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Area forecast discussion 
National Weather Service Mobile Alabama
640 PM CDT Wednesday Apr 1 2015

Aviation...
02.00z taf cycle...VFR conditions will prevail through 02.01z. We
anticipate periods of ceilings below IFR...as low as 400 feet...and
visibility below IFR...as low as 1 mile in overnight patchy fog.
Visibility to rebound to MVFR category (~4sm) by middle morning
Thursday. Numerical and statistical models continue to favor early
morning isolated showers near the coast justifying adding vcsh. 77/blowing dust

&&

Previous discussion... /issued 335 PM CDT Wednesday Apr 1 2015/

Short term [tonight through Thursday afternoon]...a large area of
high pressure situated across the eastern Continental U.S. Has a surface ridge
extending southwest across the Gulf of Mexico. The center of the
high pressure will move east over the western Atlantic through
Thursday afternoon...however the surface ridge will remain anchored
across the Gulf of Mexico. This pattern will keep a light to
moderate southerly wind flow across the region through Thursday
afternoon...along with increasing boundary layer moisture. A few
rain showers or a thunderstorm or two could still develop late this
afternoon into early evening over the northern portion of the
forecast area as a weak surface boundary advances northward.
Otherwise it will be dry overnight into early Thursday morning...
with patchy fog first forming along the coastal sections and
spreading northward overnight. A slight chance of showers and
thunderstorms could develop again Thursday afternoon over the
northern portion of the forecast area during the maximum heating
hours.

Low temperatures tonight will range from 60 to 65 degrees. High
temperatures Thursday will reach the lower 80s inland areas...and
range from 74 to 79 degrees along the coastal sections due to the
cooler Gulf waters and advancing seabreeze. /22

Long term... (thursday evening through next wednesday)...period
begins with aforementioned cold front in the Southern Plains poised
to move our way and eventually move through the northwest half of
the area by sunrise Saturday and then clear the marine area by early
afternoon. Patchy fog will greet Friday morning's sunrise across
most of the areas as light southerly flow persists Thursday night.
As the surface front moves through Friday night...mid-tropospheric
cyclonic shear-induced vorticity passes well to our north so cold
front moves away from its upper support. 1.50-1.65" precipitable water values
concentrate along and ahead of the surface front with the surface-850 hpa
moisture transport field shrinking with time along the band. There is
enough instability to warrant isolated thunder...but will drop that
as band departs region after 12z Saturday. Expect a general .05-.15"
of rainfall over most locations from this event between Friday sunset
and sunrise Saturday.

From Saturday afternoon on...subsidence in deep-layer dry air on
is short-lived and it will be cooler with mostly sunny skies. Clear
and cool Saturday night with lows ranging from the middle 40s over the
interior to lower 50s near the beaches. The first half of Easter
Sunday will be sunny...but increasing clouds for the remainder
(especially west of I-65) as yet another well-defined impulse of middle-
tropospheric energy moves toward our region being located over old
Mexico late Saturday night and the lower MS valley by late Sunday.
Temperatures do rebound solidly into the lower 70s on Sunday compared
to saturday's upper 60s to around 70 deg(f). Moisture...instability
and synoptic lift increase Sunday night and into Monday in
association with the aforementioned S/wave and we will re-introduce
slight chance of showers and thunderstorms to the the forecast for
the first part of next week. Looks like we will stick with slight
rain chances each day Tuesday and Wednesday as there are no
approaching fronts and lower tropospheric southeasterly winds
persist. This will set up patchy fog each overnight/early morning
from Tuesday on. Highs reach into the upper 70s Monday and the 80s
Tuesday and Wednesday with overnight lows in upper 50s to middle 60s.

Beyond midday Tuesday...time there are both timing and spatial
feature uncertainties in a split flow pattern with a much colder and
stronger northern branch in the 01.12 UTC GFS versus a more subdued
solution in the 01.12 UTC European model (ecmwf). There appears to be more baroclinic
instability in the GFS solution with quicker and more frequent Lee
cyclogenesis with associated S/waves rounding the mean southern stream trough
which could make a cloudier forecast for US in days 5-7. For the
moment...very much a wait and see that far out. /23 jmm

Aviation...
01/18z kmob/kbfm and kpns taf cycle... VFR conditions will prevail
through 02.01z. Expect periods of LIFR to IFR ceilings (~400 to 700
feet) and IFR surface visibility (~1sm to 2sm) due to fog to develop
overnight. Visibilities will improve to the MVFR category (~4sm) by
middle Thursday morning. Models continue to indicate early morning
isolated rain showers developing near the coast...so may have to add vcsh.
/22

Marine...a light to moderate east to southeast flow will become
increasingly more southerly through Thursday as a cold front
approaches from the west. The cold front will move south across the
marine area Thursday evening...with winds becoming northwest and
increasing in the wake of the front. A moderate to strong offshore
flow will then continue through early Saturday before weakening late
in the weekend as high pressure builds over the marine area. /22

&&

Preliminary point temps/pops...
Mobile 64 79 65 80 58 / 05 10 05 20 40
Pensacola 65 78 66 79 62 / 05 10 05 10 40
Destin 66 76 66 77 65 / 05 10 05 10 30
Evergreen 60 82 61 83 56 / 20 10 05 20 50
Waynesboro 60 83 64 79 52 / 20 20 10 30 70
Camden 61 83 61 81 53 / 20 20 10 20 70
Crestview 60 81 60 83 61 / 05 10 05 10 40

&&

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

$$

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