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Subtropical Storm Alberto Discussion Number   3
NWS National Hurricane Center Miami FL       AL012018
1000 PM CDT Fri May 25 2018

Satellite imagery, earlier aircraft data, and surface observations
indicate that Alberto is rather disorganized.  A prominent mid-level
center is near the western tip of Cuba, with the convection somewhat
organized around it.  However, the low-level center is about 170 n
mi south-southwest of the mid-level center. There are no recent
observations of gale-force winds, so the initial intensity will
remain an uncertain 35 kt.  An upper-level trough just to the west
and northwest of the cyclone is advecting cool and dry air into
Alberto, and thus the system remains a subtropical cyclone at this
time.

The initial motion is a somewhat uncertain 090/4.  Alberto should
turn northward during the next 12 h or so in response to the
nearby upper-level trough, with this motion continuing through
about 36 h.  After that, a north-northwestward motion is likely as
the aforementioned trough becomes a closed low over the central
Gulf of Mexico and Alberto moves around the northeast side.  This
evolution should cause Alberto to move through the eastern Gulf of
Mexico during the next 2-3 days, and then make landfall on the
northern Gulf Coast between 72-96 h.  After landfall, Alberto should
continue northward through the southeastern United States.  The new
forecast track is nudged a bit to the east of the previous track
during the first 36 h based on the initial position, and it lies
just to the west of the consensus models.  One uncertainty in the
track forecast is the possibility that the center could re-form to
the north, which at the least could change the timing of the
forecast track.

The dynamical models forecast Alberto to reach an area of stronger
upper-level divergence in about 24 h, with the models agreeing on
more significant development starting about that time.  The
intensity forecast shows a slower development rate for the first 24
h than the previous forecast, then shows a faster development to
the 55-kt peak intensity of the previous forecast.  After landfall,
Alberto should quickly weaken over land.  The new intensity forecast
is near the intensity consensus and the SHIPS model.

Some of the intensity guidance suggests that Alberto could become a
hurricane before landfall.  If the guidance trends stronger, a
hurricane watch could be needed for a portion of the Gulf Coast on
Saturday.

KEY MESSAGES:

1. Regardless of its exact track and intensity, Alberto is expected
to produce heavy rainfall and flash flooding over the northeastern
Yucatan Peninsula of Mexico, western Cuba, southern Florida and the
Florida Keys. Rainfall and flooding potential will increase across
the central U.S. Gulf Coast region and the southeastern United
States later this weekend and early next week when Alberto is
expected to slow down after it moves inland.

2. Tropical-storm-force winds and hazardous storm surge are
possible along portions of the central and eastern U.S. Gulf Coast
beginning on Sunday, including areas well east of the track of
Alberto's center, and tropical storm and storm surge watches are in
effect for portions of these areas. Residents in the watch areas are
encouraged not to focus on the details of the forecast track of
Alberto and should follow any guidance given by their local
government officials.

3. Dangerous surf and rip current conditions are affecting portions
of the Yucatan Peninsula and western Cuba and will likely spread
along the eastern and central U.S. Gulf Coast later this weekend.


FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 19.4N  85.7W   35 KT  40 MPH
 12H  26/1200Z 20.7N  85.4W   35 KT  40 MPH
 24H  27/0000Z 22.9N  85.1W   40 KT  45 MPH
 36H  27/1200Z 25.4N  85.4W   50 KT  60 MPH
 48H  28/0000Z 27.0N  86.3W   55 KT  65 MPH...TROPICAL CYCLONE
 72H  29/0000Z 29.5N  87.5W   55 KT  65 MPH...TROPICAL CYCLONE
 96H  30/0000Z 32.5N  88.0W   30 KT  35 MPH...INLAND
120H  31/0000Z 36.5N  85.5W   20 KT  25 MPH...INLAND

$$
Forecaster Beven

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