000 WTNT44 KNHC 012045 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 500 PM EDT SAT OCT 01 2016 Matthew's cloud pattern has improved this afternoon, with the small eye becoming more distinct. A NOAA hurricane hunter aircraft recently found peak SFMR winds of around 130 kt, and a peak 7,000-ft flight-level wind of 135 kt. The initial intensity is raised to 130 kt for this advisory. The wind field has contracted today, and the radius of maximum winds is now about 6 n mi. The latest minimum pressure based on a dropsonde from the aircraft is 940 mb. Radar imagery from the NOAA plane suggests that an outer eyewall may be forming, but the current eye has been resilient today. Some gradual net weakening is expected during the next day or so, but Matthew is expected to remain a powerful hurricane until it begins to interact with the landmasses of Jamaica, eastern Cuba, and Hispaniola in 48 to 72 hours. Some weakening is expected during that time, but conditions appear conducive for restrengthening once Matthew moves into the Bahamas late in the forecast period. The NHC forecast is well above the intensity consensus through much of the period. Note that there will likely be short-term fluctuations in intensity like we've seen today due to internal dynamics, including eyewall replacement cycles, that are not shown here. Matthew has made a small cyclonic loop since the last advisory, and the initial motion estimate is a northwestward drift at around 3 kt. The mid-level ridge centered near Bermuda is expected to weaken and shift eastward, causing Matthew to turn northward while it moves into a weakness in the ridge during the forecast period. The track model guidance has shifted a little to the east in the short range, and the NHC track during this time has been adjusted in that direction, in agreement with the latest multi-model consensus. Late in the period the track model spread remains considerable, as the global models continue to have issues depicting the synoptic- scale pattern over the eastern United States and western Atlantic in 4-5 days. The evolution of the mid/upper-level low currently centered over the Ohio Valley and how it interacts with the western Atlantic subtropical ridge appear to be critical to the long-term track of Matthew. The UKMET and ECMWF tracks have shifted westward and slower by day 5, while the GFS has trended east. This has narrowed the guidance envelope somewhat, but given the lack of run-to-run consistency I'd hesitate to say that confidence in the long-range track forecast has increased by any appreciable measure. The new NHC track at these times leans heavily on continuity, and by day 5 is close to the GFS/ECMWF blend and left of the latest multi-model consensus aid TVCN. It is important to remind users that average NHC track forecast errors are around 175 miles at day 4 and 230 miles at day 5. Therefore, it is too soon to rule out possible hurricane impacts from Matthew in Florida. FORECAST POSITIONS AND MAX WINDS INIT 01/2100Z 13.5N 73.4W 130 KT 150 MPH 12H 02/0600Z 13.6N 73.8W 125 KT 145 MPH 24H 02/1800Z 14.8N 74.4W 120 KT 140 MPH 36H 03/0600Z 16.1N 74.9W 115 KT 130 MPH 48H 03/1800Z 17.6N 75.0W 110 KT 125 MPH 72H 04/1800Z 21.0N 75.0W 95 KT 110 MPH 96H 05/1800Z 24.5N 75.5W 100 KT 115 MPH 120H 06/1800Z 26.5N 76.0W 100 KT 115 MPH $$ Forecaster Brennan