[Tropical] Tropical Cyclone Discussion

EMWIN Server emwin at nashvilleweather.net
Mon Aug 31 15:42:10 CDT 2015


WTNT41 KNHC 312041
TCDAT1

HURRICANE FRED DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062015
500 PM AST MON AUG 31 2015

Fred likely peaked in intensity this morning.  Microwave data
received since the previous advisory shows that the eye has become
open over the southern semicircle, however, the center remains
embedded in an area of cloud top temperatures below -70C.  Although
Dvorak T-numbers have changed little since the previous advisory,
the initial wind speed has been lowered to 70 kt, based on the
degraded inner-core structure.  The environment ahead of Fred is
expected to become increasingly hostile with marginal sea surface
temperatures, increasing southwesterly shear, and less favorable
thermodynamic conditions.  As a result, steady weakening is
predicted.  Since Fred is a small tropical cyclone, it is likely to
succumb to the shear faster than indicated by the statistical
guidance, and the NHC forecast is slightly lower than the SHIPS/LGEM
models.  Despite warmer SSTs along the forecast track at days 4 and
5, the shear and dry mid-level air are likely to cause Fred to
become a remnant low by the end of the forecast period.

The initial motion estimate is 310/10 kt.  The center of Fred
will pass near or over the northwestern Cape Verde Islands through
early tonight.  A turn toward the west-northwestward is expected on
Tuesday as the subtropical ridge to the north of Fred builds
westward.  A west-northwestward heading should then continue during
the remainder of the forecast period.  The GFS and ECMWF models
remain on the southern side of the guidance envelope and the NHC
forecast is near a consensus of these typically reliable models.
The NHC forecast at the long-range leans a bit closer to the ECMWF,
which shows a weaker Fred moving more westward.

Please note that the track/cone graphic, an automatically generated
product, does not have the capability of displaying warnings for the
Cape Verde Islands.

FORECAST POSITIONS AND MAX WINDS

INIT  31/2100Z 17.2N  24.6W   70 KT  80 MPH
 12H  01/0600Z 18.2N  25.9W   65 KT  75 MPH
 24H  01/1800Z 19.2N  27.7W   60 KT  70 MPH
 36H  02/0600Z 20.1N  29.3W   55 KT  65 MPH
 48H  02/1800Z 20.8N  31.0W   45 KT  50 MPH
 72H  03/1800Z 22.0N  34.0W   35 KT  40 MPH
 96H  04/1800Z 23.2N  37.5W   30 KT  35 MPH
120H  05/1800Z 25.0N  41.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brown
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