Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 211204 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
704 AM CDT Sun Apr 21 2019

.DISCUSSION...Updated for latest aviation discussion below.


12Z issuance....VFR conditions continue through the period. Light
and variable winds this morning transition to a southerly flow by
noon. /22


.PREV DISCUSSION... /issued 450 AM CDT Sun Apr 21 2019/

NEAR TERM /Now Through Sunday night/...A surface ridge of high
pressure building over the southeast states and northeastern Gulf
of Mexico this morning will persist through tonight, resulting in
variable winds less than 10 mph across the forecast area. The
axis of an upper level ridge of high pressure west of the
Mississippi River will shift east of the river by late tonight as
the eastern conus upper trough moves off the eastern seaboard.
With large scale subsidence in place across the region, expect
another sun- drenched day today with near normal temperatures
ranging from 73 to 77 degrees, with lower 70s at the beaches.
Light winds and a strong radiational window will allow for another
cool night, with low temperatures 4 to 8 degrees below normal,
ranging from the mid 40s to lower 50s, with mid to upper 50s at
the beaches. /22

SHORT TERM /Monday Through Tuesday night/...n upper level ridge
remains stationary over the Southeast, bringing near to above
seasonal temperatures to the forecast area through the Short Term.
Highs in the low to mid 80s expected Monday and Tuesday. Lows
increase from the 50s Monday night to upper 50s to low 60s Tuesday
night as southerly flow on the west side of a weakly organized
surface ridge over the Southeast slowly brings Gulf moisture inland
over the region.

LONG TERM /Wednesday Through Saturday/...In the extended,
the return of rain to the area, along with the chances of any strong
to severe weather are the main items to deal with.

Guidance is advertising the Desert Southwest upper trough working
its way slowly east over the Southern Plains, then east-southeast to
over the Southeast Gulf coast by Friday. Both develop a surface low
over the Southern Plains, then move it southeastward to over the
north-central Gulf (and the marine portion of the KMOB area of
responsibility) Thursday into the weekend. Current guidance is in
good agreement with path and speed of both the upper system and
surface low, lending to better timing confidence. With a slower
eastward progression of the upper system, guidance is now
advertising rain overspreading the forecast area from the west
Thursday into Thursday evening. Ahead of the approaching upper
system, the weakly organized surface ridge over the Southeast and
its modest onshore low level flow keep the moisture return on the
slow side of the approaching system. Instability and shear remain
limited Thursday through most of Thursday night, with little chance
of any strong to marginally severe weather. It`s not until late
Thursday night into Friday that instability rises high enough
(MLCapes rising into the 500-700J/kg range) for strong storms.
Guidance also is advertising the upper system becoming more
disorganized at this point, limiting any upper support to storm
development. With the better timing and speed consistency being
counterbalanced by run-to-run inconsistency, am limiting the current
forecast to general thunderstorm with the system`s passage and
continue to monitor for any strong to marginally severe storms.

MARINE...A light southerly flow will develop this afternoon and
each afternoon through Tuesday, followed by a light northeast to
east wind late each night, as a weak surface ridge of high pressure
settles over the northeast Gulf. Southerly winds and seas will build
Thursday in response to a surface low pressure area approaching from
the west. /22




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