Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 172123
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
323 PM CST Sun Dec 17 2017

.DISCUSSION...

A wet unsettled weather pattern will set up over the Mid-South
this week as the area remains underneath southwest flow aloft.
Temperatures will be mild, but there won`t be much sunshine.

Tonight, abundant cloud cover will remain over the area. Areas of
drizzle and fog will develop. Don`t expect temperatures to drop
too much as a result. Lows will be in the lower to mid 40s.

Clouds should lift by Monday afternoon for at least Northeast
Arkansas, but by Monday evening will begin spreading back to the
north as the SFC low develops along the Texas Gulf Coast. Rain
ahead of the system will begin to push into Northwest Mississippi
and East Central Arkansas after midnight Monday Night.

Chances for rain will increase during the Tuesday through
Wednesday time frame as the SFC low moves northeastward into the
Tennessee Valley and the associated upper low tracks across the
Mid-South. Rain will be heavy at times. In addition, there will be
some embedded thunderstorms with the system. The latest NAM and
ECMWF has shifted the heaviest QPF further north which would be
beneficial to Northeast Arkansas where drought conditions are the
worse. Although, if the rain comes down too hard it may runoff and
create flash flooding concerns despite the drought conditions.
Meanwhile, the GFS keeps the heaviest QPF band along and just
south of the TN/MS border. For now have raised POPS across
Northeast Arkansas, the Missouri Bootheel, and Northwest Tennessee
from slight chances on Tuesday to chance POPS and from likelys
Tuesday Night to categorical. Wherever the heavy rain bands set
up, there will be the potential to see rainfall amounts of 4
inches or more. Stay tuned to future forecasts for the latest
updates.

Temperatures will be mild ahead of the system with highs reaching
into the lower to mid 60s Monday into Tuesday. Temperatures will
cool slightly on Wednesday behind the departing low pressure
system, but will remain slightly above normal with highs in the
mid to upper 50s.

Wednesday Night into Thursday will be dry as the area will be
between systems. Thursday will be the best day to see some
sunshine. Winds will turn around to the south ahead of the next
developing low pressure system. Thus expect highs to return to the
60s.

Warm air advection showers will occur after midnight Thursday
Night and temperatures will remain mild with lows staying in the
50s.

Models are in decent agreement with a potent cold front moving
into the Mid-South on Friday. Although the latest ECMWF is a tad
slower but both models show a line of showers possibly with a few
embedded thunderstorms pushing into the Mid-South Friday afternoon
into Friday Night. Both models also show the front stalling over
the Mid-South through the weekend. The only difference is the
location of exactly where the front will stall. Both models also
show the arctic air behind the front will be slower moving into
the area which should keep precipitation all rain through the
weekend. If this scenario does play out, then the risk for flash
flooding will be increased wherever the front stalls especially
after the potential for heavy rainfall mid-week. In addition, the
ECMWF also shows the arctic air eventually creeping into the Mid-
South just beyond the end of the forecast period possibly bringing
winter precipitation to the area. As I stated yesterday, models
have changed with every run regarding this system thus there is
low confidence with the forecast beyond Friday. Until the system
comes ashore over the Northwest United States mid week and the
models can get some good upper air data, confidence in the
forecast will remain low and will continue to change. Models
continue to show an extremely cold airmass plunging down into the
region sometime during the day 7 to day 10 period thus holiday
travelers should stay alert for future forecasts as there will be
the possibility of winter weather occurring sometime during that
period.

KRM



&&

.AVIATION...

Weak flow regime in place in the wake of the departing system
with a good deal of leftover low level moisture. As a result
expect low clouds through much of the period. Should see a bit of
improvement to MVFR this afternoon at most places before cigs
deteriorate to IFR this evening and eventually to LIFR overnight
with fog/drizzle. Slow improvement expected on Monday...returning
to VFR in the afternoon. Winds will be light through the period.

SJM

&&

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

$$



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