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Hurricane MATTHEW Forecast Discussion Number 9
2016-09-30 10:49:12| National Hurricane Center (Atlantic)
Issued at 500 AM AST FRI SEP 30 2016 000 WTNT44 KNHC 300849 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 500 AM AST FRI SEP 30 2016 There are no data currently available from the inner core of Matthew, so it is unclear whether the earlier rapid intensification is continuing. A well-defined elliptical eye is seen in data from the Curacao radar. However, the latest satellite imagery shows that the central convection is somewhat asymmetric and that an eye is yet to form. Satellite intensity estimates are 90 kt from TAFB and 77 kt from SAB. Based on continuity from the previous advisory and no improvement in the satellite signature, the initial intensity is held at a possibly conservative 85 kt. It is notable that the rapid intensification has occurred despite an ongoing 20 kt of southwesterly vertical wind shear. The initial motion is 265/12. There is little change to the track forecast philosophy from the previous advisory. A low- to mid-level ridge to the north of Matthew should keep it moving westward or south of westward for the next 36 hours with some decrease in forward speed. From 48-120 hours, the ridge is forecast to weaken and shift eastward as a mid- to upper-level trough moves into the central and eastern Gulf of Mexico. This evolution should cause Matthew to turn northwestward and then northward. There is a significant spread in where the turn will occur and how fast Matthew will move afterwards. The ECMWF and UKMET are on the eastern side of the guidance envelope and slower than the other models, while the GFS and Canadian models are to the left of the center of the guidance envelope and much faster. The various consensus models split these differences in both track and speed, and the new forecast track lies close to them. Overall, the new track is a little south of the previous track through 48 hours and a little west of the previous track from 72-120 hours. The intensity forecast is very problematic. The ongoing shear has so far done little to keep Matthew from intensifying. Despite this, the intensity guidance is in unanimous agreement that the cyclone should weaken from 12-48 hours, most likely due to shear. From 48-96 hours, the shear is expected to diminish, and during that time Matthew is expected to intensify until it interacts with land. The intensity forecast will smooth through what could be some ups and downs in intensity. First, it assumes that the current strengthening will continue for another 12-24 hours, with Matthew reaching major hurricane strength. Then, it keeps the intensity at 100 kt from 24-48 hours, followed by some intensification as the shear lets up. Weakening due to land interaction is forecast after 72 hours. The intensity forecast lies near the upper edge of the intensity guidance, but it is less intense than the HWRF model from 72-120 hours. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 14.0N 69.9W 85 KT 100 MPH 12H 30/1800Z 13.8N 71.2W 95 KT 110 MPH 24H 01/0600Z 13.7N 72.5W 100 KT 115 MPH 36H 01/1800Z 13.9N 73.7W 100 KT 115 MPH 48H 02/0600Z 14.5N 74.8W 100 KT 115 MPH 72H 03/0600Z 17.0N 76.0W 105 KT 120 MPH 96H 04/0600Z 20.5N 76.0W 90 KT 105 MPH...INLAND 120H 05/0600Z 24.5N 76.0W 85 KT 100 MPH...OVER WATER $$ Forecaster Beven
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