Hurricane Francine

[GaWx]

Per this Francine is about to be designated:

AL, 06, 2024090912, , BEST, 0, 227N, 947W, 45, 1002, TS, 34, NEQ, 40, 100, 140, 140, 1008, 180, 70, 0, 0, L, 0, , 0, 0, FRANCINE, S, 0, , 0, 0, 0, 0, genesis-num, 014,

[NorthHillsWx]

1 hour ago, olafminesaw said:

Not your typical  hurricane!

This is an absolutely insane look for early September but ventilation to the NE won’t be a problem lol

[NorthHillsWx]

35 minutes ago, GaWx said:

Per this Francine is about to be designated:

AL, 06, 2024090912, , BEST, 0, 227N, 947W, 45, 1002, TS, 34, NEQ, 40, 100, 140, 140, 1008, 180, 70, 0, 0, L, 0, , 0, 0, FRANCINE, S, 0, , 0, 0, 0, 0, genesis-num, 014,

For what it’s worth at range banding features appear to be increasingly evident on Brownsville radar 

[BoulderWX]

Plots by Model via Allan Huffman

[GaWx]

WTNT31 KNHC 091455
TCPAT1

BULLETIN
Tropical Storm Francine Advisory Number 4
NWS National Hurricane Center Miami FL AL062024
1000 AM CDT Mon Sep 09 2024

...DISTURBANCE BECOMES TROPICAL STORM FRANCINE...
...EXPECTED TO INTENSIFY WITH STORM SURGE AND HURRICANE WATCHES
ISSUED FOR THE LOUISIANA COAST...


SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...23.0N 94.9W
ABOUT 245 MI...395 KM SE OF MOUTH OF THE RIO GRANDE
ABOUT 480 MI...770 KM SSW OF CAMERON LOUISIANA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES


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

A Storm Surge Watch has been issued from east of High Island, 
Texas, eastward to the Mississippi/Alabama Border, including 
Vermilion Bay, Lake Maurepas, and Lake Pontchartrain. 

A Hurricane Watch has been issued from Cameron eastward to Grand
Isle in Louisiana.

A Tropical Storm Watch has been issued east of High Island, Texas, 
to Cameron, Louisiana, and from Grand Isle, Louisiana, to the Mouth 
of the Pearl River including Lake Pontchartrain and Lake Maurepas.
 

[GaWx]

Tropical Storm Francine Discussion Number   4
NWS National Hurricane Center Miami FL       AL062024
1000 AM CDT Mon Sep 09 2024

The structure of the system on satellite imagery has improved this 
morning, with a large circular region of cold convection between -70 
to -85 near the estimated center. An Air-Force Reconnaissance 
Aircraft is sampling the system this morning and earlier found a 
cyclonic wind shift from southeasterly to northwesterly flow near 
the center of the mass of deep convection. This data provides enough 
evidence that a well-defined circulation now exists, and thus PTC 
Six has become Tropical Storm Francine with sustained winds of    
45 kt this advisory.

The estimated motion is still tricky given the center only recently 
formed but is estimated still off to the north-northwest at    340/4 
kt. The system is expected to gradually turn northward and then 
north-northeastward as it moves between a mid-level ridge centered 
over Cuba and a broad mid- to upper-level trough located to its 
northwest over Texas. The guidance this cycle has shifted a little 
eastward and faster, and the NHC track forecast was once again 
nudged in that direction. The current track splits the difference 
between HCCA and TVCN and still shows Francine moving ashore of 
Louisiana sometime on Wednesday evening. There remains a decent 
amount of track uncertainty with the GEFS and EPS ensembles showing 
along-track spread implying some speed differences near landfall. 

While the system is now a tropical storm, the inner core wind field 
per reconnaissance observations is still broad and in the organizing 
stage, and initial intensification will be gradual. However, after 
an inner-core becomes established, and assuming the cyclone's 
vertical structure becomes aligned, a period of more significant 
intensification is possible while storm is embedded in a low shear, 
high mid-level moisture, and over very warm 30-31 C sea-surface 
temperatures.  The SHIPS rapid intensification (RI) indices are 
pretty elevated, and a period of RI could also occur between   24-48 
h. For now, the NHC intensity forecast will not explicitly forecast 
RI, but is higher than the previous cycle and shows a 75 kt peak in 
48 h, in good agreement with the intensity consensus aids. After 
that period, southwesterly vertical wind shear quickly increases 
from 10 kt to more than 30 kt and the intensity could plateau as it 
approaches the northwestern U.S. Gulf coastline, though the system 
is forecast to remain a hurricane at landfall. The NHC intensity 
forecast continues to be in good agreement with the consensus aids, 
but is a bit under the HAFS-A/B and COAMPS-TC models.

FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 23.0N  94.9W   45 KT  50 MPH
 12H  10/0000Z 24.0N  95.4W   50 KT  60 MPH
 24H  10/1200Z 24.9N  95.7W   55 KT  65 MPH
 36H  11/0000Z 26.3N  95.0W   65 KT  75 MPH
 48H  11/1200Z 28.0N  93.5W   75 KT  85 MPH
 60H  12/0000Z 29.7N  92.2W   75 KT  85 MPH...ON THE COAST
 72H  12/1200Z 32.4N  90.7W   35 KT  40 MPH...INLAND
 96H  13/1200Z 36.2N  89.6W   25 KT  30 MPH...POST-TROPICAL
120H  14/1200Z 37.5N  88.8W   20 KT  25 MPH...POST-TROPICAL

$$
Forecaster Papin

[CurlyHeadBarrett]

What a cheeky monkey

[WxWatcher007]

Not sure when we’ll get a VDM, but recon is finding a much tighter and more organized center in that deep convection. Winds aren’t terribly strong, but it’s the organization that matters. 

[salbers]

James van Fleet video with SRFS model discussion:

https://x.com/SpireWxClimate/status/1833165234900451340

[WxWatcher007]

I’ll be interested in seeing 18z more because I think the recon data will be included, but as the NHC notes the SHIPS output is quite robust. 

[wthrmn654]

00z versus actual,  shows verification versus forecasted and what has happened intensity wise.

[wthrmn654]

And this is 12z intensity forecast. 

[wthrmn654]

[wthrmn654]

[GaWx]

12Z UKMET: comes into LA a little further E and slightly stronger (990) vs 0Z (993). Then goes NE to just N of L Ponch. to MS/AL border, where it turns N into W KY. Afterward it turns NE into Indiana, where it finally dissipates:

TROPICAL STORM 06L        ANALYSED POSITION : 22.7N  93.9W

     ATCF IDENTIFIER : AL062024

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 09.09.2024    0  22.7N  93.9W     1004            38
    0000UTC 10.09.2024   12  23.8N  95.7W     1000            39
    1200UTC 10.09.2024   24  24.8N  95.3W      998            39
    0000UTC 11.09.2024   36  26.5N  94.2W      994            35
    1200UTC 11.09.2024   48  28.3N  92.4W      992            46
    0000UTC 12.09.2024   60  30.3N  90.0W      990            37
    1200UTC 12.09.2024   72  32.6N  88.8W      994            29
    0000UTC 13.09.2024   84  35.6N  88.3W      996            20
    1200UTC 13.09.2024   96  36.9N  88.7W     1000            16
    0000UTC 14.09.2024  108  38.1N  87.0W     1006            27
    1200UTC 14.09.2024  120  40.0N  86.8W     1009            21
    0000UTC 15.09.2024  132  40.1N  86.7W     1010            18
    1200UTC 15.09.2024  144              CEASED TRACKING

[WxWatcher007]

A substantial drop in extrapolated pressure between passes on that new apparent center under the deep convection. From just over 1001mb to 995.6mb. Again this extrapolated, so more of an estimate. Still, that’s very impressive. 

[gymengineer]

3 minutes ago, WxWatcher007 said:

A substantial drop in extrapolated pressure between passes on that new apparent center under the deep convection. From just over 1001mb to 995.6mb. Again this extrapolated, so more of an estimate. Still, that’s very impressive. 

Dropsonde verifies- 996 mb on a 5-kt surface wind. 

[Witness Protection Program]

Isn't a large major approaching on the eastern edge of the current cone considered the worst case scenario for New Orleans, at least for storm surge?

Not that I expect everything to come together for that, just seem to recall that was the findings of a study an LSU professor did years before Katrina.

[BoulderWX]

Circulation becoming more evident on Brownsville Radar. I think she tops out around 90mph before weakening before landfall due to some pretty strong shear 

[NorthHillsWx]

Brownsville radar actually shows a very strong circulation embedded out there. Not sure that’s the one NHC is tracking, looks like multiple centers in a gyre 

[Normandy]

19 minutes ago, NorthHillsWx said:

Brownsville radar actually shows a very strong circulation embedded out there. Not sure that’s the one NHC is tracking, looks like multiple centers in a gyre 

No question this is the center.  Very clear eye like feature

 

[WxWatcher007]

1 minute ago, Normandy said:

No question this is the center.  Very clear eye like feature

 

For now at least, there’s a nascent eyewall. 
 

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 9th day of the month at 17:22Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF98-5308
Tropical Depression: Six (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 08 ( See all messages of this type for this mission. )

A. Time of Center Fix: 9th day of the month at 16:45:10Z
B. Center Fix Coordinates: 23.69N 95.85W
B. Center Fix Location: 186 statute miles (299 km) to the SE (146°) from Brownsville, TX, USA.
C. Minimum Height at Standard Level: 1,387m (4,551ft) at 850mb
D. Minimum Sea Level Pressure: 996mb (29.42 inHg)
E. Dropsonde Surface Wind at Center: From 140° at 5kts (From the SE at 6mph)
F. Eye Character: Open in the west
G. Eye Shape & Diameter: Circular with a diameter of 20 nautical miles (23 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: Not Available
I. Location & Time of the Estimated Maximum Surface Wind Inbound (Undecoded): NA
J. Maximum Flight Level Wind Inbound: From 308° at 31kts (From the NW at 35.7mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 6 nautical miles to the SW (219°) of center fix at 16:43:30Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 47kts (54.1mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 55 nautical miles (63 statute miles) to the NE (47°) of center fix at 17:02:00Z
N. Maximum Flight Level Wind Outbound: From 133° at 58kts (From the SE at 66.7mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 12 nautical miles (14 statute miles) to the NE (44°) of center fix at 16:49:00Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,523m (4,997ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,524m (5,000ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 18°C (64°F)
R. Sea Surface Temp (collected at same location as temp inside eye): Not Available
S. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
S. Fix Levels (surface & flight level centers within 5nm of each other): Surface and 850mb
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 1 nautical mile

Remarks Section:
 

Maximum Flight Level Wind: 58kts (~ 66.7mph) which was observed 12 nautical miles (14 statute miles) to the NE (44°) from the flight level center at 16:49:00Z

[Floydbuster]

Wow nice shape, Francine!

[NorthHillsWx]

16 minutes ago, Normandy said:

No question this is the center.  Very clear eye like feature

 

Recon found another broad circulation SE of this. While this may take over as the overall center, there are some issues with the overall storm structure still as it’s organizing. If this center becomes distinct it could intensify at a more rapid pace as it’s firmly embedded under an apparent cdo. Wouldn’t jump the gun on this going bangers yet. Also this center appears to be moving west or west southwest seemingly within the broad center.

[WxWatcher007]

Just now, NorthHillsWx said:

Recon found another broad circulation SE of this. While this may take over as the overall center, there are some issues with the overall storm structure still as it’s organizing. If this center becomes distinct it could intensify at a more rapid pace as it’s firmly embedded under an apparent cdo. Wouldn’t jump the gun on this going bangers yet. Also this center appears to be moving west or west southwest seemingly within the broad center.

Yeah I think it’s one of those things where the broader circulation isn’t quite aligned with whatever lower level center wants to become the primary. I think given recon and radar that the area seeing significant pressure drops NW of the original low level spin is the leader in the clubhouse, but there’s still some organizational work to do before this can really go. The big pressure drop and visible appearance are eye opening to me though. 

[Normandy]

For sure.  There is still a broad gyre but that center is tight enough that I think it becomes dominant.  

[GaWx]

29 minutes ago, NorthHillsWx said:

Recon found another broad circulation SE of this. While this may take over as the overall center, there are some issues with the overall storm structure still as it’s organizing. If this center becomes distinct it could intensify at a more rapid pace as it’s firmly embedded under an apparent cdo. Wouldn’t jump the gun on this going bangers yet. Also this center appears to be moving west or west southwest seemingly within the broad center.

I assume the NW center is the old 90L former NW Gulf frontal low that’s been dropping S and the other is from the AEW originating 91L, itself. They should soon combine.

[purduewx80]

2 minutes ago, GaWx said:

I assume the NW center is the old 90L former NW Gulf frontal low that’s been dropping S and the other is from the AEW originating 91L, itself. They should soon combine.

I think most of 90L has already rotated into the southeast Gulf and is evident just northwest of the Yucatán on GOES vis and ASCAT. If you look at some of the 850 vort progs, this had been shown for several days. 

[AccuChris]

Pretty obvious on visible imagery an eye is trying to clear out

[olafminesaw]

A bit concerning with respect to surge potential especially if this thing comes in a little stronger. Thankfully, for the most part, coastal LA does not build in the flood zones.