Severe Thunderstorm Warning 313, NWS Memphis, TN

Area Forecast Discussion
National Weather Service Memphis TN
745 PM CDT Wed Aug 9 2023

...New MESOSCALE UPDATE...

.MESOSCALE UPDATE FOR SEVERE WEATHER...
Issued at 745 PM CDT Wed Aug 9 2023

The quasi-stationary front just south of the Memphis area has
shown some indication of lifting north over the past hour in
response to surface pressure falls just to the north of the
boundary. This is occurring downstream of a strong shortwave
trough currently approaching the Ozarks. This wave will traverse
the region tonight, providing strong forcing for ascent across the
Mid-South. This synoptic lift will maintain 700-500 mb lapse
rates near 7 C/km, keeping large hail as a potential hazard
tonight, despite unfavorable anticipated storm modes. MLCAPE will
be greatest along and south of the front 2500-3500 J/kg,
decreasing farther north of the front. Much of the Enhanced Risk
looks to reside in an area of 1500-2500 J/kg MLCAPE, more than
sufficient for severe weather.

Deep-layer shear is enhanced by a band of strong mid-level
westerly winds at the base of the trough. Effective bulk shear of
50-60 kts is anticipated tonight with 0-3 km bulk shear exceeding
40 kts. This shear will support organized convection overnight.
Supercells upstream over southern MO will likely grow upscale into
linear, bowing segments, perhaps maintaining some supercell
characteristics. The 0-3 km shear is important in assessing the
potential for mesovortices and possible spin-up tornadoes based on
the orientation of the shear relative to the line segment.

One important caveat for tonight's storms is the potential for
this convection to be elevated. This can limit the wind/tornado
potential, especially on the cool side of boundaries like we have
tonight. However, there does appear sufficient MLCAPE for the
ongoing storms be surface-based, presenting a strong potential
for damaging winds and perhaps a few tornadoes. The hail threat
will persist, though it will likely decrease with time as storms
grow upscale. The current convection looks to affect the Mid-South
mainly after 10 PM with the leading edge racing to the TN River
by 3 AM. Trailing convection will linger through the night, but it
is not expected to be as intense.

Finally, we're looking at the potential for another 1-2" of rain
tonight, with localized higher amounts. Some areas have already
picked up a couple of inches from today's earlier convection.
We'll be monitoring the potential for training storms that could
lead to urban and/or riverine impacts for those areas with
already saturated conditions.

MJ

&&

.SYNOPSIS...
Issued at 253 PM CDT Wed Aug 9 2023

Additional strong to severe thunderstorms are possible across the
Mid-South tonight as a cold front moves into the Mid-South. Large
hail, damaging winds, a few tornadoes, and some heavy rainfall
are the threats for thunderstorms that become severe. This front
is expected to stall out over north and Central Mississippi
Thursday and Friday bringing continued shower and thunderstorm
chances into the weekend. Another cold front will bring cooler
temperatures and reduced rain chances by early next week.

&&

.DISCUSSION...
(This evening through next Tuesday)
Issued at 253 PM CDT Wed Aug 9 2023

GOES-16 Satellite trends indicate a mature Mesoscale Convective
System present across the Mid-South this afternoon. KNQA WSR-88D
radar trends show numerous to widespread showers and thunderstorms
north of I-40 with a stronger bowing segment across portions of
extreme northeast Mississippi and west Tennessee near the
Tennessee River. Latest surface analysis places a warm front
starting to push northeast into North Mississippi. As of 2 PM CDT,
temperatures range from the 70s along and north of the TN/MS
border and 80s to lower 90s south into East Arkansas and North
Mississippi where precipitation has been mostly absent thus far.
Severe thunderstorm potential tonight is the predominant concern
in this afternoon's forecast issuance.

Short term models including Convective Allowing Model solutions
indicate a small window of opportunity for additional convection
to develop just ahead of a warm front late this afternoon.
Otherwise, it appears there may be a break in the convection
before another round of showers and thunderstorms arrives along
and ahead of a cold front late this evening into early Thursday
morning. Steep 700-500 mb layer mid-level lapse rates around 7
C/km combined with surface-based CAPE values around 2000 J/kg, 0-6
km Bulk Shear values in excess of 50 kts, and 0-1 km storm
relative helicity values in excess of 300 m2/s2 support the
potential for organized severe convection with this next round
later this evening. Some uncertainty exists with the quality of
instability especially towards the MO/KY border due to morning
activity. However, it appears there may be enough time for some
recovery to occur across the area.

A Flash Flood Watch remains in effect for portions of Northeast
Arkansas, the Missouri Bootheel, and Northwest Tennessee until
midnight tonight as flash flood guidance remains low with the
potential for additional rainfall between 2-4 inches tonight.

This front is expected to gradually move into Mississippi and
become quasi-stationary towards central Mississippi for Thursday
into Friday, then retreat back north as a warm front on Saturday.
This will bring continued chances for isolated/scattered showers
and thunderstorms to the Mid-South into the weekend. There is a
potential for heat index values to approach 105 degrees Thursday
afternoon across northwest Mississippi but have held off on any
potential heat advisories due to the potential for convection
tonight and into Thursday.

Long-term models suggest another cold front will move through the
Lower Mississippi Valley by early next week bringing cooler
temperatures and reduced rain chances.

CJC

&&

.AVIATION...
(00Z TAFS)
Issued at 710 PM CDT Wed Aug 9 2023

The first round of convection is coming to a close this evening,
but lingering and/or backbuilding showers and thunderstorms may
intermittently impact all sites for the next few hours. The next,
more robust round is expected to start back up around 03Z tonight
for JBR, closer to 04-05Z elsewhere. Hi-res forecast reflectivity
shows very potent looking bowing signatures for the initial push
overnight. Included TEMPOs at all sites overnight for strong gusty
westerly winds, reduced visibilities, and possible MVFR ceilings.

After the strongest clusters have moved through, the northern
extent of the lingering convection becomes a bit of a question
mark tomorrow as the warm front looks to stall just south of
the TN-MS state line by 12Z. Prevailing -SHRA with VCTS in the
TAF ends around 12Z tomorrow morning for MEM, but it may go on
for quite a bit longer than that if the boundary meanders any
farther north. Confidence was high enough to keep this going
essentially through the period tomorrow evening at TUP. Mostly VFR
conditions should return after the brunt of the convection clears
out tomorrow, but ceilings look to hover around 3 kft AGL and may
temporarily drop to MVFR. Expect mostly south/southwesterly winds
8-10 kts through tomorrow evening.

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Flood Watch until midnight CDT tonight for ARZ009-018.

MO...Flood Watch until midnight CDT tonight for MOZ113-115.

MS...None.
TN...Flood Watch until midnight CDT tonight for TNZ001>004-019>022.

&&

MESOSCALE UPDATE...MJ
PUBLIC FORECAST...CJC
AVIATION...CAD

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Preliminary Local Storm Report
National Weather Service Memphis TN
446 PM CDT Wed Aug 9 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1125 AM     Tstm Wnd Dmg     3 SE Midtown Memphis    35.10N 89.94W
08/09/2023                   Shelby             TN   Public

            Corrects previous tstm wnd dmg report from 3
            SE Midtown Memphis. Major tree damage in
            Sherwood Forest area of east Memphis.
            Microburst detected via radar.

&&

MJ

Preliminary Local Storm Report
National Weather Service Memphis TN
450 PM CDT Wed Aug 9 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1140 AM     Hail             4 N Southeast Memphis   35.13N 89.89W
08/09/2023  E1.50 inch       Shelby             TN   Broadcast Media

            Corrects previous hail report from 3 NNE
            Southeast Memphis. Reported hail near Walnut
            Grove and White Station.

&&

MJ

Preliminary Local Storm Report
National Weather Service Memphis TN
526 PM CDT Wed Aug 9 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0115 PM     Tstm Wnd Dmg     2 WSW Bartlett          35.21N 89.87W
08/09/2023                   Shelby             TN   Public

            Herrington Creek was out of its banks and
            flooding nearby parking lot near Stage Rd.

&&

MJ

Preliminary Local Storm Report
National Weather Service Memphis TN
528 PM CDT Wed Aug 9 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0120 PM     Flash Flood      2 SW Lakeland           35.22N 89.76W
08/09/2023                   Shelby             TN   Broadcast Media

            Several inches of fast flowing water over
            the road in the Davis Plantation area.

&&

MJ

Preliminary Local Storm Report
National Weather Service Memphis TN
529 PM CDT Wed Aug 9 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0115 PM     Flash Flood      2 WSW Bartlett          35.21N 89.87W
08/09/2023                   Shelby             TN   Public

            Corrects previous tstm wnd dmg report from 2
            WSW Bartlett. Herrington Creek was out of
            its banks and flooding nearby parking lot
            near Stage Rd.

&&

MJ