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Tropical Storm HERNAN Forecast Discussion Number 6
2014-07-27 16:35:38| National Hurricane Center (East Pacific)
Issued at 800 AM PDT SUN JUL 27 2014 000 WTPZ43 KNHC 271435 TCDEP3 TROPICAL STORM HERNAN DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014 800 AM PDT SUN JUL 27 2014 Enhanced BD-curve infrared imagery and an earlier GCOM-W1 (AMSR2) microwave overpass indicate that Hernan has continued to strengthen this morning. The imagery shows an impressive well-developed banding feature over the northwest quadrant of the cyclone with -80 to -90 deg C cloud tops, while the microwave pass reveals a more distinct inner core with a partial eyewall feature. Based on a blend of the Dvorak classifications from TAFB and SAB, and the latest UW-CIMSS SATCON estimate, the NHC initial intensity is raised to 60 kt. Current favorable environmental conditions should allow for further intensification during the next 8-12 hours, and Hernan still has a chance to become a hurricane today or tonight. Afterward, increasing westerly shear and decreasing sea surface temperatures are expected to weaken Hernan through the remainder of the forecast period. The available statistical/dynamical guidance agree with weakening Hernan into a remnant low in 96 hours. The initial motion is estimated to be northwestward, or 305/13 kt. Hernan continues to be steered by the mid-level southeasterly flow produced by a ridge over the southwestern United States. The cyclone should move in this general direction through the 36 hour period, and then turn westward within the low-level trade wind flow as a degenerated, vertically shallow system. The official NHC forecast is based on the multi-model consensus and is slightly to the right of the previous forecast beyond 48 hours. FORECAST POSITIONS AND MAX WINDS INIT 27/1500Z 17.8N 111.1W 60 KT 70 MPH 12H 28/0000Z 19.0N 112.8W 65 KT 75 MPH 24H 28/1200Z 20.5N 115.2W 60 KT 70 MPH 36H 29/0000Z 21.9N 117.6W 50 KT 60 MPH 48H 29/1200Z 22.9N 119.8W 45 KT 50 MPH 72H 30/1200Z 23.9N 123.0W 30 KT 35 MPH 96H 31/1200Z 24.0N 126.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 01/1200Z 24.0N 129.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Roberts
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