962
FXUS64 KMEG 041843
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
143 PM CDT Fri Apr 4 2025

...New DISCUSSION...

.KEY MESSAGES...
Updated at 143 PM CDT Fri Apr 4 2025

-Severe storms and excessive rainfall are expected to continue
 through Saturday night.

-A Moderate Risk of severe weather is in effect through tonight
 for portions of northeast Arkansas and the Missouri Bootheel.

-An Enhanced Risk of severe weather is in effect for much of the
 rest of the Mid-South through Saturday night.

-A High Risk of excessive rainfall is in effect through Saturday
 night. Total rainfall amounts of 10 to 15 inches along and north
 of I-40 are likely. This is not your average flood risk.
 Generational flooding with devastating impacts are possible.

&&

.DISCUSSION...
(This evening through next Thursday)
Issued at 143 PM CDT Fri Apr 4 2025

Another day, and another round of severe weather as we continue
through an extremely active weather episode. A large upper trough
continues east today and is gradually picking up speed. To its
east and closer to the surface, a cold front extends south through
central Texas with a warm front lifting north from the Arklatex
through the Midsouth into the Ohio River Valley. A warm, tropical
airmass will then move into the region and persist through the
next 36-48 hours, producing heavy rain, severe thunderstorms, and
significant flooding.

The severe weather threat this afternoon will be characterized by
two rounds: warm sector cells and a QLCS overnight. Strong
southerly flow and upper height falls have allowed the retreat of
yesterdays cold air mass. Rapid destabilization is already under
way across our northern counties where upwards of 4000 J/kg of
SBCAPE are possible by midafternoon. The upper low to the west
will bring increasing upper winds and allow for 0-6 km bulk shear
in excess of 50 knots, favoring supercells and strong bowing line
segments within the QLCS. ESRH is currently lackluster (100-200
0-3 km) but is expected to increase into the evening and along the
warm frontal zone. Therefore, any storms that are able to form in
the open warm sector that reside through the evening or interact
with the warm front will pose a threat for all severe hazards,
especially across West Tennessee, East Arkansas, and the Missouri
Bootheel. However, there is still uncertainty in the coverage,
longevity, and location of warm sector storms going into this
afternoon and evening.

More severe weather is likely tomorrow as a cold front and
western upper low pass over through the region. A forced line and
the potential for prefrontal cells exist once again. However,
convection today will likely shove instability further south
towards the TN/MS border with 2000+ J/kg MUCAPE to the south. High
ESRH, especially in the lowest 1 km, will be high and streamwise.
Therefore, storms will rotate and organize quickly. Storm mode is
expected to be a line with embedded mesovortices/mesocyclones
that will have the potential to produce tornadoes and damaging
winds. Prefrontal cells are still possible tomorrow but extensive
cloud cover might preclude sufficient surface instability to break
through any capping. Storms are expected to leave the area by
Sunday afternoon with a few showers behind the front that are not
expected to add much rainfall.

Alongside the severe weather, significant and possibly
destructive flash flooding is likely starting today that will last
into Sunday across much of the Midsouth. PWATs currently sit above
the 99th percentile (1.8"-2") here and upstream towards the Gulf.
Strong integrated moisture transport and training convection will
aid in very heavy, long-lasting rain rates starting this
afternoon. Mean storm motion is not expected to change much
between tonight and Saturday evening. Expect north/south bands of
significant rainfall. Furthermore, much of the region has already
experienced 4-7 inches of rain. These saturated soils will fail
to contain new rainfall accumulations which are expected to be as
high as 6-10 inches through Sunday over western Tennessee,
Arkansas, and extreme northern Mississippi. Any areas that have
already experienced this rainfall will flood quickly. So heed
warnings immediately!

The upper pattern will then slow down after the upper trough exits
to our east. Northwest flow is expected to prevail over the region
for several days, with high pressure as the surface. This regime
will keep cooler than average temperatures around through Tuesday
with temperatures expected to warm into Wednesday and Thursday
ahead of a new upper surface low to our northwest. Moisture is
expected to be scoured off the Gulf as far south as the Yucatan
Peninsula. Therefore, significant moisture return is unlikely as
continental air is recycled into the CONUS. Some showers could
occur Thursday afternoon as the upper system responsible for the
surface low passes through, but no significant threat for severe
weather is anticipated at this time.

&&

.AVIATION...
(12Z TAFS)
Issued at 630 AM CDT Fri Apr 4 2025

Periods of IFR CIGs at MEM and JBR should improve shortly as a
stalled boundary wobbles north by midday. MVFR/VFR ceilings will
return in the afternoon. Another round of thunderstorms will kick
off early afternoon and last into the overnight hours, mainly
impacting MEM and JBR. Added LLWS mention in the taf for time
periods not encompassed with TS mention as a LLJ orients across
the airspace after sunset. Otherwise, expect gusty south winds in
excess of 25 kts.

ANS

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Flood Watch through Sunday morning for ARZ009-018-026>028-035-
     036-048-049-058.

MO...Flood Watch through Sunday morning for MOZ113-115.

MS...Flood Watch through Sunday morning for MSZ001>005-007-008-
     010>014-020.

     Flood Watch from midnight CDT tonight through Sunday afternoon
     for MSZ006-009-015>017-021>024.

TN...Flood Watch through Sunday morning for TNZ001>004-019>022-
     048>055-088>092.

&&

$$

PUBLIC FORECAST...JAB
AVIATION...ANS