Flash Flood Warning 54, NWS Jackson, MS

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1244 PM CDT Sun Jul 21 2024

...New AVIATION...

.MESOSCALE UPDATE...
Issued at 1010 AM CDT Sun Jul 21 2024

Convection have moved out or dissipated within the last hour or
so. Dewpoints across the east/southeast were in the mid to upper
70s, which is still brutal for temps in the mid 80s. There were a
few breaks in the clouds, so looking for some brief warming.
Otherwise, models show convection returning by early afternoon.
Made some small adjustments to pops to account for the break. No
other real changes to the short term forecast.

&&

.DISCUSSION...
Issued at 426 AM CDT Sun Jul 21 2024

Today through Tonight...

Early morning water vapor/RAP analysis indicate stagnant trough
axis centered over the MS Valley to Gulf Coast, driven by Rex
Block synoptic pattern locked in. The main corridor of the
vertically stacked low is analyzed over the Hudson Bay but is
progged to swing to the east today. Deep ridging persists in the
Desert Southwest to SoCal, Rockies to the Interior Plains/Prairie
Provinces of Canada. Subtropical ridge remains in the southwestern
Atlantic, Bahamas into the eastern Gulf of Mexico. Shortwave
trough is analyzed in water vapor imagery & evening synoptic
analysis in the Mid-West. This wave will slowly sink southward
through the aftn to evening & slightly close off before enough
positive vorticity advection (PVA) lifts it back northeast into the
morning hours. Heavy rain potential persists today, especially with
precipitation developing early, but HREF probs > 3 inches
have shifted slightly to the south of the I-20 corridor today, so
trimmed the "Limited" flood graphic for today to focus along & south
of a line from Franklin-Tensas parishes in LA to Warren-Rankin-Leake-
Neshoba-Noxubee & into Hwy 82 but east of I-55 into early next week.
The mesoscale features remain the same: light to chaotic propagation
vectors, >90th percentile precipitable water (PWs) southeast of the
Natchez Trace/tropical airmass & deep warm cloud depth >14.5-15kft.
This is progged to persist into the aftn to evening hours. Any areas
that have seen recent rain may have more responsive soils & lower
flash flood guidance (FFGs) for faster, sufficient runoff,
especially in low-lying & urban areas, so localized flash flooding
remains possible.

Drier air is analyzed in GOES East total PWs <1.5 inches northwest
of the Natchez Trace, so rain & any storm chances will be at a
minimum in the Delta. Highs will be near to seasonably cool in the
upper 80s to low 90s northwest of the Natchez Trace, where rain
chances will be more limited. Lows will be seasonable in the upper
60s to low 70s. Some patchy fog is possible in areas this morning &
again into tonight, especially in areas that receive sufficient
rainfall. Dense fog chances have been mostly at a minimum. Light
flow should preclude severe chances but a stronger storm or two
can't be ruled out. /DC/

Monday through Sunday...

Not to sound like a broken record but...not much has changed
throughout the longterm period. We will remain in this stagnant
pattern full of rain chances everyday, with variable intensity
and coverage, as tropical moisture and multiple rounds of
shortwave energy continues to flow into the southeastern states.

Through the longterm our area will be situated in between an upper
level trough across the central states with an associated stalled
front and ridging over the southeastern states resulting in a
southwesterly flow with a steady stream of tropical moisture
across the region. While most rain chances will be diurnally
driven, this frontal boundary will often be influenced by rounds
shortwave energy of a low pressure system as it makes its way
through the Mid-West, which will provide shortwave energy and
forcing to help keep rain chances constant. With ample amounts of
deep moisture in the atmosphere, rainfall will be efficient with
areas of heavy downpours at times with several inches possible
over a short amount of time. Thus, a "Limited" flash flooding
threat will continue into mid-week for areas south of I-20 and
portions of the northeast. The coverage of the "Limited" graphic
will be reevaluated day-to-day to include or exclude areas as
needed. As for heat, consistent cloud cover and rain chances will
keep the heat in check keeping max temps well below climo for this
time of the year.

By late week, the pattern does begin to change with high pressure
expanding into the Gulf, possibly signaling a change in the rainy
pattern the Gulf Coast region has been stuck in. /KVP/

&&

.AVIATION...
(18Z TAFS)
Issued at 1244 PM CDT Sun Jul 21 2024

Patchy MVFR ceilings remain across parts of south MS and central
LA with VFR conditions elsewhere. SHRA and TS are currently
developing across central and south MS and will becoming more
numerous through the afternoon, bringing brief ceiling and
visibility reductions at times in heavier rain...mainly southeast
of GLH and GWO. Coverage of rain will diminish this evening with
another round of low stratus and/or fog possible overnight into
Sunday morning, especially across south MS and central LA. /DL/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       72  88  72  86 /  30  80  60  70
Meridian      71  89  70  88 /  40  90  60  70
Vicksburg     72  88  72  86 /  20  70  70  70
Hattiesburg   73  88  73  90 /  50  90  40  70
Natchez       72  87  71  85 /  40  80  60  70
Greenville    71  88  71  83 /  10  50  60  70
Greenwood     71  88  71  84 /  10  60  60  70

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&

07/DC/KVP/DL

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Special Weather Statement
National Weather Service Jackson MS
117 PM CDT Sun Jul 21 2024

MSZ073-211900-
Lamar MS-
117 PM CDT Sun Jul 21 2024

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL LAMAR COUNTY THROUGH 200
PM CDT...

At 117 PM CDT, Doppler radar was tracking a strong thunderstorm 7
miles northeast of Pine Burr, or 12 miles west of Purvis, moving east
at 10 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Hattiesburg, Purvis, Oak Grove, and Pine Ridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3111 8966 3126 8965 3132 8935 3110 8935
TIME...MOT...LOC 1817Z 270DEG 10KT 3120 8960

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

DL