Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
315 PM CDT Wednesday Jul 23 2014
Currently...a cold front is pushing south toward the region this
afternoon triggering showers and thunderstorms across parts of the
midsouth. One mesoscale convective system has moved across western Kentucky/southeast MO into the MO
bootheel and NE Arkansas this afternoon with some reports of wind
damage. Another cluster of strong storms and heavy rain extends
just south of I-40 from Selmer northeast toward Lexington
Storms are feeding on a very unstable airmass with dewpoints in
the lower 70s...convective available potential energy greater than 3000 j/kg and lifted index
values of -7c to -8c. Wind fields aloft are not that strong with
middle level at about 30 kts...but enough to sustain organization.
A Severe Thunderstorm Watch continues until 7 PM across MO
bootheel and much of east Arkansas. The mesoscale convective system over NE Arkansas will
continue to propagate south-southwest over the next couple of hours with
mainly a wind threat. Elsewhere expect isolated-scattered storms to develop
some of which may be strong to severe with mainly a wind threat as
well. Localized flash flooding is also possible with heavier slow
Tonight...mesoscale convective system will depart into central Arkansas by early this
evening and a cold front will sweep south. Models are indicating
some additional development along the front as it passes through.
At that point instability should be on the wane with a diminishing
severe threat. By midnight most of the activity will be south of
I-40 with a drier...cooler airmass beginning to move into northern
Thursday and Friday...the front will push south of the area
Thursday morning with clearing skies and diminishing rain chances.
An unseasonably cool and dry airmass will push in for Thursday and
Thursday night. Highs will be in the lower to middle 80s with lows in
the upper 50s to middle 60s. Friday will be a little warmer...though
humidity levels will still be low...as upper level high pressure
starts to build back in.
Saturday and Sunday...Summer heat tries to build over the area
thanks to a strengthening 594 dm upper ridge over the Southern
Plains. Looks like highs will rebound into the lower and middle 90s
with increasing humidity levels. Still think the mex is too hot
with its upper 90s. Heat index values may climb above 100 degrees
over the weekend. By Saturday night an approaching cold front may
launch an mesoscale convective system across the northern tier of the midsouth so kept
slight chance probability of precipitation across the northern tier. Thunderstorms chances
will increase across the area Sunday into Sunday night as another
cold front is driven through the area by another unseasonably
strong upper trough across the Great Lakes.
Monday into Wednesday...dry and cool weather filters in behind the
front. Well below normal temperatures and dry weather expected.
18z taf cycle
VFR and possibly MVFR conditions are expected throughout
the forecast period. Thunderstorms have begun to move into the
area ahead of a cold front extending from Quebec into the
Southern Plains. The hrrr model has coverage of these storms
decreasing as they enter into the region. Added thunderstorms in the vicinity for kjbr and
kmkl through this evening. A low pressure system over the northern
Gulf has caused thunderstorm activity over north Mississippi so I
added thunderstorms in the vicinity at ktup. Fog is possible tonight at ktup and kmkl due
to light winds and lower level moisture. Winds will be south ahead
of the front and will turn to the north after the front passes
each taf site beginning with kjbr around 00z.