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Area forecast discussion 
National Weather Service Mobile Alabama
309 PM CDT Tuesday Sep 23 2014

Short term (tonight through Friday night)...for tonight through
Wednesday...the upper low noodling around over the southeastern
Continental U.S. Opens and begins to get drawn north as more energy swing east
over the plains and miss River Valley. At the surface...the affect
of the southeastern upper energy is to develop a surface low over
the Carolina coast and take it north. This weakens the northeasterly
flow from a surface ridge stretching SW along the eastern
Seaboard...and limiting any further moisture push over the forecast area from
the east. What moisture that has moved in is not expected to
contribute to precipitation development the first 24hrs of the
forecast...but will affect the temperature curves...with a tighter temperature
curve over eastern portions of the forecast area as apposed to western. Another
night of temperatures below seasonal expected...especially over the western
half of the forecast area (with a significant cut to guidance temps). /16

For Wednesday night through Friday night...a weakening upper low
over over the east central states moves to the northeast through
Thursday as weak upper ridging builds into the southeast states.
The weak upper ridging over the region retreats slowly to the east
through Friday night as an upper low move slowly over the Southern
Plains. A large surface high meanwhile dominates the eastern states
through the period with fairly strong ridging over the extreme
southeast states. The gradual change in the pattern over the region
allows for a transition from a northeasterly deep flow to an east to
occasionally southeast flow on Friday. This allows for fairly dry
deep layer air over the region to increase mainly Friday into Friday
night with precipitable water values initially near 1.0 inches to
increase somewhat to 1.25 inches well inland and more significantly
to around 2.0 inches near the coast. Dry conditions continue
through Thursday night with a gradual return of small probability of precipitation to mainly
the southern portion of the area Friday into Friday night where the
best deep layer moisture return will occur. Temperatures will be
near seasonable levels Wednesday night then trend gradually warmer
to slightly degrees above normal by Friday. /29

Long term (saturday through tuesday)...the upper low over the
Southern Plains advances slowly eastward and may later become
absorbed into a longwave trough slowly advancing into the western
states. An inverted trough is expected to develop over the western
Gulf on Saturday with the slow approach of the upper low...with the
potential for a surface low to form over the lower Mississippi River
valley Sunday into Sunday night per the European model (ecmwf)...or later on Tuesday
per the GFS. While there continues to be uncertainty with
timing...this pattern does support a trend of increasing rain
chances through Sunday which may persist later in the period
depending on the evolution. As noted by previous shifts...with
abundant deep layer moisture expected to be in place over the
area...may see a potential for locally heavy rains as well and will
continue to monitor. Temperatures will be near to slightly above
seasonable values. /29

&&

Aviation...
18z issuance...current wildcard aviation-wise is dissolving MVFR
level stratus deck over the eastern half of the forecast area. The last area to
clear...according to satellite loop trends...will be the western Florida
Panhandle. Am anticipating the entire forecast area to be cloud free overnight
into Wednesday. With a tight pressure gradient along and south of
the coast...strong low level winds are possible these areas through
the forecast. /16

&&

Marine...an upper low over the southeastern Continental U.S. Moves to the
Carolina coast before opening and getting pushed off by more energy
moving over the northern miss River Valley. This movement in the
upper troposphere pushes surface high pressure over the middle miss
river/Ohio River valleys eastward to the middle Atlantic
Seaboard...where it gets absorbed by another surface high moving
rapidly east north of the US/California border. For our neck of the
Woods...this means a tight pressure gradient continuing over the
northern Gulf Coast...and moderate to strong northeasterly flow
lasting through the week. The gradient eases later into the week into
the weekend as it becomes more easterly...with the surface ridge over
the eastern Continental U.S. Weakening and a weak surface low forming over the
Yucatan Peninsula. /16

&&

Preliminary point temps/pops...
Mobile 60 84 64 85 67 / 05 00 05 10 10
Pensacola 64 83 67 85 69 / 05 00 05 10 10
Destin 65 83 68 85 71 / 05 05 05 05 10
Evergreen 58 83 60 85 63 / 05 00 05 05 10
Waynesboro 58 84 59 86 63 / 05 00 00 05 10
Camden 58 83 59 85 62 / 05 00 05 05 05
Crestview 60 83 61 85 64 / 05 05 05 05 10

&&

Mob watches/warnings/advisories...
Alabama...none.
Florida...none.
MS...none.
GM...Small Craft Advisory until 7 PM Wednesday for the following
zones: Choctawhatchee Bay...coastal waters from Destin to
Pensacola Florida out 20 nm...coastal waters from Pensacola Florida
to Pascagoula MS out 20 nm...Mississippi Sound...northern
Mobile Bay...Pensacola Bay system...Perdido Bay...southern
Mobile Bay...waters from Destin to Pensacola Florida from 20 to
60 nm...waters from Pensacola Florida to Pascagoula MS from 20
to 60 nm...

&&

$$

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