Flash Flood Warning 29, NWS Memphis, TN

Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
601 PM CST Tue Nov 5 2024

...New AVIATION...

.SYNOPSIS...
Issued at 206 PM CST Tue Nov 5 2024

Wet weather will continue through Thursday as a cold front stalls
out over the region. Rainfall totals could reach up to 3 inches
over portions of northern Mississippi and western Tennessee
during this time frame. High temperatures will cool into the upper
60s and low 70s by the end of the week. Rain chances arrive again
this weekend ahead of another frontal system.

&&

.DISCUSSION...
(This evening through next Monday)
Issued at 206 PM CST Tue Nov 5 2024

A cold front, currently in central AR, will move into the region
tonight. Synoptically, this front is driven by a large upper
trough now exiting the Rockies. This trough is forecast to become
sheared out, with southerly upper flow overspreading the region
over the next couple days as it progresses northeast over the
CONUS.

As for today, marginal severe chances will persist through the
evening hours. Clearing across N MS has allowed for MLCAPE to jump
to near 1000 J/kg per RAP mesoanalysis with around 40 knots of
effective bulk shear and around 200 ESRH. Normally these values
would promote concerns for higher severe chances, but the lack of
upper level ascent and surface forcing have kept storm coverage
low. Therefore, marginally severe winds are the most likely
hazard with any severe storms.

The cold front will drape itself across the center of the region
tonight. With no upper level support as the upper low pivots
northeast, this front is expected to remain stationary in this
location for a few days. Upper winds are expected to retain a
large southerly component, which is parallel to the boundary,
leading to training thunderstorms. This is already being seen this
afternoon from radar observations. PWATs near 2" and a frontal
zone as a focus for convection has given WPC enough confidence for
a slight risk ERO. Any storms that train over regions for a long
interval are capable of potentially causing flash flooding
concerns this evening and tonight in areas across N MS and W TN.

Showers will gradually diminish in coverage through Thursday as
the frontal boundary become more diffuse. Additional rainfall
should be limited to less than 1 inch Wednesday through Thursday.
Eventually, high pressure begins to reign and easterly/southeasterly
winds will begin to kick the front out. However, weather will
remain humid with higher PoPs after tonight returning this weekend
thanks to a new trough ejecting from the Rockies. Similar to
today's system, another set of frontal passages are likely, but
ensemble confidence is still too low for specific impacts. And
just in time to add even more uncertainty to the forecast, TS
Rafael's potential track is still too unresolved to forecast its
impacts on the Midsouth's forecast next week.

&&

.AVIATION...
(00Z TAFS)
Issued at 559 PM CST Tue Nov 5 2024

A challenging weather pattern for aviation. A subtropical low
level moisture axis extends north along MS River. The Midsouth
will remain under the right entrance region of an upper jet core
over the middle MS River Valley through most of the overnight.
The net effect will be continued favorable upper level support for
SHRA IFR/MVFR conditions.

Marginal instability will support isolated TS overnight,
particularly if accompanied by any weak midlevel disturbance
lifting north from the Arklamiss. Higher cloud tops were noted on
GOES IR imagery over northern LA at discussion time. This may be
indicative of a weak shortwave that may provide a mid/late evening
bump in TS chances MEM. Confidence limited by the marginal
instability.

The upper level jet pattern will become less supportive of heavy
persistent rain and TS on Wednesday. Low MVFR/IFR will likely be
the biggest impacts for the Wednesday evening MEM inbound push.

PWB

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

PUBLIC FORECAST...JAB
AVIATION...PWB