Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
315 PM CDT Tuesday Sep 2 2014
thunderstorms have developed this afternoon along an outflow
boundary from a decaying nocturnal mesoscale convective system over the Ozark Plateau. This
outflow boundary delineated the warm sector...which was southeast
of a Forest City Arkansas... to Memphis to Dyersburg Tennessee line at 3 PM.
Best low level instability was noted over north MS... this will be
the area most favored for thunderstorms into early evening.
While thunderstorms gradually dissipate over north MS this evening...
models depict additional thunderstorm formation over the Central
Plains. Models may be overdoing the immediate upstream convective
potential... given the cool bubble high from this morning/S mesoscale convective system
over the Ozark Plateau. In any case...building midlevel heights
and weaker zonal steering winds should keep the bulk of overnight
thunderstorms to the north.
Thunderstorms chances for Wednesday and Thursday will likely be
driven by differential surface heating and subtle low level boundary
interactions under the upper ridge. Temperatures will average well above
normal...with heat indices Thursday likely in excess of 100 degrees.
Upper level heights falls over the much of the central and
northern Continental U.S. Will drive a surface cold front into the Ohio
Valley and Southern Plains by Friday evening. Low level moisture
pooling and stronger midlevel winds will bring an increase in
daytime rain chances for the midsouth. GFS mex guidance temperatures
appear too warm for the pattern...particularly if prefrontal
thunderstorms develop as depicted by the GFS and European model (ecmwf).
European model (ecmwf) and GFS models have remained consistent in bringing a cold
front through the midsouth on Saturday. Scattered to numerous
showers and thunderstorms and low level cold advection should
provide a noticeable cooldown following the midweek heat.
Sunday will see best rain chances follow the front on it/S way to
central/south MS. Drier air will edge in from the north to close
out the weekend and persist into Monday. Low level will return to
the southerly direction on Tuesday...as upper heights build in
advance of a midweek longwave upper trough dropping into the Central
Plains and northern plains.
18z taf cycle
Outflow boundary from last night/S convective activity combined
with daytime heating is producing numerous rain showers/S with some
embedded thunderstorms in the vicinity along and south of mem. Thus will keep thunderstorms in the vicinity in at
tup and reintroduce mention at mem/mkl around after 02/19z. MVFR
conditions are anticipated to improve to VFR conditions this afternoon.
Abundant low level moisture may lead to fog and MVFR/IFR
conditions overnight. S/SW winds between 6-10 kts will become
light after 03/00z.