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Hurricane CRISTOBAL Forecast Discussion Number 18
2014-08-28 04:32:50| National Hurricane Center (Atlantic)
Issued at 1100 PM AST WED AUG 27 2014 000 WTNT44 KNHC 280232 TCDAT4 HURRICANE CRISTOBAL DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 1100 PM AST WED AUG 27 2014 Cristobal has a fairly circular area of deep convection over the estimated low-level center, with cloud tops occasionally to -70 deg C. The initial intensity is kept at 65 kt, in agreement with a Dvorak estimate from TAFB. The symmetric appearance of the cloud pattern suggests that vertical shear has not yet become very strong, but the latest SHIPS guidance indicates a significant increase in shear in 18-24 hours. The hurricane could strengthen some over the next day or two as a tropical cyclone, or due to baroclinic processes. The official intensity forecast is close to the intensity model consensus through 36 hours, and a little above it thereafter. Extratropical transition is likely to have occurred by 48 hours since the global models depict the system as fully embedded within a frontal zone by that time. Post-tropical Cristobal is likely to be an intense extratropical cyclone with winds to hurricane force over the north Atlantic in a couple of days. The hurricane is beginning to accelerate northeastward, and the motion estimate is 050/17. The track forecast is unchanged from the previous advisory. Cristobal is currently rounding the northwestern periphery of a subtropical anticyclone over the west-central Atlantic. A mid-latitude shortwave trough to the northwest of the hurricane should cause the hurricane, or its post-tropical counterpart, to accelerate further and move into the higher-latitude westerlies. The official forecast track is in good agreement with the multi-model consensus TVCA. The track, intensity and wind structure forecasts have been coordinated with the Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 28/0300Z 34.1N 69.9W 65 KT 75 MPH 12H 28/1200Z 36.1N 66.6W 65 KT 75 MPH 24H 29/0000Z 39.3N 59.6W 70 KT 80 MPH 36H 29/1200Z 43.4N 51.5W 75 KT 85 MPH 48H 30/0000Z 47.5N 44.5W 70 KT 80 MPH...POST-TROP/EXTRATROP 72H 31/0000Z 56.0N 32.0W 65 KT 75 MPH...POST-TROP/EXTRATROP 96H 01/0000Z 62.5N 25.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 02/0000Z...ABSORBED $$ Forecaster Pasch
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