Area Forecast Discussion
Issued by NWS Memphis, TN

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883
FXUS64 KMEG 071135 AAA
AFDMEG

Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
535 AM CST Wed Dec 7 2016

.UPDATE...
Updated for 12Z Aviation Forecast Discussion below.

&&

.PREV DISCUSSION... /issued 324 AM CST Wed Dec 7 2016/

DISCUSSION...

At 3 AM CST around the Mid-South a calm morning is ongoing under
the influence of surface high pressure. Temperatures are currently
in the mid 30s to lower 40s, with light winds. Surface analysis
depicts a cold front now well to the east of the FA with high
pressure continuing to build in behind. Meanwhile, 09z H5 analysis
reveals southwest flow aloft over the region as an upper level
trough associated with a potent upper low currently situated over
northern Minnesota amplifies over the leeward Rocky Mountains.

Cloud cover will persist on Wednesday, despite surface high
pressure, as southwest flow aloft enhances ahead of the
approaching upper trough axis. Under cloudy skies and with surface
winds from the north along the eastern periphery of the surface
high, temperatures will generally be in the 40s on Wednesday. By
late Wednesday a reinforcing cold front will be to the west of the
FA. Models have been consistently dry with this feature, with
model soundings indicating dry low levels with its passage. Have
thus only gone with low end POPs with very little QPF likely
across the FA. Temperatures will fall in earnest, with some of the
precipitation possibly falling as a light rain and snow flurry
mix. However, thinking is with the dry air surging into the
region, any precipitation could be done before the atmosphere
cools enough to support any flakes. Nonetheless, did include rain
and snow early Thursday, but do not anticipate any accumulation or
any significant impacts from the precipitation.

Cold and dry conditions settle into the region with high pressure
building for Thursday and Friday. Highs in the upper 30s to mid
40s will be even cooler on Friday, with highs likely not even
reaching 40, as the upper trough axis transits over the region
with northwest flow aloft ensuing. This will be the coldest air
experienced so far this season, with overnight lows both Thursday
and Friday night only in the teens to lower 20s. Highs will warm
to the lower 40s on Saturday as flow aloft becomes more zonal,
with surface winds becoming southerly again as the surface high
presses east ahead of a developing low pressure system to the
west.

Rain will be possible again on Sunday as a surface low deepens
over the Midwest. Models still do not agree on timing and
strength, with the GFS amplifying an upper trough to aid and move
the surface low quickly through the region, while the ECMWF is
currently slower with this upper development, causing the surface
front to linger longer over the local area. Thus kept at least
slight POPs through late Monday, with temperatures warming to be
more seasonable Sunday through Tuesday. Dry conditions return on
Tuesday as high pressure builds into the region again.

ZDM

&&

.AVIATION...
12Z TAFs

MVFR deck will likely persist into at least midmorning, as elevated
moist inversion overrides slightly drier but well-mixed layer
below.

Leading edge of dry Arctic airmass arrives late tonight, VFR cigs
likely prevailing.

PWB

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

$$



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