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Area forecast discussion...aviation update 
National Weather Service Mobile Alabama
1130 PM CDT sun Sep 21 2014

Aviation...
22.06z issuance
VFR conditions will prevail through much of the period. A weak cold
front will move toward the coast during the afternoon. Isolated to
scattered showers and thunderstorms are possible as the front
approaches during the afternoon and have included thunderstorms in the vicinity at all
terminals. /13

&&

Short term (tonight through Wednesday night)...tonight...a strong
shortwave dives into an upper trough over the eastern Continental U.S.. this
shortwave pushes a surface front to the northern fringes of the forecast area
by sunrise Monday. Temperatures overnight drop into the 60s away from the
coast...but remain a bit above seasonal. A few showers may dampen
northern-most regions of the forecast area...but am expecting these to be more
of an annoyance at this point.

Monday...the front gets pushed across the forecast area to the coast by around
18z...then slows a bit...reaching the southern fringes of the marine
portion of the forecast area by Monday evening. With the cooler air moving over
the northern half of the forecast area...temperatures around seasonal likely over the
northern half of the forecast area. Over the southern half...with heating
occurring before the front gets to the coast and a bit better
moisture availability...a better chance of thunderstorms and rain/rain showers is possible
Monday afternoon. Have limited this precipitation to the southern third to
half of the forecast area and the marine portion of the forecast area. /16

For Monday night through Wednesday night...a powerful shortwave over
the extreme southeast states partially ejects off to the northeast
but leaves a weak upper low which lingers over the southeast states
through Wednesday night. In the wake of the cold front which moved
through the area on Monday...a large surface high dominates the
eastern states through Wednesday night with ridging gradually
strengthening over the extreme southeast states. Much drier air
flows into the region in the wake of the cold front with surface
dewpoints dropping to the lower fifties for much of the area Monday
night. Monday night will be the first taste of autumn with
overnight lows ranging from the lower fifties inland to the lower to
middle sixties close to the coast. Near seasonable temperatures follow
for Tuesday through Wednesday night except Tuesday night will be
slightly below normal. Dry conditions are expected through the
period. /29

Long term (thursday through sunday)...the upper pattern evolves
into a relatively weak Rex block pattern through Saturday as the
weak upper low lingers over the southeast states and a stronger
upper high moves into the northeast states. This breaks down on
Sunday but leaves a broad upper low over the southeast states.
While a surface high continues to dominate the eastern states
through much of the period with fairly strong ridging persisting
over the extreme southeast states...a blend of the GFS/European model (ecmwf)
continues to show an inverted surface trough gradually developing over
the northeastern Gulf with a surface low developing near the area
either Saturday or Sunday. Deep layer moisture gradually increases
through Friday...then more quickly Saturday into Sunday as the
surface low develops. Small probability of precipitation on Thursday mainly over the
coastal counties gradually expand and increase to chance probability of precipitation across
the area for Saturday and Sunday...and should the surface low
develop...much higher probability of precipitation may eventually be warranted this coming
weekend once the evolution of the pattern becomes clearer.
Temperatures will remain near seasonal levels through the period. /29

&&

Marine...shortwave energy moving southeast across the eastern Continental U.S.
Will push a front over area coastal waters Monday afternoon...but
with the dynamics moving off...the front stalls just south of the
marine portion of the forecast area. This leaves a tight gradient across area
waters....and high end moderate to strong northeasterly flow. This
gradient is expected to last into Thursday...with a slow easing
later Wednesday night into the weekend. /16

&&

Preliminary point temps/pops...
Mobile 70 89 61 86 64 / 10 40 05 10 10
Pensacola 72 88 65 86 67 / 10 40 10 10 10
Destin 76 86 69 86 70 / 10 40 10 10 10
Evergreen 68 88 55 85 59 / 10 20 05 10 05
Waynesboro 69 84 54 85 58 / 10 20 05 05 05
Camden 68 84 54 84 58 / 10 20 05 05 05
Crestview 69 89 60 86 60 / 10 40 10 10 10

&&

Mob watches/warnings/advisories...
Alabama...none.
Florida...none.
MS...none.
GM...none.
&&

$$

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