FXUS64 KMOB 271132 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
632 AM CDT Sat May 27 2017

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


12Z issuance...IFR/MVFR conditions with low clouds this morning
will become VFR by this afternoon. Another round of low clouds can
be expected tonight into the Sunday morning. /13


.PREV DISCUSSION... /issued 354 AM CDT Sat May 27 2017/

NEAR TERM /Now Through Saturday night/...
Surface and upper level ridging will continue across the area today
before gradually shifting eastward tonight. Meanwhile, mostly cloudy
skies can be expected this morning as low level moisture around 925
mb is advected into the area. Skies will become partly cloudy
through the morning as mixing increases. Another dry day expected
with the upper ridge overhead and strong subsidence continuing.
Highs this afternoon will warm 4-5 degrees over those observed on
Friday as 850 mb temps warm. Higher dewpoints will also move into
the area through the day, creating heat index values in the low to
mid 90s by the afternoon.

The upper and sfc ridge begin to move east of the area tonight. This
will continue to bring moisture back into the region with another
round of low clouds expected overnight. Lows tonight will range from
the low 70s inland to mid 70s along the coast. /13

SHORT TERM /Sunday Through Monday night/...
Ridging, both at the surface and aloft, will begin to weaken and
slide east Sunday as a shortwave trough pushes into the Mid-
Mississippi Valley. This is expected to aid in pushing a cold front
into the Mid-South Sunday evening and south/east of the Natchez
Trace by Monday morning. Moisture will start to increase as the
ridging retreats, resulting in forecast precipitable water values
approaching 2 to 3 standard deviations above climatological means by
Sunday evening.

I think Sunday will largely remain dry across our area. A few of the
convection allowing models are hinting that a few showers or
thunderstorms could develop. I suppose this is plausible given
weakening ridging and increasing low-level moisture. However,
forecast soundings continue to strong a "fairly healthy" subsidence
inversion just below 850 mb. This is evidence of lingering ridging
over the region and should preclude much in the way of convection.
I'll go below precipitation probabilities in the model blends, but
maintain non-zero odds of seeing convection Sunday afternoon
(especially north/west).

Odds of seeing precipitation increase Sunday night into Monday as
the cold front moves into the forecast area. Diminishing cross-
isobaric flow Monday will result in the front's forward speed
slowing as it heads toward the Gulf Coast. Ample instability,
moisture, and forcing should be present by Monday afternoon to
result in the development of scattered to numerous showers and

Convective coverage should be the greatest from Southeast
Mississippi into interior portions of the forecast area. NAEFS
integrated water vapor transport suggests values approaching 3
standard deviations above climatological means in this region.
Convective coverage should diminish somewhat after sunset Monday,
despite the presence of increased synoptic scale forcing. /02/

LONG TERM /Tuesday Through Friday/...
Precipitation probabilities should remain elevated through mid-week
as the cold front slowly sinks offshore. With the departure of broad
upper-level troughiness over the area, the front should gradually
dissipate. Less convective coverage is then expected for Thursday
and Friday as ridging attempts to reassert itself across the
region. Most of the convective development for Days 6 and 7 should exhibit
a stronger diurnal trend. /02/

A light to moderate southwest wind flow will continue through Sunday
as high pressure shifts east of the area. A weak cold front will
stall along the coast Monday night and will have little effect on
winds and seas through late Tuesday. It will bring an increase in
rainfall coverage. Winds become light and variable on Tuesday due to
the proximity of the front. Surface high pressure becomes
established on Wednesday with a return to more of a normal sea-
breeze pattern by late week. /13




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