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Area forecast discussion...updated
National Weather Service Mobile Alabama
520 PM CST Tue Nov 19 2019

Discussion...updated for latest aviation discussion below.

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Aviation...
00z issuance...VFR conditions next 24 hrs. Overnight winds light.
/10



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Previous discussion... /issued 406 PM CST Tue Nov 19 2019/

Near term /now through Wednesday/...upper level ridging will
continue to build over the area on Wednesday as an upper low digs
across the southwestern states. With surface and upper level ridging
in place, strong subsidence will continue with clear skies and dry
conditions expected. Due to the strong upper ridging in place, have
continued to go a few degrees above guidance values for highs on
Wednesday with low 70s expected. Lows tonight will range from the
low to mid 40s inland to around 50 near the coast. /13

Short term /Wednesday night through Friday night/...ridging moves
off to the east of the forecast area, especially Thursday
afternoon and beyond, bringing return flow in off the Gulf and
gradually moderating atmosphere with regard to temperatures and
moisture levels as a more southerly low level flow develops. Thursday
through Thursday night, another upper trough digging south over
the Great Lakes region combines with the southwestern conus upper
low to start de-amplifying the upper ridge over the eastern conus
as it continues to shift east to over, then east of the East
Coast. This pattern will bring a developing surface front toward
the region from the west, being located generally along the
Mississippi River by the end of the day Friday and moving into the
western or even central portions of our forecast area by late Friday
night (depending on which model solution verifies the best). The
GFS and European model (ecmwf) have become much better in agreement over the past
few runs, and the ECMWF, which was the slower model, is actually
now slightly faster than the GFS. Expect chance pops to increase
from the west during the afternoon on Friday, and then good chance
to near categorical pops spreading west to east across the area
Friday night. At this time, most of this precipitation will be in
the form of showers, with only a few isolated embedded thunderstorms
due to the lack in instability. Temperatures moderating through
the short term period as the front approaches, with lows Wednesday
night ranging from the low 40s inland to near 50 at the coast...
warming to the lower 50s inland to lower 60s coastal for lows by
Friday night. Thursdays highs in low to mid 70s across the region,
and in the mid 70s Friday. /12

Long term /Saturday through Tuesday/...the European model (ecmwf) now has the front
nearly all the way through our forecast area by 12z Saturday,
while the GFS has the frontal position generally over the western
half of our forecast area. If the GFS pans out, the frontal passage will be
more during the day on Saturday, and while instability still
appears to be rather low convective available potential energy are a little higher than what was
noted yesterday, with MUCAPE possibly approaching 400 j/kg south
and east of the I-65 corridor from late morning into the afternoon
hours on Saturday. While this is still rather marginal
instability, it does warrant an inclusion of a chance of
thunderstorms across the area on Saturday in association with the
frontal passage. But, various models do indicate that there could be
sufficient shear and dynamics for a few stronger storms in the
areas with the higher cape, and we will continue to monitor these
trends. As of now, spc's outlook for Saturday indicates that the
potential is too low to predict any severe storms, and that agrees
with the scenario that we just mentioned. Temperatures cool
through the long term period in the wake of the front, with highs
primarily in the 60s and lows in mainly in the 30s (although
mostly remaining above freezing) and 40s. /12

Marine...surface high pressure will drift east along the northern
Gulf Coast through Friday. Winds will remain light but will shift to
southeasterly by Thursday. Southerly winds and seas will increase
late in the week as a cold front approaches from the northwest. The
cold front is expected to move through the marine area Saturday
morning with a moderate offshore flow in the wake of the front.
/13

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