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Hurricane JOAQUIN Forecast Discussion Number 34
2015-10-06 04:52:32| National Hurricane Center (Atlantic)
Issued at 1100 PM AST MON OCT 05 2015 000 WTNT41 KNHC 060252 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 34 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 1100 PM AST MON OCT 05 2015 While Joaquin's eye is no longer present in the shortwave infrared imagery from the GOES-East geostationary satellite this evening, a distinct eye has been visible in the microwave imagery from the SSMIS polar orbiting satellite passes at 2231Z and 2316Z. There is even a suggestion of a concentric eyewall at about a 50 nm radius. Dvorak Current Intensity numbers from SAB and TAFB remain at 4.5, supporting continuing with an intensity of 75 kt. The wind radii were expanded slightly based upon a CIRA AMSU wind radii analysis from 2104Z. Joaquin is currently embedded in moderate southwesterly vertical shear with somewhat dry mid-tropospheric air, and is traversing over SSTs near 27C. During the next day, the shear picks up substantially. However, with Joaquin moving in the same direction as the shear vector, the negative impact of the shear is lessened as indicated in the SHIPS output. Within two days, Joaquin will move north of the Gulf Stream and will encounter very cold waters while the shear increases even more. This would typically lead toward a quick decay of a tropical cyclone, but Joaquin is expected to transform into an extratropical cyclone in about 48 hours. The baroclinic processes should allow Joaquin instead to slowly decay. The intensity forecast is based upon the tightly clustered IVCN multi-model consensus through 36 hours, and then is based on guidance provided by the Ocean Prediction Center for the 48-120 hour period. The initial motion of Joaquin is 35 deg/12 kt, fairly confidently known because of the microwave fixes. Joaquin is being swept up in the mid-latitude westerlies and should begin accelerating off toward the east-northeast during the next two to three days. The track prediction is based upon the tightly clustered TVCN multi-model consensus through 36 hours, and then is based on guidance provided by the Ocean Prediction Center for the 48-120 hour period. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 36.8N 62.7W 75 KT 85 MPH 12H 06/1200Z 38.1N 59.9W 75 KT 85 MPH 24H 07/0000Z 39.6N 54.5W 70 KT 80 MPH 36H 07/1200Z 41.0N 47.2W 65 KT 75 MPH 48H 08/0000Z 42.0N 38.8W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 09/0000Z 45.0N 23.8W 55 KT 65 MPH...POST-TROP/EXTRATROP 96H 10/0000Z 46.0N 17.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 11/0000Z 48.0N 12.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Landsea
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