[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 310240
TCDAT1

TROPICAL STORM FRED DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062015
1100 PM AST SUN AUG 30 2015

Fred has been maintaining strong convection in its CDO, and
microwave data show a well-defined inner core.  Subjective and
objective Dvorak intensity estimates have not increased over the
past several hours, however.  The current intensity estimate is 60
kt, which is slightly above the most recent ADT values from
UW-CIMSS.  Upper-level outflow is well-defined over the tropical
cyclone.  The system should remain over marginally warm sea surface
temperatures with moderate vertical shear for the next day or so,
and sounding data from Sal in the Cape Verde Islands indicate that
the Saharan Air Layer is not very prominent ahead of Fred.  Given
these conducive factors in the short term, the storm is likely to
strengthen into a hurricane overnight.  By 36 hours, vertical shear
is forecast to increase significantly and a weakening trend should
be underway by that time.  Late in the forecast period, model
guidance shows very dry low- to mid-level air affecting Fred with
the shear remaining strong.  This should result in the cyclone
degenerating to a depression by the end of the period.  The official
intensity forecast is similar to the SHIPS and LGEM guidance and is
the same as the previous one.

Geostationary and microwave satellite imagery show that Fred
continues on its northwestward trek.  The track forecast reasoning
is unchanged from the previous package.  For the next few days,
a weakening mid-level subtropical ridge over the eastern Atlantic
should result in the tropical cyclone continuing northwestward with
decreasing forward speed.  Late in the forecast period, the ridge
builds westward a bit and this, along with the weakening cyclone
responding more to the lower-level flow, is likely to result in a
turn to the left with time.  The official track forecast is close to
a consensus of the ECMWF and GFS solutions and lies on the southern
side of the guidance suite.  This is basically an update of the
previous NHC track prediction.

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  31/0300Z 15.3N  22.4W   60 KT  70 MPH
 12H  31/1200Z 16.2N  23.7W   70 KT  80 MPH
 24H  01/0000Z 17.5N  25.5W   70 KT  80 MPH
 36H  01/1200Z 18.8N  27.3W   65 KT  75 MPH
 48H  02/0000Z 19.6N  29.0W   60 KT  70 MPH
 72H  03/0000Z 20.8N  32.8W   50 KT  60 MPH
 96H  04/0000Z 22.0N  36.5W   40 KT  45 MPH
120H  05/0000Z 23.0N  39.5W   30 KT  35 MPH

$$
Forecaster Pasch
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