Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 241812
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
1212 PM CST Sat Feb 24 2018

.DISCUSSION...

Updated for aviation discussion

&&

.PREV DISCUSSION... /issued 944 AM CST Sat Feb 24 2018/

UPDATE...

A warm front currently stretches from near Batesville, Arkansas to
Paducah, Kentucky this morning. Dense fog has developed north of
the front. The front is not expected to lift north of this area
until the early afternoon hours thus have issued a Dense Fog
Advisory through 1 PM for Randolph, Clay, Greene, Lawrence, and
Dunklin Counties.

Latest CAM models show convection currently developing across
Western Arkansas racing into Northeast Arkansas by noon. A few of
these storms could become severe. Although, the best chances for
severe weather will come later in the afternoon with the expected
line of convection ahead of the cold front. May make some minor
adjustments to POPS and temperatures. Otherwise, current forecast
looks good.

KRM

DISCUSSION... /issued 431 AM CST Sat Feb 24 2018/

Severe thunderstorms are possible across all of the Midsouth this
afternoon into tonight. The Storm Prediction Center has included
all of the Midsouth in an enhanced risk for severe thunderstorms.
Hail looks to be the least likely mode of severe weather with
damaging winds the most likely. There is also the potential for
tornadoes. Supporting parameters of severe thunderstorms include
dew points in the middle 60s resulting in modest CAPE values
between 500 and 1000 J/KG, diffluent flow aloft, a 60-70kt LLJ,
large curved low level hodographs and favorably located upper
level jet streaks. The timing of the arrival of the storms will
also coincide with peak heating optimizing thermodynamic
instability. Factors un-supportive of severe thunderstorms are
hard to find. Cloud cover may be the biggest hindrance to severe
storms...limiting the potential instability. Dew points are
already in the middle to upper 60s in north Mississippi...tapering
off to the low 50s in Northwest Arkansas. Flooding also remains a
concern. Precipitable water values are expected to be in excess
of 1.5 inches resulting in the potential for rain rates over two
inches per hour. Storm total rainfall from the last few days has
exceeded 3 inches over a large portion of the Midsouth..especially
northeast Arkansas, the Missouri Bootheel and North
Mississippi...with some areas over 6 inches. As a result, the
ground is already saturated so additional rainfall will likely
quickly lead to flooding. Saturated soil also makes trees easier
to topple. In these conditions even 35-45 mph winds can bring
trees down.

Some post frontal showers may linger in North Mississippi Monday.
For the rest of the Midsouth Monday and Tuesday look dry.

By midweek, it appears we will face another threat of multiple
days of heavy rain much like we are currently experiencing. WPC`s
day 4-5 product(Tuesday morning through Thursday morning) shows
over 2 inches of rain over nearly all of the Midsouth centered
over Memphis. The threat area for severe thunderstorms midweek has
shifted slightly farther South and West...but still includes
portions of North Mississippi and East Arkansas. Both the GFS and
the ECMWF show similar solutions featuring strong Southwest
flow...high PW`s and a series of shortwaves moving from Southeast
Texas across the Midsouth during the middle of the week.

River flooding will remain a concern for the foreseeable future.

Temperatures will remain above normal through the forecast period.
The warmest temperatures will likely be this afternoon. Portions
of North Mississippi may reach 80 degrees today. The coolest
temperatures will likely occur late in the work week behind a cold
front. Highs Friday will be in the upper 50s with morning lows in
the middle to upper 30s.

30

&&

.AVIATION...

MVFR cigs prevail across the Mid-South with a cluster of SHRAs
and TSRAs across the western half of the Mid-South. The cluster
of SHRAs and TSRAs will move across eastern AR and NW TN including
KJBR this afternoon. A line of strong to severe storms will
organize along a cold front this afternoon and sweep west this
evening with ocnl IFR cigs/vsbys and gusty winds reaching KJBR
around 25/22z...KMEM at 25/01z...KMKL at 25/02z and KTUP at
25/04z. Some post frontal rain will follow the frontal passage
then VFR conditions will return by 25/06z at KJBR spreading east
to KTUP by 25/12z.

South winds 15-20kts with higher gusts this afternoon ahead of the
front shifting to WSW as the line moves through this evening and
remaining gusty. Winds will continue to veer to the north and
diminish through Sunday morning.

SJM

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Flood Watch through late tonight for Clay-Craighead-Crittenden-
     Cross-Greene-Lawrence-Lee AR-Mississippi-Phillips-Poinsett-
     Randolph-St. Francis.

     Dense Fog Advisory until 1 PM CST this afternoon for Clay-Greene-
     Lawrence-Randolph.

MO...Flood Watch through late tonight for Dunklin-Pemiscot.

     Dense Fog Advisory until 1 PM CST this afternoon for Dunklin.

MS...Flood Watch through late tonight for Alcorn-Benton MS-Coahoma-
     DeSoto-Marshall-Panola-Quitman-Tate-Tippah-Tunica.

TN...Flood Watch through late tonight for Benton TN-Carroll-Chester-
     Crockett-Decatur-Dyer-Fayette-Gibson-Hardeman-Hardin-
     Haywood-Henderson-Henry-Lake-Lauderdale-Madison-McNairy-
     Obion-Shelby-Tipton-Weakley.

&&

$$



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