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Hurricane JOAQUIN Forecast Discussion Number 13
2015-10-01 04:50:22| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT WED SEP 30 2015 000 WTNT41 KNHC 010250 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 13 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 1100 PM EDT WED SEP 30 2015 Joaquin has rapidly intensified during the past 24 hours with the satellite presentation continuing to improve this evening. The eye has recently become apparent near the center of the very symmetric central dense overcast. An Air Force Reserve Hurricane Hunter aircraft that has been investigating the hurricane this evening has measured peak 700 mb flight-level winds of 113 kt and 102 kt surface winds from the SFMR. These data support an initial intensity of 100 kt, making Joaquin the second major hurricane of the 2015 Atlantic hurricane season. NOTE: Communications problems have delayed the public release of the Air Force reconnaissance data. Joaquin continues to move slowly southwestward with an initial motion estimate of 220/5 kt. The hurricane is forecast to move slowly southwestward or west-southwestward for another 24 hours or so while it remains to the south of a narrow northeast to southwest oriented ridge. This ridge is expected to weaken by Friday as a trough deepens and cuts off over the southeastern United States. This should cause Joaquin to turn northward within 48 hours. The 18Z runs of the GFS and HWRF remain in general agreement with the 12Z UKMET and Canadian models moving Joaquin around the northeastern portion of the cut-off low and bring the hurricane inland over the Carolinas or mid-Atlantic states. The 12Z ECMWF remains the outlier by showing a track toward the northeast out to sea. The NHC forecast continues to follow the trend of the bulk of the guidance and takes Joaquin toward the U.S east coast. The NHC track is similar to the previous advisory and is once again east of the multi-model consensus. The NOAA G-IV aircraft has recently completed its synoptic surveillance flight, and data collected during this mission should be assimilated into the 0000 UTC models, hopefully reducing the spread of the track guidance. The upper-level wind pattern over the hurricane is forecast by the global models to become even more conducive during the next couple of days. This favors additional intensification, with the only possible limiting factors being upwelling of cool SSTs beneath the slow-moving hurricane and eyewall cycles which could cause some fluctuations in intensity. By 72 hours, increasing southwesterly shear, dry air intrusion, and lower SSTs are expected to cause gradual weakening. The updated NHC intensity forecast has been significantly increased from the previous advisory primarily due to the higher initial intensity. The official forecast is between the lower statistical guidance and the higher HWRF during the first 36-48 hours, and is near the SHIPS/LGEM guidance after that time. KEY MESSAGES: 1. Preparations to protect life and property within the warning areas in the Central Bahamas should be completed now. 2. Confidence in the details of the forecast after 72 hours remains low, since we have one normally excellent model that keeps Joaquin far away from the United States east coast. The range of possible outcomes is still large, and includes the possibility of a major hurricane landfall in the Carolinas. 3. Every effort is being made to provide the forecast models with as much data as possible. The NOAA G-IV jet has begun a series of missions in the storm environment, and the National Weather Service has begun launching extra balloon soundings. 4. Because landfall, if it occurs, is still more than three days away, it's too early to talk about specific wind, rain, or surge impacts from Joaquin in the United States. Regardless of Joaquin's track, strong onshore winds will create minor to moderate coastal flooding along the coasts of the mid-Atlantic and northeastern states through the weekend. 5. A hurricane watch for a portion of the U.S. coast could be required as early as Thursday evening. 6. Many portions of the eastern U.S. are currently experiencing heavy rains and gusty winds associated with a frontal system. These heavy rains are likely to continue for the next few days, even if the center of Joaquin stays offshore. The resulting inland flood potential could complicate preparations for Joaquin should it head toward the coast, and even more substantial inland flooding is possible if Joaquin later passes near or over these same areas. FORECAST POSITIONS AND MAX WINDS INIT 01/0300Z 23.8N 73.1W 100 KT 115 MPH 12H 01/1200Z 23.5N 73.8W 110 KT 125 MPH 24H 02/0000Z 23.6N 74.5W 120 KT 140 MPH 36H 02/1200Z 24.7N 74.8W 120 KT 140 MPH 48H 03/0000Z 26.6N 74.7W 110 KT 125 MPH 72H 04/0000Z 31.6N 74.7W 95 KT 110 MPH 96H 05/0000Z 36.2N 75.6W 85 KT 100 MPH 120H 06/0000Z 38.5N 76.5W 55 KT 65 MPH $$ Forecaster Brown
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