Major Hurricane Florence: STORM MODE THREAD

[ag3]

4 minutes ago, jayson said:

It will be, but it will also be a blessing for interior NC/SC where they were showing 2-3 feet of rain this time yesterday. 

I am going to go out on a limb and say that if this blocking pattern sets up this strongly at the coast, I would expect Flo to weaken pretty significantly in the run-up to the coast, likely losing major hurricane status pretty quickly.

The majority of the EPS members are category 1s or 2s as they slow and stall.

[ChineseFood4Snow]

On Flight Radar 24 I see NOAA49 out of Lakeland heading in.

[Santa Clause]

Good deal of EPS seem to weaken Florence below major level during the slowdown and stall...just another scenario on the dry erase board.

[40/70 Benchmark]

8 minutes ago, ag3 said:

The majority of the EPS members are category 1s or 2s as they slow and stall.

Exactly what I was thinking.

Thanks.

[RUNNAWAYICEBERG]

Good trends if you want to save property and lives inland. 

[jayson]

2 minutes ago, RUNNAWAYICEBERG said:

Good trends if you want to save property and lives inland. 

Yes, and I would argue that most homes on the coast would be ok in a non-major hurricane. Codes have improved greatly over the years.

The flooding however...

[CLTwx]

Alans update....

[eaglesin2011]

https://www.star.nesdis.noaa.gov/GOES/CONUS_band.php?sat=G16&band=09&length=96

Me thinks that system in the gulf gonna have something to do with where Flo goes in the end.... Def starting to blow up down there

[Windspeed]

Images Me thinks that system in the gulf gonna have something to do with where Flo goes in the end.... Def starting to blow up down there.

This really needs its own thread vs lagging down the main thread. 

Edit: Thanks for fixing and embedding one main animated url image versus 20+.

 

 

 

 

 

 

 

 

 

 

 

[SnowGoose69]

Forecast will probably change multiple times.  The ridging issue is apparent again though.  Undermodeled by most guidance beyond 48-60.  That is ultimately perhaps why more than anything we are seeing the stall now.   It’s not so much the forward speed because two days ago the slow forward speed was the primary reason for the stall.  Now the forward speed over the next couple of days is faster than expected a couple days ago, but because of the ridge the system makes a westward bend and that west bend allows time for the steering flow to weaken and the storm to stall.    It’s entirely possible if that ridge strength increases on further runs this may not come anywhere near NC at all and may stall well off SC and then eventually back in

[Roger Smith]

Despite the generally good performance of models recently in tracking hurricanes 72-96 hours out, is it not true that most of the errors have been actual tracks further right than forecast? I can think of several recent examples, and cannot recall a storm that went left of its predicted track around eastern U.S. landfall. So that might argue for some caution in this consensus about a southward drift and high impacts around Wilmington into SC. The typhoon that recently hit Japan was also a little to the right of its model track despite ominous signs at 48h that it might actually come in west (left). This one may prove to be an exception however. 

[yoda]

BULLETIN
Hurricane Florence Advisory Number  50
NWS National Hurricane Center Miami FL       AL062018
500 PM AST Tue Sep 11 2018

...DANGEROUS FLORENCE EXPECTED TO BRING LIFE-THREATENING STORM
SURGE AND RAINFALL TO PORTIONS OF THE CAROLINAS AND MID-ATLANTIC...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...27.5N 67.1W
ABOUT 360 MI...580 KM SSW OF BERMUDA
ABOUT 785 MI...1260 KM ESE OF CAPE FEAR NORTH CAROLINA
MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...945 MB...27.91 INCHES


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

A Storm Surge Warning has been issued from South Santee
River, South Carolina, to Duck, North Carolina, and the Albemarle
and Pamlico Sounds, including the Neuse and Pamlico Rivers.

A Hurricane Warning has been issued from South Santee
River, South Carolina, to Duck, North Carolina, and the Albemarle
and Pamlico Sounds.

A Tropical Storm Watch has been issued from north of the North
Carolina/Virginia border to Cape Charles Light, Virginia, and for
the Chesapeake Bay south of New Point Comfort.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* South Santee River South Carolina to Duck North Carolina
* Albemarle and Pamlico Sounds, including the Neuse and Pamlico
Rivers

A Storm Surge Watch is in effect for...
* Edisto Beach South Carolina to South Santee River South Carolina
* North of Duck North Carolina to the North Carolina/Virginia border

A Hurricane Warning is in effect for...
* South Santee River South Carolina to Duck North Carolina
* Albemarle and Pamlico Sounds

A Hurricane Watch is in effect for...
* Edisto Beach South Carolina to South Santee River South Carolina
* North of Duck North Carolina to the North Carolina/Virginia border

A Tropical Storm Watch is in effect for...
* North of the North Carolina/Virginia border to Cape Charles Light
Virginia
* Chesapeake Bay south of New Point Comfort

Interests elsewhere in the southeastern and mid-Atlantic states
should monitor the progress of Florence.  Additional watches and
warnings may be required tonight or Wednesday.

[mempho]

1 hour ago, TriPol said:

Has there ever been a storm that's stalled right before making landfall in the Carolinas?

I remember Felix- the 1995 version....it had an almost due west heading coming in and it stalled and looped.  

[yoda]

NHC not buying the stall and SW movement in their 5pm map

 

[DopplerWx]

CDO really expanding the last few frames.

https://www.tropicaltidbits.com/sat/satlooper.php?region=06L&product=ir

[beanskip]

NHC pretty much discounts 12z Euro -- still has Florence on shore north of Cape Fear by Friday. Probably as good of a strategy as any. They are in a total no-win here.

[harrisale]

5 minutes ago, yoda said:

NHC not buying the stall and SW movement in their 5pm map

I suspect they will wait at least another 24 hours before modifying the public forecast to reflect this... if indeed this 'trend' remains on the models. Not enough confidence in a stall just yet to change the cone so dramatically. Could send a confusing message. Though they did add more of a west turn to the cone once the storm moves inland.

[jpeters3]

CDO is starting to look a lot more symmetric.  Looks like the brief uptick in shear this AM is abating (per the CIRA product).

 

Edit: that's odd, it seems to have embedded an older version of the shear product than what is currently displayed on the website.  There has been a downtick in the 200-850 hPa shear over the past 6 hours.

The latest microwave pass shows improvement in the inner core structure as well:
 

[NavarreDon]

NHC not buying the stall and SW movement in their 5pm map
 

This would be a bad setup for the Mnts in WNC especially along the escarpment!




.

[Hoosier]

10 minutes ago, yoda said:

NHC not buying the stall and SW movement in their 5pm map

 

NHC has it at 115 mph at 2 pm Fri, around the time of forecasted landfall.

[Windspeed]

545 
WTNT41 KNHC 112056
TCDAT1

Hurricane Florence Discussion Number  50
NWS National Hurricane Center Miami FL       AL062018
500 PM AST Tue Sep 11 2018

Microwave satellite data indicate that Florence completed a full
eyewall replacement cycle (ERC) a few hours ago, and recent visible
and infrared imagery suggests that the eye has contracted slightly.
Outflow continues to expand in all quadrants, and the outflow jets
to the northwest and east have become better defined. Satellite
intensity estimates from TAFB, SAB, and UW-CIMSS ADT are all
T6.0/115 kt, and recent NHC objective intensity estimates are
T6.2/120 kt. Given that the eye has mostly cleared out and has also
warmed to near 19 deg C, the initial intensity has been bumped
upward to 120 kt, which could be conservative. All of the wind radii
had to be expanded/increased based on a blend of the earlier
reconnaissance data and a 1430 UTC ASCAT scatterometer pass.

The initial motion estimate is now 300/15 kt. There remains no
significant to the previous track forecast or reasoning. Overall,
the global and regional models have done a good job capturing the
evolving synoptic- scale flow pattern across CONUS, with an
amplifying trough moving onshore the the northwestern U.S. coast,
which is inducing downstream ridging across the northeastern U.S.
and the northwestern Atlantic Ocean. Water vapor imagery indicates
that the blocking high pressure northwest of Bermuda is continuing
to build and shift slowly eastward. The 12Z GFS model made a
significant shift to the west, the UKMET made a shift to the east,
and the ECMWF track has remained basically unchanged through 72
hours. As a result the consensus models have made only minor track
shifts to the west. What is noticeable is that all of the global and
regional models are indicating that the steering currents will
collapse by 72 h when Florence is approaching the southeast U.S.
coast. The weak steering currents are expected to continue through
the weekend, which makes the forecast track on days 3-5 quite
uncertain. The latest NHC forecast track is very similar to the
previous two advisory tracks, and lies the middle of the guidance
envelope between the consensus models TVCA to the north and the HCCA
and FSSE models to the south.

During the next 24 hours or so, Florence is expected to remain in a
very favorable environment consisting of low shear near 5 kt, an
expanding upper-level outflow pattern, and above-average SSTs of
29.0-29.5 deg C, which should result in additional strengthening.
By 48 h, the decreasing forward speed along with the large
inner-core wind field should induce some upwelling and gradual
weakening. Although the GFS- and ECMWF-based SHIPS intensity models
are indicating an increase in the southwesterly shear to near 20 kt,
this could be due to the SHIPS model capturing Florence's own
strong outflow from the GFS and ECMWF model fields. Despite the
weakening shown at 72 hours, Florence is still expected to remain a
dangerous hurricane through landfall. After Florence moves inland,
the slow forward speed of less than 5 kt should cause a rapid spin
down and weakening of the hurricane's circulation. The new NHC
intensity forecast is a little above the highest guidance based on
the aforementioned very favorable synoptic outflow pattern, and to
maintain continuity with the previous forecast.

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
ensure they have their hurricane plan in place 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
has been issued for a part of this area.  Damaging winds could also
spread well inland into portions of the Carolinas and Virginia.

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  11/2100Z 27.5N  67.1W  120 KT 140 MPH
 12H  12/0600Z 28.7N  69.3W  130 KT 150 MPH
 24H  12/1800Z 30.4N  72.1W  135 KT 155 MPH
 36H  13/0600Z 32.1N  74.5W  130 KT 150 MPH
 48H  13/1800Z 33.4N  76.2W  120 KT 140 MPH
 72H  14/1800Z 34.5N  77.7W  100 KT 115 MPH...NEAR THE COAST
 96H  15/1800Z 35.0N  78.8W   40 KT  45 MPH...INLAND
120H  16/1800Z 35.7N  81.7W   25 KT  30 MPH...INLAND

$$
Forecaster Stewart

 

[5speed6]

16 minutes ago, harrisale said:

Though they did add more of a west turn to the cone once the storm moves inland.

Consensus line is south of the 2:00 guidance, too. 

[Radtechwxman]

They also said the intensity assigned at this outlook may have been conservative. So I'm guessing they derived it from satellite estimates. I thought they used hurricane hunters at least for the major updates at 5am, 11am, 5pm, 11pm? When are they supposed to fly in Florence again? 

[Chicago Storm]

CDO is once again fairly lopsided, with cloud tops on the western side showing steady warming.

Shear is definitely still an issue.

[ncskywarn]

It's early but GFS is a little Northeast of 12Z at hour 24 Edit: Even more NE at 36 ridge is not as strong.

[ncskywarn]

Stalled out between Wilmington & Morehead City at hour 66. Edit: Still sitting there at hour 78.

[ncskywarn]

Neven made landfall moving SW at 108 off shore between Myrtle Beach & Charleston very Euro like.

[negative-nao]

2 minutes ago, ncskywarn said:

Neven made landfall moiing SW at 108 off shore between Myrtly Beach & Charleston very Euro like.

I think the GFS is playing catch up. Lets see if this trend continues

[CoastalWx]

Gfs and euro look like a running back trying to find a hole.  

[CoastalWx]

Loop H5 on the models. Boy what a tricky setup. That piece of vorticity at edge of s/w trough southeast of Maine is a precarious setup. Those pieces diving southwest can be tough to model. Especially when 20 miles means the eyewall onshore or offshore.