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#876578 (Received by flhurricane at: 10:58 AM 02.Oct.2016) TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 1100 AM EDT SUN OCT 02 2016 The eye of Matthew has become obscured on visible satellite images, which is often an indication of weakening. Microwave images showed a distinct dry slot over the southwestern and western portions of the circulation. Also there has been a persistent, but inexplicable, cluster of deep convection located a couple of degrees to the east of the hurricane and the effect of this feature on Matthew's intensity evolution is unknown. An Air Force Hurricane Hunter aircraft investigated the northeastern eyewall, the strongest part of the circulation, and found that the winds had decreased somewhat from earlier this morning. The intensity is set to 120 kt for this advisory. The vertical shear is not forecast to become much stronger while Matthew is in the Caribbean, so the hurricane should remain near category 4 status for the next 36-48 hours. Once Matthew moves into the Atlantic, some increase in shear along with a decrease in oceanic heat content should result in a little weakening. However, there is significant uncertainty in the 3-5 day forecast intensities. After a northwestward motion, the center has meandered westward over the past few hours. Matthew is expected to turn northward and move between a mid-level ridge to the east and a weak trough over the Gulf of Mexico for the next few days. Later in the forecast period, the global models show a slight building of a ridge to the northeast of Matthew which would induce a turn toward the left in 3-5 days. The timing and magnitude of this turn is still uncertain however. Looking at the better-performing models, the track guidance suite is bracketed by the GFS model on the left and the HWRF model on the right. The official forecast is slightly west of the multi-model consensus and very similar to the previous NHC track. 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 02/1500Z 14.0N 74.6W 120 KT 140 MPH 12H 03/0000Z 14.9N 74.8W 120 KT 140 MPH 24H 03/1200Z 16.1N 75.0W 115 KT 130 MPH 36H 04/0000Z 17.7N 74.7W 115 KT 130 MPH 48H 04/1200Z 19.5N 74.5W 110 KT 125 MPH 72H 05/1200Z 23.2N 75.0W 100 KT 115 MPH 96H 06/1200Z 26.5N 76.0W 95 KT 110 MPH 120H 07/1200Z 29.5N 76.5W 90 KT 105 MPH $$ Forecaster Pasch |