Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
307 PM CDT Wednesday Jul 27 2016
Unsettled weather will be the main story across the mid-south for
the next several days. Weak tropical upper low continues moving
slowly north along the Arkansas/MS border. Daytime heating and upper low
combined to produce shra/tsra. Currently most numerous west of the
MS river, but another area getting organized near and south of our
Upper low to continue lifting out tonight, with a larger-scale
trough settling generally over the Ohio Valley area. Expect
rain showers/thunderstorms and rain to continue, with high precipitable water values favorable for
efficient/locally heavy rain. Will hold off on Flash Flood Watch
for now given expected localized nature of heavy rain, but will
highlight heavy rain threat in social media and messaging.
Upper trough to remain in place over the mid-south through Sunday.
Several small vort maxes to rotate through the upper trough. At this
time, best estimate of timing looks to be Thursday afternoon/eve,
Friday night, and Saturday night/early Sunday. Timing of such subtle
features is challenging at best, so will broad-brush chance /30-50/
pops and further evaluate as events get closer.
Upper ridge builds back over the area early next week. This will
bring warmer temps and a return to more scattered/diurnal pops.
18z taf period
Current radar trends and short term models suggest increasing
coverage of showers and storms as a low moves through the region.
Increased moisture in the low levels will lead to ceilings flirting
with MVFR levels throughout the rest of the afternoon and evening.
Confidence in the coverage of precipitation decreases after
01-02z, so the decision was made to only include thunderstorms in the vicinity at all 4 taf
sites through the night. Ceilings could lower to IFR and even LIFR
levels tomorrow morning at the southernmost sites as the low lifts
out of the area.