Major Hurricane Florence: STORM MODE THREAD

[NJwx85]

2 minutes ago, csnavywx said:

The tendency is restrengthening after the completion of an EWRC, especially since it will be in ideal conditions over the next 48 hours.

If the HWRF/HMON are correct a large eye and surrounding wind field should emerge over the next 24 hours or so.

[jm1220]

EWRC's are a roll of the dice as to when they occur. Harvey blew up at a very bad time for the Corpus Christi area, other storms like Rita/Katrina peaked too early and were on a weakening trend as they came in. If overall shear increases as Florence comes ashore (maybe that should still be called an if, considering where the stall/loop may occur and how the ridge builds overhead), it may be enough to disrupt the overall environment for it to come down to maybe Fran-like intensity. If the shear doesn't materialize, there's little to stop it IMO from being Harvey or Hugo-like strength coming in. 

I'm guessing at a slightly rightward track from current, and coming ashore around Morehead City or over Pamlico Sound given the model trends today, but it's a guess. The Euro being steadfast on a further south track means something, and would be the more devastating scenario IMO. 

[Eskimo Joe]

27 minutes ago, TPAwx said:

Animate from here, h72 in Tropical Tidbits:

where is my captain

 

Thanks.  Those amounts are pretty tame compared to a few days ago.

[yotaman]

Carteret County NC is under mandatory evacuation beginning Tuesday. Pamlico County mandatory evacuations also starts tomorrow at 3pm. Both are for the entire county, all cities and towns.

[David Reimer]

Honestly, it looks like the EWRC may already be well underway. It'll be critical to see how long it takes for the inner eye-wall to disintegrate, as that is when the outer can become dominant. Once that process completes expect a broadening of the wind field and probably a decent pressure drop. Winds may take a while to respond upward to any pressure drop with a broader wind field. It has been a 'rubber-band' effect in previous intense hurricanes. The pressure drops considerably, but winds don't increase for a while - until the 'rubberband' breaks and you see a rapid uptick in winds in the eyewall. (This explanation was for those of the general public who may have wandered onto this forum) 

 

[bdgwx]

45 minutes ago, Jfreebird said:

Can someone explain why more models are showing a loop? This is the latest 00z (not sure if this is the correct form to ask in)

Sent from my SM-G930V using Tapatalk
 

The green tracks (TABS, TABM, TABD) are the beta-advection models. They use the mean flow of the GFS winds over different layers with a correction made for the beta drift. The different variations loop in different ways depending on how deep of steering flow you want to consider. S is for shallow, M is medium, and D is for deep. They loop largely because the GFS shows a breakdown of the steering flow. It's my understanding that a skilled forecaster can make some interesting inferences about the cyclone environment based on the TABx tracks. As a general rule you'll probably want to ignore them and instead focus on TVCN (or maybe TVCX). It is the consensus of the best track models which as of 2018 are an equal weighting of GFS, ECMWF, UKMET, HWRF, and COAMPS.

[SN_Lover]

6 minutes ago, bdgwx said:

The green tracks (TABS, TABM, TABD) are the beta-advection models. They use the mean flow of the GFS winds over different layers with a correction made for the beta drift. The different variations loop in different ways depending on how deep of steering flow you want to consider. S is for shallow, M is medium, and D is for deep. They loop largely because the GFS shows a breakdown of the steering flow. It's my understanding that a skilled forecaster can make some interesting inferences about the cyclone environment based on the TABx tracks. As a general rule you'll probably want to ignore them and instead focus on TVCN (or maybe TVCX). It is the consensus of the best track models which as of 2018 are an equal weighting of GFS, ECMWF, UKMET, HWRF, and COAMPS.

Also, the beta models can be run on your cell phone. they are not reliable. 

[Radtechwxman]

Excellent write up David. Florence has at least another 24-36hrs in a very favorable environment before it gets closer to land and stronger shear. So def could see it ramp up again. I think our next advisory will have either a weaker storm or holding where it is. I'm betting on slightly weaker

[DJnVa]

In SEVA, Chesapeake schools closed starting tomorrow due to some evacuations in the city, Norfolk as well. Virginia Beach not closing til Thursday, at least as of now.

[SN_Lover]

0z NAM is actually SW at 30. 

[friedmators]

3 minutes ago, SN_Lover said:

0z NAM is actually SW at 30. 

I mean it only initialized 30mb high.  Let's run with it!

[SN_Lover]

2 minutes ago, friedmators said:

I mean it only initialized 30mb high.  Let's run with it!

It's not that. Ridge is stronger...

[WhiteoutWX]

PBP of the NAM looking for track clues belongs in banter thread 

[Hoosier]

If we're going to be talking about the NAM, yes it is southwest of 18z, but the position at 66 hr is almost identical to the 12z run at 78 hr.  Just some context.

[yoda]

BULLETIN
Hurricane Florence Advisory Number  47
NWS National Hurricane Center Miami FL       AL062018
1100 PM AST Mon Sep 10 2018

...FLORENCE CHANGES LITTLE IN STRENGTH DURING THE PAST SEVERAL
HOURS...
...HURRICANE AND STORM SURGE WATCHES LIKELY TO BE ISSUED ON
TUESDAY...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.9N 62.4W
ABOUT 465 MI...750 KM SSE OF BERMUDA
ABOUT 1085 MI...1745 KM ESE OF CAPE FEAR NORTH CAROLINA
MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...944 MB...27.88 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.

Interests in the southeastern and mid-Atlantic states should monitor
the progress of Florence.  Storm Surge and Hurricane watches are
likely be issued for portions of these areas on Tuesday.


DISCUSSION AND OUTLOOK
----------------------
At 1100 PM AST (0300 UTC), the center of Hurricane Florence was
located near latitude 25.9 North, longitude 62.4 West.  Florence is
moving toward the west-northwest near 13 mph (20 km/h).  A west-
northwestward to northwestward motion and an increase in forward
speed are expected during the next couple of days.  On the forecast
track, the center of Florence will move over the southwestern
Atlantic Ocean between Bermuda and the Bahamas Tuesday and
Wednesday, and approach the coast of North Carolina or South
Carolina on Thursday.

Maximum sustained winds are near 140 mph (220 km/h) with higher
gusts.  Florence is a category 4 hurricane on the Saffir-Simpson
Hurricane Wind Scale.  Some strengthening is expected during the
next 36 hours, and Florence is expected to be an extremely dangerous
major hurricane through Thursday.

Hurricane-force winds extend outward up to 40 miles (65 km) from the
center and tropical-storm-force winds extend outward up to 150 miles
(240 km).

The latest minimum central pressure estimated from Air Force
Reserve Hurricane Hunter aircraft data is 944 mb (27.88 inches).


HAZARDS AFFECTING LAND
----------------------
SURF:  Swells generated by Florence are affecting Bermuda and
portions of the U.S. East Coast.  These swells are likely to cause
life-threatening surf and rip current conditions.  Please consult
products from your local weather office.


NEXT ADVISORY
-------------
Next complete advisory at 500 AM AST.

$$
Forecaster Beven

[yoda]

Hurricane Florence Discussion Number  47
NWS National Hurricane Center Miami FL       AL062018
1100 PM AST Mon Sep 10 2018

The rapid intensification of Florence ended just after the last
advisory, with the central pressure falling to near 939 mb.  Since
that time, the eyewall convection has become a bit ragged and the
latest central pressure from the Air Force Reserve Hurricane Hunter
aircraft is near 944 mb.  The initial intensity will remain a
possibly generous 120 kt for this advisory based on the aircraft
winds.  Microwave imagery suggests that Florence may be starting an
eyewall replacement cycle.  However, the winds from the Hurricane
Hunter did not clearly indicate the presence of an outer eyewall.

Florence should remain in a light shear environment and over sea
surface temperatures near 29C for at least the next 48 h.  Thus,
there is little other than eyewall replacement cycles to keep the
hurricane from intensifying further as indicated by all of the
intensity guidance.  The new intensity forecast calls for continued
strengthening to near category 5 strength, although at a slower rate
than what occurred during the last 30 h.  Florence is expected to
encounter southwesterly shear near the 72 h point, which could
cause slight weakening before landfall.  However, there remains high
confidence that Florence will be a large and extremely dangerous
hurricane, regardless of its exact intensity.

The initial motion is 290/11.  A building mid-level ridge over the
northwestern Atlantic is expected to steer Florence
west-northwestward to northwestward with an increase in forward
speed during the next 48 h.  After that time, a marked decrease in
forward speed is likely as another ridge builds over the Great
Lakes to the north of Florence.  The track guidance continues to
show some spread between the ECMWF on the left side of the envelope
and the GFS on the right side.  Overall, though, the guidance has
again shifted a little to the right, and the 72-96 h points are
nudged just a little to the right from the previous forecast.  It is
important not to focus on the exact forecast track as average NHC
errors at days 3, 4, and 5 are about 100, 140 and 180 n mi,
respectively, and dangerous hazards will extend well away from the
center.

The NOAA G-IV jet will continue to conduct synoptic surveillance
missions every 12 h through at least Wednesday. In addition, special
0600 UTC and 1800 UTC radiosonde launches have been expanded to
additional upper-air stations across the U.S. to collect extra data
for the numerical models.  The next Air Force Reserve Hurricane
Hunter mission into Florence is scheduled for near 12Z.

Key Messages:

1. A life-threatening storm surge is likely along portions of the
coastlines of South Carolina, North Carolina, and Virginia, and
a Storm Surge Watch will likely be issued for some of these areas by
Tuesday morning. 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 freshwater flooding is likely from a prolonged
and exceptionally heavy rainfall event, which may extend inland over
the Carolinas and Mid Atlantic for hundreds of miles 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 Watch
will likely be issued by Tuesday morning.  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  11/0300Z 25.9N  62.4W  120 KT 140 MPH
 12H  11/1200Z 26.5N  64.5W  125 KT 145 MPH
 24H  12/0000Z 27.9N  67.5W  130 KT 150 MPH
 36H  12/1200Z 29.6N  70.4W  135 KT 155 MPH
 48H  13/0000Z 31.3N  73.2W  130 KT 150 MPH
 72H  14/0000Z 34.0N  76.5W  120 KT 140 MPH
 96H  15/0000Z 35.5N  78.0W   50 KT  60 MPH...INLAND
120H  16/0000Z 36.5N  79.0W   25 KT  30 MPH...INLAND

$$
Forecaster Beven

[yoda]

NHC now has Florence making landfall between ILM and OBX on its 11pm track that it shifted slightly to the east per the 11pm NHC disco

[olafminesaw]

To kick off the 0z models, the ICON takes a pretty decent shift to the left with a landfall around Cape Lookout.

[ncskywarn]

New NHC track forecast take it from extream Western Wake County on the 5 pm update to Extream Eastern Wake County and over Wake Forest on the 11 pm track update.

[WidreMann]

4 minutes ago, olafminesaw said:

To kick off the 0z models, the ICON takes a pretty decent shift to the left with a landfall around Cape Lookout.

The great convergence has begun.

[40/70 Benchmark]

1 hour ago, David Reimer said:

Honestly, it looks like the EWRC may already be well underway. It'll be critical to see how long it takes for the inner eye-wall to disintegrate, as that is when the outer can become dominant. Once that process completes expect a broadening of the wind field and probably a decent pressure drop. Winds may take a while to respond upward to any pressure drop with a broader wind field. It has been a 'rubber-band' effect in previous intense hurricanes. The pressure drops considerably, but winds don't increase for a while - until the 'rubberband' breaks and you see a rapid uptick in winds in the eyewall. (This explanation was for those of the general public who may have wandered onto this forum) 

 

I think a best case scenario for the coast would have been a later ERC, but tough to tell for sure...could very well be another.

The ambient environment when the ERC begins is often a good indicator of how well it will recover, thereafter, so it will likely shrug it off tomorrow.

[Radtechwxman]

1 minute ago, 40/70 Benchmark said:

I think a best case scenario for the coast would have been a later ERC, but tough to tell for sure...could very well be another.

The ambient environment when the ERC begins is often a good indicator of how well it will recover, thereafter, so it will likely shrug it off tomorrow.

Convection already exploding around the center again. Starting to look more robust again. Not sure if ewrc finished but looks improved on satellite 

[hlcater]

Just now, StormChaser4Life said:

Convection already exploding around the center again. Starting to look more robust again. Not sure if ewrc finished but looks improved on satellite 

Could just be the diurnal minimum encouraging renewed convection and colder cloud tops.

[40/70 Benchmark]

1 minute ago, StormChaser4Life said:

Convection already exploding around the center again. Starting to look more robust again. Not sure if ewrc finished but looks improved on satellite 

ERC can sometimes be accompanied by like a 50mph decrease in winds....but I don't think this one will.

JMO.....sorry for the clutter.

[SENC]

SST's from Frying Pan Tower are at.. 87F to 86 on the beach.. that is all.. 

 

Gasoline

[ncskywarn]

GFS is a tad West of 18Z at hour 18. Ridge looks a like stronger lets see wherer it goes.

[WidreMann]

West trend continues through 27. May not be enough to avoid the loop.

[senc30]

Continued west through 54

[gjlp]

Just now, senc30 said:

Continued west through 54

Yup... more west/south and 8mb stronger than previous run

[ncskywarn]

GFS is West of at hour 54. Ridge is definitely stronger. Not sure it stays off the coast this run.