000 WTNT44 KNHC 030851 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 21 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 500 AM EDT MON OCT 03 2016 The Air Force Reserve reconnaissance mission that ended shortly before 0600 UTC did not find flight-level or surface winds as high as reported during the previous flight yesterday afternoon. It is not clear from microwave imagery if the reduction in winds is the result of an eyewall replacement. There was no evidence of a double wind maximum in the aircraft data, but the crew reported that the eyewall was open to the southwest. Using a blend of the aircraft data and recent satellite intensity estimates, the initial intensity has been reduced to 115 kt for this advisory. The center of Matthew has recently passed over NOAA buoy 42058 in the central Caribbean Sea, which reported a minimum pressure of 943 mb and light winds around 0650 UTC. Satellite and aircraft fixes show that Matthew is moving northward or 360/5 kt. The hurricane is expected to move generally northward around the western periphery of a subtropical ridge over the west-central Atlantic during the next couple of days, and little change was needed to the NHC forecast through 48 hours. Once Matthew moves near the southeastern Bahamas on Wednesday, it is forecast to turn northwestward or north-northwestward in southeasterly flow between the ridge and a mid- to upper-level low/trough over the southeastern Gulf of Mexico and northwestern Caribbean Sea. The model guidance is in relatively good agreement through 72 hours, but begin to diverge by days 4 and 5. The UKMET which was previously the western outlier, has shifted eastward this cycle, and is now close to the GFS. The 0000 UTC ECMWF trended westward and that model is now along the western edge of the guidance envelope. The NHC track has been nudged westward at days 4 and 5, and lies close to the GFS and UKMET solutions. This is a bit west of the model consensus since the higher quality models are on that side of the guidance envelope. Matthew is forecast to remain in low shear and over warm water while it moves northward toward the Greater Antilles. Some restrengthening is possible, but fluctuations in intensity are likely due to eyewall cycles that are difficult to predict. Some weakening is forecast when the hurricane interacts with land in a couple of days, however Matthew is expected to remain a powerful hurricane throughout much of the forecast period. Although the official forecast continues to show a track east of Florida, it is still too soon to rule out possible hurricane impacts there. It is also too soon to know whether, or how, Matthew might affect the remainder of the United States east coast. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 15.2N 74.9W 115 KT 130 MPH 12H 03/1800Z 16.2N 74.9W 115 KT 130 MPH 24H 04/0600Z 17.9N 74.7W 115 KT 130 MPH 36H 04/1800Z 19.7N 74.6W 115 KT 130 MPH 48H 05/0600Z 21.4N 74.8W 105 KT 120 MPH 72H 06/0600Z 24.6N 75.9W 105 KT 120 MPH 96H 07/0600Z 27.6N 76.9W 95 KT 110 MPH 120H 08/0600Z 30.8N 77.0W 90 KT 105 MPH $$ Forecaster Brown