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Tropical Storm FLORENCE


Tropical Storm Florence Discussion Number   9
NWS National Hurricane Center Miami FL       AL062018
1100 AM AST Sat Sep 01 2018

Satellite images indicate that Florence's cloud pattern has improved
in organization with the low-level center embedded within the
convection, and a cyclonically curved band surrounding the system. A
blend of subjective and objective Dvorak numbers from TAFB, SAB, and
the UW-CIMMS yield an initial intensity of 40 kt.

My predecessor wrote a very clear explanation of the reasoning of
his track and intensity forecasts, and I do not think I can improve
on it. The environment continues to be mixed with favorable and
unfavorable conditions for Florence to strengthen. Currently,
the shear is low and favors strengthening, but the ocean along the
cyclone's forecast path is cooler. The latter condition should
inhibit significant intensification.  After 3 days, the opposite is
anticipated -- the ocean will be warmer, but the shear will likely
be high. Only at the very long range could both factors become
favorable. The best option at this time is to show only a gradual
strengthening at the rate indicated by the intensity consensus aids.

Florence is still moving toward the west-northwest or 295 degrees
at 12 kt. No change in track is anticipated during the next 3 days
while Florence is located to the south of the subtropical ridge.
After that time, Florence will reach a break in the ridge causing
the cyclone to turn toward the northwest with a decrease in forward
speed. The confidence in the forecast is high during the next 3 days
when the track guidance envelope is tightly packed. Thereafter, the
confidence is not so high since the envelope widens and becomes
bounded by the easternmost HWRF and the westernmost ECMWF models.
Since the guidance envelope shifted a little bit westward, the NHC
forecast was also adjusted slightly in that direction, primarily
during the end of the forecast period.


INIT  01/1500Z 14.8N  27.8W   40 KT  45 MPH
 12H  02/0000Z 15.3N  29.7W   45 KT  50 MPH
 24H  02/1200Z 16.1N  32.4W   50 KT  60 MPH
 36H  03/0000Z 16.5N  35.0W   50 KT  60 MPH
 48H  03/1200Z 17.0N  37.5W   55 KT  65 MPH
 72H  04/1200Z 19.0N  42.5W   60 KT  70 MPH
 96H  05/1200Z 21.0N  46.5W   60 KT  70 MPH
120H  06/1200Z 23.5N  50.0W   55 KT  65 MPH

Forecaster Avila