Area Forecast Discussion
Issued by NWS Memphis, TN

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000
FXUS64 KMEG 200924
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
424 AM CDT Mon Aug 20 2018

.DISCUSSION...

Showers featuring occasional thunder are moving quickly across
the Midsouth, most numerous across east central Arkansas and North
Mississippi. Rainfall totals through sunrise should be less than
one half of an inch. No strong or severe thunderstorms are
expected through sunrise.

Another round of showers and thunderstorms is expected later this
afternoon as a deep trough and associated surface low track to the
East along the Missouri Iowa state line. A trailing cold front
will eventually sweep across the Midsouth tonight. Ahead of the
front all of the Midsouth will be in the warm sector of a
seasonably strong storm system. However, several factors may
limit the potential for severe thunderstorms. The lack of cold air
aloft will limit lapse rates and ongoing rain and associated
cloud cover will likely limit thermodynamic instability. Model
guidance keeps CAPE generally below 2000 J/KG this afternoon and
that may be generous if we don`t see significant breaks in cloud
cover. On the other hand dynamic parameters are seasonably
strong. Low level southwest flow on the order of 30-40kt is
expected to move over the area late this afternoon during or just
after peak heating. Surface flow is expected to remain southerly
resulting in sufficient shear to support healthy updrafts.
Multicellular storms look most likely with the potential to
produce locally damaging winds. The Storm Prediction Center does
mention the potential for a Tornado, but damaging wind is far more
likely. High resolution short term guidance brings a narrow, fast
moving line of strong to severe thunderstorms across the Midsouth
between around 4 pm and 10 pm. Will include a low to moderate
confidence of severe thunderstorms in the HWO...but my gut feeling
is that the limiting factors discussed above will curb our severe
potential.

Otherwise, there does not appear to be any significant impact
weatherwise over the next 7 days. Behind tonight`s cold front,
cooler and drier air will move into the Midsouth. The coolest day
should be Thursday when morning lows may dip into the 50s near the
Tennessee River. Most of us will be in the low to middle 60s.
highs Thursday are expected to be in the lower 80s across most of
the area. A weak ridge aloft and surface high pressure will keep
us mostly dry through Friday, with a few showers returning late
Friday into Saturday. Temperatures will trend warmer Friday
through the weekend, rebounding to near normal by Sunday.

30

&&

.AVIATION...
/06z TAFs/

A line of thunderstorms moving into eastern AR will gradually
weaken over the next few hours, likely limiting TSRA potential to
JBR/MEM. A few embedded storms may persist in the trailing
stratiform region as this complex decays, but otherwise mainly
rain showers are anticipated after 09z, lingering through mid-
morning. Low clouds are expected to develop overnight with IFR
ceilings anticipated in some areas. However, convection will
contaminate the boundary layer moisture profile and may result in
significant variability in cloud heights. Thus, confidence is
relatively low.

Another line of storms is expected to move across the Mid-South
on Monday. Timing looks to be roughly 21-04z (from northwest to
southeast). Severe weather will be possible with this line of
storms, including gusty winds and large hail (at least early
during the event). Included a 4 hour window of VCTS for each site
for now but prevailing/tempo TSRA may be added in later in
subsequent updates.

Johnson

&&

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

$$


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