Official Discussion issued by the National Hurricane Center

Florence (AL062018) DATA RELEASED: 9/3/2018 5:00:00 AM UTC

Copy of official data

Tropical Storm Florence Discussion Number  16
NWS National Hurricane Center Miami FL       AL062018
500 AM AST Mon Sep 03 2018

The structure of Florence has recovered overnight. Several recent
microwave images indicate that the tropical storm's center is still
dislocated to the south of most of the associated convection, but
convective banding has increased. There is also evidence that
Florence has developed better defined low-level inner-core.
Satellite intensity estimates have increased and now range from 45
to 60 kt. As a compromise of the various estimates, the initial
intensity has been raised slightly to 50 kt, but its worth noting
that this increase is within the noise level of our ability to
observe the intensity of tropical storms over the open ocean.

Based on SHIPS diagnostics, the southwesterly shear affecting
Florence could remain moderate for the next 12 h, and some slight
intensification is possible. However, by 24 h, an increase in the
shear should kick off a gradual weakening trend. By the end of the
forecast period, the tropical storm is forecast to re-intensify
while it moves over warmer SSTs and the environmental shear
decreases. Given the improved current structure of Florence, the new
official intensity forecast shows slight intensification for the
first 12 h. Beyond that time, the models are in good agreement and
the NHC forecast is near the middle of the relatively tight
intensity guidance envelope.

The tropical storm is still moving west-northwestward, at an
estimated 14 kt. A continued west to west-northwest motion is
forecast by all the global models for the next couple of days. By
the end of the forecast period, nearly all of the guidance shows a
turn toward the northwest, and the main source of uncertainty in
the track forecast continues to be exactly when and to what extent
Florence will make this turn. At this point I have no reason to
depart from the various consensus models, and the track forecast is
very close to the previous advisory.


INIT  03/0900Z 18.0N  37.5W   50 KT  60 MPH
12H  03/1800Z 18.3N  39.6W   55 KT  65 MPH
24H  04/0600Z 18.7N  42.0W   50 KT  60 MPH
36H  04/1800Z 19.3N  44.2W   45 KT  50 MPH
48H  05/0600Z 20.0N  46.5W   45 KT  50 MPH
72H  06/0600Z 22.2N  51.1W   40 KT  45 MPH
96H  07/0600Z 24.5N  54.5W   45 KT  50 MPH
120H  08/0600Z 26.0N  57.0W   55 KT  65 MPH

Forecaster Zelinsky