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Area forecast discussion 
National Weather Service Memphis Tennessee
938 am CDT Sat Aug 23 2014

Discussion...

Morning forecast continues to be on track with no updates needed.
The noon hour still appears favorable for the start of today's
heat advisory. Other than that...an isolated afternoon shower or
storm remains in question over northwest Tennessee as satellite
trends indicate the ridge eroding the current cloud cover.

Jab

&&

Previous discussion... /issued 620 am CDT Sat Aug 23 2014/

Discussion... /issued 424 am CDT Sat Aug 23 2014/

Late Summer heat wave will continue into early next week...as a
large upper level height ridge remains anchored over the lower MS
River Valley.

Today should see temperatures a degree or two warmer than Friday if NAM
model soundings are correct. In addition...NAM soundings depict
dewpoints through the mixing layer averaging several degrees warmer
than Friday...suggesting limited potential for drier air to mix to
the surface.

A heat advisory has been issued for all of the midsouth today...
effective from noon through 8 PM CDT. Some locations near the Tennessee
River vally may struggle to reach 105 heat indices...particularly
if isolated afternoon thunderstorms develop near the upper ridge/S
eastern periphery.

Sunday will see the upper ridge axis migrate slightly westward...
opening the potential for additional thunderstorms near the Tennessee
River valley... perhaps with a little better coverage than today.
A heat advisory will likely be needed for Sunday over at least a
portion of the midsouth.

Midlevel moisture increases Monday and Tuesday...along with
sufficient low level moisture for attainable convective temperatures over
a broader area of the midsouth. Where thunderstorms form will be
most dependent on mesoscale processes such as boundary interactions
and differential heating. Coverage of thunderstorms should remain
limited...but may result in heat indices peaking just below
advisory levels Monday and Tuesday.

GFS and European model (ecmwf) remain at odds for the middle to late portions of next
week. The GFS brings a progressive upper trough and associated
surface cold front through the MS River Valley Wednesday night
through late Thursday. The GFS solution depicts frontal
thunderstorms Thursday...followed by northwest flow aloft along
with drier and cooler surface conditions Friday through the
upcoming weekend. Conversely... the European model (ecmwf) maintains the upper
ridge over the southeast states through midweek...which will
stall a nearly cutoff upper trough over the plains through the weekend.
European model (ecmwf) depicts southwesterly flow aloft and deep subtropical
moisture prevailing over the midsouth during the latter half of
next week.

With the GFS and European model (ecmwf) showing markedly different solutions beyond
120 hours...forecast confidence through the extended periods is
low. Of the two models...the GFS has shown greater interrun
consistency and have applied a heavier weight to the GFS for the
extended forecast periods.

Pwb

&&

Aviation...

12z taf set

VFR conditions expected over the next 24 hours. Isolated rain showers/thunderstorms and rain showers
will be possible across west Tennessee near the Tennessee River
late this afternoon into the early evening hours. Will introduce a
thunderstorms in the vicinity at kmkl between 21-02z. SW winds will remain 7 kts or less
through the period at kmem.

Krm

&&

Meg watches/warnings/advisories...
Arkansas...heat advisory until 8 PM CDT this evening for Clay-Craighead-
Crittenden-cross-Greene-Lawrence-Lee Arkansas-Mississippi-
Phillips-Poinsett-Randolph-St. Francis.

MO...heat advisory until 8 PM CDT this evening for Dunklin-Pemiscot.

MS...heat advisory until 8 PM CDT this evening for Alcorn-Benton MS-
Calhoun-Chickasaw-Coahoma-DeSoto-Itawamba-Lafayette-Lee MS-
Marshall-Monroe-Panola-Pontotoc-Prentiss-Quitman-
Tallahatchie-Tate-Tippah-Tishomingo-Tunica-Union-Yalobusha.

Tennessee...heat advisory until 8 PM CDT this evening for Benton Tennessee-Carroll-
Chester-Crockett-Decatur-Dyer-Fayette-Gibson-Hardeman-
Hardin-Haywood-Henderson-Henry-Lake-Lauderdale-Madison-
McNairy-Obion-Shelby-Tipton-Weakley.

&&

$$

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