[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 040252
TCDAT1

HURRICANE JOAQUIN DISCUSSION NUMBER  26
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112015
1100 PM AST SAT OCT 03 2015

While the cloud pattern has deteriorated a little this evening,
reports from an Air Force Reserve Hurricane Hunter aircraft
indicate that Joaquin is still a Category 4 hurricane.  The
aircraft reported 700-mb flight-level winds of 131 kt southeast of
the center along with a central pressure near 944 mb.  Surface wind
estimates from the Stepped Frequency Microwave Radiometer were as
high as 126 kt, but it is uncertain how reliable these are.  Based
mainly on the flight-level winds, the initial intensity is decreased
to 115 kt.  The aircraft also reports that the size of the 50 kt and
64 kt wind radii have expanded in the southeastern quadrant.

Joaquin has moved a little to the right for the past several hours
and the initial motion is now 050/17.  Water vapor imagery shows a
mid- to upper-level low near 34N 71W and a mid- to upper-level
ridge east of 60W between 25N and 40N.  Joaquin is expected to turn
north-northeastward between these features during the next 12 hours,
with this motion continuing through about 48 hours.  After that
time, the tropical cyclone is expected to recurve northeastward into
the westerlies and accelerate.  The forecast track, which has been
shifted about 30 n mi eastward from the previous track, lies near
the center of the tightly clustered track guidance models.

The intensity guidance is in good agreement that Joaquin should
weaken during the forecast period as it encounters episodes of
moderate to strong vertical wind shear.  However, it is likely to
be a Category 2 hurricane in 24-36 hours at the time of closest
approach to Bermuda.  Extratropical transition should begin around
72 hours and be complete by 96 hours, with the winds decreasing
below hurricane force during the transition.  The new intensity
forecast is an update of the previous forecast and lies near the
upper edge of the intensity guidance.

The combination of the shift in the forecast track and the expansion
of the hurricane-force winds requires a hurricane warning for
Bermuda at this time.


FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 28.0N  68.9W  115 KT 130 MPH
 12H  04/1200Z 29.9N  67.3W  105 KT 120 MPH
 24H  05/0000Z 32.3N  66.2W   95 KT 110 MPH
 36H  05/1200Z 34.3N  65.0W   85 KT 100 MPH
 48H  06/0000Z 36.4N  62.7W   80 KT  90 MPH
 72H  07/0000Z 41.0N  52.5W   70 KT  80 MPH
 96H  08/0000Z 45.5N  36.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
120H  09/0000Z 50.5N  22.0W   55 KT  65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven
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