Issued at 1000 PM EST Tue Nov 05 2024
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