Tropical Storm DORIAN (Text)


Tropical Storm Dorian Discussion Number  10
NWS National Hurricane Center Miami FL       AL052019
500 PM AST Mon Aug 26 2019

Dorian's convective pattern has waxed and waned this afternoon due
to intrusions of dry mid-level air while the upper-level outflow
pattern has continued to expand and become more symmetrical.
Although the inner-core convection has decreased recently, a recent
burst of strong convection with cloud tops colder than -80C has
redeveloped just north of the low-level center. The initial
intensity remains at 50 kt based on a an average of satellite
intensity estimates ranging from 45 kt to 61 kt from TAFB, SAB, and
UW-CIMSS SATCON and ADT. An Air Force Reserve reconnaissance
aircraft is scheduled to investigate Dorian by 0000 UTC this
evening, and will provide a better estimate of the cyclone's

The initial motion is west-northwestward or 290/12 kt. There is no
significant change to the previous forecast track or reasoning. The
latest NHC model guidance remains in very agreement that Dorian will
move west-northwestward across the central Lesser Antilles tonight
and into the northeastern Caribbean Sea on Tuesday as the cyclone
moves around the edge of the Bermuda-Azores ridge located well to
the north. On Wednesday, Dorian should turn northwestward into a
small weakness in the ridge, allowing the tropical cyclone to pass
near or between western Puerto Rico and the eastern Dominican
Republic. By late Thursday and Friday, the ridge is forecast to
build back in as an upper-level trough lifts out to the north,
causing Dorian to turn back toward the west-northwest in the
vicinity of the central Bahamas. The new official forecast track is
just an extension of the previous one since the latest model
guidance, especially the consensus models, are tightly packed around
the previous track forecast.

The intensity forecast remains something of an enigma. The majority
of the environmental conditions support at least steady
strengthening, with the main hindrance being the very dry mid-level
air surrounding the cyclone and occasionally being entrained into
Dorian's inner-core region. The small but robust circulation should
continue mix out the brief dry air intrusions, but when an eyewall
will form is still uncertain. Given that Dorian will be moving into
the convective maximum period later tonight, the intensity forecast
still calls for Dorian be near hurricane strength when it passes
through the Windward Islands. Interaction with Hispaniola and
possibly Puerto Rico should result in some weakening in 72-96
hours, followed by restrengthening on days 4 and 5 when Dorian will
be moving over the very warm waters in the Bahamas in low shear
conditions. Most of the global models along with the statistical-
dynamical SHIPS and LGEM intensity models are now showing pronounced
strengthening while Dorian is moving near or through the Bahamas, so
the official forecast shows a significant change to the previous
one at 96 and 120 hours. However, confidence in the intensity
forecast at days 4 and 5 is very low given the uncertainty about how
much of Dorian's core will interact with Hispaniola.

Key Messages:

1. Dorian is expected to bring tropical storm conditions to portions
of the Lesser Antilles tonight and Tuesday, where tropical storm
watches and warnings are in effect. Hurricane conditions are
possible in St. Lucia, where a Hurricane Watch is in effect.
Rainfall of 3 to 8 inches is expected from Martinique to St.
Vincent, including Barbados, with isolated totals as high as 10
inches possible.

2. Tropical storm conditions are possible in Puerto Rico on
Wednesday, where a tropical storm watch has been issued. Rainfall
of 2 to 4 inches with maximum totals of 6 inches are possible
across Puerto Rico and St. Croix.

3. Watches will likely be issued for portions of Hispaniola tonight
or Tuesday, as the threat of wind and rain impacts continues to

4. While uncertainty is high, wind and rain impacts are possible in
the Bahamas and Florida later this week and this weekend. Residents
in these areas should monitor the progress of Dorian and ensure that
they have their hurricane plan in place.


INIT  26/2100Z 12.7N  58.8W   50 KT  60 MPH
 12H  27/0600Z 13.4N  60.5W   55 KT  65 MPH
 24H  27/1800Z 14.5N  62.6W   60 KT  70 MPH
 36H  28/0600Z 15.7N  64.6W   65 KT  75 MPH
 48H  28/1800Z 17.1N  66.7W   70 KT  80 MPH
 72H  29/1800Z 20.1N  70.2W   50 KT  60 MPH
 96H  30/1800Z 23.0N  73.8W   55 KT  65 MPH
120H  31/1800Z 25.5N  78.0W   60 KT  70 MPH

Forecaster Stewart


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Page last modified: Tuesday, 31-Dec-2019 12:09:13 UTC