BULLETIN
Subtropical Storm Alberto Advisory Number 9
NWS National Hurricane Center Miami FL AL012018
1100 AM EDT Sun May 27 2018
...ALBERTO MOVING NORTHWARD TOWARD THE NORTHERN GULF COAST...
SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...27.1N 84.4W
ABOUT 130 MI...210 KM WSW OF TAMPA FLORIDA
ABOUT 185 MI...295 KM SSE OF APALACHICOLA FLORIDA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...N OR 5 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.36 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
The Tropical Storm Warning for the Dry Tortugas has been
discontinued.
The Tropical Storm Watch along the north-central Gulf Coast has
been discontinued.
The Storm Surge Watch has been discontinued west of the
Florida/Alabama border.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Watch is in effect for...
* Crystal River to the Florida/Alabama border
A Tropical Storm Warning is in effect for...
* Bonita Beach to the Mississippi/Alabama border
A Storm Surge Watch means there is a possibility of life-
threatening inundation, from rising water moving inland from the
coastline, in the indicated locations. For a depiction of areas at
risk, please see the National Weather Service Storm Surge
Watch/Warning Graphic, available at hurricanes.gov.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.
For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.
DISCUSSION AND OUTLOOK
----------------------
At 1100 AM EDT (1500 UTC), the center of Subtropical Storm Alberto
was located near latitude 27.1 North, longitude 84.4 West. The
storm is moving toward the north near 14 mph (22 km/h). A turn
toward the north-northwest at a slower forward speed is forecast
tonight. A north-northwestward to northward motion is expected late
Monday through Wednesday. On the forecast track, the center of
Alberto will cross the eastern and northern Gulf of Mexico today and
approach the northern Gulf Coast in the warning area tonight or
Monday. Heavy rainfall and tropical storm conditions will likely
reach the northern Gulf Coast well before the arrival of the center
of Alberto. Alberto is expected to move northward into the
Tennessee Valley on Tuesday and Wednesday.
Maximum sustained winds have increased to near 50 mph (85 km/h) with
higher gusts. Some additional strengthening is forecast before the
system reaches the northern Gulf Coast. Steady weakening is
expected after landfall, and Alberto is forecast to become a
tropical depression by Monday night or Tuesday.
Winds of 40 mph extend outward up to 125 miles (205 km) primarily to
the east of the center.
The latest minimum central pressure reported by an Air Force
Reserve reconnaissance aircraft is 994 mb (29.36 inches).
HAZARDS AFFECTING LAND
----------------------
RAINFALL: Alberto is expected to produce the following rain
accumulations through Tuesday:
Central Cuba...Additional 5 to 10 inches, isolated storm totals of
20 inches.
The Florida panhandle into eastern Alabama and western Georgia...4
to 8 inches, isolated 12 inches.
The Florida Keys and south Florida...Additional 3 to 6 inches,
isolated storm totals of 10 inches.
Rest of the Florida peninsula...1 to 4 inches.
Rest of the southeast U.S. from Tennessee to the Carolinas...2 to 6
inches.
Rains in Cuba could produce life-threatening flash floods and
mudslides. Flooding and flash flooding are possible in the southeast
United States, including Florida.
WIND: Tropical storm conditions will spread northward in the
warning area along the west coast of Florida today and will reach
the warning area along the northern Gulf Coast by this evening.
STORM SURGE: The combination of storm surge and the tide will cause
normally dry areas near the coast to be flooded by rising waters
moving inland from the shoreline. The water could reach the
following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide...
Crystal River to the Florida/Alabama border...2 to 4 ft
The deepest water will occur along the immediate coast. Surge-
related flooding depends on the relative timing of the surge
and the tidal cycle, and can vary greatly over short distances. For
information specific to your area, please see products issued by
your local National Weather Service forecast office.
TORNADOES: A few tornadoes are possible across the Florida
peninsula today.
SURF: Swells generated by Alberto will affect the eastern and
northern Gulf Coast through Tuesday. These swells are likely
to cause life-threatening surf and rip current conditions. For more
information, consult products from your local weather office.
NEXT ADVISORY
-------------
Next intermediate advisory at 200 PM EDT.
Next complete advisory at 500 PM EDT.
$$
Forecaster Brown
Subtropical Storm Alberto Discussion Number 9
NWS National Hurricane Center Miami FL AL012018
1100 AM EDT Sun May 27 2018
The satellite and radar presentation of Alberto has improved
markedly over the past 12 hours or so. Deep convection has
increased and become organized in a primary band that wraps around
the western and northwestern portions of the storm and the
circulation has also become much better defined than 24 hours ago.
An Air Force Reserve reconnaissance aircraft has recently indicated
that the pressure has fallen to 994 mb. The aircraft has also
reported peak flight-level winds of 49 kt and believable SFMR winds
of around 40 kt, however, the aircraft has not yet sampled the
northwestern portion of the circulation where the deepest convection
is located. Assuming that there are slightly higher winds in that
area, the initial intensity has been increased to 45 kt.
With deep convection closer to the center and a slightly smaller
radius of maximum winds, it appears that Alberto is beginning its
transition to a tropical cyclone. The reconnaissance aircraft data
also indicate that a shallow warm core is present. It is likely
that Alberto will make the transition to tropical storm later today
or tonight. As this transition occurs, some additional
strengthening is forecast while Alberto moves over marginally warm
sea surface temperatures and the shear relaxes. However, dry mid-
level air wrapping around the eastern portion of the circulation
could slow the intensification process before Alberto reaches the
coast.
The initial motion estimate of 005/12 is again highly uncertain due
to the center re-formations that have occurred over the past 12 to
24 hours. The cyclone should move generally northward today, then
turn northwestward around the northeastern side of a cutoff low over
the central Gulf of Mexico. The timing and location of landfall of
the center will be dependent on when the northwestward turn occurs.
The latest ECMWF forecast moves Alberto faster northward before it
makes the turn and therefore brings the center onshore much sooner
and farther eastward than the UKMET and GFS. The NHC forecast is
near the model consensus, and is somewhat faster than the previous
advisory. Users should remember not to focus on the exact timing
and location of landfall since wind and rain will continue to spread
northward over the northeastern Gulf Coast well ahead of the center.
KEY MESSAGES:
1. Alberto is expected to produce heavy rainfall with a risk of
flooding and flash flooding over western Cuba, the Florida Keys, and
south Florida today. The risk for heavy rainfall and flooding will
then spread over much of the southeast U.S. tonight and Monday.
2. Hazardous storm surge is possible along portions of the eastern
Gulf Coast beginning later today, including areas well east of the
track of Alberto's center. Residents in the storm surge watch area
are encouraged to follow any guidance given by their local
government officials.
3. Tropical storm conditions are likely within the tropical storm
warning area along the Florida west coast today and within the
warning area along the northern Gulf Coast by tonight.
4. Dangerous surf and rip current conditions will continue to
affect portions of the eastern and northern Gulf Coast through
Monday.
FORECAST POSITIONS AND MAX WINDS
INIT 27/1500Z 27.1N 84.4W 45 KT 50 MPH
12H 28/0000Z 28.7N 84.9W 50 KT 60 MPH...TROPICAL STORM
24H 28/1200Z 30.3N 85.9W 50 KT 60 MPH...INLAND
36H 29/0000Z 31.6N 86.4W 35 KT 40 MPH...INLAND
48H 29/1200Z 33.6N 86.7W 25 KT 30 MPH...INLAND
72H 30/1200Z 38.3N 87.2W 20 KT 25 MPH...INLAND
96H 31/1200Z 43.3N 84.7W 15 KT 15 MPH...POST-TROP/REMNT LOW
120H 01/1200Z 46.5N 79.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
$$
Forecaster Brown
