Hurricane Rafael Forecast Discussion

000
WTNT43 KNHC 060300
TCDAT3

Hurricane Rafael Discussion Number  10
NWS National Hurricane Center Miami FL       AL182024
1000 PM EST Tue Nov 05 2024

We have been fortunate to receive an abundance of in-situ data from 
both an Air Force Reserve C-130 and a NOAA-P3 Hurricane Hunter 
aircraft tonight. Their data indicated that Rafael had become a 
hurricane just after 00 UTC with peak 750 mb flight level winds of 
79 kt from the NOAA-P3 and 700 mb winds of 73 kt from the Air Force 
C-130. On satellite imagery Rafael's structure continues to improve 
with very cold deep convection near the center rotating around the 
center. Radar reflectivity out of Grand Cayman Island also shows the 
inner core continues to improve with a 10-15 n mi diameter eyewall, 
though is still occasionally open on the southwest side. The initial 
intensity is set to 70 kt, based on NOAA-P3 Tail Doppler Radar 
velocities up to 85 kt in the NE eyewall boundary layer, which was 
matched by an Air Force Recon dropsonde also launched in the NE 
eyewall at 0025 UTC that had a 500 m layer average wind of 85 kt.

Rafael continues to move northwestward at 320/11 kt. A prominent 
low- to mid-level ridge centered offshore of the Southeastern U.S. 
should continue to steer the hurricane northwestward for the next 
day or so. This track will lead to Rafael moving through the Cayman 
Islands for the next few hours and then across the western portion 
of Cuba during the afternoon on Wednesday. Thereafter, Rafael will 
emerge into the southeastern Gulf of Mexico, where it is becoming 
increasingly likely that the aforementioned ridging will begin to 
build to the north of Rafael, leading to the hurricane turning more 
west-northwestward and slowing down as it moves into the central 
Gulf of Mexico. There have been notable changes in the global model 
guidance today, with the GFS track shifting significantly to the 
south and west over the past four cycles, closer to the ECMWF track. 
This evolution is likely partially related to changes in the 
upstream synoptic flow pattern, now showing a cutoff low digging 
into the four corners region rather than being more progressive 
moving eastward in the Great Plains. Such an evolution will allow a 
narrow ridge to become oriented directly over Rafael, substantially 
slowing its forward motion. Because it is becoming more evident the 
ECMWF synoptic flow pattern may end up being correct, the NHC track 
has been shifted leftward, especially beyond 48 h, compared to the 
previous forecast track. At the very end of the forecast, Rafael 
will likely become a shallow cyclone, drifting slowly northward in 
the low-level flow. 

Environmental conditions are very favorable for continued 
intensification, and given that Rafael now possesses a tight inner 
core and eyewall, rapid intensification seems likely. Strangely, the 
HAFS models did not appear to initialize correctly at 18 UTC, and 
were a good 5-10 mb too weak at 00 UTC tonight. Despite this, HAFS-B 
raw model output shows Rafael becoming a category 2 hurricane before 
moving over Cuba, and the NHC intensity forecast will now show 
Rafael becoming a Category 2 hurricane in 12 h. It is also not 
impossible Rafael becomes a major hurricane before impacting Cuba, 
with at least one hurricane-regional model showing this possibility 
this cycle (HMON). Rafael should briefly weaken over Cuba. After the 
hurricane emerges into the Gulf of Mexico, the environment is not as 
favorable as the northwestern Caribbean, but is also not especially 
unfavorable from 24-48 h as it will remain over 27-28 C waters, and 
only 10-15 kt of vertical wind shear. However, mid-level shear 
begins to substantially increase after that time, and sea-surface 
temperatures from wave drifters just north of Rafael's forecast 
track are only 26-27 C. This one two negative punch will likely 
begin to result in weakening, which should become more rapid towards 
the end of the forecast period as very dry air over the western Gulf 
of Mexico is likely to be ingested into the storm. The NHC intensity 
forecast is at the upper-end of the guidance in the first 12 h, but 
then falls closer to the HCCA consensus aid between 24-48 h, before 
dropping into the middle of the intensity guidance envelope by the 
end of the forecast. Rafael might be close to becoming post-tropical 
as global model guidance suggests it may  lose most of its remaining 
convection in about 120 h. 


Key Messages:

1. Rafael is forecast to be a hurricane when it passes near or over
the Cayman Islands during the next 12 hours, where damaging
hurricane-force winds, a dangerous storm surge, and destructive
waves are expected. Additional strengthening is expected before
Rafael reaches western Cuba and the Isle of Youth on Wednesday. A
hurricane warning is in effect for this region, where damaging
hurricane-force winds, life-threatening storm surge, and destructive
waves are also expected.

2. Tropical storm conditions are expected in the Lower and Middle
Florida Keys beginning Wednesday and Wednesday night.

3. It is too soon to determine what, if any, impacts Rafael could
bring to portions of the northern Gulf Coast.  Residents in this
area should regularly monitor updates to the forecast.

4. Rafael will bring areas of heavy rain across portions of the
western Caribbean through early Thursday, including Jamaica and the
Cayman Islands, along with southern and western portions of Cuba.
Flash flooding and mudslides are possible along the higher terrain
in Jamaica and Cuba.


FORECAST POSITIONS AND MAX WINDS

INIT  06/0300Z 19.7N  80.4W   70 KT  80 MPH
 12H  06/1200Z 21.2N  81.5W   90 KT 105 MPH
 24H  07/0000Z 23.0N  83.2W   80 KT  90 MPH...ON THE N CUBA COAST
 36H  07/1200Z 24.3N  84.6W   85 KT 100 MPH
 48H  08/0000Z 24.8N  85.9W   85 KT 100 MPH
 60H  08/1200Z 25.1N  87.4W   80 KT  90 MPH
 72H  09/0000Z 25.4N  89.0W   75 KT  85 MPH
 96H  10/0000Z 26.7N  91.2W   55 KT  65 MPH
120H  11/0000Z 27.9N  91.6W   35 KT  40 MPH

$$
Forecaster Papin