Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 212350

Area Forecast Discussion
National Weather Service Mobile AL
650 PM CDT Fri Jul 21 2017

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


22/00Z issuance...Primarily VFR ceiling and surface visibility
tonight through Saturday. Periods of MVFR ceiling and visibility
in and near isolated convection this evening, and then scattered
convection that will redevelop across parts of the region on
Saturday. Surface winds becoming mostly light and variable over
most inland areas tonight, light onshore near the coast. On
Saturday surface winds will be generally light southerly across
entire area. 12/DS


.PREV DISCUSSION... /issued 344 PM CDT Fri Jul 21 2017/

NEAR TERM /Now Through Saturday/...Scattered showers and
thunderstorms continue to develop on the west side of the broad mid
to upper low centered mostly over the adjacent gulf waters of the
western FL panhandle this afternoon, which is progged to continue
moving west weakening and filling over the north central and
northwest gulf through Sat afternoon. To the northwest a broad upper
ridge centered mostly over the central plains states will continue
to nose eastward over the central Mississippi river valley and north
central gulf states through Sat allowing for some dryness to settle
southward in the mid levels, combined with the lower height fields
associated with the upper low to the south, leading to slightly
better lapse rates in the lower to middle layers of the boundary
layer through Sat afternoon. With this pattern expect mostly
scattered showers and thunderstorms to continue over much of the
forecast area through the near term with the best coverage over the
southern half of the forecast area overnight through Sat morning
shifting inland Sat afternoon into early Sat evening. Initial
development offshore and near the immediate coast early in the day
will likley be near and along existing outflow boundaries from
earlier convection then forming ahead and along an northward
advancing seabreeze front later in the day. A few strong to
marginally severe thunderstorms will still be possible with this
pattern both late this afternoon and early this evening and during
the morning and afternoon hours on Sat. Gusty straight line winds
frequent cloud to ground lightning and very heavy rainfall will be
the main threat with he stronger storms. Also, still can`t rule out
some minor flooding, mostly isolated due to the good movement to the
west and southwest.

As for temps with better clouds and rain expected in the near term
tonights lows should be a tad warmer than the last couple of nights
followed by slightly lower afternoon highs on Sat compared to the
earlier in the week. Lows tonight will range from the middle 70s for
most inland areas and the middle to upper 70s along the immediate
coast. Highs Sat will climb to the lower to middle 90s inland and
the upper 80s to near 90 along the immediate coast. 32/ee

SHORT TERM /Saturday night Through Monday night/...An upper
trough over the Southeast gets twisted and squashed as an upper
ridge builds west over the Gulf of Mexico and an upper high
organizes over the southern Rockies. It remains close enough to
the north-central Gulf coast though, when combined with moisture
levels at or above seasonal levels (due to a general south to
southwest flow off the Gulf), keeping the chance of rain around
to a bit above seasonal for the short term. Subsidence, albeit
weak, from the upper ridge over the Gulf when combined with the
moisture levels will help to keep temps at or above seasonal
levels, especially overnight lows. Lows in the low to mid 70s
inland, upper 70s close to the coast expected. Highs are expected
to rise into the low to mid 90s, around 90 along the coast.

Daytime heat indices continue to rise above 100, with most areas
seeing 100 to 105 each day.


LONG TERM /Tuesday Through Friday/...Guidance is advertising the
shortwave energy centered just to the west of the forecast area
organizing and shifting east as the upper high over the southern
Rockies gets an eastward shove. With the forecast area coming
under a less favorable position for added upper support, the
chance of rain trends down through the extended. With increasing
subsidence from the eastward building upper high, temps rise to
well above seasonal levels by Friday.


MARINE...Expect another round of thunderstorms, some strong, to
develop late tonight and continue through Sat morning before
shifting inland by Sat afternoon. Similar to this morning gusty
straight line winds, possibly up 40 knots, with frequent lightning
and very heavy rainfall will accompany the stronger cells. Movement
will generally be to the west southwest early tonight then more to
the north and northeast by early Sat morning as the main upper
system in the mid to upper levels continues to shift off to the
west. Outside of the thunderstorms winds will be generally be from
the south to southwest at 8 to 10 knots through early Sun increasing
to 8 to 13 knots by Sun afternoon continuing through early next
week. Sea will generally range from 1 to 2 feet through early Sun
then build to 2 to 3 feet late Sun through midweek. 32/ee




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