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Area forecast discussion...aviation update 
National Weather Service Mobile Alabama
1140 PM CDT Thursday Jul 31 2014

Aviation update (01/06z issuance)...middle to high level clouds
continue to stream out of eastern Texas and across the central Gulf
Coast region and expect this through Friday. VFR conditions forecast
in the near term with a light wind flow pattern. By Friday
afternoon...isolated to scattered showers and storms will return to
the forecast...mostly interior areas so mention only thunderstorms in the vicinity in terminals.


Previous discussion... /issued 308 PM CDT Thursday Jul 31 2014/

Short term...(tonight through Saturday night)...for tonight through
Friday...forecast area is positioned at the base of a long wave high
level trough axis. Upstream...a middle level impulse over northeast Texas
was slipping southeast atop a surface frontal wave of low pressure.
Although surface pressures are not entirely low with this feature
(with minimum central pressures ~ 1014 millibars)...the satellite
representation shows a large cyclonic circulation centered over Tyler
Texas. To the east...deep layer moisture is forecast to slowly
recover tonight over the central Gulf Coast...but the lower levels
remain dry enough as to limit precipitation despite the central Gulf
Coast being influenced by the base of the high level trough. Although
not mentioned in the zones for tonight...probabilities of
precipitation forecast less than 10% does account for any light
sprinkles that may make it to the ground from the higher level cloud
cover spreading in from the west. At the surface...a weak pressure
pattern is forecast resulting in light wind flow. Lows will range
from the middle 60s inland to lower 70s near the coast.

For Friday...a weak surface pressure trough is forecast to be aligned
just an east to west fashion across the central Gulf
Coast. With deep layer moisture recovering (precipitable water values
near 2 inches) through the day...enough lift from the passage of
upper level perturbations at the base of long wave upper trough and
surface focus with boundary nearby...supports a chance of showers and
storms. Daytime highs on Friday in the upper 80s/lower 90s. /10

This afternoon's wet microburst risk: none

Friday night...a weak piece of upper energy moved east of the axis of
the upper trough over the eastern Continental U.S. ( Just east of the miss
river valley). This piece of energy works with the stalled boundary
over the southeastern states...creating an area of isentropic upglide
along and south of i20...and over southern miss. For the forecast area...this
limits the chance for rain and increased cloudiness to mainly
northern regions of the forecast area.

Saturday...another piece/pieces of energy pass north of the forecast area. With
deeper moisture re-established over the forecast area and the surface boundary
around...a greater chance of rain is possible...with a likely chance
inland. With this being mostly late morning into afternoon time-
frame...temperatures rising to near seasonal expected.

Saturday night...guidance is advertising more upper energy diving
into the eastern Continental U.S. Trough as the Friday energy swings out of the
base of the trough. The exiting energy will help to prolong the
chance of rain into the evening hours...especially over the northern
half of the forecast area. Temperatures around seasonal expected.

Long term...(sunday on)...the long-wave trough over the
eastern states weakens to a weak upper trough over the region by
Wednesday and advances eastward somewhat...with deep layer moisture
remains high on Sunday with precipitable water values near 2 inches
but then decreasing gradually to 1.3-1.7 inches later in the period
with lower values well inland. The weak frontal boundary located
near the southern portion of the forecast area shifts southward into
the Gulf on Sunday as a surface high builds into the interior
eastern states. The frontal boundary returns to near the coast by
Tuesday morning but looks to finally dissipate later on Tuesday as
surface ridging builds into the eastern Gulf and establishes a
southwesterly flow over the forecast area. Chance to good chance
probability of precipitation continue for Sunday then chance probability of precipitation follow for most of the
area for the remainder of the period...except for slight chance probability of precipitation
over the northernmost portion where less deep layer moisture will be
present. Temperatures will be near to slightly below seasonable
values on Sunday then trend gradually warmer to slightly above
seasonable values through the period. /29

[31.18z taf issuance]...a large area of clouds was located
from the Red River valley of Texas/Oklahoma associated with an area
of surface frontal low pressure. Eastern extent of clouds was
expanding slowly east into the interior of southeast Mississippi.
Cloud bases are at middle to high levels. VFR conditions forecast in the
near term with a light wind flow pattern. /10

Marine...a weak pressure pattern results in a prevailing light wind
flow with varying direction. Small sea states. Winds...waves and
seas will be locally higher in and near showers and thunderstorms.


Preliminary point temps/pops...
Mobile 67 90 70 91 71 / 05 30 10 40 40
Pensacola 70 91 72 91 73 / 05 10 10 40 30
Destin 73 89 75 88 76 / 05 10 10 40 30
Evergreen 65 92 69 92 70 / 10 30 10 60 40
Waynesboro 65 89 67 91 68 / 10 30 20 60 40
Camden 65 89 69 91 69 / 10 30 20 60 40
Crestview 65 92 70 91 71 / 05 10 10 50 30


Mob watches/warnings/advisories...


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