849
FXUS64 KMEG 171729
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
1229 PM CDT Wed Jul 17 2024

...New AVIATION...

.SYNOPSIS...
Issued at 350 AM CDT Wed Jul 17 2024

Cooler conditions finally arrive in the Midsouth today. Much of
the region should remain at or below 90 degrees, the exception
being portions of north Mississippi where there will be one more
day in the low to middle 90s. Rain and thunderstorms will sweep
across the region ahead of a cold front during the day today.
Below normal temperatures are expected to continue through the
middle of next week and beyond. Enhanced rain chances look to
return Sunday and continue through midweek.

&&

.DISCUSSION...
(Today through Tuesday)
Issued at 350 AM CDT Wed Jul 17 2024

A cold front is approaching the Midsouth but is currently masked
by outflow from a few rounds of showers and thunderstorms that
have occurred over southern Missouri and northeast Arkansas since
the late afternoon hours yesterday. A few showers have finally
moved into northeast Arkansas but continue to be impeded by higher
pressure over the deep south. By sunrise, showers should become
reinvigorated by a shortwave as it swings across north Arkansas
and make a stronger push into the Midsouth. The shortwave is not
as pronounced in ECMWF output, and slower in the NAM output
introducing some uncertainty to the scenario described above.
Nonetheless, the overall pattern today should be at least a
marginal increase in showers and thunderstorms across the region
with cooler temperatures for much of the area today. Highs should
be at or below 90 degrees area wide tomorrow.

NBM probabilistic guidance suggests there is only about a 45%
chance of reaching 90 degrees in northeast Arkansas today, about
a 75-85% chance near Memphis and Jackson, Tennessee and increases
to a 99% chance in southern portions of north Mississippi. One
more Heat Advisory will be needed in portions of north Mississippi
today, generally from Clarksdale to Tupelo and points farther
south. However, if the GFS is accurate in bringing the rain/storms
across the region faster and farther south, this product may not
verify. Thursday, the cold front should be well into central
Mississippi and Alabama. As a result, the probability of reaching
90 degrees or higher decreases to generally 0% to 50% area wide.
Showers and thunderstorms will remain possible north of the front
as far north as Forest City, AR, Memphis, and Jackson, Tennessee
Thursday. Coverage should decrease from north to south through
the day.

Precipitable water values will remain high across the region
today, and in portions of north Mississippi Thursday. Expect PW
values around generally around 2 inches or in the 90th percentile
for mid-July. As a result, heavy rain will remain possible, but
the threat of flooding looks to be low since we have not seen more
than about an inch of rain at any location in the last 24 hours.

The synoptic pattern Thursday into Friday will consist of a
595-597dam ridge over the Desert Southwest, extending north into
the Great Basin, and a trough over the Mississippi River. As a
result we will see north-northwest flow west of the Mississippi
River and southwest flow to the east. This should keep us dry
through at least Saturday before the CONUS pattern retrogrades
resulting in southwest flow across the central and lower
Mississippi River Valley.

High temperatures should remain below 90 degrees through at the
least the Middle of next week with some indication that below
normal readings will continue into next weekend. Showers and
thunderstorms will become more likely Sunday into midweek.

12/Sirmon

&&

.AVIATION...
(18Z TAFS)
Issued at 1218 PM CDT Wed Jul 17 2024

A messy convective forecast will dominate through the TAF period
as several rounds of showers and thunderstorms impact terminals.
A brief lull in precipitation should occur later this afternoon
with winds shifting north. 12Z CAMs continue to suggest potential
for another round of convection developing overnight. Confidence
for timing and location of this is low, so kept PROB30 groups in
TAF. Low MVFR CIGs may materialize overnight within storms.

ANS

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...Heat Advisory until 9 PM CDT this evening for MSZ010>013-015>017-
     020>024.

TN...None.
&&

$$

PUBLIC FORECAST...JDS
AVIATION...ANS