Flash Flood and Damaging Wind in Mississippi, June 6, 2021

Area Forecast Discussion
National Weather Service Mobile AL
645 AM CDT Sun Jun 6 2021

.AVIATION...
12Z issuance...Showers and thunderstorms will increase in coverage
across the area through the late morning and afternoon hours. MVFR
to IFR conditions are expected through much of the period in
SHRA/TSRA. /13

&&

.PREV DISCUSSION... /issued 354 AM CDT Sun Jun 6 2021/

NEAR TERM UPDATE /Now Through Monday/...We continue to be
sandwiched between an upper low over the southern Plains to the west
and an upper ridge over the southeastern US coast to the east. At
the surface, high pressure continues over the Appalachians. This
pattern has lead to an influx of deep layer moisture, with PWATs
ranging from 1.8-2.2 inches earlier today. Model guidance indicates
even higher PWAT values on Sunday, between 2.0-2.2 inches over much
of the area. Hi-Res guidance as well as synoptic models agree with
an increase in shower/storm chances by early Sunday morning over
southeast Mississippi and southwest Alabama. Numerous to definite
showers, with chances for thunderstorms (~500 J/kg MLCAPE), will
then overspread much of the local area by this afternoon. A slight
decrease in shower/storm activity is then anticipated this evening
and overnight, with another day of numerous showers and chances for
thunderstorms (500-1000 J/kg MLCAPE) on Monday. Model PWATs will
again be elevated on Monday, though not as much as on Sunday, due to
the upper low progressing northward towards the Mississippi Valley
during the day (along with the greater deep layer moisture). Values
range between 1.8-2 inches.

Through Monday, storm total rainfall ranges from around 2-5 inches
generally west of the Alabama River (locally higher amounts
possible) with about 1.5 inches or less east. Thus, with the
additional heavy rainfall, flash flooding will be a concern. This is
especially true for areas already saturated from recent rains. A
Flash Flood Watch remain in effect for all of our southeast
Mississippi counties along with Choctaw, Washington, Clarke, and
Mobile counties in Alabama from 12Z this morning through 6Z Monday
to account for this threat.

High temperatures this afternoon will be cooler in the west (higher
coverage of showers) and warmer in the east (less coverage of
showers). Anticipating upper 70s to lower 80s west of I-65 and lower
to mid 80s east of I-65. Lows Sunday night will again be warm
because of elevated dew points, in the upper 60s to lower 70s north
of I-10 and in the lower to mid 70s south. Highs Monday will then be
in the lower to mid 80s.

Lastly, there is a LOW RISK of rip currents through tonight. This
will then be followed by a MODERATE RISK on Monday due to building
seas and persistent southeasterly flow. 26/13

SHORT TERM /Monday night Through Tuesday night/...Guidance
continues to advertise an upper level closed low that has moved over
the eastern Central Plains meandering north a bit in a building
upper ridge over the central and eastern Conus. An upper trough
remains stretching south west of the Mississippi River from the
weakening upper low. A surface ridge stretching west over the
northern Gulf coast (which is a bit farther south from yesterday's
guidance) becomes better organized, with more organized low level flow.
Deep layer southerly flow Monday night becomes more southwesterly
in the mid and upper levels into mid week, though, with the
building upper ridge. Moisture levels see a decrease into mid
week over the Southeast with the increasing subsidence from the
building upper ridge and the shifting mid and upper level flow the
cause. Precipitation coverage decreases with the decreasing
moisture levels and increasing upper subsidence, but continue to
remain highest over areas west of the Alabama River, closer to the
upper trough. High temperatures will see an uptick Tuesday into
Wednesday, with around normal upper 80s to around 90 expected
Tuesday and around 90 to mid 90s Wednesday. Low temperatures will
see a drop of a degree or two overall with the decreasing
moisture levels, but generally remain in the around 79 to mid 70s
range through mid week.
/16

EXTENDED TERM /Wednesday Through Saturday/...As the upper level low
disappears from existence, we enter a more benign upper level
pattern over the southeastern Conus. Rain chances will be confined
mostly to the typical daytime isolated to scattered showers and
thunderstorms we normally see during the summer months through the
extended term. Our surface pattern remains unchanged with Atlantic
high pressure nosing west into the southeastern U.S. allowing for
continued southerly to southeasterly low level winds helping to keep
low level moisture replenished across the region. High temperatures
each day will be near normal in the mid 80s and lower 90s, with
perhaps even some mid 90's over south central Alabama into the
northern portions of the Florida panhandle by the end of the week,
with heat indices in the upper 90s. /22

MARINE...A light to moderate southerly flow will prevail through
the middle of the week. Seas gradually build to 3 to 4 feet by
Monday. /13

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Flash Flood Watch through late tonight for ALZ051>053-261-263-
     265.

FL...None.
MS...Flash Flood Watch through late tonight for MSZ067-075-076-078-
     079.

GM...None.
&&

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