Major Hurricane Florence: STORM MODE THREAD

[David Reimer]

Hurricane Harvey taught many observers in meteorology all the way up to long-time meteorologists that sometimes the craziest weather model solutions actually end up verifying. At some point, one has to start accepting the possibility that something almost unheard of/not really experienced before may actually happen. This is becoming one of those situations where something crazy is probably going to happen. When two different global models and their ensembles show a similar solution for several runs in a row you have to start considering that idea. I honestly can't believe we're having to deal with this just a year after Harvey. Just mindboggling... 

Did South Carolina go through with their evacuation of the entire coastline? I certainly hope so - because the solution being depicted by the Euro ensembles would result in a significant coastal flood event for several hundred miles. You don't want to have a last-minute evacuation of several hundred thousand individuals. 

The next USAF recon flight should be departing from Savanah, GA in the next hour. We'll begin to have aircraft in the system for a majority of the day this afternoon as recon shifts to a 3-hour schedule (versus the 6-12 they've been on). 

[weathernerd]

As of 0430 the IR returns are showing her SW quad has become much better organized. Looking very menacing at the moment. 

[forecasterjack]

If we can get this ring of -70C cloud tops to close off and maintain itself around the eye, and if we can eliminate that dry air on the western side, whoever finds the core is gonna have some big time troubles down the line. Right on the cusp of taking it to the 'next level' IMO, we'll see if it actually happens. Link to where I got this image from: https://weather.us/satellite/692-w-301-n/top-alert-superhd-1min.html#play2

[Bhs1975]

Looks like the eye is tightening up.


.

[HillsdaleMIWeather]

NHC goes southwest, significantly increases rainfall because of the stall

[Rtd208]

This storm is going to be amazing to watch unfold. The Euro ensembles/EPS are just unreal.

[Windspeed]

564 
WTNT41 KNHC 120853
TCDAT1

Hurricane Florence Discussion Number  52
NWS National Hurricane Center Miami FL       AL062018
500 AM EDT Wed Sep 12 2018

The eye of Florence remains very distinct in infrared satellite
imagery this morning.  There has been little change to the cloud top
temperatures surrounding the eye overnight, however, the overall
cloud shield and central dense overcast has become slightly more
symmetric.  An Air Force Reserve Hurricane Hunter aircraft that was
in the hurricane until just after midnight measured a peak 700-mb
flight-level wind of 130 kt, and a SFMR wind of 107 kt in the
northeast eyewall.  A blend of these data and recent subjective and
objective satellite intensity estimates supports an initial wind
speed of 115 kt.  Florence will be moving over sea surface
temperatures of around 29C and through an area of low vertical wind
shear during the next day or so.  These conditions favor some
strengthening, but eyewall replacement cycles could cause some
fluctuations in intensity during that time. After that time, an
increase in southwesterly shear, upwelling, and interaction with
land is likely to lead to some weakening, however, Florence is
expected to remain a dangerous major hurricane as it approaches the
coastline.  The new NHC intensity forecast is near the higher
statistical guidance through 48 hours, then follows the trend of
the decay SHIPS model after that time.

Florence is moving west-northwestward or 300 degrees at 15 kt.
There has been no change to the track forecast or reasoning for the
first 36-48 hours, as Florence will continue to be steered
west-northwestward to northwestward around the southwestern portion
of a mid-level ridge centered northeast of Bermuda.  By late
Thursday, a mid-level ridge is forecast to begin building over the
east-central United States, which is expected to cause Florence
to slow down significantly by 48 hours.  The track guidance is in
good agreement through the first couple of days of the forecast
period, and the NHC track forecast again brings the center of the
hurricane very close to the coasts of North and South Carolina
within 48 hours.  Later in the period, the dynamical model spread
increases but most of the guidance has continued its southward
shift, and now take Florence southwestward near the coast of South
Carolina by day 4.  The NHC track has been adjusted southward at
days 4 and 5, and is a little north of the consensus out of respect
for continuity, however, the GFS, ECMWF, and the ECMWF ensemble mean
is south of the NHC track forecast, and additional southward
adjustment may be warranted in future advisories.

It is important for users to realize that significant impacts extend
well away from the center of Florence, and serious hazards such as
a dangerous storm surge and flooding rains will cover a large area
regardless of exactly where the center moves.

Key Messages:

1. A life-threatening storm surge is now highly likely along
portions of the coastlines of South Carolina and North Carolina, and
a Storm Surge Warning is in effect for a portion of this area.  All
interests from South Carolina into the mid-Atlantic region should
complete preparations and follow any advice given by local
officials.

2. Life-threatening, catastrophic flash flooding and significant
river flooding is likely over portions of the Carolinas and
Mid-Atlantic states from late this week into early next week, as
Florence is expected to slow down as it approaches the coast and
moves inland.

3. Damaging hurricane-force winds are likely along portions of the
coasts of South Carolina and North Carolina, and a Hurricane Warning
is in effect.  Strong winds could also spread inland into portions
of the Carolinas.

4. Large swells affecting Bermuda and portions of the U.S. East
Coast will continue this week, resulting in life-threatening surf
and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  12/0900Z 29.0N  70.1W  115 KT 130 MPH
 12H  12/1800Z 30.3N  72.1W  120 KT 140 MPH
 24H  13/0600Z 32.0N  74.4W  125 KT 145 MPH
 36H  13/1800Z 33.2N  76.1W  120 KT 140 MPH
 48H  14/0600Z 33.8N  77.3W  105 KT 120 MPH...NEAR THE COAST
 72H  15/0600Z 33.8N  78.2W   85 KT 100 MPH...NEAR THE COAST
 96H  16/0600Z 33.6N  79.7W   45 KT  50 MPH...INLAND
120H  17/0600Z 34.2N  82.7W   25 KT  30 MPH...INLAND

$$
Forecaster Brown

 

[Windspeed]

5 AM EDT graphic.

[Rtd208]

 

[Jaguars]

Unreal there’s even the possibility that people in North Florida could end up dealing with a hurricane approaching from the north.

[MattPetrulli]

Anyone else think the 9-13 ft surge estimates are underdone somewhat?

[RUNNAWAYICEBERG]

Worst case scenario for SE coastal communities unfolding. Surge and flooding rains relentless for days. 

[CoastalWx]

Yeah it's looking more of possible surge and fresh water flooding impact, vs wind damage. They'll be wind issues, but I think that's the not biggest problem.

[forecasterjack]

Had a few minutes there where the convective appearance seemed for the first time so far to be A+. But thankfully, we're back down to a degraded and lopsided storm. -70C tops are to the SE, with the -60 ring barely hanging on in the NW quad. Perhaps an artifact of Florence moving too fast, a la Gordon in the GOM? Watching closely (1min GOES-16 link in case you don't already have one or are looking for a new one: https://weather.us/satellite/692-w-301-n/top-alert-superhd-1min.html#play2)

[hooralph]

6 minutes ago, CoastalWx said:

Yeah it's looking more of possible surge and fresh water flooding impact, vs wind damage. They'll be wind issues, but I think that's the not biggest problem.

We tend to fetishize landfall intensity but the costliest and deadliest mainlaind storms of modern times were:

• A rapidly weakening Cat 3 (even that was generous)
• A hybrid Cat 1
• A former Cat 4 that looped as a TS for days.

All with unique characteristics. This one has plenty of its own for sure. Multiple high-tide cycles and feet of rain on the coast will deliver unprecedented conditions to someone.

[Amos83]

3 hours ago, David Reimer said:

Hurricane Harvey taught many observers in meteorology all the way up to long-time meteorologists that sometimes the craziest weather model solutions actually end up verifying. At some point, one has to start accepting the possibility that something almost unheard of/not really experienced before may actually happen. This is becoming one of those situations where something crazy is probably going to happen. When two different global models and their ensembles show a similar solution for several runs in a row you have to start considering that idea. I honestly can't believe we're having to deal with this just a year after Harvey. Just mindboggling... 

Did South Carolina go through with their evacuation of the entire coastline? I certainly hope so - because the solution being depicted by the Euro ensembles would result in a significant coastal flood event for several hundred miles. You don't want to have a last-minute evacuation of several hundred thousand individuals. 

The next USAF recon flight should be departing from Savanah, GA in the next hour. We'll begin to have aircraft in the system for a majority of the day this afternoon as recon shifts to a 3-hour schedule (versus the 6-12 they've been on). 

They did not. The SC Gov. cancelled the mandatory evacuation for the southern coastal counties yesterday morning.

[friedmators]

943.8i/110 SFMR per recon.  Quite surprised shes still this strong with the IR temps being shown.

[Earthling]

4 hours ago, forecasterjack said:

Another pretty crazy Euro run with the center meandering 5-10 miles offshore, while the NE quad scours the coast from Jacksonville to Wilmington and then beyond. Storm a little weaker on its SW drift compared to yesterday, probably reasonable given upwelling. Free/sharable ECMWF via https://weather.us/model-charts/euro/785-w-343-n/gusts-3h-mph/20180914-2100z.html 

 

 

 

 

Isn't that path off of SC right over the gulf stream?

[Suncat]

1 minute ago, Earthling said:

Isn't that path off of SC right over the gulf stream?

Yes, it looks like the model wants the storm to travel against the gulf stream current.

[Buddy1987]

7 minutes ago, Suncat said:

Yes, it looks like the model wants the storm to travel against the gulf stream current.

Makes sense. Follow the path of least resistance. I could def see that being a plausible scenario. Would be catastrophic for the entire SC coast. CHS airport closes at midnight tonight. 

[Earthling]

9 minutes ago, Suncat said:

Yes, it looks like the model wants the storm to travel against the gulf stream current.

Then the upwelling would still be some mighty warm water.

[mappy]

beautiful

 

[RamblinRed]

The 8 am update has the pressure down to 943 MB.

Also, if the storm follows the recent Euro run I don't think GA is really prepared for that. The preparations in GA have not been nearly as substantial as the Carolinas.

That run where it goes up over central GA would have it going right over Atlanta which has over 6M people.

[MJO812]

The saving grace will be if the storm stalls just offshore and weakens as it moves southwest.

[CoastalWx]

Eye is decent, I think that satellite image is a bit older and skewed. Some nice recent images on the TT page.

[NJwx85]

[NJwx85]

2 minutes ago, CoastalWx said:

Eye is decent, I think that satellite image is a bit older and skewed. Some nice recent images on the TT page.

The end of the loop is less than an hour old, but point taken.

[DopplerWx]

2 minutes ago, NJwx85 said:

The eye is starting to look a bit ragged again

 

looks fine to me, -60c cloud tops surrounding it with on -70s on the western side trying to wrap around.

https://weather.us/satellite/692-w-301-n/top-alert-superhd-1min/20180912-1236z.html

[CoastalWx]

1 minute ago, NJwx85 said:

The end of the loop is less than an hour old, but point taken.

It's cool...was just noting the nice floater stuff that TT has. 

[SomeguyfromTakomaPark]

1 minute ago, NJwx85 said:

The end of the loop is less than an hour old, but point taken.

https://weather.cod.edu/satrad/exper/?parms=meso-meso1-14-48-0-100-1&checked=map&colorbar=undefined

It looks remarkably symmetrical here.