Area Forecast Discussion
Issued by NWS Memphis, TN

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000
FXUS64 KMEG 210043
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
743 PM CDT Sun Aug 20 2017

.UPDATE...

Updated for the 00z Aviation Discussion.

&&

.PREV DISCUSSION... /issued 643 PM CDT Sun Aug 20 2017/

UPDATE...
Updated for cancellation of heat advisory and to adjust cloud
cover tomorrow.

DISCUSSION...
Convection...outflow boundaries and cloud cover has allowed for
temperatures in the southwest delta counties to fall below
advisory criteria. Therefore the heat advisory was expired early.
In addition short term models showing more cloud cover across the
northwestern counties for tomorrow...where convection may develop
or move into the the region by early afternoon. Have adjusted the
sky forecast accordingly.

JAB

&&

.PREV DISCUSSION... /issued 315 PM CDT Sun Aug 20 2017/

Showers and thunderstorms continue over the region this
afternoon, resultant from a remnant outflow boundary from an
overnight MCS which impacted portions of the Midwest. This
activity will gradually come to an end this evening with the loss
of daytime heating. Latest H5 analysis depicts a ridge of high
pressure over much of the southeastern CONUS, with a shortwave
trough evident north of the local region over north central
Illinois.

Temperatures will be in the low to mid 70s overnight, with
conditions dry again. The upper high begins to shift further east
early on Monday, allowing southwest flow to set up over the
region. Surface flow will also be southerly, which will allow
moisture advection and the potential for diurnal convection. The
best chances for this will be over eastern Arkansas, nearer to the
western periphery of the upper high. Clouds will be present
tomorrow afternoon for eclipse viewing, but sky coverage will
likely remain less than 50 percent, which should not greatly
inhibit viewing. Temperatures will be in the low to mid 90s on
Monday afternoon, with temperatures likely dropping a couple of
degrees during the peak of the eclipse. Heat indices will not
likely be as warm tomorrow as today, and thus the heat advisory
will end this evening and will not be warranted for tomorrow.

A longwave upper trough begins to swing across the Midwest on
Tuesday, with an attendant surface low deepening. As a strong cold
front associated with the low begins to drop south on Tuesday,
chances for showers and thunderstorms will increase across the
Mid-South. The front will move through the region late Tuesday and
into Wednesday. Guidance suggests a moderately unstable
environment; this mixed with decent forcing by the front and
support of upper height falls will allow for a few strong to
severe storms. The primary threats with these storms will be
damaging winds, with heavy rainfall also possible.

The front finally clears the region by late Wednesday, with cool
and dry high pressure moving in behind. This will create nearly a
10 degree drop in high temperatures between Tuesday and Wednesday
afternoons. Temperatures will remain some 5 to 10 degrees cooler
than average midweek until next weekend as the high remains in
place and dominant of conditions under northwest flow aloft.
Models begin to develop a shortwave trough to the west of the
region by next weekend, which could signal a return to
precipitation chances.

ZDM

&&

.AVIATION.../00z TAFs/

VFR cigs will prevail through much of the period, outside of any
convection. There may be some vsby reductions late tonight into
early Monday morning in patchy fog. Isolated storms may again
develop along and west of the Mississippi River to include KJBR
and KMEM by Monday afternoon.

Winds should remain light again through the period.

JLH

&&

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

$$



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