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Tropical Storm MATTHEW Forecast Discussion Number 5
2016-09-29 16:55:42| National Hurricane Center (Atlantic)
Issued at 1100 AM AST THU SEP 29 2016 000 WTNT44 KNHC 291455 TCDAT4 TROPICAL STORM MATTHEW DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 1100 AM AST THU SEP 29 2016 The center of Matthew is exposed to the southwest of the deep convection due to moderate southwesterly shear. Despite the shear, data from an Air Force Reserve reconnaissance aircraft show that Matthew is a little stronger this morning. The aircraft has measured peak 850 mb flight-level winds of 80 kt, and believable SFMR winds of around 60 kt, which is the basis for the initial intensity. The minimum central pressure reported by the aircraft is down to 996 mb. Given the current shear and structure of Matthew, only slight strengthening is predicted during the next 24 hours. The shear is forecast to slowly decrease over the next few days, although there are some differences in the upper-level wind forecasts between the ECMWF and GFS models. The ECMWF keeps a band of southwesterly upper-level winds near Matthew, while the GFS generally shows lower shear. The NHC forecast assumes that there will be a reduction in shear and calls for intensification similar to the previous advisory. The official wind speed forecast is between the lower statistical guidance and the more aggressive HWRF and GFDL models. Matthew is moving at 275/14 kt. The tropical storm is expected to move westward to the south of a mid- to upper-level ridge over the western Atlantic during the next couple of days. In about 48 hours, Matthew should turn northwestward when it approaches the western periphery of the ridge. After that time, the tropical cyclone is forecast to turn northward while a mid- to upper-level trough develops over the Gulf of Mexico. The GFS is still much faster than the ECMWF at taking Matthew northward. Although the east/west spread among the higher quality track models is somewhat smaller this morning, there is still significant spread among the ECMWF ensembles beyond 3 days, and the overall confidence in the track forecast is still low. The new NHC track forecast is essentially an update of the previous forecast and is very close to the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 29/1500Z 14.2N 66.3W 60 KT 70 MPH 12H 30/0000Z 14.3N 68.0W 60 KT 70 MPH 24H 30/1200Z 14.1N 70.2W 65 KT 75 MPH 36H 01/0000Z 13.9N 71.8W 70 KT 80 MPH 48H 01/1200Z 13.9N 72.8W 75 KT 85 MPH 72H 02/1200Z 15.3N 74.4W 80 KT 90 MPH 96H 03/1200Z 18.0N 75.2W 85 KT 100 MPH 120H 04/1200Z 21.5N 75.5W 80 KT 90 MPH $$ Forecaster Brown
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