Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 181604

Area Forecast Discussion
National Weather Service Memphis TN
1104 AM CDT Thu Apr 18 2019


Rain continues to fall along and west of the Mississippi River
this morning. Temperatures will stay below 70 degrees across this
area this afternoon. Meanwhile, temperatures across Northeast
Mississippi have already climbed into the lower 70s. As a result,
best chances for severe storms will be along and south of a
Charleston, Mississippi and Savannah, Tennessee line. South of
this line will have the best instability. Latest Day One Outlook
has already trimmed Northeast Arkansas, the Missouri Bootheel, and
Northwest Tennessee out of any severe weather risk. Current
forecast looks on track.



.DISCUSSION.../issued 320 AM CDT Thu Apr 18 2019/

Currently skies were clear across the southeast counties with
partly to mostly cloudy skies elsewhere. Temperatures were in the
60s with south winds of 5-15 mph. Line of convection on radar
associated with shortwave lifting northeast over the Ozarks is
maintaining an occasional strong intensity as it rolls through
central Arkansas. This activity should reach the western counties
shortly and the MS River by 5 am.

For today and tomorrow...Plains storm system will bring bouts of
heavy rain and a slight risk for severe weather to the area.
First round is progged to weaken early this morning as it gets
east of the Mississippi River. Training of new storms and heavy
rainfall will set up before noon across eastern Arkansas in
advance of the approaching shortwave in Texas. So questions
remain on the timing of convection in the far southeast counties.
CAM`s have been slowing things down a bit rain may
hold off until after 4 pm in far northeast Mississippi. The Day1
outlook has nearly removed the Enhanced Risk out of the CWA...due
mainly to marginal midlevel lapse rates and significant cloud
cover maintaining a weak cap near 850mb. These actions are
reducing SBCAPE amounts to under 400 j/kg during what would be
peak heating (late afternoon). The shear though will be
increasing after 21z as a surface wave and frontal boundary slide
into northwest Mississippi. So a line of convection with
occasional bowing segments seems the most plausible outcome as it
marches east. In addition brief spin-ups will be possible if the
convection at times can become orthogonal to the mean storm flow.
Storms should cross over into Alabama between 7-8pm.

As far as the flash flood threat...have expanded the watch to
encompass the entire Midsouth. The ground has remained just under
saturation since the past weekend`s 2 to 3 inches amounts. Now
latest guidance is suggesting more 3 than 2 inch amounts falling
today over the western and northern counties...posing a more
widespread problem for both river`s and urban/low lying areas.
Extended the watch out in time as well to accommodate the slower
exit of precipitation. The heavier rain should shift east of the
area around midnight but clouds and light showers and/or drizzle
will continue nearly all day tomorrow...especially in the east as
the main upper trough closes off. After seeing highs today in the
upper 60s to mid 70s...breezy northwest winds tomorrow will
provide for readings in the 50s. Basically normal highs for
late February. Partial clearing of skies Friday night will drop
temperatures to the low 40s.

Saturday through Monday...dry this 3-day period with temperatures
moderating back to above normal starting Easter Day.

Middle of next week...seasonal to slightly above seasonal
temperatures with the slow approach of the next shortwave and
cold front. Extended models differ on exact precipitation timing
so left rain chances under 50 percent.




12Z TAFs

Ongoing showers and thunderstorms should begin to impact MEM and
MKL over the next hour or two resulting in MVFR vis. Guidance
redevelops another round of showers and thunderstorms this
afternoon, so maintained prevailing thunderstorms for much of the
day at MEM, MKL and TUP. Winds will remain enhanced, generally
12-15kts through the TAF cycle shifting from the Northwest as the
prevailing thunder ends. Cigs are expected to lower to IFR levels




AR...Flash Flood Watch through this evening for Clay-Craighead-
     Crittenden-Cross-Greene-Lee AR-Mississippi-Phillips-
     Poinsett-St. Francis.

MO...Flash Flood Watch through this evening for Dunklin-Pemiscot.

MS...Flash Flood Watch through this evening for Alcorn-Benton MS-
     Calhoun-Chickasaw-Coahoma-DeSoto-Itawamba-Lafayette-Lee MS-

TN...Flash Flood Watch through this evening for Benton TN-Carroll-


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