Flash Flood Watch 3, NWS Memphis, TN

Clay County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Greene County, AR, Lee County, AR, Mississippi County, AR, Phillips County, AR, Poinsett County, AR, St. Francis County, AR, Alcorn County, MS, Benton County, MS, Calhoun County, MS, Chickasaw County, MS, Coahoma County, MS, DeSoto County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Marshall County, MS, Monroe County, MS, Panola County, MS, Pontotoc County, MS, Prentiss County, MS, Quitman County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tishomingo County, MS, Tunica County, MS, Union County, MS, Yalobusha County, MS, Benton County, TN, Carroll County, TN, Chester County, TN, Crockett County, TN, Decatur County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Henry County, TN, Lake County, TN, Lauderdale County, TN, Madison County, TN, McNairy County, TN, Obion County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN

Area Forecast Discussion
National Weather Service Memphis TN
1138 PM CDT Sat Apr 11 2020

.DISCUSSION...

Updated for aviation discussion

&&

.PREV DISCUSSION... /issued 721 PM CDT Sat Apr 11 2020/

Update...

Showers are beginning to spread into the Mid-South. The showers
are associated with a shortwave that is moving through the area.
Additional shower and thunderstorm development will occur during
the overnight hours as a warm front begins to lift north. Some of
the thunderstorms during the overnight hours could produce hail.
Have updated to adjust POPS accordingly.

KRM

DISCUSSION... /issued 331 PM CDT Sat Apr 11 2020/

.SEVERE WEATHER OUTBREAK IS EXPECTED TOMORROW INTO SUNDAY
EVENING ACROSS THE MID-SOUTH...

Any preparation for strong to severe thunderstorms should be
completed this afternoon as thunderstorms are expected to be
ongoing Sunday morning.

South wind has increased to around 10-15mph today with a few gusts
to 20mph. Dew points currently remain mostly in the 30s but
strengthening Southerly flow is expected to transport deeper
moisture across the Midsouth tonight, resulting in Dew Points
mostly in the 50s by morning. This will be the first ingredient in
what could be a significant severe weather outbreak across a large
portion of the Southeastern US, including all of the Midsouth.
The Eastern edge of this moisture gradient could be the focus for
elevated thunderstorms capable of producing severe hail before
sunrise. The main threat would be along the Mississippi River in
North Mississippi.

Tomorrow, a highly amplified trough over West Texas is expected to
move quickly East, moving across the Mississippi River around
Midnight. Showers and elevated thunderstorms are expected to be
ongoing at sunrise Sunday, becoming surface based as temperatures
warm. Hail will remain the greatest threat from these storms but
the threat for damaging wind and tornadoes will increase as a warm
front lifts into North Mississippi and East Arkansas midday
through the afternoon hours. Dew points will surge into the low
to middle 60s resulting in MLCAPE values between 1500 and 3000
j/kg south of the warm front Sunday afternoon. In addition, a 500
mb jet will increase to 70-80kt with a LLJ around 40-50kt over
North Mississippi during the afternoon hours. Any storms that
develop along the warm front would likely pose the greatest threat
for tornadoes Sunday afternoon...and certainly the biggest threat
from strong, long tracked tornadoes. Additionally, outflow
boundaries from storms earlier in the day could act as a focus for
initiation of severe storms.

Storms will likely evolve into a QLCS around sunset and race East
across West TN and North Mississippi. Individual storms will
likely track to the Northeast at over 70kt with the QLCS moving
East a 40-50kt. The threat for large, long tracked tornadoes
should diminish tomorrow evening, but widespread wind damage and
quick, short-lived tornadoes will remain a threat for portions of
the Midsouth until the cold front moves into Middle Tennessee and
Alabama. We should see improved conditions by Midnight...though
models have trended slightly slower with the system.

Gradient winds tomorrow should be just below Advisory criteria,
around 18-22 mph with gusts to 30. Heavy rain is also expected,
especially during the day tomorrow as deep moisture returns to the
area. The current Forecast has 1.5 to 3.5 inches of rain beginning
tonight, through Sunday night...highest over North Mississippi.
After coordination with surrounding offices, decided on holding
off on a Flash Flood watch for now, but if storms begin to train
over any particular area, a watch may be needed later tonight or
tomorrow.

The remainder of the forecast does not appear to be as active.
Temperatures will turn 10-15 degrees cooler early next week. We
could see some patchy frost in portions of East Arkansas, the
Missouri Bootheel and Northwest TN Tuesday and Wednesday mornings.
We could also see some light showers Tuesday but no organized
storm systems are expected during the upcoming work week.
Temperatures will trend warmer next week, with widespread highs in
the low 60s midweek and upper 60s to low 70s by the end of the
week.

30

&&

.AVIATION...

SHRAs continue to spread into the Mid-South. Expect cigs to
remain VFR through much of the overnight. Additional elevated
convection will spread into the area during the overnight hours as
a warm front surges north. Cigs will lower to IFR shortly after
sunrise before the convection lifts off to the northeast. Expect a
lull in activity during the early afternoon hours before surface
based convection develops. Would not be surprised to see Cigs
scatter out possibly back to VFR for a short time before next
round of convection starts developing over the area as a cold
front approaches. Have added tempo groups for all sites for best
timing of convection. Winds will generally be from the south
around 10-12 KTS with higher gusts occurring during the day on
Sunday and with the line of TSRAs expected to move through during
the early evening. Expect gusty winds in the wake of the cold
front with lingering MVFR cigs.

SJM

&&

.AVIATION...

&&

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

Hazardous Weather Outlook
National Weather Service Memphis TN
335 PM CDT Sat Apr 11 2020

ARZ009-018-026>028-035-036-048-049-058-MOZ113-115-MSZ001>017-
020>024-TNZ001>004-019>022-048>055-088>092-122245-
Alcorn-Benton MS-Benton TN-Calhoun-Carroll-Chester-Chickasaw-Clay-
Coahoma-Craighead-Crittenden-Crockett-Cross-DeSoto-Decatur-
Dunklin-Dyer-Fayette-Gibson-Greene-Hardeman-Hardin-Haywood-
Henderson-Henry-Itawamba-Lafayette-Lake-Lauderdale-Lee AR-Lee MS-
Madison-Marshall-McNairy-Mississippi-Monroe-Obion-Panola-Pemiscot-
Phillips-Poinsett-Pontotoc-Prentiss-Quitman-Shelby-St. Francis-
Tallahatchie-Tate-Tippah-Tipton-Tishomingo-Tunica-Union-Weakley-
Yalobusha-
335 PM CDT Sat Apr 11 2020

This hazardous weather outlook is for portions of East Arkansas...
the Missouri Bootheel...North Mississippi...and West Tennessee.

.DAY ONE...This Afternoon and Tonight

A few strong to possibly severe thunderstorms capable of
producing large hail may move into Northwest MS before sunrise.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

There is a moderate risk for severe thunderstorms over much of
North Mississippi Sunday afternoon and evening. An enhanced risk
for severe thunderstorms exists along the remainder of the Mid-
South. Large hail, damaging winds, and tornadoes are all possible
with a secondary threat of heavy rainfall. A few strong tornadoes,
and perhaps a long track tornado are also possible over North
Mississippi. The time of greatest threat for severe thunderstorms
will be between 2 PM and 11 PM.

Heavy rain may result in the threat for Flooding or flash flooding
Late tomorrow into tomorrow night. A Flood watch may be needed.

Frost and freeze conditions may be possible across portions of the
Mid-South late Tuesday night into early Wednesday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed Sunday afternoon into
evening in support of severe weather operations while following
all local, state, and CDC guidelines.