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Hurricane GONZALO Forecast Discussion Number 11
2014-10-15 05:15:11| National Hurricane Center (Atlantic)
Issued at 1100 PM AST TUE OCT 14 2014 000 WTNT43 KNHC 150315 TCDAT3 HURRICANE GONZALO DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082014 1100 PM AST TUE OCT 14 2014 Data from an Air Force Hurricane Hunter reconnaissance aircraft indicate that Gonzalo has continued to strengthen. The plane reported maximum flight-level of 125 kt in the northeastern quadrant and peak SFMR winds of 108 kt. The minimum surface pressure also has fallen about 17 mb during the last 9 hours to 954 mb. Satellite images show that the eye has warmed and shrunk to a diameter of 8 n mi while the inner core has generally become better defined. However, Gonzalo has been maintaining an asymmetric distribution of convection, presumably due to around 15 kt of south-southwesterly shear of affecting the cyclone according to the latest SHIPS and UW-CIMSS shear analyses. A blend of the flight- level and SFMR wind data is used to raise the initial intensity of 110 kt. Water vapor imagery and cloud-tracked wind vectors show an upper- level trough between Bermuda and the southeastern U.S. responsible for the south-southwesterly shear over Gonzalo, but the shear should not be enough to prevent additional intensification from taking place over warm waters of 28-29 deg C during the next day or so. At some point during this time, fluctuations in strength due to difficult-to-forecast inner core evolution are probable. By 72 hours, a significant increase in south-southwesterly shear should induce a considerable weakening trend. Increasing baroclinicity in the near-storm environment, much cooler waters, and drier and more stable air wrapping around the hurricane's circulation should result in extratropical transition by day 4. The NHC intensity forecast is about the same as the previous one, and is near or higher than the highest intensity guidance (SHIPS/LGEM) through 36 hours but close to the multi-model consensus after that. Gonzalo has continued to move on a northwestward course, or 320/11, though the center has wobbled a bit toward the left during the last couple of hours. The hurricane should gradually turn north- northwestward and then northward and slow down as it moves around the western periphery of an eastward-shifting central Atlantic ridge during the next 24 to 36 hours. By 48 hours, Gonzalo should encounter a deep-layer south-southwesterly flow associated with a potent mid-latitude trough swinging out of the east-central United States. This flow pattern should turn Gonzalo north-northeastward with increasing forward speed. Although the track guidance is tightly clustered through 72 hours, there is still some along-track spread in the model solutions, with the ECMWF depicting a weaker and much-slower-moving cyclone. The new NHC forecast places less weight on the ECMWF, owing to Gonzalo's current intensity. The official NHC forecast lies on the far eastern side of the guidance envelope and to the right of the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 22.2N 66.6W 110 KT 125 MPH 12H 15/1200Z 23.4N 67.6W 120 KT 140 MPH 24H 16/0000Z 24.9N 68.5W 120 KT 140 MPH 36H 16/1200Z 26.3N 68.7W 115 KT 130 MPH 48H 17/0000Z 28.5N 67.7W 110 KT 125 MPH 72H 18/0000Z 34.7N 64.1W 100 KT 115 MPH 96H 19/0000Z 45.1N 56.7W 80 KT 90 MPH...POST-TROP/EXTRATROP 120H 20/0000Z 52.5N 42.0W 65 KT 75 MPH...POST-TROP/EXTRATROP $$ Forecaster Kimberlain
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