Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
1146 PM CDT Tuesday Aug 4 2015
Updated for 06z aviation discussion
Previous discussion... /issued 939 PM CDT Tuesday Aug 4 2015/
Latest hrrr and NAM are in pretty good agreement that a large area
of showers and thunderstorms will move into areas along and west
of the Mississippi River overnight. Looking at the latest radar
images...a small area of showers and thunderstorms is currently affecting
northern Arkansas. This is likely the beginning of the development
that the models are picking up on. Thus expect the area to expand
over the next couple of hours. Will update to raise probability of precipitation.
Discussion... /issued 343 PM CDT Tuesday Aug 4 2015/
Temperatures climbed quickly this morning under sunny skies...but
leveled out midday and are currently within a degree or so of
where we were yesterday at this time. We may still see another
degree or two of warming...especially in north Mississippi and
portions of west Tennessee...but with ever increasing cloud cover
many locations have likely all reached their afternoon highs. If
the forecast is accurate we should not see temperatures this warm
for several days...perhaps until Sunday or Monday.
A stalled front remains in place to our north...draped across
central Missouri. The ridge responsible for the recent hot
temperatures will continue to break down tonight and tomorrow. And
a fairly strong shortwave for this time of the year will track out
of the plains...shifting across the midsouth tomorrow. Additional
smaller impulses will track over the area tomorrow night and
Thursday...but the main threat for any strong or severe storms
should be tomorrow afternoon. Thursday and Friday...we will be
under generic northwest flow.
As for the severe potential...it isn't looking like anything to be
overly concerned about. There will be some enhanced shear near
and ahead of the shortwave...but otherwise dynamics look
unimpressive. Dew points should be in the low 70s with surface
temperatures in the 80s to near 90 supporting convective available potential energy of up to 2500
j/kg. However...if rain is ongoing early in the day...this amount
of instability may be optimistic.
Thursday and Friday strong storms may still be possible...but the
overall severe threat should diminish as the shortwave exits the
region. Basin average rainfall totals midweek through Friday
should range between a third of an inch in north Mississippi to
as much as one inch in northeast Arkansas. Locally higher
accumulations are likely where individual thunderstorms develop.
Most of the widespread rain chances will come to an end by
Saturday and temperatures will begin to rebound. Guidance wants to
build the ridge back in Sunday into early next week resulting in
similar conditions to what we saw yesterday and today.
06z taf cycle
Thick cirrus across the region should prevent fog so removed that
from kmkl and ktup. Convection continues to develop across
southern Missouri and northern Arkansas. Expect several
disturbances to move across the midsouth over the next 24 hours.
First disturbance should bring rain showers/thunderstorms and rain showers into kjbr around
09z...kmem at 12z and kmkl at 14z. This first round probably will
not reach ktup. Should be somewhat of a break through much of the
day with some popup activity before another round develops in the
afternoon and works its way southeast into the early evening.
Outside of rain showers/thunderstorms and rain showers expect VFR conds and light and variable