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Tropical Depression Nineteen Discussion Number 2
NWS National Hurricane Center Miami FL AL192020
1100 PM EDT Fri Sep 11 2020
Doppler radar data from Miami and satellite images indicate that
the depression is gradually becoming better organized. The
low-level center is estimated to be near the northwestern edge of
the main area of deep convection due to some northerly wind shear.
Surface observations and satellite classifications support holding
the initial intensity at 30 kt. The minimum pressure appears to be
a little lower than before, now 1007 mb.
The tropical depression is moving west-northwestward at about 7
kt. A subtropical ridge extending from the southeast U.S. to the
western Atlantic should steer the depression west-northwestward
across south Florida tonight and Saturday morning and then over the
eastern Gulf of Mexico late Saturday and Sunday. After that time,
the ridge is forecast to weaken due to an approaching trough,
but the trough is not expected to be strong enough to cause the
cyclone to turn northward. Instead, the models suggest that a slow
west-northwestward motion very near the northern Gulf coast is
likely during the early and middle portions of next week.
Although the models all show a relatively similar scenario, there
is a fair amount of spread by the time the system nears the
northern Gulf coast. The NHC track forecast lies roughly near the
middle of the guidance envelope close to the consensus aids.
Several of the local National Weather Service forecast offices
across the southeast U.S. will be launching weather balloons four
times per day, which should provide the models with excellent data
in hopes to provide better track guidance during the next couple of
Since the depression is expected to move over very warm SSTs, once
it reaches the eastern Gulf of Mexico tomorrow, and remain in an
environment of low wind shear and high moisture, gradual
strengthening seems likely. The models suggest that there could
be an increase in westerly shear around the time the cyclone is
forecast to move inland along the northern Gulf coast in about 4
days. Based on these expected environmental conditions,
strengthening is forecast during the next few days, and the NHC
intensity forecast follows the trend of the IVCN and HCCA models.
The depression will likely be at or near hurricane strength when
it reaches the northern Gulf coast.
Users are reminded to not to focus on the exact details of
the track or intensity forecast as the average NHC track error at
96 h is around 150 miles and the average intensity error is around
15 mph. In addition, winds, storm surge, and rainfall hazards will
extend far from the center.
1. Heavy rainfall is expected to produce isolated flash flooding
over portions of central and southern Florida and prolong existing
minor river flooding across central Florida.
2. Tropical storm conditions are possible overnight and early
Saturday along the southeast Florida coast where a Tropical Storm
Watch is in effect. Tropical storm conditions are possible by
Sunday night in portions of the Florida Panhandle, where a Tropical
Storm Watch has been issued.
3. The system is forecast to strengthen to near hurricane intensity
by early next week as it moves across the northeastern Gulf of
Mexico. Dangerous impacts from storm surge, wind, and heavy rainfall
will be possible along the Gulf Coast from the Florida Panhandle to
southeastern Louisiana late this weekend and early next week.
Residents in these areas should monitor the progress of this system
and updates to the forecast, as Storm Surge, Tropical Storm or
Hurricane watches could be issued on Saturday.
FORECAST POSITIONS AND MAX WINDS
INIT 12/0300Z 25.7N 79.8W 30 KT 35 MPH
12H 12/1200Z 26.0N 81.0W 30 KT 35 MPH...INLAND
24H 13/0000Z 26.8N 82.9W 35 KT 40 MPH
36H 13/1200Z 27.9N 84.6W 40 KT 45 MPH
48H 14/0000Z 28.8N 85.9W 45 KT 50 MPH
60H 14/1200Z 29.3N 86.9W 55 KT 65 MPH
72H 15/0000Z 29.7N 87.7W 60 KT 70 MPH
96H 16/0000Z 30.2N 89.5W 60 KT 70 MPH...INLAND
120H 17/0000Z 31.3N 90.9W 25 KT 30 MPH...INLAND