Issued at 1000 PM EST Mon Nov 04 2024
000 WTNT43 KNHC 050300 TCDAT3 Tropical Storm Rafael Discussion Number 6 NWS National Hurricane Center Miami FL AL182024 1000 PM EST Mon Nov 04 2024 After a period of intensification this afternoon, Rafael has taken a brief pause on further development. Tonight's Air Force Reserve Aircraft sampled the tropical storm from 2330-0130 UTC, finding the structure still somewhat broad with a minimum central pressure of 996 mb from the last fix, only slightly lower than this afternoon. Earlier AMSR2 and GMI microwave imagery did show the outer core structure of Rafael is gradually organizing, with plenty of curved convective bands on the 37-GHz channel along the the eastern flank, though some dry air appears to be undercutting the cirrus outflow to the west and preventing organized convection from fully wrapping around the center. Aircraft flight-level winds at 850 mb were not all that impressive (40 kt peak), though peak SFMR values in the same realm still support a maximum intensity of about 40 kt for this advisory. Another Air Force Reconnaissance mission is in route to sample the storm again later tonight. Rafael appears to be turning more northwestward with a faster forward motion, estimated tonight at 335/10 kt. The track forecast for the next 48 h is fairly straightforward, as mid-level ridging builds in to the northeast of Rafael, which should maintain steering that should continue a northwestward track, bringing the tropical storm on its closest approach to Jamaica Tuesday morning, passing through the Cayman Islands Tuesday night, and nearing the Caribbean coast of western Cuba on Wednesday. After Rafael crosses Cuba and moves into the eastern Gulf of Mexico, the track forecast remains a challenge. The spread in ensemble track solutions is notable, and appears not just related to the vertical depth of Rafael, but also the synoptic pattern over the United States. A large deep-layer cutoff low is expected to dig into the four corners region of the U.S., and how progressive this feature is moving into the central U.S. will likely determine how much ridging remains over the Gulf of Mexico in 4-5 days. The latest NHC track forecast is similar to the prior track for the first 36 h, but is a shade farther right beyond that time, slightly favoring the GFS and Canadian model solutions over the UKMET and ECMWF tracks. However, the 200-850 mb steering flow depicted in the Gulf of Mexico also shows the possibility of a bifurcation point near 25N 86W in 3 days, and where Rafael ends up at the time could determine if it stays in the eastern Gulf of Mexico or moves much further westward into the central or western Gulf. Needless to say, this is a low confidence track forecast in 5 days. The inner core of Raphael still appears to be in the formative stage tonight, as convection has yet to become axis-symmetrical around the low-level circulation, which lacks a tighter wind field. Thus, the rate of intensification over the next day or so should be slower than in the final 24 h before Raphael reaches Cuba. Environmental conditions remain very favorable in the northwestern Caribbean, and SHIPS rapid intensification guidance still indicates that the cyclone has a 40-50 percent chance of a 45 kt increase in the next 36 h. The NHC intensity forecast will show 40 kt of intensification over the next 36 h, with some additional intensification possible before Raphael moves over Cuba. Once in the Gulf of Mexico, westerly shear increases to 15-25 kt, which could halt intensification and ultimately lead to weakening as it imports very dry air into Raphael by the end of the forecast. The NHC intensity forecast is similar to the prior advisory, and remains on the high side of the overall intensity guidance. Key Messages: 1. Rafael is forecast to be near hurricane intensity when it passes near or over the Cayman Islands by Tuesday night where damaging hurricane-force winds, a dangerous storm surge, and destructive waves are expected. Rafael should reach western Cuba and the Isle of Youth on Wednesday. A hurricane warning is in effect for this region, where a dangerous storm surge and destructive waves are also expected. 2. Tropical storm conditions are expected in Jamaica tonight and Tuesday. Tropical storm conditions are possible in the Lower and Middle Florida Keys beginning late Wednesday or 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 to portions of the western Caribbean, including Jamaica and Cuba through mid-week, where flooding and landslides are possible. Heavy rainfall will spread into Florida and adjacent areas of the Southeast United States mid to late week. FORECAST POSITIONS AND MAX WINDS INIT 05/0300Z 16.3N 77.2W 40 KT 45 MPH 12H 05/1200Z 17.6N 78.3W 50 KT 60 MPH 24H 06/0000Z 19.4N 79.9W 60 KT 70 MPH 36H 06/1200Z 21.4N 81.6W 80 KT 90 MPH 48H 07/0000Z 23.3N 83.1W 80 KT 90 MPH 60H 07/1200Z 24.6N 84.3W 80 KT 90 MPH 72H 08/0000Z 25.4N 85.3W 75 KT 85 MPH 96H 09/0000Z 26.6N 87.6W 65 KT 75 MPH 120H 10/0000Z 27.1N 89.9W 45 KT 50 MPH $$ Forecaster Papin