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Hurricane JOAQUIN Forecast Discussion Number 20
2015-10-02 22:56:05| National Hurricane Center (Atlantic)
Issued at 500 PM EDT FRI OCT 02 2015 000 WTNT41 KNHC 022055 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 20 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 500 PM EDT FRI OCT 02 2015 Satellite imagery and reports from an Air Force Reserve Hurricane Hunter aircraft indicate that Joaquin has weakened a little since the last advisory, with the central pressure rising to 942 mb. Based on this, the initial intensity is decreased to 110 kt. Subsequent observations from San Salvador Island and dropsondes from a NASA aircraft suggest the pressure is still near 942 mb. While the hurricane continues to produce cold cloud tops in the eyewall, the convective pattern currently looks ragged in infrared imagery, and only occasional hints of a eye are apparent in visible imagery. The initial motion is now 360/6. Water vapor imagery shows a mid- to upper-level ridge to the north and northeast of the hurricane, while a deep-layer trough and associated surface front are located over the southeastern United States. This system is forecast to move slowly eastward with a non-tropical low forming along the front during the next couple of days. While this occurs, a mid- to upper-level low currently centered near 30N 64W should move west-northwestward to the north of Joaquin. These developments should steer Joaquin northward for the next few hours, followed by a turn toward the northeast. The track guidance is now in good agreement that Joaquin will move generally northeastward between the United States and Bermuda, with a short-lived northward turn in the 48-72 hour period. Eventually, the cyclone is expected to move into the westerlies and move quickly east-northeastward across the North Atlantic. The new forecast track is similar to the previous forecast and now lies near the consensus models. Joaquin is forecast to remain in an environment of light vertical wind shear for another 12-24 hours or so, and during this time some fluctuations in intensity are possible. After 24 hours, the shear is forecast to increase, which should start a steady weakening. Extratropical transition is expected to begin around 96 hours and be complete by 120 hours. Overall, the new intensity forecast is an update of the previous advisory and lies near the intensity consensus. KEY MESSAGES: 1. Hurricane conditions over portions of the Bahamas should continue for several more hours. 2. Swells from a hurricane moving even far offshore of the U.S. east coast can still cause life-threatening surf and rip-current conditions. Please see products from your local National Weather Service forecast office. For information on the heavy rains occurring along the U.S. Atlantic states that are mostly unrelated to Hurricane Joaquin, please see products from the NWS Weather Prediction Center and your local forecast office. 3. Since the direct threat of hurricane conditions to land areas is diminishing significantly, this will be the last set of key messages unless the threat increases. FORECAST POSITIONS AND MAX WINDS INIT 02/2100Z 24.1N 74.7W 110 KT 125 MPH 12H 03/0600Z 25.1N 73.9W 110 KT 125 MPH 24H 03/1800Z 26.9N 72.1W 105 KT 120 MPH 36H 04/0600Z 29.2N 70.0W 100 KT 115 MPH 48H 04/1800Z 31.7N 68.7W 90 KT 105 MPH 72H 05/1800Z 36.5N 67.0W 75 KT 85 MPH 96H 06/1800Z 40.5N 60.5W 65 KT 75 MPH 120H 07/1800Z 45.0N 46.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven
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