Major Hurricane Isaias

[40/70 Benchmark]

I still like Choctawhatchee Bay for max surge of 10'.

[Interstate]

19 minutes ago, LawdogGRNJ said:

Not to take away from the immediate impact dangers, but being up in NJ, I'm starting to be concerned with the remnants hitting like Ida did.  We got over six inches of rain in just a few hours causing significant flooding.

There will be no remnants.  It will be just a simple low pressure system on a front with some tropical moisture.  Only the Euro give NJ more than in inch and that is only in isolated spots.

[GaWx]

3 hours ago, sakau2007 said:

i respectfully disagree with you. the 3 games i am aware of closest to the storm's impacts are Georgia/Alabama in Tuscaloosa (storm will be effectively over by kickoff), Georgia Tech/Duke in Atlanta (breezy and rainy, but no big deal in the whole scheme of things) and Vanderbilt/Ole Miss in Nashville (similar to Atlanta, with probably less overall impact, and less tornado threat).
 

 
 The point some of us have been making is the double standard being applied regarding the concern for the attendees in Tuscaloosa vs that for those in Atlanta:

 Tuscaloosa: SATURDAY  
TROPICAL STORM CONDITIONS POSSIBLE. SHOWERS, COOLER  
WITH HIGHS IN THE MID 70S. NORTHEAST WINDS 25 TO 30 MPH WITH  
GUSTS UP TO 45 MPH, BECOMING SOUTH 10 TO 15 MPH WITH GUSTS UP TO  
30 MPH IN THE AFTERNOON. CHANCE OF RAIN NEAR 100 PERCENT.

Atlanta: SATURDAY  
SHOWERS. A SLIGHT CHANCE OF THUNDERSTORMS IN THE  
MORNING, THEN A CHANCE OF THUNDERSTORMS IN THE AFTERNOON. BREEZY  
WITH HIGHS IN THE LOWER 70S. EAST WINDS 15 TO 25 MPH WITH GUSTS  
UP TO 50 MPH. CHANCE OF RAIN NEAR 100 PERCENT.

—————

 As one can see, the forecast is actually much worse for the afternoon gametime in ATL for Duke/GT than it is not just for the evening gametime in Tuscaloosa but even during the tailgating time in Tuscaloosa well before the game even starts!

 So, gusts to 50 with possible thunderstorms/heavy rain and even a slight chance for a tornado in ATL for the game itself vs gusts only to 30, much lighter rain, and no thunderstorms in Tuscaloosa during the entire PM tailgating period well before the game even starts!

 @PhiEaglesfan712@vortex95

[vortex95]

12 hours ago, 40/70 Benchmark said:

Yea, I brought up Lily and Opal yesterday...Ivan was another.

Oh yes Dennis.  That underwent rapid weakening leading up to landfall as well, after rebounding big time once off Cuba.

[jm1220]

26 minutes ago, LawdogGRNJ said:

Not to take away from the immediate impact dangers, but being up in NJ, I'm starting to be concerned with the remnants hitting like Ida did.  We got over six inches of rain in just a few hours causing significant flooding.

It won’t be that coherent a system by the time it gets up here. Shear will eventually get to it. I agree that these big N Gulf systems usually have a Part 2 big impact area way further north like Camille 1969 and Ida but that’s when it can remain a coherent consolidated system. Up here it looks more like a strung out frontal system. 

[PhiEaglesfan712]

Of those storms, Lili is probably the best match/analog, as that happened during a high shear/low activity/el nino year. Opal and Dennis happened in low shear/hyperactive years, so they aren't really good matches.

[vortex95]

5 hours ago, Nomz said:

So far, a complete coup for Google DeepMind

HAFS A/B yesterday did an excellent job on showing Isaias deepening in the
last 12 hr and its current intensity.

 

For the past 2 years these models have shown significant improvement

over the previous TC models.  I seem to recall last year the HWRF and

HMON were to be discontinued, but that has not happened

 

IMHO, there are already too many operational models the exist or available.

More is not always better, and too many can distract from proper subjective 

forecast skill.  You get *one* model that is an outlier, and that can sway you 

away from a better forecast.  Also, the less scrupulous people on social media 

looking for clicks/like will often post the model that shows the worse case 

scenario, even if it obviously out to lunch.  That makes our job that much 

harder because often we have to spend an inordinate amount of time 

debunking wild or bogus forecasts.

 

I know some are not thrilled with the NAM and it derived products ending

soon, but eventually we do need to move forward and the RRFS replaces the

NAM.  The NAM as a model and early name, ETA, has been around for 33 years,

so time to move on.

Also, from the big Nor'easter last month, the RRFS was too aggressive in showing

a tropical transition for this storm, so that suggests it may not do well for TCs.

Has anyone been following the RRFS as how it has handled Isaias so far?

[40/70 Benchmark]

2 minutes ago, PhiEaglesfan712 said:

Of those storms, Lili is probably the best match/analog, as that happened during a high shear/low activity/el nino year. Opal and Dennis happened in low shear/hyperactive years, so they aren't really good matches.

This won't weaken as much as Lilly...that went from 145mph to 100mph at LF.

[Vicious Fluid]

This is probably more apparent to those with background in weather/forecasting, but I'm curious: is the outflow from Simon potentially disrupting some of the effect of the sheer on the western side? I know the outflow affects Isaias' ventilation, but does it also have an independent effect on the actual environment of sheer?

[Floydbuster]

Wow, what a complete turnaround overnight in the last 12 hours. Isaias was looking very ill organized about 10 hrs ago, but I am impressed this morning. Unfortunately, this obviously increases the chances for more severe impacts at the coastline.

That radar from Mobile shows quite a nasty eyewall. Here is hoping it weakens in the next 12 hrs, but now the NHC sounds less sure that this wont make landfall as a major hurricane.

[OHweather]

The models were pretty insistent that Isaias would be able to gradually deepen and improve structurally through most of the day today as long as it stays on a NNE heading, with shear and dry air likely to rapidly begin affecting the inner core in the last few hours before landfall as the storm's heading starts bending more towards the left/due north. 

The strong west-southwesterly shear and very dry mid-level air are definitely impinging on the core of Isaias this morning, but convection has continuously wrapped around the upshear side of the storm and is insolating the core from this unfavorable environment for now as a shortwave approaches from the west. With the storm over very warm waters and beneath enhanced upper-level divergence ahead of the shortwave it can continue to gradually intensify/deepen. With a very intense convective burst ongoing in the NW eyewall right now, we probably have one more burst of intensification into the afternoon. 

The shear will increase further in a few hours and the storm motion will become less parallel to the shear vector this evening, so it remains likely the unfavorable environment starts affecting the inner core as landfall approaches. Per the regional hurricane models the inner core may break down pretty quickly tonight right around the time of landfall, though with a bit more near-term intensification and only a few hours for the environment to negatively affect Isaias this evening before landfall my guess is landfall occurs with a peak wind between 90-100kt, with the wind field beginning to expand by then due to interaction with the incoming shortwave. 

[vortex95]

4 hours ago, Interstate said:

I know this is banter... but why, because of this?  This is the weather for Atlanta.

It will be like a typical non-tropical low pressure once inland, like a Miller A storm.  Atlanta has been through this many times.  The problem is media hype and knee-jerk reactions from authorities end up resulting in overdoing the cancellations and shutdowns. 

Just b/c this storm has (had) a name on it, does not make it different overall once it goes PT/ET and for locations far inland, yes there are exceptions, like Helene, but that's not the case here.  Many PT/ET storms out of the Gulf have produced the same impacts to the SEUS as Isaias will.  I posted earlier about the Gulf storms in Oct 1992 and 1994.

You watch, the ET part of Isaias is going to impact the entire E Coast.  It will be no different than typical Nor'easter and not even as strong or impactful as the Nor'easter last month, say DCA-BOS. but it will be treated as "worse" b/c it was a former hurricane and you'll see unnecessary cancellations for it.  There is no scaling or quantification of wx events these days, all are the same as to being worst ever, unprecedented, or absolute high-end events as to impact that we all have to hide and cower in fear from.  Being constantly "held hostage" by the wx is not a good thing. esp for business and commerce.  You can't hide behind the excuse "better safe that sorry" for every single wx situation.  This mindset has real impacts.  The door swings both ways here.

[vortex95]

3 hours ago, CoastalWx said:

Through history, the opposite has occurred vs intensifying. The recent ones to intensify had much weaker shear vs what is forecasted. 

Wow @CoastalWx chiming in on AmrWx somewhere else than the New England forum and the sports threads?  Be still my beating heart!   Guess he has to breakup this "boring" pattern somehow!

[SnoSki14]

35 minutes ago, Interstate said:

There will be no remnants.  It will be just a simple low pressure system on a front with some tropical moisture.  Only the Euro give NJ more than in inch and that is only in isolated spots.

It's still a tropical entity that will bring an influx of moisture. I could see 2-3" amounts. 

[Interstate]

Question... when the give the position of a storm... if the position the exact middle of the eye?

[NorthHillsWx]

Recon shows this has either peaked or leveled off. NHC noted they now expect a major at/just before LF

[yoda]

BULLETIN
Hurricane Isaias Advisory Number  12
NWS National Hurricane Center Miami FL       AL092026
1000 AM CDT Fri Oct 09 2026
 
...CENTER OF ISAIAS EXPECTED TO REACH THE WESTERN FLORIDA PANHANDLE
COAST THIS EVENING...
...LIFE-THREATENING STORM SURGE AND DEVASTATING WINDS LIKELY ALONG 
THE FLORIDA PANHANDLE AND ALABAMA COASTS...
 
 
SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...27.7N 87.3W
ABOUT 195 MI...310 KM S OF PENSACOLA FLORIDA
ABOUT 145 MI...235 KM SE OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H
PRESENT MOVEMENT...NNE OR 25 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...959 MB...28.32 INCHES
 

[yoda]

Hurricane Isaias Discussion Number  12
NWS National Hurricane Center Miami FL       AL092026
1000 AM CDT Fri Oct 09 2026
 
An Air Force Reserve Hurricane Hunter aircraft currently 
investigating Isaias measured a peak 700-mb flight-level wind of 
120 kt within the eastern eyewall a few hours ago, prompting an 
upgrade of the hurricane to major hurricane status with estimated 
surface winds of 105 kt. Based on the last several dropsondes 
released in the eye, the central pressure appears to have leveled 
off around 959 mb. On the last pass through the eastern eyewall, 
just about a half hour ago, the plane measured a flight-level 
wind of 111 kt, suggesting that the peak winds may have also 
leveled off. The eye itself has become cloud filled in visible 
satellite imagery, but it is now moving into range of several 
WSR-88D radars along the northern Gulf coast.

Strong deep-layer shear has definitely increased as forecast, with 
various analyses now showing 30-40 kt out of the southwest. 
However, the shear vector is nearly aligned with the storm's 
motion, which limits its adverse effects, and upper-level 
divergence is also increasing over the hurricane. This setup has 
likely allowed the hurricane to intensify this morning, and the 
hurricane regional models (HAFS-A, HAFS-B, and HWRF), as well as 
the statistical-dynamical models (SHIPS and LGEM), all suggest that 
Isaias could maintain major hurricane intensity up until its 
landfall this evening. Therefore, the NHC official forecast depicts 
Isaias with 100-kt winds just offshore the western Florida 
Panhandle this evening. Weakening will occur after landfall, but 
sustained hurricane-force winds will likely occur near and along 
Isaias's track up to 100 miles inland from the coast into southern 
Alabama, and gusts to hurricane force could extend even farther 
north into central Alabama. Isaias is likely to lose its tropical 
characteristics by 36 hours when it is over northern Alabama.

Aircraft fixes indicate that Isaias has drifted a bit east of the 
previous forecast track. NHC's track forecast leans on the eastern 
side of the guidance envelope, closest to the latest HCCA and GDMI 
guidance, and implies a potential landfall along the extreme 
western Florida Panhandle coast this evening. After moving inland, 
the center of Isaias is expected to continue northward through 
Alabama, before turning northeastward over the Tennessee and Ohio 
Valleys (as a post-tropical remnant low) on Sunday.

Now that the eye has become visible in WSR-88D coastal radars, 
hourly Tropical Cyclone Updates will be issued beginning at 11 AM 
CDT (1600 UTC).

 
Key Messages:
 
1. A life-threatening storm surge is expected from the Mouth of the
Mississippi River to Suwannee, Florida. Residents under evacuation 
orders should leave immediately and follow advice from local 
officials. 
 
2. Extremely dangerous and damaging hurricane force-winds are 
expected over portions of the Florida Panhandle, southern Alabama, 
and southern Mississippi where a Hurricane Warning is in effect. 
Residents in these areas should have a safe room to ride out the 
storm and prepare for long-duration power outages.
 
3. Damaging wind gusts are likely over a large portion of the 
southeastern United States from western and northern Georgia 
westward over much of central and northern Alabama, southern middle 
Tennessee, and Mississippi, especially in areas of higher terrain.
Residents should secure loose outdoor items, avoid driving 
high-profile vehicles, prepare for power outages, and be aware of 
the potential for falling trees.
 
4. Isaias will bring areas of heavy rainfall to the central U.S. 
Gulf coast and much of the Southeast through the weekend. 
Considerable flash and urban flooding, and significant river 
flooding, are possible.

5. The tornado potential will increase this afternoon and continue 
through tonight. The greatest risk will be east of the center, 
particularly across the Florida Panhandle into southern Georgia. 
This risk will continue spreading north-northeast across
parts of the Southeast on Saturday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/1500Z 27.7N  87.3W  105 KT 120 MPH
 12H  10/0000Z 29.7N  86.8W  100 KT 115 MPH
 24H  10/1200Z 32.1N  87.1W   55 KT  65 MPH...INLAND
 36H  11/0000Z 34.2N  87.2W   35 KT  40 MPH...POST-TROP/INLAND
 48H  11/1200Z 36.5N  85.0W   25 KT  30 MPH...POST-TROP/INLAND
 60H  12/0000Z 39.1N  81.0W   20 KT  25 MPH...POST-TROP/INLAND
 72H  12/1200Z...DISSIPATED
 
$$
Forecaster Berg

[WxWatcher007]

Idk. While the impacts in the Mid-Atlantic and northeast may be more mundane, I do think that the fact this is going to eventually interact with a shortwave as it pulls north is a red flag for inland areas that are on the eastern side of the center. That combo can be a prolific tornado producer. 

I also think we need to consider how this holds together inland. This is one of the areas where models like HAFS have been falling short. Now we see this being fairly well put together inland, and that means hurricane gusts could be possible well inland. From the 11am discussion in part: 
 

Weakening will occur after landfall, but 
sustained hurricane-force winds will likely occur near and along 
Isaias's track up to 100 miles inland from the coast into southern 
Alabama, and gusts to hurricane force could extend even farther 
north into central Alabama. Isaias is likely to lose its tropical 
characteristics by 36 hours when it is over northern Alabama.

[olafminesaw]

Good writeup on Opal here, provides an excellent analog for impacts, albeit Opal was a category stronger at peak and landfall. Supports the idea of 10 ft storm surge and 100 mph + gusts at landfall along the immediate coast with hurricane Force gusts just inland 

https://www.weather.gov/mob/opal

 

[vortex95]

3 hours ago, sakau2007 said:

i respectfully disagree with you. the 3 games i am aware of closest to the storm's impacts are Georgia/Alabama in Tuscaloosa (storm will be effectively over by kickoff), Georgia Tech/Duke in Atlanta (breezy and rainy, but no big deal in the whole scheme of things) and Vanderbilt/Ole Miss in Nashville (similar to Atlanta, with probably less overall impact, and less tornado threat).

i do agree with you that this could come in like Opal... in the sense that the pressure might rise 25 millibars prior to landfall off its peak.

 

That's a good point.  TIMING is everything!  But I see far too often a wx event is taken as "all day" and so events that will clearly be before or after  sig storm impacts are done and do not be to be cancelled.  I mean, you now get *indoor* events cancelled for just some typical wind and rain now.  Really?

We can fine-tune forecasts better than ever now w/ models like the HRRR, RRFS, and HAFS, so we do not have to just issue a generic, blanket forecast. esp for the short-range.  Having this capability saves an enormous amount of $$ and allows business and commerce to function better.

It reminds me of something years ago.  One evening, I went out to get pizza, and when I picked up my order, the person said "it's been slow tonight b/c of snow forecast!"  You know what the forecast was?  1-3" of snow starting *after* midnight.  So my previous posits about business and commerce being impacts is valid, and it hurts revenue for many businesses, big and small.  You see how incessant hype and not quantifying risks/threats  properly are detrimental to society.

Cancellation of a major sport event is non-trivial as to costs, and it goes far beyond just that single event.  They have to reschedule and that has downstream impacts often to the entire league.
I often ask myself, what if the SB was in MSY or MIA, and there was a MDT or HIGH risk for svr wx for that day?  I would not want to be the one to make the decision!  In this case, the ante is extremely high on both sides!  Actually, I do recall a case like this.  In 2004, the Indy 500 was held despite a HIGH risk svr and a sig tor outbreak was likely.  And when the event was over and people were leaving the area, there were tornadoes occurring in the IND area not more than 5 mi away!
 

[WEATHER53]

Last night a lot of talk about how it would not get this strong and fall apart quick.  It’s a new age now and a great increase in hurricanes that maintain and even strengthen at landfall

[vortex95]

3 hours ago, cptcatz said:

Yep, people seem to only remember the ones that intensified upon landfall. But Idalia in 2023 weakened right before landfall, Delta in 2020 did too, and of course Katrina weakened big time before landfall.

We tend to recall the ones that did RI just before landfall, and that human nature and the wx weenie in us!  But the flip side of the coin is just and important.  What causes RI is just as important as what causes RW from a forecast POV, both short- and long-term.

It remind me growing up, how frustrating it was in ern MA trying to figure out if the tstms coming in from the W would hold together or weaken./collapse.  @CoastalWx knows this all too well I know.  So that drives you to learn, figure out the deal, and it makes your a better forecaster.

[vortex95]

3 hours ago, 40/70 Benchmark said:

Recency bias.

We have been "spoiled" since 1995.  Trust me, 1970-1994 was a bad time if you like Atlantic TCs.  Not that there were not some biggies and some areas got hammered, but overall, it was quite lame.

[GaWx]

20 minutes ago, vortex95 said:

That's a good point.  TIMING is everything!  But I see far too often a wx event is taken as "all day" and so events that will clearly be before or after  sig storm impacts are done and do not be to be cancelled.  I mean, you now get *indoor* events cancelled for just some typical wind and rain now.  Really?

We can fine-tune forecasts better than ever now w/ models like the HRRR, RRFS, and HAFS, so we do not have to just issue a generic, blanket forecast. esp for the short-range.  Having this capability saves an enormous amount of $$ and allows business and commerce to function better.

It reminds me of something years ago.  One evening, I went out to get pizza, and when I picked up my order, the person said "it's been slow tonight b/c of snow forecast!"  You know what the forecast was?  1-3" of snow starting *after* midnight.  So my previous posits about business and commerce being impacts is valid, and it hurts revenue for many businesses, big and small.  You see how incessant hype and not quantifying risks/threats  properly are detrimental to society.

Cancellation of a major sport event is non-trivial as to costs, and it goes far beyond just that single event.  They have to reschedule and that has downstream impacts often to the entire league.
I often ask myself, what if the SB was in MSY or MIA, and there was a MDT or HIGH risk for svr wx for that day?  I would not want to be the one to make the decision!  In this case, the ante is extremely high on both sides!  Actually, I do recall a case like this.  In 2004, the Indy 500 was held despite a HIGH risk svr and a sig tor outbreak was likely.  And when the event was over and people were leaving the area, there were tornadoes occurring in the IND area not more than 5 mi away!
 

 
 The main issue some of us have is the double standard of concern in Tuscaloosa vs virtually no concern in ATL (at least earlier…maybe this will change). The forecasted conditions for during the GT/Duke game in ATL Sat. afternoon are far worse than those for even the tailgating period (6 hrs before kickoff) in Tuscaloosa. Furthermore, the forecast for ATL is actually quite a big deal, which along with thunderstorm chances has a high wind warning and thus would be far worse than the typical breeziness of a Miller A:

 

[Brasiluvsnow]

2 hours ago, suzook said:

Its out of the south by Sunday

Thank You ,,,, and Suzook or anyone else ,,,, if I left charlotte today ( I can be out of here by 1 pm ) I could be in Jacksonville and heading farther South by 6 pm would I be asking for trouble doing this drive at that time today as I know landfall is sometime this afternoon ,,, thanks again in advance 

[jm1220]

13 minutes ago, WEATHER53 said:

Last night a lot of talk about how it would not get this strong and fall apart quick.  It’s a new age now and a great increase in hurricanes that maintain and even strengthen at landfall

GOM hasn't had any significant tropical activity this year so the waters are quite warm. That helps.

[vortex95]

2 hours ago, CoastalWx said:

If it weakens right before landfall and the core erodes like some models have, best winds may be found in the convection modeled on the NW side of the center. Would make it more difficult to maximize best winds in that area accounting for forward motion. You really need good mixing to maximize your best winds at the surface. That’s why it makes all the difference when a storm is intensifying as it makes landfall vs weakening. 
 

I’m not minimizing this, just stating what we know with these storms. 

From a sensible wx impact for winds, there is big difference if a HU is intensifying vs. weakening at landfall 

An intensifying storm is more efficient in mixing down the very high winds found only 300-500 m up due to better convective updraft/downdraft couplets.  This is one reason why Andrew was so nasty.

You do not have this in a weakening HU.  The convection is not as intense and often only partially encircling the center, so mixing down of the much stronger winds aloft is less.

What you can get regardless of the trend, esp. just inland, is some very high gusts due to the collapsing convection in the form of downbursts.
 

[Brasiluvsnow]

Disregard my last post I know the answer I should be pouring in Jacksonville and Daytona  y 5 and 6 pm ,,, I should have left earlier today ,,,, I will just punt and leave Sunday ,,,,, sorry for the banter guys 

[vortex95]

2 hours ago, WxWatcher007 said:

Yeah, very tough call. Just a few hours made the difference here, though it's incredibly impressive how well GDM has been through the entirety of this one. Like you said in another post, it was easy to hedge east for this one, and GDM never backed down on a higher end peak. 

Well, keep in mind that Idalia hit one of the least populated areas of the state. Idalia's eyewall was legit, but less damage=less need for retirement. That won't be the case with this one, even if it's weakening at the end, because it's hitting real population centers.

Not to mention the yet to be seen inland impacts in the south. 

Agree with this too. There's going to be a line of discussion here tonight about why we're not seeing G125 across the landfall zone and it'll be because 1) that's not how things work lol and 2) the strongest winds in a decaying core may be concentrated in a few spots. Still bad to be clear with other impacts and with wind itself, but as I've found, eyewall dynamics and impacts are more mesoscale than people tend to realize. 

If a HU is a Cat 3 or higher for a U.S landfall, that usually means it gets retired, but not always (Brett in 1999 is an example).  Anything less is typically not.  The exceptions are when it produces big excessive rains, and you can have only a TS landfall and it will get retired, like Allison in 2001 and Imelda in 2019. 

And exception will be outside the tropics or subtropics  Like a Mid-Atlantic or New England landfall Gloria in 1985 was a Cat 1 at LI landfall, and it was retired.  I think that is largely due to the rarity of HU landfalls here, so overall impact is more since these areas not "used to" HU landfalls, unlike from Hatteras S.