Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 221354
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
854 AM CDT Sun Oct 22 2017

.UPDATE...
Updated to reduce morning rain chances.

&&

.DISCUSSION...

Based off area radar trends lowered rain chances across the
region for this morning...concentrating mainly on points east of a
Union City TN to a Coffeeville MS line. In addition lowered
thunderstorm chances as most of the activity has become isolated
at best.

Questions starting to arise for later today as short term models
continue to show a second surge of precipitation arriving near
sunset. However current line of convection heading towards the
Gulf Coast may cut-off moisture...reducing overall QPF amounts.

JAB

&&

.PREV DISCUSSION... /issued 631 AM CDT Sun Oct 22 2017/

DISCUSSION... /issued 415 AM CDT Sun Oct 22 2017/

Early this morning, KLZK radar showed a gradually-weakening line
of thunderstorms lifting east through AR. Radar trends were
corroborated by warming cloud top temperatures evident on GOES IR
imagery.

Early morning intensity trends aside, a few strong winds will be
possible early this morning, mainly from east central AR into
northwest MS. Cold pool maintenance and strong wind threat is a
more in question later this morning and afternoon, given limited
available instability ahead of an approaching upper level trof.

00z Saturday ECMWF run broke from the model consensus showing a
more open and faster-moving upper level trof and today`s 00Z GFS
and ECMWF concur. Primary impact for the Midsouth is an earlier
forecasted end to the rainfall- tonight, with sunshine making an
earlier than previously expected return on Monday along with low
humidity.

Upstream energy over southwest Canada will dive southeast and
carve out an longwave upper trof over the MS River valley by
Tuesday morning. A secondary dry cold front will push through the
Midsouth early Tuesday, setting the stage for surface winds to
decouple in the valleys of west TN and north MS early morning
Wednesday. Outside of these areas, surface pressure gradient may
be sufficient to keep winds mixed and frost formation from
occurring.

The upper level longwave trof over the eastern US will lift out
Thursday, leaving zonal flow to prevail over the Midsouth. Low
level winds will return to southerly and strengthen in advance of
another deep upper level trof developing over the upper Midwest.
Strengthening southwesterly flow will aid in the development of
and unstable warm sector over the lower MS River valley on Friday.
The 00Z medium range models showed timing and placement
differences with respect to the upper trof and associated surface
front, leading to lower and more temporally-broad PoPs from the
blended model guidance. In any case, next weekend looks to be on
the cool side, with high temps next Sunday in the 50s, with
sunshine.

PWB

&&

.AVIATION...

12Z TAF Set

A weakening line of convection is pushing into the Mid-South at
this time. Rain has just started at KJBR. Whatever is left of the
line will impact KMEM after 14Z and possibly KMKL by 15Z.
Redevelopment of TSRAS are expected just west of a KMKL to KTUP
line around 19Z. Have added a tempo group to KMKL and KTUP for the
expected line of TSRAS. MVFR CIGS will spread into all four TAF
sites this morning into the early afternoon hours with the SHRAS
and/or TSRAS. Lingering light SHRAS or drizzle will continue
behind the initial line of convection through the late afternoon
and evening hours. Conditions may go IFR at KMKL and KTUP during
the overnight hours while improving conditions will occur at KJBR
and KMEM. Gusty southerly winds will turn around to the northwest
behind the front. Speeds may stay gusty for the first couple of
hours behind the front, but will gradually diminish to around 5
KTS during the overnight hours.

KRM

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

$$



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