Official Discussion issued by the National Hurricane Center

Florence (AL062018) DATA RELEASED: 9/6/2018 11:00:00 PM UTC

Copy of official data

Tropical Storm Florence Discussion Number  31
NWS National Hurricane Center Miami FL       AL062018
1100 PM AST Thu Sep 06 2018

Deep convection near the center of Florence has continued to
decrease during the past several hours, and the overall cloud
pattern remains elongated from southwest to northeast.  The latest
Dvorak estimates and a recent scatterometer pass suggest that
Florence is no longer a hurricane, and the initial wind speed is
set to 60 kt.

Some further weakening is anticipated since the shear isn't forecast
to change much in the short term.  However, all of the global models
show a significant reduction of shear during the next several days,
especially later this weekend.  In combination with waters warming
to near 29C, these conditions should promote strengthening into a
hurricane again in a day or two and a major hurricane by early next
week. The intensity guidance is higher than the last cycle at long
range, which is hard to argue with considering the large upper-level
anticyclone forecast in the vicinity of Florence.  The NHC intensity
forecast follows the trend of the previous prediction, a bit
elevated from the previous forecast at days 4 and 5, although still
below the intensity guidance.

A recent scatterometer pass indicates that Florence has slowed down
and turned left, estimated at 290/6.  A narrow ridge over the
subtropical Atlantic Ocean should continue to turn the storm
westward overnight, albeit traveling at a relatively slow pace due
to the strength of the ridge.  This ridge is forecast is strengthen
at long range, steering Florence faster to the west-northwest over
the western Atlantic Ocean.  Except for the UKMET, most of the
historically reliable guidance is in reasonable agreement on this
scenario, which is a bit surprising given the recent trials and
tribulations from the guidance suite. The models continue to shift
westward at long range, however, owing to differences on the
strength and position of that ridge, and the official NHC track
forecast is moved in that direction.

Key Messages:

1. Regardless of Florence's eventual track, large swells will begin
to affect Bermuda on Friday and portions of the U.S. East Coast this
weekend, resulting in life-threatening surf and rip currents.

2. There is still very large uncertainty in Florence's track
beyond day 5, and it is too soon to determine what, if any, other
impacts Florence could have on the U.S. East Coast next week.

3. Since we are near the peak of hurricane season, this is a good
time for everyone who lives in a hurricane-prone area to ensure they
have their hurricane plan in place.


INIT  07/0300Z 25.1N  49.8W   60 KT  70 MPH
12H  07/1200Z 25.2N  50.8W   55 KT  65 MPH
24H  08/0000Z 25.2N  52.2W   60 KT  70 MPH
36H  08/1200Z 25.2N  53.6W   65 KT  75 MPH
48H  09/0000Z 25.3N  54.7W   75 KT  85 MPH
72H  10/0000Z 26.1N  57.3W   90 KT 105 MPH
96H  11/0000Z 27.6N  62.2W  105 KT 120 MPH
120H  12/0000Z 30.0N  68.5W  110 KT 125 MPH

Forecaster Blake