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000
FXUS64 KMEG 211532
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
1032 AM CDT Mon Sep 21 2020

.UPDATE...
Morning forecast update.

&&

.DISCUSSION...
An upper-level ridge remains centered on the Southeast CONUS this
morning. Geopotential heights at 12z are in the 591-592 dam
range, which is in the 90th percentile of climatology. Despite
these anomalous heights, temperatures are expected to be a few
degrees below normal with highs in the mid 70s to near 80 degrees.
Winds have finally come back around to the southeast on the
backside of the 1040 mb surface high over the Northeast. Expect
dry weather today with scattered clouds and southeast winds at
10-15 mph.

Tropical Storm Beta continues to approach the TX coast and will
begin to influence the Mid-South beginning today. Total blended
precipitable water shows most of the area at less than 1 inch.
However, tropical moisture is creeping north, with PWATs near 2"
as far north as extreme southeast AR. As this moisture lifts
poleward tonight, showers may affect the MS/AR delta counties,
spreading farther north and east by Tuesday morning. Rainfall
amounts for tomorrow look to remain light, but we`re still
monitoring the potential for a few inches of rain across north MS
during the midweek period as TS Beta moves across the region.

MJ

&&

.PREV DISCUSSION... /issued 347 AM CDT Mon Sep 21 2020/

DISCUSSION...

Currently...Skies are mostly clear across the Mid-South with temps
in the 50s to lower 60s. Winds are light from the east. Upper
ridging prevails over the region while surface high pressure
dominates the eastern half of the U.S. TS Beta is closing in on
the Texas Coast and will eventually impact the weather across the
Mid-South.

Before that another nice day is on tap for the Mid-South with a
good deal of sunshine, an easterly breeze and temps in the upper
70s to near 80. Humidity levels will continue to be comfortable as
well. High clouds associated with TS Beta will increase later
today into tonight from south to north. Expect coolest temps
tonight across NE sections of the forecast area as this area will
be last to cloud up. Lows will range from lower 50s NE to lower
60s SW. Chances for rain will start to increase across the Delta
by sunrise as deeper moisture starts to lift north into the
region.

Tuesday...Moisture from Beta will start to overrun the cool
airmass in place across the Mid-South leading to showers
spreading SW to NE into the area. Best chances for rain will be
across the Delta SW of Memphis. This day should not be a wash out
with precip amounts remaining fairly light. Temps will be quite
cool as precip falls into a dry airmass. Temps will generally be
in the lower 70s...coolest where rain falls.

The upper level remnants of Beta will be absorbed by a developing
upper low over the southern plains that will track through the
Mid-South Wed/Thu. Meanwhile the weakening surface circulation is
forecast to eventually move into the Lower MS Valley by Thursday
night. This will result in increasing rain chances Tuesday night
into Thursday. Deepest tropical moisture looks to be restricted to
north MS where the heaviest rainfall is likely. A couple inches
of rain is possible south of I-40. Rain and clouds will keep temps
below normal Wed and Thu. Wed looks especially cool since the
surface high to the northeast will still be influencing the region
by advecting in cooler, drier air at the surface while overrunning
occurs aloft. A little milder on Thursday as the surface high
retreats and milder air bulges north with the remnants of Beta.

By Friday the surface circulation dissipates and the upper low
weakens into a trough and pushes east along with the deepest
moisture. Rain chances should start to diminish on Friday. Blends
are still holding on to decent chances for the weekend as there is
quite a bit of uncertainty as to whether some subtropical energy
will lift into the area ahead of an approaching cold front.
Timing on the cold front is also highly uncertain, ranging from
Sunday afternoon (GFS) to Monday (ECMWF). Looking ahead to next
week there are discrepancies as to how deep the upper trough will
be across the central/eastern U.S. but cool NW flow and more
below normal temperatures are looking fairly likely. Fall is here.

SJM

&&

.AVIATION...
/12Z TAFs/

VFR conditions continue at all sites. Included a brief TEMPO at
MKL for 4SM BR as winds are light and skies are clear. Otherwise,
the big story today will be increasing cloud cover from south to
north as a result of TS Beta. High clouds will start moving in
by mid-morning with mid-level clouds streaming in a bit later in
the period. ENE winds, if not already, will start to veer to the
SE through the day 7-12kts. SE winds will be lighter overnight.
Rain chances will also start to increase overnight but
probabilities were to low to include in this TAF issuance.

17

&&

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

&&

$$