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Hurricane GONZALO Forecast Discussion Number 10
2014-10-14 22:41:05| National Hurricane Center (Atlantic)
Issued at 500 PM AST TUE OCT 14 2014 000 WTNT43 KNHC 142041 TCDAT3 HURRICANE GONZALO DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082014 500 PM AST TUE OCT 14 2014 Data from an Air Force Reserve Hurricane Hunter aircraft earlier today indicated flight-level and SFMR wind data that were just below the threshold of a major hurricane. On the last flight leg, the aircraft measured a central pressure of 971 mb, which was down 2 mb from what was measured at the start of the mission. The eye had also contracted from a 20 nmi diameter down to about 16 nmi on the last report. Recent data from the NOAA Doppler radar in San Juan indicate that the eye has contracted to about 15 nmi at an altitude of about 36,000 ft since the aircraft departed a few hours ago, signifying that the eye diameter is likely smaller at lower altitudes. In addition, satellite imagery indicates that the eye has cleared out and warmed while cloud tops have cooled significantly in the surrounding eyewall. Based on the trends noted in the radar and satellite data, the intensity has been increased to 100 kt, which is supported by a UW-CIMSS ADT value of T5.4/100 kt. Gonzalo continues to move steadily northwestward with a motion of 320/11 kt. The NHC model guidance is tightly packed and remains is in excellent agreement on Gonzalo moving steadily northwestward around the periphery of a deep-layer ridge located to its north during the next 36 hours or so. By 48 hours, a deep mid-tropospheric trough and cold front are expected to move eastward across the Bahamas and weaken the western portion of the ridge. This should allow the cyclone to turn slowly northward, and then accelerate northeastward by 72 hours ahead of the aforementioned trough and front, with the hurricane potentially threatening Bermuda on Day 3. Gonzalo is expected to merge with the cold front or become extratropical by 120 hours. The new track forecast is just an update of the previous advisory track, and lies close to a blend of the GFEX and TVCA consensus models. With the eye of Gonzalo having contracted and become more distinct in satellite, radar, and recon wind data, the system appears primed for intensification into a category 4 hurricane later tonight or on Wednesday. Sea-surface temperatures ahead of the cyclone are sufficiently warm enough at 28C-28.5C to support a category 4 hurricane through at least the next 36 hours. The global models continue to indicate that the best vertical shear conditions and 200 mb upper-level outflow pattern are expected to occur on Wednesday and continue into Thursday morning. Afterwards, eyewall cycles and possible cold upwelling beneath the hurricane are likely to cause some fluctuations in the intensity. By 72 hours, increasing vertical wind shear ahead of the aforementioned deep trough is expected to induce weakening. By 120 hours, Gonzalo will be over sub-20C SSTs in the North Atlantic and experiencing vertical shear of 50-60 kt, which should result in the cyclone becoming an extratropical low. The NHC intensity forecast is similar to the previous advisory and remains above all of the available intensity guidance. FORECAST POSITIONS AND MAX WINDS INIT 14/2100Z 21.2N 66.0W 100 KT 115 MPH 12H 15/0600Z 22.5N 67.1W 110 KT 125 MPH 24H 15/1800Z 24.0N 68.2W 115 KT 130 MPH 36H 16/0600Z 25.4N 68.7W 120 KT 140 MPH 48H 16/1800Z 27.2N 68.3W 110 KT 125 MPH 72H 17/1800Z 32.0N 65.6W 100 KT 115 MPH 96H 18/1800Z 39.9N 60.4W 85 KT 100 MPH 120H 19/1800Z 49.0N 50.0W 65 KT 75 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart
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