florida. According to the NHC’s latest discussion, this storm will be in the 90th percentile of major hurricane size at this latitude. In other words, it’s big, and the winds from Helene will be felt, especially on the east side far away from the center and outside the cone.

An aggressive storm surge forecast continues given the expectation of Helene’s strength and size. (NOAA NHC)

The forecast has changed little since this morning. We still anticipate a major hurricane making landfall in or near the area between the Big Bend and Apalachee Bay in Florida. The size of the storm will complicate the surge potential somewhat on the west coast of Florida, leading to surge values that should be as bad or worse than were experienced in Idalia. We covered that a bit more earlier today.

18z tropical models showing a clustering of weaker outcomes that seem difficult to trust and a clustering of Cat 1 to Cat 3 intensity outcomes. Folks in Florida should be preparing for the higher end to be safe. (Tropical Tidbits)

The intensity forecasts on tropical modeling for Helene have stalled somewhat today, certainly not a bad thing! However, I would be hesitant to read into that too much, as we’ve seen many examples of storms “overachieving” in this part of the Gulf. The biggest question that I have at this point is how close to peak intensity Helene will be when it comes ashore. There is a noteworthy difference between a 115 mph storm making landfall on an upswing versus one that has peaked and is weakening. Idalia was bad enough last year, but it was also past peak and likely less bad than it could have been. Can we pull that off twice? I don’t know, but I know to never trust the Gulf.

More to come tomorrow, and we can hopefully iron out some forecast details farther inland into Georgia and the Carolinas as well.

Helene continues to get itself in order as we focus on the risks to Florida and beyond (UPDATED: 11:40 AM CT)

(11:40 AM CT Update): PTC 9 has been upgraded to Tropical Storm Helene. No big changes have been made to the forecast. According to the National Hurricane Center, there is still a bit of uncertainty on the exact center location, and this means that despite the great model agreement, there is still a bit of uncertainty in the track forecast. Aside from that, everything else appears on track.

The Lower Keys were added to the Tropical Storm Warning with this advisory. Previous post follows.

Headlines

  • PTC 9 continues to fight off a little shear which is slowing its initial organization.
  • As that relaxes, rapid intensification and organization should ensue, with PTC 9 expected to become Major Hurricane Helene by Thursday.
  • Landfall is a little later on Thursday now, likely somewhere between Panama City and Tampa with a focus on Apalachicola through Cedar Key. There is still some uncertainty on this.
  • Storm surge from the Big Bend and Nature Coast through Tampa Bay is expected to be as bad or worse than what occurred during Hurricane Idalia in 2023.
  • Impacts from wind and rain will extend far beyond the landfall point with Georgia and the Carolinas likely to see strong winds and flash flooding.

PTC 9 this morning

PTC 9 continues to lack the ingredients necessary to be a depression just yet, but we continue to edge closer to that point.

PTC 9 continues to slowly organize in the northwest Caribbean. (Weathernerds.org)

What’s holding it back so far? There’s a bit of wind shear mixed in with all this from an upper low over the Yucatan. Tropical systems don’t like wind shear, and as long as that continues, the pace of development will be sluggish. That is not expected to be the case, however, as modeling weakens the shear in the next day or so, allowing PTC 9 to have a less hostile environment over some of the warmest water in the Atlantic basin. That should lead to strengthening and potentially rapid strengthening at that.

PTC 9’s forecast: Angles matter

The overall forecast for PTC 9 has not changed a whole lot since yesterday.

The forecast for PTC 9 continues mostly in line with what was predicted yesterday. (NOAA NHC)

The cone has narrowed a hair to between Panama City and Tampa. Hurricane Watches are now in effect for the Florida coast, as well as inland in the Panhandle. Tropical Storm Watches including Orlando are now posted as well. Expect some of these watches to expand later today.

On the surface, this looks like a pretty easy forecast: Tropical models are in generally good agreement on a track to the northwest, then north, then north-northeast. The clustering is pretty solid in the modeling in Apalachee Bay or near the Big Bend of Florida. So, simple right? For my college football fans: Not so fast, my friends.

The fundamental problem in predicting storms that turn is the angle at which it all happens. Generally, models handle the concept of this well, and indeed we have very good agreement right now in the models.

Tropical models for PTC 9 are in good agreement on the general track. Florida’s geography poses a unique challenge. (Tropical Tidbits)

Because of Florida’s unique geography with a peninsula jutting out to the south, the exact landfall point gets harder and harder to pin down when a storm comes in from the south or southwest. A shift of 10 to 15 miles out over the Gulf can lead to a shift of 20 to 40 miles with respect to landfall location in Florida. We often talk about not focusing on the exact track, and indeed there’s a reason for that as impacts extend far from the center. But for things like storm surge, that exact landfall point is crucial in determining how things will turn out. It also makes the difference for places even well inland to be on the “dirty” eastern side of the storm or the slightly less menacing western side.

As long as the tropical models are correct, we’re likely to see this chug north-northeast into Apalachee Bay or the Big Bend. However, if the models are not quite grasping the interaction with an upper low over Arkansas properly, well, that could change things a bit. There’s a path to get a storm much closer to Tampa, as we discussed last night and as the ICON model continues to show this morning with a track coming ashore near Cedar Key rather than Apalachee Bay. For now, the most likely window for landfall appears to be Apalachicola to Cedar Key, with lesser bands around that to Panama City on the west and Tampa on the south/east.

The takeaway here is that this is a storm where focusing on the entire cone makes a lot of sense.

In terms of intensity, not much has changed since yesterday. We still struggle with intensity forecasts. One needs to only look at Hurricane John yesterday, which came ashore after 9 PM as a 120 mph category 3 storm in Mexico while initially forecast to be a 70 mph tropical storm at 3 AM. (Credit to the NHC however for constantly stating in their discussions that there were higher risks, and even substantially higher risks than the explicit forecast showed).

But we still expect that PTC will become Hurricane Helene and a major hurricane at that. The National Hurricane Center has this as a category 3 storm at landfall. And model support is generally for a strong storm.

Model forecast intensities for PTC 9 still show a very wide spread in options, but most seem to agree on this becoming at least a category 2 or 3 storm. (Tropical Tidbits)

The takeaway: A powerful hurricane is likely to strike Florida’s coast late Thursday, likely somewhere between Apalachicola and Cedar Key but with risks extending just beyond those goal posts.

Impacts from Helene/PTC 9

We have our first look at storm surge today from the NHC advisory, and it’s not great news.

Storm surge as high as 10 to 15 feet above ground level is possible near and east of where PTC 9/Helene comes ashore in Florida. About 5 to 8 feet of surge is possible in Tampa Bay. (NOAA NHC)

Values of 10 to 15 feet in the Big Bend would be in line with or worse than what occurred in Idalia last summer. A 5 to 8 foot surge in Tampa Bay would also be in line with or worse than Idalia. So for planning purposes, those areas should consider Idalia as a benchmark for minimum impacts, with risk for something worse. The wind field and size of this storm is expected to be somewhat broader than in Idalia, which also is concerning from a potentially worse impact standpoint.

PTC 9’s forward speed is likely to aid in carrying tropical storm and hurricane force winds well inland. The map below shows roughly where, given the current track, tropical storm and hurricane force winds could extend. And that’s a huge area. Things get complicated on Florida’s east coast, including Jacksonville, as well as up toward Savannah where stronger winds are possible than in other inland areas near there.

A rough outline of where tropical storm and hurricane force winds could occur with Helene/PTC 9 as it comes inland. (Weather Bell)

The extension of hurricane force winds inland will depend on the intensity of the storm at landfall and its exact forward speed from there. But suffice to say this has the potential to be a destructive inland wind event too, extending from North Florida into much of Georgia and South Carolina and even parts of North Carolina.

In addition to the wind will be heavy rainfall, and that’s expected to cover a massive area of the Southeast.

While these aren’t the most extreme rain totals we’ve seen in recent years, the coverage and intensity of this rain is likely to contribute to widespread flash flooding in the Southeast. (NOAA WPC)

We’ve seen worse rain events, but spatially, this is going to put a lot of places at risk of flash flooding.

Obviously, isolated tornadoes are a possibility along and to the right/east of where this storm goes.

The takeaway: Significant impacts from PTC 9/Helene are expected to extend well inland from the coast.

We will update this post today as we can if anything changes. We’ll aim to have another post out early this evening with the latest.