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Area forecast discussion 
National Weather Service Mobile Alabama
458 am CDT Wednesday Aug 20 2014

..heat indices will be on the increase across the central Gulf
Coast region through this weekend...

Short term [today through Thursday night]...short wave trough that
lead to better forcing in the middle to upper levels of the atmosphere
yesterday continues to shift east of the central Gulf Coast region
this morning dampening out somewhat over Georgia and the Carolinas. In the
wake of this system a deep ridge of high pressure over the western
Atlantic...much of Florida and the north central Gulf will shift northward
through tonight allowing for more stable conditions across the lower
part of the forecast area today leading to slightly less coverage of
showers and thunderstorms for much of the region through this
afternoon. The best chance for measurable rain will be near and along
a developing seabreeze boundary moving inland later this afternoon
and possibly early this evening. Todays convection will also be more
diurnally driven resulting in little to no coverage after sunset this
evening. With better dry air aloft we will also have a better chance
for a few strong thunderstorms...especially inland generally east of
the 1-65 corridor late this afternoon. Otherwise...with better
ridging and subsidence especially to the south expect more sunshine
than clouds today resulting in slightly warmer temperatures for most areas
later this morning and this afternoon. With a light to moderate
onshore flow redeveloping with the seabreeze better low level
moisture near the surface will continue to advect inland resulting in
another hot muggy day for the region. With slightly higher surface dewpoints
expected today heat indices will range from 102 to 106 degrees for
most areas making conditions feel a little more uncomfortable
compared to yesterday. As for temperatures will use a blend of the mav and
European model (ecmwf) MOS guidance through tonight. Todays highs will climb to the
middle 90s for most inland areas and the lower 90s closer to the coast.
Lows tonight will range from the lower to middle 70s inland and the
upper 70s to near 80 along the immediate coast. 32/ee

This afternoon's wet microburst risk will be high for most inland
areas generally east of the I-65 corridor...and moderate for all
other areas.

The upper level ridge of high pressure will continue to strengthen
over much of the deep south Thursday...with short range solutions
showing a 594-595 dm high centered in the vicinity of central
Mississippi by late Thursday afternoon. Low level thermal ridging
will become enhanced across much of the southern states...with 925
mb temperatures prognosticated to range between 25-27 c across much of our
forecast area Thursday afternoon. High temperatures should
subsequently rise into the lower to middle 90s near the coast and in the
upper 90s across much of the interior Thursday. These above normal
readings combined with afternoon surface dewpoints ranging from
around 70 over the interior to the lower to middle 70s near the coast
will result in afternoon heat indices ranging from 102 to 107 across
much of the forecast area...though isolated locations could
experience heat indices around 108. The overall heat index average
should remain just below our heat advisory criteria of 108...but we
will continue to mention the elevated heat indices the next couple of
days in the hazardous weather outlook and graphicasts. Otherwise...
convection should become more isolated in coverage Thursday afternoon
given the strengthening ridge...and mainly located near the seabreeze.
We will keep the isolated coverage focused mainly south of the U.S.
Highway 84 corridor. Isolated storms that develop could again be
locally strong with potential for localized wind gusts over 45
miles per hour...frequent lightning and locally heavy rain given MLCAPE values
of 2500-3500 j/kg and precipitable water values of 1.7 to 1.9 inches.
Mostly clear skies are expected Thursday night with lows in the lower
70s inland and the middle 70s to around 80 near the coast. /21

Long term [friday through tuesday]...upper level high pressure will
remain the dominant feature across much of the deep south late this
through the weekend...which will result in continued heat across our
forecast area Friday through Sunday. Afternoon highs should continue
to range from the middle to upper 90s through the weekend...with a few
of the typically warmer spots in the County warning forecast area possibly getting close to
100. Humid conditions will also result in continued afternoon heat
indices mostly in the 102 to 107 range Friday through Sunday.
Isolated mainly afternoon showers and thunderstorms will remain
possible near the seabreeze through the weekend. Medium range
solutions show the center of the upper ridge building northward into
the vicinity of the Tennessee and Ohio Valley regions Monday into
Tuesday. A slug of deep layer moisture is prognosticated to spread from the
eastern Seaboard toward the central Gulf Coast region around the
southeastern and southern fringe of the ridge axis early next
week...with precipitable water values rising to 2 to 2.25 inches
across our forecast area Monday into Tuesday. The increased moisture
within easterly flow aloft will bring an increasing chance of showers
and thunderstorms back into the forecast early next week and perhaps
slightly cooler temperatures. /21


Aviation [20.12z issuance]...MVFR to VFR conditions through the
21.12z. Lower ceilings mostly in and around scattered showers and
thunderstorms forming this afternoon continuing through about
21.00z. Winds will be mostly southwest at 5 to 8 knots today and
early tonight shifting west to northwest at 3 to 6 knots overnight
and early Thursday morning. A few strong storms will also be possible
later this afternoon. 32/ee


Marine...a persistent surface to 500 mb ridge of high pressure will
continue to build from the western Atlantic to the central Gulf
through much of the week...resulting in a light to moderate
southwest to west wind flow over the marine area through Sunday.
Winds and seas will gradually build next week as the ridge of the
high pressure begins to weaken. Less coverage of showers and
thunderstorms can be expected through the weekend as the ridge of
high continues...then increase in coverage next week as a more
unsettled pattern begins to develop over the eastern and lower
Gulf. 32/ee


Preliminary point temps/pops...
Mobile 94 75 94 75 95 / 30 10 20 10 20
Pensacola 93 76 94 78 94 / 30 10 20 10 20
Destin 92 79 94 80 93 / 30 10 20 10 20
Evergreen 96 71 97 72 98 / 30 10 20 10 10
Waynesboro 96 72 97 73 98 / 30 05 10 10 10
Camden 96 72 97 72 98 / 20 10 10 10 10
Crestview 95 72 97 72 97 / 30 10 20 10 20


Mob watches/warnings/advisories...



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