[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 050854
TCDAT1

HURRICANE JOAQUIN DISCUSSION NUMBER  31
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112015
500 AM AST MON OCT 05 2015

The weakening that Joaquin has experienced during the past day or
so appears to have temporarily stopped overnight.  Deep convection
has increased near the center, and an eye has intermittently been
seen infrared satellite pictures.  The initial wind speed of 75 kt
is based on recent Dvorak satellite estimates from TAFB and SAB.
Only a slight reduction in strength is expected during the next day
or so while Joaquin remains within an area of light to moderate
vertical wind shear and over sea surface temperatures of around 27C.
After that time, increasing southwesterly shear and cooler waters
should cause gradual weakening. Joaquin is expected to interact with
a baroclinic zone in a couple of days and become an extratropical
cyclone within 72 hours. The global models slowly weaken the
extratropical low as it moves eastward over the central and eastern
Atlantic later this week.

The initial motion estimate is 025/11 kt. Joaquin should turn
northeastward and move at a slightly faster forward speed by
tonight as a ridge to the northeast of the hurricane weakens.
Joaquin should become embedded within the mid-latitude westerlies
in 36 to 48 hours and accelerate east-northeastward.  The track
guidance is in good agreement on this scenario and the NHC
forecast is near the center of the guidance envelope.  The track
of the extratropical low is a blend of the previous advisory and
guidance provided by the Ocean Prediction Center.

The tropical storm force wind radii have been expanded outward
based on earlier ASCAT data.  Tropical storm conditions are likely
to continue on Bermuda for a few more hours.


FORECAST POSITIONS AND MAX WINDS

INIT  05/0900Z 34.1N  65.2W   75 KT  85 MPH
 12H  05/1800Z 35.4N  64.0W   70 KT  80 MPH
 24H  06/0600Z 37.1N  61.4W   70 KT  80 MPH
 36H  06/1800Z 38.6N  56.9W   70 KT  80 MPH
 48H  07/0600Z 39.9N  50.7W   65 KT  75 MPH
 72H  08/0600Z 42.0N  36.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
 96H  09/0600Z 43.5N  23.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  10/0600Z 45.0N  17.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown
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