Tropical Storm Francine Forecast Discussion

000
WTNT41 KNHC 092053
TCDAT1

Tropical Storm Francine Discussion Number   5
NWS National Hurricane Center Miami FL       AL062024
400 PM CDT Mon Sep 09 2024

Since the prior advisory, Francine's structure has continued to 
improve. Curved bands are becoming more obvious on geostationary 
satellite imagery, even if the coldest cloud tops have warmed from 
earlier today. The last Air Force reconnaissance mission into 
Francine on its final center fix found a formative inner-core with a 
partial eyewall, 850 mb flight level winds up to 58 kt, and pressure 
down to 996 mb, a significant drop from this morning. These data 
were the basis for bringing the 18 UTC intensity up to 50 kt. Since 
then, a mid-level eye feature on the Brownsville radar has become 
apparent. Assuming some additional deepening, the initial intensity 
is set to 55 kt for this advisory. 

With the center becoming better established, the motion is a bit 
easier to estimate, currently at 340/6 kt. While the system has 
reformed a bit west of the previous track, the overall thinking has 
not changed much, as Francine will be moving around the periphery of 
a mid-level ridge centered over Cuba, and an upper-level trough 
propagating into Texas. This trough will ultimately shift the track 
of a more vertically deep Francine northeastward tomorrow with 
gradual acceleration until the storm makes landfall sometime between 
48 to 60 h. The track guidance this cycle has shifted westward, 
likely due to the more westward initial position, and is also a 
little faster. The latest NHC track forecast follows suit, showing a 
shift to the west and a faster motion, blending the prior forecast 
towards the reliable consensus aids TCVN and HCCA.

With the forming inner-core earlier observed by recon and still seen 
on radar currently, the tropical storm appears poised to intensify 
more significantly in the short term. Given the low vertical wind 
shear, ample moisture, and very warm sea-surface temperatures, a 
faster rate of intensification is shown over the next 36 h, and 
Francine is now forecast to become a hurricane tonight or tomorrow 
morning, and a Category 2 hurricane by Wednesday. In the final 
12-18 h before landfall, shear is expected to increase markedly, 
which will likely halt the intensification, though Francine is 
expected to be a Category 2 hurricane at landfall. Rapid weakening 
is expected after the system moves inland. The NHC intensity 
forecast is on the upper-end of the overall intensity guidance, but 
still is lower than some of the hurricane-regional model guidance 
(HAFS-B, HMON). 

Given the changes to the forecast, Hurricane and Storm Surge 
Warnings have been issued for a significant portion of the 
Louisiana coastline.

An experimental cone graphic that includes inland Hurricane and 
Tropical Storm Watches and Warnings in the U.S. is now available on 
the NHC website. Due to the time needed to compile the inland watch 
and warning information, the experimental cone graphic will not be 
available as quickly as the operational cone. Once it is available, 
the experimental cone graphic can be found from a red weblink above 
the operational cone graphic at 
www.nhc.noaa.gov/graphics_at1.shtml?cone#contents. Users are 
encouraged to take the experimental product survey found below the 
experimental cone.

KEY MESSAGES:

1.  Francine is expected to be a hurricane when it reaches the coast 
of Louisiana on Wednesday, and there is a danger of life-threatening 
storm surge for portions of the Upper Texas and Louisiana coastlines 
where a Storm Surge Warning is now in effect.  Residents in the 
warning area should follow advice, including evacuation orders, 
given by local officials. 

2. Damaging and life-threatening hurricane-force winds are expected 
in portions of southern Louisiana Wednesday, where a Hurricane 
Warning is now in effect. Preparations to protect life and property 
should be complete by Tuesday night since tropical storm conditions 
are expected to begin within this area early Wednesday.

3. Francine is expected to bring heavy rainfall and the risk of 
considerable flash flooding along the coast of northeast Mexico, 
the far lower and far upper Texas coasts, southern Louisiana, and 
southern Mississippi into Thursday morning.  A risk of flash and 
urban flooding exists across portions of the Mid-South from 
Wednesday into Friday morning.


FORECAST POSITIONS AND MAX WINDS

INIT  09/2100Z 24.0N  96.0W   55 KT  65 MPH
 12H  10/0600Z 24.8N  96.4W   65 KT  75 MPH
 24H  10/1800Z 25.9N  95.9W   75 KT  85 MPH
 36H  11/0600Z 27.4N  94.7W   85 KT 100 MPH
 48H  11/1800Z 29.4N  92.8W   85 KT 100 MPH
 60H  12/0600Z 31.8N  91.3W   45 KT  50 MPH...INLAND
 72H  12/1800Z 34.2N  90.8W   30 KT  35 MPH...INLAND
 96H  13/1800Z 36.9N  90.3W   25 KT  30 MPH...POST-TROPICAL
120H  14/1800Z 38.2N  89.1W   20 KT  25 MPH...POST-TROPICAL

$$
Forecaster Papin