ATL: FLORENCE - Post-Tropical - Discussion

[FLpanhandle91]

Hurricane hunters finding multiple wind maxima in northeast eyewall.

[Ken711]

Can someone explain to me the following from the 11AM discussion in regards to potential change in track in days 3-5?

The shortwave trough over the southern Plains seen in water vapor imagery could end up being a significant factor as it rounds the narrow ridge over the Tennessee Valley and is expected to erode the ridge along the U.S. mid-Atlantic coast on days 3-5.

[sponger]

I noticed the forward speed dropped to 15.

[longhorn2004]

Just my opinion only, but just as I said yesterday, I think this will make landfall as a Cat 2 or Cat 3. But that is still an incredibly strong storm. So I hope everyone is prepared.

What factors will weaken it from the Cat 4/5 it is today? The cooler water near the shore? Shear?

[sponger]

Just my opinion only, but just as I said yesterday, I think this will make landfall as a Cat 2 or Cat 3. But that is still an incredibly strong storm. So I hope everyone is prepared.

What factors will weaken it from the Cat 4/5 it is today? The cooler water near the shore? Shear?

Upwelling colder water from below.

[meriland29]

Hurricane hunters finding multiple wind maxima in northeast eyewall.

https://www.tropicaltidbits.com/recon/recon_AF306-1106A-FLORENCE_timeseries.png

So another etc? Maybe she will just be stuck doing that till she hits..

[rolldamntoad]

https://twitter.com/MrTopStep/status/1039887739263623169

My father-in-law hates Sunbeam bread, so when Harvey was approaching and people left Sunbeam on the shelves, he used that in support of his argument.

[ronjon]

The problem with the stall is that the storm, even somewhat weaker, will continue to pile water up the rivers and sounds in NC northeast of the eyewall. I hope people evacuated these floodprone areas as the surge may occur over several high tide cycles and current projections are anywhere from 6 to 13 feet above ground. The tidal surge may also occur tens of miles inland of the coast on area rivers.

[supercane4867]

Multiple windmaxima may indicate Florence is attaining a multiple simultaneous eyewall structure, which may delay the start of next EWRC process.

[tarheelprogrammer]

This thing is going through a million eye wall replacement cycles. Cue the conspiracy theories I hope it continues. We need it much weaker.

[Ken711]

The shortwave trough over the southern Plains seen in water vapor imagery could end up being a significant factor as it rounds the narrow ridge over the Tennessee Valley and is expected to erode the ridge along the U.S. mid-Atlantic coast on days 3-5.

Does this mean Florence could now turn more west or northwest around the weakened high rather than move SW?

[ConvergenceZone]

Seems more likely at this point, but with a Cat 4 surge.

I agree. And a Cat 2 is still dangerous. And the flooding itself is going to be really really bad.

It depends on the exact location of initial landfall. If she makes landfall near Wilmington with faster foward speed it would likely remain a strong CAT3. If she stalls offshore and doesn't make the landfall until SC then it could weaken to a CAT1

I think for it have a shot as a Cat 3, it will need to get back to a mid Cat 4 status short term,then I think a Cat 3 landfall is possible

[edu2703]

 https://twitter.com/MJVentrice/status/1039895342609772544

[SconnieCane]

50 posts about how there are double wind maxima so it must be starting another EWRC...no, it's just completing the one that started several hours ago.

[dhweather]

Friendly reminder: Katrina was "only" a category 3 hurricane at Landfall in Mississippi. DO NOT UNDERESTIMATE FLORENCE. If your local officials say get out, then GET OUT.

[meriland29]

50 posts about how there are double wind maxima so it must be starting another EWRC...no, it's just completing the one that started several hours ago.

Yeah I am getting confused...

[GCANE]

https://twitter.com/MrTopStep/status/1039887739263623169

My father-in-law hates Sunbeam bread, so when Harvey was approaching and people left Sunbeam on the shelves, he used that in support of his argument.

Sunbeam bread with margarine - a sure killer.

[sittingduck]

I know someone else asked this question but hoping one of the smart peeps - well smarter than me at least - can translate this from the 11 am discussion. Thanks in advance

The
shortwave trough over the southern Plains seen in water vapor
imagery could end up being a significant factor as it rounds the
narrow ridge over the Tennessee Valley and is expected to erode the
ridge along the U.S. mid-Atlantic coast on days 3-5. At this time,
little change has been made to the NHC track forecast, which remains
very close to the aforementioned consensus aids through 72 hours.

[supercane4867]

Friendly reminder: Katrina was "only" a category 3 hurricane at Landfall in Mississippi. DO NOT UNDERESTIMATE FLORENCE. If your local officials say get out, then GET OUT.

And a much much weaker high-end TS can even bring conditions look like this

 https://twitter.com/ReedTimmerAccu/status/1037187875996160004

[GCANE]

For those without a decoder implanted in their brains.
Dewpoint increasing, another marker of an EWRC

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 12th day of the month at 15:26Z


A. Time of Center Fix: 12th day of the month at 14:57:20Z
B. Center Fix Coordinates: 29.93N 71.35W
D. Minimum Sea Level Pressure: 947mb (27.97 inHg)
F. Eye Character: Open in the south
G. Eye Shape & Diameter: Circular with a diameter of 28 nautical miles (32 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 99kts (113.9mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 21 nautical miles (24 statute miles) to the NE (53°) of center fix at 14:51:00Z
J. Maximum Flight Level Wind Inbound: From 138° at 123kts (From the SE at 141.5mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 24 nautical miles (28 statute miles) to the NE (52°) of center fix at 14:50:00Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 82kts (94.4mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 23 nautical miles (26 statute miles) to the SW (233°) of center fix at 15:14:30Z
N. Maximum Flight Level Wind Outbound: From 305° at 87kts (From the NW at 100.1mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 7 nautical miles to the WSW (245°) of center fix at 15:09:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 10°C (50°F) at a pressure alt. of 3,049m (10,003ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 16°C (61°F) at a pressure alt. of 3,047m (9,997ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 15°C (59°F)

Remarks Section:

Maximum Flight Level Wind: 123kts (~ 141.5mph) which was observed 24 nautical miles (28 statute miles) to the NE (52°) from the flight level center at 14:50:00Z