[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

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
This weather bulletin was brought to you by:
www.nashvilleweather.net