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Tropical Storm Gabrielle Discussion Number   5
NWS National Hurricane Center Miami FL       AL082019
500 PM AST Wed Sep 04 2019

Recent microwave data suggest that Gabrielle continues to gradually
become better organized, and the last few GOES-16 images show a
convective burst forming over the center. The initial intensity is
estimated at 45 kt based on the Dvorak number from TAFB and an
earlier ASCAT pass from this morning, but it's possible that this
intensity estimate may be conservative.  The storm could intensify
a little more in the short-term, but overall it is expected to
remain in a marginal environment during the next couple of days,
characterized by moderate southerly to southwesterly wind shear, low
values of mid-level relative humidity and SSTs near 26-27C. Little
overall change in strength is predicted during the next two days.
Thereafter, some strengthening is likely as Gabrielle moves on the
northeastern side of an upper-level low into a lower shear region,
at the same time the cyclone moves over warmer water. The new NHC
intensity forecast shows Gabrielle reaching hurricane strength in
about 5 days, which is consistent with the latest HWRF, NOAA
corrected-consensus and COAMPS-TC models.

The initial motion is estimated at 325/8. For the next 5 days,
Gabrielle is forecast to move generally northwestward toward a break
in the Bermuda-Azores high pressure ridge. An increase in forward
speed is expected due to the gradient between an upper-level low to
the west and the ridge to the northeast. The latest models have
shifted a little to the west for the point of recurvature in about 5
days, and the official forecast splits the difference between the
previous NHC forecast and the latest various consensus models in the
day 4 to 5 time period.


FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 21.0N  34.0W   45 KT  50 MPH
 12H  05/0600Z 21.7N  34.6W   50 KT  60 MPH
 24H  05/1800Z 22.8N  35.8W   50 KT  60 MPH
 36H  06/0600Z 24.2N  37.4W   45 KT  50 MPH
 48H  06/1800Z 26.1N  39.1W   45 KT  50 MPH
 72H  07/1800Z 30.0N  43.2W   50 KT  60 MPH
 96H  08/1800Z 33.0N  47.5W   55 KT  65 MPH
120H  09/1800Z 36.5N  48.5W   65 KT  75 MPH

$$
Forecaster Blake/Hagen

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