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| #804359 (Received by flhurricane at: 4:55 AM 01.Oct.2015) TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 500 AM EDT THU OCT 01 2015 Data from the last aircraft mission indicated the Joaquin had strengthened a little more, and the intensity of 105 kt is supported by flight-level, SFMR, and dropsonde data from the plane. The central pressure of 948 mb is based on a dropsonde that measured 950 mb with 20 kt of wind. The satellite presentation of the hurricane continues to gradually improve, with cold tops expanding near and west of the center, although the eye is not yet apparent in infrared imagery. Another hurricane hunter aircraft will be investigating Joaquin later this morning. Joaquin is expected to intensify a little more in the next 12 to 24 hours while over very warm waters and with decreasing vertical shear. After that time, there could be some fluctuations in intensity due to eyewall replacement cycles and perhaps some upwelling of cold waters due to the slow motion of the hurricane. After 48 hours, cooler SSTs and increasing shear should result in gradual weakening as Joaquin moves northward. The new NHC intensity forecast is similar to the previous one and close to the HWRF through 24 hours. After that time, the NHC prediction is above the intensity consensus since the official forecast keeps the cyclone offshore, while the remainder of the intensity guidance shows weakening due to decay over land. The initial motion of the hurricane is still toward the southwest or 230/04 under the influence of a narrow ridge to the north. A slow motion with a bending of the track toward the west and then the west-northwest is expected during the next 24 hours as the ridge weakens. During this time the NHC track has been adjusted southward following the latest trend in the guidance. The slow motion of Joaquin will mean a prolonged period of hurricane conditions in portions of the central Bahamas, along with very heavy rain and storm surge. By 36 hours, Joaquin should begin to move faster toward the north as it comes under the influence of a deep-layer trough that cuts off over the southeastern United States. There have been big changes in some of the track guidance overnight, perhaps due to data from the synoptic surveillance mission flown by the NOAA G-IV jet for the 00Z model cycle. In particular, the GFS and UKMET have shifted eastward by several hundred miles in 3 to 4 days relative to their previous solutions. Overall for this cycle there has been a spreading out of the guidance envelope beyond 2 days, with a wide range of solutions shown. The HWRF and GFDL are the fastest to bring Joaquin north out of the Bahamas and still show a sharp westward turn taking the cyclone inland over the Carolinas in 3 to 4 days. The GFS has trended slower coming out of the Bahamas and now shows a track toward Long Island and southern New England in 5 days, with the UKMET farther offshore. The latest ECMWF is still the slowest and farthest east with a track just west of Bermuda in 4 to 5 days. Given the large shift in some of the guidance, the NHC track has been adjusted just a little to the east and slower at days 3 through 5, and now lies on the left side of the multi-model consensus and left of the GFS, UKMET and ECMWF solutions. Confidence remains very low in the eventual track of Joaquin and any potential impacts for the United States, and further adjustments to the NHC track may be needed later today. KEY MESSAGES: 1. Preparations to protect life and property in the central Bahamas should be complete. The slow motion of Joaquin during the next 24 to 36 hours will bring a prolonged period of hurricane force winds, storm surge, and very heavy rainfall to those islands. 2. Confidence in the details of the forecast after 72 hours remains low, as there have been some large changes in the model guidance overnight. The range of possible outcomes is still large, and the possibility of a hurricane landfall in the Carolinas still cannot be ruled out. 3. Efforts continue to provide the forecast models with as much data as possible. The NOAA G-IV jet flew the first in a series of missions in the storm environment last night, and these missions will continue today. The National Weather Service also continues to launch 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 tonight. 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 01/0900Z 23.4N 73.7W 105 KT 120 MPH 12H 01/1800Z 23.1N 74.2W 115 KT 130 MPH 24H 02/0600Z 23.4N 74.8W 120 KT 140 MPH 36H 02/1800Z 25.0N 74.8W 120 KT 140 MPH 48H 03/0600Z 26.8N 74.1W 110 KT 125 MPH 72H 04/0600Z 32.5N 74.0W 95 KT 110 MPH 96H 05/0600Z 36.0N 74.5W 80 KT 90 MPH 120H 06/0600Z 39.0N 74.0W 60 KT 70 MPH $$ Forecaster Brennan |
