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Hurricane JOAQUIN Forecast Discussion Number 15
2015-10-01 17:04:56| National Hurricane Center (Atlantic)
Issued at 1100 AM EDT THU OCT 01 2015 000 WTNT41 KNHC 011504 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 1100 AM EDT THU OCT 01 2015 An Air Force Reserve Hurricane Hunter aircraft reported 700-mb flight-level winds of 119 kt in the northwestern eyewall, with a 117 kt surface wind estimate from the Stepped Frequency Microwave Radiometer in the southwestern eyewall. The latest central pressure was 942 mb. Based on these data, the advisory intensity is increased to 110 kt. Satellite imagery indicates that an eye is trying to form in the central dense overcast, and that the cirrus outflow is good in all directions. Joaquin is expected to intensify a little more in the next 12 to 24 hours as it remains over very warm waters and in an environment of decreasing vertical shear. After that time, there could be some fluctuations in intensity due to eyewall replacement cycles. There is some uncertainty in the intensity forecast in the 48-96 hour period. The statistical models suggest that Joaquin should weaken due to increasing shear. However, several of the global models forecast the hurricane to move into an area of strong upper-level divergence and show a falling central pressure. The new forecast will continue to show weakening during this time, but it would not be a surprise if it is stronger than currently forecast. The initial motion is 220/5. Water vapor imagery shows a mid- to upper-level ridge north of the hurricane, with a developing deep-layer trough over the eastern and southeastern United States. The dynamical models forecast this trough to become a cut-off low as it moves southeastward and weakens the ridge. This pattern evolution should cause Joaquin to turn northwestward in 24 hours or so and then turn northward. After 36 hours, the guidance remains very divergent. The Canadian, GFDL, HWRF, and NAVGEM models forecast Joaquin to turn northwestward and make landfall over the Carolinas and mid-Atlantic States. The ECMWF continues to forecast a slower northeastward motion taking Joaquin near Bermuda and out to sea. The UKMET and GFS are in between these extremes showing a generally northward motion. Given the spread and the possibility that the 1200 UTC guidance could show additional changes, the forecast track after 36 hours is nudged only slightly to the east at this time. The new track lies to the east of the landfalling models, but to the west of the GFS, UKMET, ECMWF, and the various consensus models. Further adjustments to the track may be needed later today depending on how the models do (or do not) change. KEY MESSAGES: 1. Preparations to protect life and property in the central Bahamas should be complete. The slow motion of Joaquin over the next day or so 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 is still low, since there have been some large changes in the model guidance overnight and a large spread in the model solutions remains, with potential impacts from the Carolinas through New England. It is also possible that Joaquin will remain far from the U.S. east coast. A hurricane watch for the U.S. coast would likely not occur until at least Friday morning. 3. Efforts to provide the forecast models with as much data as possible continue, with twice daily NOAA G-IV jet missions in the storm environment, and extra NWS balloon launches. 4. 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. 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 01/1500Z 23.0N 73.9W 110 KT 125 MPH 12H 02/0000Z 22.9N 74.2W 115 KT 130 MPH 24H 02/1200Z 23.7N 74.6W 120 KT 140 MPH 36H 03/0000Z 25.2N 74.4W 120 KT 140 MPH 48H 03/1200Z 27.5N 73.7W 110 KT 125 MPH 72H 04/1200Z 32.0N 73.0W 95 KT 110 MPH 96H 05/1200Z 36.0N 73.5W 75 KT 85 MPH 120H 06/1200Z 40.0N 72.5W 55 KT 65 MPH $$ Forecaster Beven
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