Area Forecast Discussion
Issued by NWS Memphis, TN

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000
FXUS64 KMEG 170248
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
848 PM CST Sat Dec 16 2017

.DISCUSSION...00Z Upper air analysis this evening places an upper
level low over Eastern New Mexico and portions of the Texas
Panhandle. A shortwave trough over Eastern Texas embedded within
southwest flow aloft will move across the Lower Mississippi
Valley tonight into Sunday morning. Regional WSR-88D radar trends
along with METAR observations indicate some rain occurring across
South/Southwest Arkansas. Short term HRRR/WRF models indicate the best
potential for onset of rain across the Mid-South will be
predominantly after 12 AM. Will make some minor timing adjustments
to rain chances and any other elements as needed.

CJC

&&

.PREV DISCUSSION... /issued 535 PM CST Sat Dec 16 2017/

UPDATE...
Updated to include the 00z aviation discussion.

PREV DISCUSSION... /issued 319 PM CST Sat Dec 16 2017/

DISCUSSION...

The long dry spell will come to an end tonight as an active
weather pattern will set up over the Mid-South for the next seven
to ten days.

Tonight, a SFC low will move northeastward from the Texas Gulf
Coast to Southern Louisiana by sunrise Sunday as an upper trof
pushes eastward out of the Southern Plains. Rain ahead of the
system will begin to push into Eastern Arkansas shortly before
midnight. Between midnight and sunrise, expect widespread rain to
spread over the entire Mid-South. The system will be a quick mover
thus expect the rain to begin tapering off by 7-9 am across
Eastern Arkansas and be east of the Tennessee River by noon.
Clouds will keep highs a little bit cooler from today, but will
still be near normal with readings ranging from around 50 to the
mid 50s.

A cloudy and possibly foggy night will occur Sunday Night. Thus
lows will only drop to the lower to mid 40s.

The work week will be mild, but will also be wet as the upper
flow remains out of the southwest. One wave after another will
move through the region with the first moving into portions of
North Mississippi by late Monday afternoon. Highs on Monday will
reach into the lower to mid 60s. Rain chances will spread
northward Monday Night and will continue as an upper level low
moves out of the Southwestern United States into the Mid-South by
Wednesday.

A brief lull will occur Wednesday Night into Thursday. However by
Thursday Night into Friday, rain chances will begin to occur again
as a cold front moves into the Mid-South. Models are in pretty
good agreement through Friday. Beyond Friday is where things start
to get interesting.

Arctic air will be plunging southward behind Friday`s cold front.
The GFS remains consistent with developing another upper level low
over the southwest early next weekend while the ECMWF has now
flip flopped and no longer shows an upper low developing. If the
GFS is correct, an extended period of precipitation would occur
next weekend as moisture would be streaming northeastward into
the Mid-South possibly over arctic air. Meanwhile, the ECMWF is
cold and dry for early next weekend, but does show a shortwave
diving down for the latter part of next weekend that also could
produce some wintry precipitation. At this point, the confidence
in the forecast beyond Friday is extremely low. Will likely not
get a better picture of what will happen until mid week when we
start getting some upper air sampling from the developing system.
Holiday travelers should stay alert for future forecasts as there
is the possibility of winter weather occurring over the region
sometime during the day 7 to day 10 period.

KRM

&&

.AVIATION...
/00z TAFs/

High clouds continue to stream across the region this afternoon
and ceilings will gradually lower overnight, decreasing to 6-8
kft after 06z. Scattered rain showers will be developing across
the region by this time and will increase in coverage during the
early morning hours. Rain is most likely between 08z-14z before
ending from west to east Sunday by midday Sunday. MVFR ceilings
are expected to develop around or just after 12z with some areas
likely dipping into IFR category. Ceilings are forecast to improve
slightly Sunday afternoon but are expected to remain MVFR through
the remainder of the TAF period. Winds will remain light from a
generally south to southeast direction through Sunday morning.

Johnson

&&

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

$$



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