Major Hurricane Helene

[StantonParkHoya]

3 minutes ago, SnowGoose69 said:

The 3km NAM I think illustrates how the strength of this determines how fast it gets tugged., comes in at 908mb  The 00Z 3k NAM does not really begin pulling this NNW til it gets over 966mb in CNTRL GA.  In the end its maybe 50-60 miles east of the NHC track.   This is why I have been saying, Cat 3 or 4 at LF, the NHC track over N-CNTRL GA may be as much as 80 miles too far west.  If this somehow comes in as a 1 or 2 it might get pulled hard fast and something crazy like those extreme west tracks may happen like even 20 miles west of the NHC one into AL.  

It’s not just the NHC track, the 0z spaghetti models are literally in Alabama 

[Radtechwxman]

4 minutes ago, MUWX said:

Looks like it’s taking another big gulp of dry air on IR. 

It's been the same one all day spiraling around its core. It's trying to mix it out. 

 

6 minutes ago, andyhb said:

Warm waters don't mean much until it gets rid of the dry air.

Think it will be able to shake it off? Not a Tswift reference 

[40/70 Benchmark]

30 minutes ago, Floydbuster said:

I just hope Helene isn't doing what Michael did, which was basically to stay in check until the final 12-15 hours and then begin to explode.

I don't think the timing of the cycle of internal processes bodes well for FL....they need to pray this never quite gets its act together. I said when it interacted with Yucatan that any chance of a prelandfall EWRC was out the window.

[WxWatcher007]

A new high risk (rainfall) for part of the panhandle tomorrow. FFW west of Tallahassee tonight. 

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
853 PM EDT Wed Sep 25 2024
Day 2
Valid 12Z Thu Sep 26 2024 - 12Z Fri Sep 27 2024

...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL IN PORTIONS OF THE
SOUTHERN APPALACHIANS AND NORTHEAST GEORGIA...

..LIFE-THREATENING FLASH FLOODING LIKELY OVER THE SOUTHERN
APPALACHIANS AND PORTIONS OF THE SOUTHEAST..

The extensive period of heavy rainfall during the D1 period will
continue through D2 across portions of the interior Southeast U.S
with a primary focus across the Southern Appalachians where the
back end of our predecessor rainfall event (PRE) will still be
occurring. Further to the south, all eyes turn to Hurricane Helene
as the storm continues to move quickly through the Eastern Gulf
within the weakness created by the trough to the north. The
northern extent of Helene's tropical moisture will begin nosing
into the Gulf coast with PWAT anomalies steadily rising from 1-2
deviations above normal to as high as 4 deviations above normal by
the time it makes landfall on Thursday evening. Despite a fast
forward propagation, copious amounts of rainfall will impact the
Florida Panhandle over to the Big Bend with the feeder bands on the
eastern flank of the cyclone impacting the coastal areas of the
Florida Peninsula. Rainfall amounts between Panama City to
Tallahassee will reach between 8-12" with local maxima of up to 15"
possible within the axis of Helene's landfall as the storm moves
almost due north, perpendicular to the coastal plain. For this
reason, a High Risk was added to portions of the Florida
Panhandle/Big Bend, including the Tallahassee area, as well as
across Apalachicola.

By Thursday night into Friday morning, Helene will continue making
steady progress northward with a large rain shield capable of
dropping 3-6" of rainfall within the core of the cyclone in short
periods of time. A swath of 6+ inch totals will progress northward,
eventually cascading into the Atlanta metro and surrounding
locales generating a higher threat of flash flood potential within
the urban corridor. Areas in the path of Helene will undoubtedly
see significant flood potential with small rivers and streams
likely becoming inundated very quickly to exacerbate the flood
threat within the rural areas of Georgia. The recent HREF blended
mean QPF footprint is robust for the period with a large areal
extent of 5+ inches with the secondary maxima positioned across
Northeast GA where the next round of significant rains will
approach with Helene's core making an approach.

The situation across the Southern Appalachians is becoming
increasingly severe with regards to the ongoing flash flood threats
from the PRE and eventually with the approach of Helene's core
as the cyclone moves up through Western GA. This will place the
eastern quadrant of the cyclone across Central and Northern GA with
a strong, prevailing east southeast flow expected to bank against
the terrain situated over North GA through the Western Carolinas, a
mechanism for maximizing ascent within a deep tropical moisture
plume that will enhance rainfall rates for several hours moving
through late Thursday night into Friday morning. The 12z HREF mean
QPF output continued to signal for prospects of 3-6+ inches within
a short time frame as the core of higher PWATs advect into the
region and douse the Southern Appalachians in another round of
significant rainfall with rates generally steady between 1-2"/hr
with some small probabilities (10-15%) for hourly rates pushing
close to 3"/hr in the stronger convective cores embedded in the
precip shield. The HREF neighborhood probability for >5" has peaked
at 90+% for the Southern Appalachian front, a signal reserved for
only the most impactful events, correlating well with the EAS
signal of >90% as well for at least 3". The combination of multiple
periods of heavy rainfall with elevated rates likely thanks to
Helene will produce significant, life- threatening flash flooding
across the area over Northeastern GA through the Blue Ridge of SC
and NC, including areas in and around Asheville and to the west of
Greenville- Spartanburg in Upstate SC. Several landslides due to
the prolific rainfall are very likely with a history of these types
of events producing catastrophic damage from both flooding and the
prospects of land and mudslides within the complex terrain. For
these purposes, and in coordination with the GSP and FFC WFO's, the
High Risk was maintained and expanded further southwest to just
northeast of the Atlanta metro to account for the most significant
signals for flash flood prospects during the period.

Considering the scope of Helene's size, the flash flood threat will
not be relegated to a small corridor like we see in some tropical
events. The trough to the west will play a pivotal role in the
steering mechanism for Helene as the storm approaches the latitude
of North GA, eventually pulling the cyclone more northwest towards
the back end of the forecast period. Due to the progression, there
is a growing consensus within the deterministic of the heavy rain
threat also shifting into Northern AL with the area in and around
Huntsville to the TN state line becoming more favorable for flash
flooding potential within the western flank of the cyclone. The
signal is not as prolific as the Southern Apps or where Helene
makes landfall, but the probability and QPF fields certainly
depict a significant amount of rain (3-5") within a time frame
generally between 4-8 hrs prior to the end of the forecast period.
This swath will extend across Eastern AL and Western GA up through
Northern AL, following the western periphery of the cyclone as it
moves north then northwest. The heavy rain will expand into
Southern TN before the end of the forecast period with more rain
anticipated in the Tennessee Valley after D2. Because of the
growing consensus in the heavy rainfall across the above areas, the
MDT risk was expanded further west and northwest into Alabama and
over the southern fringes of TN.

A large SLGT and MRGL risk will encompass a large area of the
Southeast and Southern Mid Atlantic as well as the outer bands of
Helene are forecast to impact the region with locally heavy
rainfall possible as is customary with these types of tropical
evolutions.

Kleebauer

 

[40/70 Benchmark]

2 minutes ago, jbenedet said:

Current IR shows clear signs of steady organization.

Slow and steady until dawn...then boom.

[lilj4425]

3 minutes ago, jbenedet said:

Current IR shows clear signs of steady organization.

Do you have a link where I can find this exact IR loop? Thanks. 

[wthrmn654]

1 minute ago, lilj4425 said:

Do you have a link where I can find this loop? Thanks. 

https://www.star.nesdis.noaa.gov/goes/floater.php?stormid=AL092024#homePageLink

https://www.ospo.noaa.gov/products/ocean/tropical/floaters/09L/09L_floater.html

[USCG RS]

2 minutes ago, lilj4425 said:

Do you have a link where I can find this? Thanks. I used to have it but I seem to have lost it. Thanks. 

You can toggle through imagery here:

https://www.star.nesdis.noaa.gov/GOES/conus_band.php?sat=G16&band=GEOCOLOR&length=24&dim=1

 

Edit: @wthrmn654 links are better. 

[MANDA]

1 minute ago, jbenedet said:

Current IR shows clear signs of steady organization.

Trying hard!  Next 12 hours are going to tell the tale.  I am questioning the Cat 4 at this point but Cat 3 seems like a solid call.  It has got to tighten up overnight if it is going to take a run at 4.  Sure is amazing to watch but glad I am not in the path.  A week + w/o power and potential historic flooding is definitely something I can live without.  Going to impact a lot of people once it plows inland.  Thankfully highest surge for the most part will impact sparely populated areas.  Still going to be surge issues Fl west coast though that will cause problems.  Not minimizing that.  

[SnowGoose69]

3 minutes ago, MANDA said:

Trying hard!  Next 12 hours are going to tell the tale.  I am questioning the Cat 4 at this point but Cat 3 seems like a solid call.  It has got to tighten up overnight if it is going to take a run at 4.  Sure is amazing to watch but glad I am not in the path.  A week + w/o power and potential historic flooding is definitely something I can live without.  Going to impact a lot of people once it plows inland.  Thankfully highest surge for the most part will impact sparely populated areas.  Still going to be surge issues Fl west coast though that will cause problems.  Not minimizing that.  

Sometimes, at least as far as wind a strengthening 2 at landfall can be worse than a weakening 3 or 4, we've seen how winds often do not effectively mix down as well sometimes in weakening canes.

[Metasequoia]

Great website for satellite imagery...

https://weather.cod.edu/satrad/?parms=meso-meso1-13-200-1-10-2&checked=map&colorbar=undefined

 

[Normandy]

1 hour ago, WxWatcher007 said:

 

Love this answer from eric

[wthrmn654]

SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...23.1N 86.6W
ABOUT 425 MI...680 KM SW OF TAMPA FLORIDA
ABOUT 465 MI...750 KM SSW OF APALACHICOLA FLORIDA
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...972 MB...28.71 INCHES

DISCUSSION AND OUTLOOK
----------------------
At 1000 PM CDT (0300 UTC), the center of Hurricane Helene was
located near latitude 23.1 North, longitude 86.6 West. Helene is
moving toward the north near 9 mph (15 km/h).  A northward or
north-northeastward motion at a faster forward speed is expected
during the next 36 hours.  On the forecast track, Helene will move
across the eastern Gulf of Mexico tonight and Thursday and cross the
Florida Big Bend coast Thursday evening.  After landfall, Helene is
expected to turn northwestward and slow down over the Tennessee
Valley on Friday and Saturday.

Maximum sustained winds are near 85 mph (140 km/h) with higher
gusts.  Strengthening is forecast, and Helene is expected to be a
major hurricane when it reaches the Florida Big Bend coast Thursday
evening.  Weakening is expected after landfall, but Helene's fast
forward speed will allow strong, damaging winds, especially in
gusts, to penetrate well inland across the southeastern United
States, including over the higher terrain of the southern
Appalachians.

Hurricane-force winds extend outward up to 35 miles (55 km) from the
center and tropical-storm-force winds extend outward up to 345 miles
(555 km).

The minimum central pressure reported by Hurricane Hunter aircraft 
is 972 mb (28.71 inches).

 

[wthrmn654]

Satellite images show that Helene has a well-organized appearance, 
with numerous convective banding features.  A ragged-looking eye 
feature is also apparent.  However, reports from both Air Force and 
a NOAA Hurricane Hunter aircraft investigating the system suggest 
that the it lacks a well-defined inner core with a somewhat broad 
maximum wind field for now.  The central pressure has dropped a 
little to around 972 mb.  Given the slowly falling central 
pressure, the intensity is maintained at 75 kt for this advisory.  
Helene's structure and intensity will continue to be closely 
monitored by Hurricane Hunter aircraft tonight and Thursday.

The hurricane continues moving northward with an estimated initial
motion of 360/08 kt.  For the next couple of days, the steering
scenario for this system remains basically unchanged from the
earlier advisory.  The flow between a mid-tropospheric trough over
the east-central United States and a ridge over the western
Atlantic should result in Helene accelerating northward to
north-northeastward during the next 24 to 36 hours. This motion 
will bring the center of Helene to the northeastern Gulf of Mexico 
coast in about 24 hours.  The official track forecast through 
landfall is very similar to the previous NHC prediction and remains 
close to the corrected consensus guidance. After landfall, the 
trough to the northwest of the tropical cyclone becomes a cutoff 
low, and Helene should turn leftward as it rotates around the low.  
In 3-4 days, the system should become a shallow extratropical 
cyclone within weaker steering currents.

Helene should be in an atmospheric and oceanic environment over the
eastern Gulf of Mexico that will be very conducive for 
strengthening.  The system is expected to traverse the Loop Current, 
which has especially high oceanic heat content.  This, along with 
fairly low vertical wind shear and a moist mid- to lower- 
tropospheric air mass, should likely result in rapid 
intensification before landfall.  The official forecast continues
to call for the hurricane to reach category 4 status tomorrow.  It 
should be noted that the HAFS-A and HAFS-B regional hurricane models 
show even more intensification than indicated here.

Helene is forecast to be a large major hurricane when it reaches the
Big Bend coast of Florida.   As a result, storm surge, wind, and
rainfall impacts will extend well away from the center and outside
the forecast cone, particularly on the east side.  In addition, the
fast forward speed when Helene moves inland will result in a far
inland penetration of strong winds over parts of the southeastern
United States, including strong gusts over higher terrain of the
southern Appalachians.  A higher-than-normal gust factor is 
indicated in the official forecast while Helene is inland.

[jbenedet]

18 minutes ago, 40/70 Benchmark said:

Slow and steady until dawn...then boom.

That boom moment is rapidly getting pulled forward. 
 

I.e. there is a subtle acceleration to the “steady” intensification happening at the moment.
 

 

[RU848789]

NHC not backing down on the Cat 4 forecast and hasn't really changed the projected track either, with landfall still likely between Apalachicola and Alligator Island tomorrow evening.  

 

FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 23.1N  86.6W   75 KT  85 MPH
 12H  26/1200Z 25.4N  86.1W   95 KT 110 MPH
 24H  27/0000Z 29.5N  84.5W  115 KT 130 MPH
 36H  27/1200Z 34.3N  84.7W   50 KT  60 MPH...INLAND
 48H  28/0000Z 36.7N  87.1W   30 KT  35 MPH...POST-TROP/EXTRATROP
 60H  28/1200Z 36.8N  88.5W   25 KT  30 MPH...POST-TROP/EXTRATROP
 72H  29/0000Z 36.7N  87.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 96H  30/0000Z 36.7N  84.9W   15 KT  15 MPH...POST-TROP/EXTRATROP
120H  01/0000Z...DISSIPATED

[Radtechwxman]

NHC not backing down on cat 4 landfall. But mentioning it's lacking inner core. If that doesn't develop overnight I don't see this hitting cat 4. Surprised they didn't mention the dry air issues plaguing it all day. 

[Amped]

1 minute ago, jbenedet said:

That boom moment is rapidly getting pulled forward. 
 

I.e. there is a subtle acceleration to the “steady” intensification happening at the moment.
 

 

Agreed the dry air source to the east has been effectively cut off by the band from the south wrapping up the east side of the storm. Any dry air left in the core is being mixed out by the minute.

[jbenedet]

22 minutes ago, WxWatcher007 said:

A new high risk (rainfall) for part of the panhandle tomorrow. FFW west of Tallahassee tonight. 

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
853 PM EDT Wed Sep 25 2024
Day 2
Valid 12Z Thu Sep 26 2024 - 12Z Fri Sep 27 2024

...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL IN interior Southeast U.S
with a primary focus across the Southern Appalachians where the
back end of our predecessor rainfall event (PRE) will still be
occurring. Further to the south, all eyes turn to Hurricane Helene
as the storm continues to move quickly through the Eastern Gulf
within the weakness created by the trough to the north. The
northern extent of Helene's tropical moisture will begin nosing
into the Gulf coast with PWAT anomalies steadily rising from 1-2
deviations above normal to as high as 4 deviations above normal by
the time it makes landfall on Thursday evening. Despite a fast
forward propagation, copious amounts of rainfall will impact the
Florida Panhandle over to the Big Bend with the feeder bands on the
eastern flank of the cyclone impacting the coastal areas of the
Florida Peninsula. Rainfall amounts between Panama City to
Tallahassee will reach between 8-12" with local maxima of up to 15"
possible within the axis of Helene's landfall as the storm moves
almost due north, perpendicular to the coastal plain. For this
reason, a High Risk was added to portions of the Florida
Panhandle/Big Bend, including the Tallahassee area, as well as
across Apalachicola.

By Thursday night into Friday morning, Helene will continue making
steady progress northward with a large rain shield capable of
dropping 3-6" of rainfall within the core of the cyclone in short
periods of time. A swath of 6+ inch totals will progress northward,
eventually cascading into the Atlanta metro and surrounding
locales generating a higher threat of flash flood potential within
the urban corridor. Areas in the path of Helene will undoubtedly
see significant flood potential with small rivers and streams
likely becoming inundated very quickly to exacerbate the flood
threat within the rural areas of Georgia. The recent HREF blended
mean QPF footprint is robust for the period with a large areal
extent of 5+ inches with the secondary maxima positioned across
Northeast GA where the next round of significant rains will
approach with Helene's core making an approach.

The situation across the Southern Appalachians is becoming
increasingly severe with regards to the ongoing flash flood threats
from the PRE 

We tried to tell em. 
 

I don’t see any mechanism for this to weaken until the center passes. Very serious situation evolving on the fresh water flooding front….

[SnowGoose69]

Looks like their first east adjustment in awhile, albeit not much

[user13]

Just now, SnowGoose69 said:

Looks like their first east adjustment in awhile, albeit not much

f I'm surprised they kept the due N peg. It does look like it's ticking east

[wthrmn654]

5 minutes ago, SnowGoose69 said:

Looks like their first east adjustment in awhile, albeit not much

Can't really tell if this shows the newsest nhc track but it gives the idea. 

[Master of Disaster]

How warm is the water ahead of this? I had a site years ago to find this but can't remember what it was. 

[wthrmn654]

1 minute ago, Master of Disaster said:

How warm is the water ahead of this? I had a site years ago to find this but can't remember what it was. 

It was posted already one or 2 times look at a page or 2 before this one

[Master of Disaster]

9 minutes ago, user13 said:

f I'm surprised they kept the due N peg. It does look like it's ticking east

That's pretty much Mexico Beach from Michael. 

[user13]

2 minutes ago, Master of Disaster said:

How warm is the water ahead of this? I had a site years ago to find this but can't remember what it was. 

87 right now

[jbenedet]

There was ~100 mile shift west to the landfall location on 0z Thurs guidance vs 18z wed.

[user13]

1 minute ago, jbenedet said:

There was ~100 mile shift west to the landfall location on 0z Thurs guidance vs 18z wed.

What's up, bro? Hope all is well

[jbenedet]

2 minutes ago, jbenedet said:

There was ~100 mile shift west to the landfall location on 0z Thurs guidance vs 18z wed. The shift is more than 200 Miles west up into central GA latitude

 

[WxWatcher007]

IR looks to be improving markedly the last hour or two, but let’s see if it actually holds.