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Area forecast discussion...updated 
National Weather Service Memphis Tennessee
1059 PM CDT Tuesday Jul 22 2014

Update...

Satellite and radar have shown some redevelopment of showers and
thunderstorms over northwest Alabama that are moving generally
westward. Other showers and thunderstorms continue to clip
Tallahatchie and Yalobusha counties in north MS. Based on the 00z
NAM and latest hrrr...updated to include at least a 20 percent
chance of showers and thunderstorms the remainder of the night
across most of north MS.

Jcl

Update... /issued 948 PM CDT Tuesday Jul 22 2014/

An upper level low pressure system was located along the South Alabama
and south MS border this evening moving slowly westward. Scattered
showers and thunderstorms associated with this system that spread
into portions of north MS and west Tennessee earlier today have just
about dissipated or moved out of the region for the night. Lingering
showers and thunderstorms rotating around this low pressure system
were moving southwestward out of Yalobusha County in north MS and
may clip the southern portions of Tallahatchie County. Otherwise
rain free weather is expected across most of the region the
remainder of the night. The latest NAM and hrrr models continue to
indicate the possibility of a few showers and thunderstorms moving
into portions of northeast Arkansas and the MO bootheel late tonight
ahead of a weak upper level short wave embedded in northwest flow
aloft...this is already indicated in the earlier forecast.

Surface dew points have really increased from recent days and are
presently mainly in the lower and middle 70s across most of the
area. This will make for a warmer night. Added patchy fog with
decreasing temperature and dew point depressions along with light
winds.

Updated grids and grids will be sent soon.

Jcl

&&

Previous discussion... /issued 345 PM CDT Tuesday Jul 22 2014/

Currently...a weak upper low located along the northern Gulf
Coast is retrograding slowly. Meanwhile to the north an upper
ridge extends into the middle Mississippi Valley. Deeper moisture
associated with the upper low has moved into north Mississippi and
into areas near the Tennessee River where the airmass is fairly
unstable with sbcapes around 2500 j/kg. As a result isolated showers
and thunderstorms have developed in those aforementioned areas.
Elsewhere skies are partly to mostly sunny. Temperatures range from the middle
80s and NE MS to around 90 elsewhere.

Tonight...the upper low will continue to retrograde and weaken
overnight. Isolated showers and thunderstorms across NE Mississippi and
along the Tennessee River will dissipate with loss of heating early this
evening. Otherwise expect a quiet and mild night with temperatures a few
degrees warmer than last night since surface dewpoints have
increased a bit in the last 24 hours. Later tonight a cold front
will start to move into the middle Mississippi Valley which will
trigger showers and thunderstorms across Missouri. Some of these
could sneak into NE Arkansas by morning so added a small pop
there.

Wednesday and Wednesday night...the upper ridge briefly sneaks in
ahead of approaching cold front allowing for a warm and muggy day
for the midsouth. Meanwhile the weak upper low along the northern
Gulf Coast will persist and may help trigger a few showers and
thunderstorms across north Mississippi. More importantly by
afternoon a cold front will be approaching northern areas of the
midsouth with chances for showers and thunderstorms. The front
will continue to push south through the area Wednesday night with
chances for showers and thunderstorms continuing. The airmass will
be quite unstable ahead of the front and scattered showers and
thunderstorms are expected with the best chances across the
northern tier. A few strong to severe storms are possible with
damaging winds the main threat Wednesday afternoon into Wednesday
night. By late Wednesday night the front will be located across
northern Mississippi and cooler/drier air will filter into
northern areas with temperatures dropping into the 60s.

Thursday through Saturday...the cold front will exit north
Mississippi in the morning and high pressure will build in with a
less humid airmass and cooler temperatures. Below normal temperatures are
expected with highs on Thursday in the 80s and lows Thursday night
in the 60s. Temperatures will climb Friday and Saturday as upper ridging
builds in. Highs will approach 90 on Friday and lower 90s on
Saturday. Cut mex temperatures a few degrees since it has been too warm
all Summer.

Saturday night through Sunday night...upper ridge starts to
weaken Saturday night and weak northwest flow develops with a
boundary located to the north of the area. This could be an mesoscale convective system
scenario. By Sunday and Sunday night the eastern U.S. Trough
strengthens once again as more energy dips south from Canada. This
drives a cold front south through the area Sunday and Sunday
night. Expect chances for showers and thunderstorms followed by
cooler and drier weather by early next week. Temperatures looks to be
well below normal Monday into much of next week.

Sjm

&&

Aviation...

00z taf cycle

Mainly VFR conditions will continue for much of the forecast
period. Some areas of fog are expected to develop overnight which
may reduce visibilities to MVFR or even IFR levels. Winds will be
light and mainly from the southwest for much of the forecast
period.

Ars

&&

Meg watches/warnings/advisories...
Arkansas...none.
MO...none.
MS...none.
Tennessee...none.
&&

$$

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