Major Hurricane Helene

[GaWx]

5 minutes ago, CoastalWx said:

Thanks. I know it says 18Z guidance, but I don’t see how those can be actual 18Z runs since they haven’t run yet. I believe those are mainly 12Z run tracks. They include UKMET, GFS, HWF, etc.

 Anyone else have more insight on this?

[Hotair]

Model track guidance is adhering to the Fujiwara effect

 

 

 

[OSUmetstud]

18z early cycle models are 12z models corrected for the current position

[StantonParkHoya]

Interesting. Most go west of ATL it appears.

[CoastalWx]

1 minute ago, OSUmetstud said:

18z early cycle models are 12z models corrected for the current position

I also was under the impression that some are also new and these plots are positions extracted from the grib files etc. The HWRF shown on that is definitely different compared to the 12z runs. 

 

Admittedly though I'm not 100% sure how those early runs are collected.

[WEATHER53]

1 hour ago, gymengineer said:

Storm surge forecast update in the intermediate advisory that will probably result in an updated graphic at 5 pm: 

Carrabelle, FL to Chassahowitzka, FL...12-18 ft
Apalachicola, FL to Carrabelle, FL...8-12 ft
Chassahowitzka, FL to Anclote River, FL...8-12 ft
Indian Pass, FL to Apalachicola, FL...6-9 ft

When there is a 12-18’ surge, how far inland  will it go before its down to like 6”-1’ of surge remaining?

[OSUmetstud]

7 minutes ago, CoastalWx said:

I also was under the impression that some are also new and these plots are positions extracted from the grib files etc. The HWRF shown on that is definitely different compared to the 12z runs. 

 

Admittedly though I'm not 100% sure how those early runs are collected.

This is from u of Wisconsin

Consequently, "early" models represent forecasts from the previous cycle - that beginning 9 hr prior to an official forecast - that are shifted forward in time by 6 hr with a position and intensity matching the storm's current attributes. For dynamical models, these models have designators that end in an I (e.g., AVNI, CMCI, etc.) to indicate their interpolated nature. Note that consensus, statistical, and statistical-dynamical guidance is also classified as "early" guidance since each are derived using "early" model inputs. Conversely, "late" models represent forecasts from the current forecast cycle that arrive late, or after the official forecast must be made. They form the basis for the next forecast cycle's "early" model forecasts. They have no special designator notation.

[gymengineer]

Isn't part of the issue with this particular track graphic that only straight lines are used between time dots? So, with a fast moving hurricane, you wouldn't be able to discern changes in direction within a 12-hr window. With Helene, what happens between the 24-hr and 36-hr dot on this 18Z graphic is landfall, which would not be accurately captured if the model is depicting any change in direction during that window. 

[franklin NCwx]

1 hour ago, NeonPeon said:

Many models show some horrific rotting band somewhere near transylvania county. NHC starting to show some 20" plus stuff there. Obviously the details of where it sets up are up in the air, but those are astonishing totals for an area that broadly is at massive flood risk in general (i.e.20%+ of properties at risk)

Large elevation gain at the Transylvania Jackson County line. That area enhances due to orographic lift

[WxWatcher007]

Starting to get the first far flung outer rain bands here and across much of Florida. Speaks to how expansive this thing is already. 

[olafminesaw]

i don't  know anything about this model output, but I believe it is what the NWS bases their forecast on

https://slosh.nws.noaa.gov/psurge/index.php?R=CONUS&S=Helene2024&Adv=9&Ty=e10&D=agl&Ti=cum&Msg=17&Mp=Street&Z=5&Lt=34.823193&Lg=-79.693886&Help=about

[Allsnow]

The pre from Helene already effecting the ATL area 

[DeltaPilot]

It sure is Allsnow. Been pouring off and on here since about 1130 am. Looks to go on for the rest of tonight and into tommorow, then we get the northern bands from Helene.

[soadforecasterx]

looks like its really getting its act together now

[SchaumburgStormer]

2 minutes ago, soadforecasterx said:

looks like its really getting its act together now

Yep, should be off to the races this evening. Minimal land interaction really has this one looking much better already than I thought it would a few days ago. 

[LithiaWx]

Is RI still forecast overnight?

[SnowGoose69]

This is the furthest east run yet by the NAM, comes in E of TLH

[Prospero]

22 minutes ago, WxWatcher007 said:

Starting to get the first far flung outer rain bands here and across much of Florida. Speaks to how expansive this thing is already. 

Had our first taste of Helene with TS gusts all around in the area in a small band. I was outside and this storm just feels really "big".

Egmont Channel at the mouth of Tampa Bay had a gust of 47 mph and 38 mph winds for a moment. We are still a long ways from the center.

[schoeppeya]

21 minutes ago, soadforecasterx said:

looks like its really getting its act together now

Pretty close to getting the dry air mixed out of the center. Recon is almost there, should be an interesting couple hours. 

[NorthHillsWx]

Me thinks this is going to be storm porn as it relates to a classic looking eye when it peaks. Getting the look already 

[Hotair]

Very windy and drenching rain in Tampa now.  Soil is going to be saturated soon  

 

not good 

 

 

 

[Amped]

One hottower stuck in the middle of the eye.   It has little if any meteorological impact, but is great at blocking our view of the eye while it forms. 

 

[Radtechwxman]

That dry air definitely made it into the COC. Degraded it more than I anticipated. Curious what hurricane hunters will find intensity wise. Wondering when Helene will really take off. 

[ineedsnow]

5 minutes ago, Radtechwxman said:

That dry air definitely made it into the COC. Degraded it more than I anticipated. Curious what hurricane hunters will find intensity wise. Wondering when Helene will really take off. 

looks like shes about to take off now.. dry air is quickly diminishing and storms are firing around the eye.. 

[schoeppeya]

8 minutes ago, Radtechwxman said:

That dry air definitely made it into the COC. Degraded it more than I anticipated. Curious what hurricane hunters will find intensity wise. Wondering when Helene will really take off. 

Pressure down a couple millibars so dont really know that it was degraded per se

[LongBeachSurfFreak]

22 minutes ago, NorthHillsWx said:

Me thinks this is going to be storm porn as it relates to a classic looking eye when it peaks. Getting the look already 

Yup, if it reaches full potential I would expect that Katrina/rita look in the gulf. 

[BYG Jacob]

976 extrap 

[yoda]

BULLETIN
Hurricane Helene Advisory Number  10
NWS National Hurricane Center Miami FL       AL092024
400 PM CDT Wed Sep 25 2024

...HELENE STRENGTHENING...
...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND
DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO
COMPLETION TODAY...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...22.5N 86.6W
ABOUT 460 MI...735 KM SW OF TAMPA FLORIDA
ABOUT 505 MI...815 KM SSW OF APALACHICOLA FLORIDA
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...N OR 355 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...978 MB...28.88 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The Storm Surge Watch east of Mexico Beach to Indian Pass has been
upgraded to a Storm Surge Warning.

The Tropical Storm Watch north of South Santee River to Little
River Inlet has been upgraded to a Tropical Storm Warning.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* Mexico Beach eastward and southward to Flamingo
* Tampa Bay
* Charlotte Harbor

A Hurricane Warning is in effect for...
* Anclote River to Mexico Beach
* Cabo Catoche to Tulum, Mexico including Cozumel

A Storm Surge Watch is in effect for...
* West of Indian Pass to Mexico Beach

A Hurricane Watch is in effect for...
* Cuban province of Pinar del Rio
* Englewood to Anclote River, including Tampa Bay

A Tropical Storm Warning is in effect for...
* Florida Keys, including the Dry Tortugas
* Flamingo to Anclote River, including Tampa Bay
* West of Mexico Beach to the Okaloosa/Walton County Line
* Flamingo northward to Little River Inlet
* Lake Okeechobee
* Rio Lagartos to Cabo Catoche, Mexico
* Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth

[weatherCCB]

85mph 978mb 

with the 5pm update

[jrips27]

The NHC intensity forecast now shows an intensity of 115 kt (Category 4) at
24 hours, which is mirrored by several of the regional hurricane
models and the SHIPS guidance.  It should be noted that additional
strengthening is possible beyond 24 hours before Helene makes
landfall Thursday evening.