Area Forecast Discussion
Issued by NWS Memphis, TN
FXUS64 KMEG 270545
Area Forecast Discussion
National Weather Service Memphis TN
1145 PM CST Sun Feb 26 2017
Updated for the 06z Aviation Discussion.
.PREV DISCUSSION... /issued 806 PM CST Sun Feb 26 2017/
Updated to increase evening shower coverage.
Based off radar trends light showers will generally affect the
southwestern Delta counties over the next few hours...with
rainfall amounts likely to be less than a tenth of inch due to
the low level dry air. Also expanded chance PoPs further east
into Northwest Tennessee for the mid evening hours.
.PREV DISCUSSION... /issued 328 PM CST Sun Feb 26 2017/
At 3PM, a dry and pleasant late Winter day taking place across
the Mid-South. Temperatures are in the mid to upper 50s areawide
with a light southeast wind under increasingly cloudy skies.
Relative humidity values have fallen below 30 percent nearly
areawide, due to the very dry arctic airmass. However any fire
weather concerns will be squashed, as the airmass quickly
moistens tonight as an approaching shortwave moves into the area.
Latest water vapor imagery currently depicts a weak shortwave
digging across Texas Panhandle at this hour. This wave will
quickly traverse into the lower Mississippi Valley by this
evening. Hi-res short term guidance, develops a cluster of storms
into a meso-convective system during the overnight hours. This
area of showers and thunderstorms will move through the southern
half of the Mid-South through tomorrow morning. QPF values will be
between a quarter inch in the north to near an inch further south.
Storms may continue over northeast Mississippi as the MCS
propagates eastward before dissipating through late Monday morning.
Other than morning activity, Monday will be mostly dry and cloudy
with low POPs throughout the afternoon and early evening hours.
Temperatures mainly in the 60s.
By Monday night, a warm front will begin to lift northward across
the area. As is does, scattered showers and thunderstorms will
possible overnight. By Tuesday, the Mid-South will be fully
encompassed by a broad warm sector characterized by mid to upper
60s dewpoints and CAPE in the 1500 to 2000 J/kg range. A few weak
impulses in the mean upper level flow may kick off a few
thunderstorms during the day.
By Tuesday night, A broad surface low over the Plains will deepen
as it lifts across the Northern Plains. Concurrently, a broad
longwave trof will swing across the central U.S. and overspread
100 meter height falls over Eastern Arkansas. A mixed mode of
convection is expected in this region, with multicluster storms
as well as possible supercells, due to the dynamic and unstable
environment. The main threats at this time appear to be large hail
and gusty winds with storms of the elevated nature. Quite a bit of
uncertainty still remains due to the lack of any identifiable
mesoscale boundaries or features at this time.
Deep layer shear and plenty of instability will continue to fuel
strong and severe thunderstorms through the overnight hours as the
trof takes on a positive tilt and swings into the Mississippi
Valley. Convective activity may congeal into a line as the cold
front swings into the Mid-South on Wednesday morning. Largely
unidirectional hodographs will likely push a squall line through
West Tennessee, the Missouri Bootheel, and north Mississippi
during the morning to early afternoon hours. The main threat would
likely be damaging winds, especially with any bowing segments
that break from the main line. The cold front is expected to move
out of the area by late Wednesday night, bringing an end to rain
Surface high pressure will build into the Mid-South on Thursday,
with a reinforcing dry front moving in on Friday. Dry weather will
persist through late Sunday, before rain chances return Sunday
VFR cigs and vsbys early in the forecast period will gradually
lower to MVFR prior to sunrise. Scattered showers will continue
overnight with the potential for a thunderstorm by morning near
KTUP. Winds will remain southeasterly at 7 kts or less.
Showers and a few thunderstorms will end from northwest to
southeast Monday morning with a continuation of MVFR cigs early.
Cigs should gradually improve through the day with a return to VFR
at all sites except KTUP where MVFR cigs will persist. Southeast
to south winds will increase through the day.
VFR/MVFR cigs Monday evening will lower just beyond the end of the
forecast period. Brisk south to southeast winds will continue with
the potential for wind shear developing late in the period.