Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 221801

Area Forecast Discussion
National Weather Service Memphis TN
1201 PM CST Thu Feb 22 2018


Updated for aviation discussion


.PREV DISCUSSION... /issued 1112 AM CST Thu Feb 22 2018/


Showers and thunderstorms continue across Northeast Mississippi
this morning near the stalled front. Latest models show this area
of convection eventually dying out during the afternoon hours
while another area of convection develops over Northern Louisiana
and Southern Arkansas. This area of convection will spread
northeastward into the area as the front begins to slowly lift to
the north. Will go ahead and bump up POPS to likely across
portions of North Mississippi and East Central Arkansas to account
for the lingering convection from this morning and the next round
expected later this afternoon. Will also extend the Flood Watch
for Tallahatchie, Yalobusha, Lafayette, and Union Counties through
00Z (6 PM) as the next round of convection will likely impact
these counties. Update will be out shortly.


DISCUSSION...  /issued 352 AM CST Thu Feb 22 2018/

Currently band of moderate to heavy rainfall was to the south of
I-40 and along and north of a stalled cold front from near
Greenwood to Fulton Mississippi. Latest rainfall rates generally
ranged form a quarter to a half inch an hour. Temperatures ranged
from the upper 30s over portions of northeast Arkansas to another
balmy 70F in Aberdeen Mississippi.

For today and tonight...heavier band of rain this morning will
shift to the northern counties the next in line
shortwave embedded in the atmospheric river starts a northerly
push of the stalled front. However...a lull in the heavier
precipitation appears likely this afternoon and into the early
evening hours...before the focus shifts with the shortwave.
Temperatures today will range from the 40s north to the 70s south.
WAA late tonight will slowly bring temperatures into the 50s over
the north...with lows in the 60s across the south.

Friday and Saturday...models in better agreement this period with
regards to the timing and deepening of a surface low ejecting out
the Texas Panhandle and into the Midwest. The GFS still is more
bullish with deeper central pressure and a stronger low level
wind field. But the NAM and EURO this run have trended to
a slightly stronger system as well. Therefore pockets of heavy
rain will remain north of I-40 tomorrow and into early
Saturday along the surging/lifting warm front...and then across
the entire area later Saturday and into Saturday night as a cold
front associated with the developing low sweeps east. Collaborated
with surrounding offices and WPC of what will be a three day
moderate risk for flooding over portions of our area/flood watch.
Additional rainfall amounts of 5+ inches can`t be ruled out
leading to 5-day storm totals encroaching on 9-10 inches for some.

With regards to a severe threat...models are showing a prefrontal
trough signal forming in eastern Arkansas by 00z Sunday as the
surface wave crosses Missouri. Another feather in the cap for the
potential for surface-based convection. A 70kt LLJ from the
southwest will form just out ahead of the trough leading to an
evening period of potentially backed surface winds and few low
level mesos and/or bowing segments. Limiting factors will be
lapse rates and instability amounts after sunset. Have placed
wording in this morning`s HWO about this severe threat.

Temperatures this period will be in the 60s and 70s...with lows
falling Saturday night into the 40s and 50s behind the cold front.

Sunday through next Wednesday...most of the Midsouth looks to be
dry through Tuesday with the exception of the far southern
counties. Gulf moisture will reside just south of the CWA
however...with both the GFS and EURO showing return southerly flow
bringing rain back starting Tuesday night into Wednesday. Thus
have ramped up PoPs this period. A modified Pacific airmass will
keep temperatures above normal this period. Could it be Spring?




Quasi stationary front situated from Middle TN through North MS
this morning. IFR/LIFR conditions N/W of this front with VFR
conditions S/E. Area of SHRAs continuing to move across NE MS will
fall apart over the next couple of hours. Meanwhile the next wave
of SHRAs with embedded TSRAs will move into western and northern
areas of the Mid-South this evening. Expect IFR/LIFR conditions
through the period at KJBR. Conditions should improve to MVFR at
KMEM and KMKL as the front lifts north by this evening though
IFR/LIFR conditions will return by Friday morning. KTUP should
remain mostly VFR until lower clouds develop Friday morning. Light
E/NE winds will gradually veer SSW through Friday morning. The
front will begin to move back south on Friday with winds shifting
to north by mid afternoon.



AR...Flood Watch through late Saturday night for Clay-Craighead-
     Crittenden-Cross-Greene-Lawrence-Lee AR-Mississippi-
     Phillips-Poinsett-Randolph-St. Francis.

MO...Flood Watch through late Saturday night for Dunklin-Pemiscot.

MS...Flood Watch through late Saturday night for Alcorn-Benton MS-

     Flood Watch until 6 PM CST this evening for Lafayette-

TN...Flood Watch through late Saturday night for Benton TN-Carroll-


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