There hasn't been a lot of new data since the Hurricane Hunter
planes departed Dorian several hours ago. The convective pattern
on infrared satellite imagery has been nearly steady state,
although the latest Dvorak estimates from TAFB and SAB rose to
T5.0/90 kt. These estimates, combined with the earlier aircraft
data, support maintaining an initial intensity of 90 kt.
Dorian's heading is very gradually turning toward the left, with
the latest estimate northwestward, or 320 degrees at 10 kt. Dorian
is now being steered between a mid-tropospheric high centered near
Bermuda and a mid-/upper-level low located over the Bahamas. The
high is expected to expand westward, with a blocking ridge becoming
established over the western Atlantic during the next several days.
With the exception of COAMPS-TC and HMON, the other reliable models
are in excellent agreement through day 3, with Dorian turning
westward south of the ridge and moving near or over the
northernmost islands in the Bahamas Sunday and Monday. After day
3, steering currents collapse as a break develops in the ridge, and
Dorian will likely slow down considerably as it approaches the
Florida peninsula. There is more spread among the deterministic
models and their ensemble members during that time, with
disagreement on exactly when and where Dorian will turn
northwestward and northward on days 4 and 5. That being said, the
tracks of the simple and corrected consensus models on this cycle
did not warrant much change to the official NHC forecast, with
perhaps just a slight southward adjustment on days 3 and 4. The
biggest concern will be Dorian's slow motion when it is near
Florida, placing some areas of the state at an increasing risk of a
prolonged, drawn-out event of strong winds, dangerous storm surge,
and heavy rainfall.
The upper-level low to the west of Dorian continues to impart some
southwesterly shear over the hurricane, which has prevented it from
strengthening rapidly. However, Dorian is expected to enter a more
favorable upper-level environment during the next 24 hours, which
should allow its structure to become more well developed. Although
overall the environment ahead of the storm appears conducive for
strengthening, some models (in particular the ECMWF) suggest that
some northerly shear could come into play while Dorian moves
through the northwestern Bahamas, and for that reason the NHC
official intensity forecast is not quite as bullish as the HCCA,
Florida State Superensemble, and HWRF models. Still, Dorian is
forecast to become a dangerous major hurricane later and maintain
that status as it heads for the northwestern Bahamas and the
1. A Hurricane Watch is now in effect for the northwestern Bahamas,
where the risk of life-threatening storm surge and hurricane-force
winds this weekend has continued to increase. Residents should
begin to execute their hurricane plans and listen to advice given
by local emergency officials.
2. There is an increasing likelihood of a prolonged period of
hazardous weather conditions that could last for a couple of days
in parts of Florida early next week.
3. The risk of life-threatening storm surge along portions of the
Florida east coast has increased, although it is too soon to
determine where the highest storm surge will occur. The risk of
devastating hurricane-force winds along the Florida east coast and
peninsula early next week has also increased, although it is too
soon to determine where the strongest winds will occur. Residents
should have their hurricane plan in place, know if they are in a
hurricane evacuation zone, and listen to advice given by local
4. Regardless of the exact track of Dorian, heavy rains are expected
to occur over portions of the Bahamas, Florida, and elsewhere in the
southeastern United States this weekend and into the middle of next
WTNT35 KNHC 300854
Hurricane Dorian Advisory Number 24
NWS National Hurricane Center Miami FL AL052019
500 AM AST Fri Aug 30 2019
...DORIAN FORECAST TO BECOME A MAJOR HURRICANE LATER TODAY...
...HURRICANE WATCH ISSUED FOR THE NORTHWESTERN BAHAMAS...
SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
ABOUT 260 MI...420 KM ENE OF THE SOUTHEASTERN BAHAMAS
ABOUT 530 MI...850 KM E OF THE NORTHWESTERN BAHAMAS
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The government of the Bahamas has issued a Hurricane Watch for the
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Watch is in effect for...
* Northwestern Bahamas
A Hurricane Watch means that hurricane conditions are possible
within the watch area. A watch is typically issued 48 hours
before the anticipated first occurrence of tropical-storm-force
winds, conditions that make outside preparations difficult or
Interests in southern and central Florida should monitor the
progress of Dorian.
For storm information specific to your area, please monitor products
issued by your national meteorological service.
DISCUSSION AND OUTLOOK
At 500 AM AST (0900 UTC), the center of Hurricane Dorian was located
near latitude 23.8 North, longitude 69.1 West. Dorian is moving
toward the northwest near 12 mph (19 km/h), and this motion is
expected to continue through the day. A slower west-northwestward
to westward motion is forecast to begin tonight and continue
through the weekend. On this track, Dorian should move over the
Atlantic well east of the southeastern and central Bahamas today,
approach the northwestern Bahamas Saturday, and move near or over
portions of the northwestern Bahamas on Sunday.
Maximum sustained winds are near 105 mph (165 km/h) with higher
gusts. Strengthening is forecast during the next few days, and
Dorian is expected to become a major hurricane later today. Dorian
is likely to remain an extremely dangerous hurricane while it moves
near the northwestern Bahamas and approaches the Florida peninsula
through the weekend.
Hurricane-force winds extend outward up to 25 miles (35 km) from the
center, and tropical-storm-force winds extend outward up to 105
miles (165 km).
The minimum central pressure based on data from an earlier
Hurricane Hunter mission is 979 mb (28.91 inches).
HAZARDS AFFECTING LAND
WIND: Hurricane conditions are possible within the watch area by
Sunday, with tropical storm conditions possible by Saturday
night or Sunday morning.
STORM SURGE: A dangerous storm surge is expected to produce
significant coastal flooding in areas of onshore winds in the
northwestern Bahamas. Near the coast, the surge will be
accompanied by large and destructive waves.
RAINFALL: Dorian is expected to produce the following rainfall
accumulations this weekend into the middle of next week:
The northwestern Bahamas and coastal sections of the Southeast
United States...6 to 12 inches, isolated 15 inches.
The central Bahamas...1 to 2 inches, isolated 4 inches.
This rainfall may cause life-threatening flash floods.
SURF: Swells are likely to begin affecting the east-facing shores
of the Bahamas and the southeastern United States coast during the
next few days. These swells are likely to cause life-threatening
surf and rip current conditions. Please consult products from your
local weather office.
Next intermediate advisory at 800 AM AST.
Next complete advisory at 1100 AM AST.