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000
FXUS64 KMEG 060919
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
419 AM CDT Thu May 6 2021

.DISCUSSION...

Another peaceful night across the Mid-South. Temperatures are
quite cool with readings in the mid 40s to lower 50s at this hour.
The latest surface analysis places a 1018mb low over southeast
Iowa with a cold front extending southwest into Kansas. The upper
level pattern is dominated by a large trough over the eastern two
thirds of the country, with a high amplitude ridge over the west.

A shortwave, currently over eastern Nebraska, will translate
southeast into the Mid-South this afternoon. This will enhance
lift over the region as a 80 knot mid-level jet moves overhead.
CAMs are consistent with a line of showers and thunderstorms
developing along an associated cold front. Limited moisture will
pool ahead of the front and produce up to 1000 J/kg of CAPE this
afternoon. The combination of shear and modest instability will
support scattered showers and thunderstorms. Some of these storms
could produce marginally severe hail and gusty winds, as mid level
lapse rates approach 8 C/km. The marginal threat will be short-
lived as the wave quickly ejects eastward by sundown.

Surface high pressure will build into the region on Friday.
Expect another stellar Spring day with plentiful sunshine, low
humidity, and temperatures near 70F areawide. A trough will begin
to dig across the Cascades late Friday night. This trough will
produce a surface low to the lee side of the Rockies by Saturday
morning.

A large 998mb low will begin to eject across the Southern Plains
during the day on Saturday. This will increase return flow across
the Lower Mississippi Valley and help lift a warm front through
Saturday afternoon. A few showers and thunderstorms will
accompany this frontal boundary, mainly along and north of I-40
during this timeframe. Thereafter, the Mid-South will become
entrenched in the warm sector of the cyclone through Sunday
afternoon. Expect dry conditions and mild temperatures overnight.

Several shortwaves will eject across the Southern Plains Sunday
afternoon and help push the aforementioned surface low in close
proximity to the forecast area. Widespread showers and
thunderstorms are expected to develop by the afternoon hours and
continue through the evening hours as a cold front pushes across
the area. Instability looks modest with 500 to 1000 J/kg of
MLCAPE, however, low level shear will be on the order of 250 to
350 m2/s2 of storm relative helicity. This environment will
be capable of supporting all modes of severe weather including:
damaging winds, large hail, and a few tornadoes. The question will
be how far east into the Mid-South this threat will extend and if
morning convection ahead of the front stabilizes the atmosphere.
Currently, the best overlap of all severe weather parameters
appears to be along and west of the Mississippi River. Will add
wording for strong storms to the HWO to account for the threat
along and west of the Mississippi River on Sunday.

Upper level flow will be nearly zonal across the Mid-South to
begin next week, as a split flow regime sets up out west. Several
perturbations will translate through the region through midweek,
mainly along the southern stream jet out of Mexico. Neither
synoptic model resolves these waves very well attm, but they do
advertise decent rain chances for Tuesday and Wednesday as a
surface low moves across the Gulf Coast. A more substantial trough
looks to dig into the Central U.S. near the end of next week.

AC3

&&

.AVIATION...
/06z TAFs/

VFR conditions will continue through the TAF period. An upper
level disturbance will clip the northern portion of the Mid-South
on Thursday. VCTS will be possible at JBR and MKL roughly between
18z-00z on Thursday. Went with VCSH at MEM given the uncertainty
of how far south the convection will travel. Otherwise, W/NW winds
will be 8-12kts with some gusts nearing 20kts Thursday afternoon.

17

&&

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

$$