Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Mobile Alabama
1158 am CST Friday Nov 27 2015
Discussion...see updated information below.
Update...current forecast looks on track with no updates planned at
the moment. /29
Marine...will update for the expiration of the Small Craft Advisory
over the near shore waters as winds continue to gradually subside.
18z issuance...have begun with VFR conditions for much of the area
except for a MVFR ceiling mainly over interior southeast
Mississippi. Expect MVFR conditions to develop across the entire area
later tonight...possibly dropping to LIFR/IFR in some locations.
Conditions improve to a MVFR/VFR ceiling by midmorning on Saturday.
Light east to southeast winds...somewhat stronger near the
coast...become a light to calm easterly flow tonight. /29
Previous discussion... /issued 539 am CST Friday Nov 27 2015/
Discussion...updated for latest aviation discussion below.
moist low level east-southeasterly flow has aided in the development
of MVFR ceilings early this morning. This will persist through the
morning hours. Occasional ceilings 3-3.5 kft above ground level are forecast west of
Pensacola this afternoon. This deck scatters out during late
afternoon. Fog and low clouds form after midnight...mainly west of
I-65 and closer to coast west of Navarre. This will bring IFR
conditions in these areas by 28.09 UTC with isolated LIFR conditions
through end of this taf period. East winds 5 to 10 knots prevail
across area terminals...and a little higher near the coast...prevail
this afternoon before light wind conditions regionwide tonight.
Previous discussion... /issued 432 am CST Friday Nov 27 2015/
High rip current risk through dark...
Near term /now through Friday night/...persistence forecast again. There
will be more middle and high clouds west of I-65 today compared to this
past beautiful Thanksgiving day with highs in the middle and upper 70s
across the region. A weak low-level moisture gradient exists from our
SW zones over interior southeast MS to our NE zones near Greenville, Alabama.
This persists through the period albeit the airmass gradually
modifies and moistens slightly. Middle-tropospheric geopotential heights
actually begin to fall this period...but deep layer thicknesses
actually increase a decameter or two...resulting in another very
warm day. The only changes to guidance was to raise maximum temperatures 2-3 degree
(f) on average and also made minor upward adjustments to overnight
min temperatures. Am expecting a bit of coastal stratus and patchy fog
Saturday morning. /23 jmm
Short term /Saturday through Sunday night/...an evolving Rex block
configuration is noted in the middle to upper level geopotential height
field forecast over the western US this period. A cutoff upper low
extends from Nevada eastward into the Rocky Mountains while an upper
ridge is positioned more poleward over the southwest Canadian
provinces. An active upper level southwest flow remains in place from
the Baja California into the plains on Saturday while a middle level ridge noses
northeast from Mexico into the southeast. The upper low out west
moves very little through Sunday with the upper ridge flattening over
the Gulf. At the surface...high pressure axis holds firm over the
southeast while a quasi-stationary frontal zone extends from the
Texas Gulf Coast to across the middle Mississippi River valley through
much of the short term period. Very little change in sensible weather
elements over the weekend. With the high off to the east...daytime
highs both Saturday and Sunday look to range from 74 to 78. Overnight
lows modify to between 54 and 58 interior to the lower 60s at the
beaches by Sunday night. With surface based moisture continuing to
ease higher...there is potential for patchy late night fog
development Saturday night. /10
Long term /Monday through Thursday/...surface high holds over the
southeast into Monday and begins to break down Tuesday as a front
approaches from the west. Frontal passage and associated wind shift
is forecast late Tuesday night into Wednesday morning. Although a
northerly component in the wind and cooler conditions are forecast
Wednesday and Thursday...the frontal slope looks to be shallow as a
high level west southwest flow keeps moisture in place. With the
passage of middle level impulses in the west to southwest flow aloft
resulting in modest Post frontal lift...will keep the forecast mostly
cloudy next week with a chance of rain. /10
Marine...stiff easterly winds of 18 to 23 knots with higher gusts
decrease and seas subside throughout the day as surface high
pressure weakens. By early afternoon...small craft conditions should
exist mostly beyond 20 nm. By midnight...small craft exercise
conditions will exist beyond 20 nm and with no additional marine
hazards. Winds gradually become southeasterly and are much lighter as a cold
front approaches from the plains. The front is expected to move
through the marine waters early Wednesday morning from west to east.
Offshore winds should...at a minimum...pick up to scec conditions
thereafter and this endures through the end of the forecast period.
We are not forecasting sea fog until the front passes...although
marine haze will at times limit visibilities to between 2 and 3
nautical miles from now until the front passes. /23 jmm
Alabama...high rip current risk until 6 PM CST this evening for alz265-266.
Florida...high rip current risk until 6 PM CST this evening for flz202-204-
GM...Small Craft Advisory until 6 PM CST this evening for gmz670-675.
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