266
FXUS64 KSHV 121728
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
1228 PM CDT Sun May 12 2024

...New AVIATION...

.UPDATE...
Issued at 1021 AM CDT Sun May 12 2024

Quick zone update issued to account for the issuance of SVR Watch
#232 for Cherokee, Angelina, and Nacogdoches Counties until 20Z.
Watching clusters of elevated convection ongoing across portions
of Cntrl/ECntrl TX in advance of a shortwave perturbation over
Cntrl TX. The steepest mid level lapse rates remain over Cntrl TX
into the Hill Country, although the latest mesoanalysis depicts a
plume of steep 2-6km lapse rates that do extend E into the Sam
Rayburn and Toledo Bend Country of Deep E TX/WCntrl LA, with
effective bulk shear of 55-60 kts maintaining this convection as
it shifts east atop the stable sfc hail. Thus, large hail will
remain the greatest threat in the more organized convection,
although this threat may become more marginal especially as areas
of convection development continues to expand E across the region
through the afternoon.

Did not adjust temps at all in the update, but did tweak pops late
this morning based on the latest radar trends, while also adding
svr wording to the Svr Watch area. Also delayed mention of heavy
rain for much of the Flood Watch area until this afternoon with
the progged increase in H850 convergence along an inverted trough
that is expected to develop from N TX SE into Deep E TX to the
Lower Sabine Valley.

15

&&

.SHORT TERM...
(Sunday through Monday)
Issued at 156 AM CDT Sun May 12 2024

The active pattern will finally get underway today, as heavy rain
chances begin to increase by this morning, and the severe weather
threat increases into the afternoon. All of this weather is
associated with a rather potent shortwave trough moving through
the Plains, with a weak low pressure and surface boundary
extending across the Slight risk area. This boundary will move
north today as a warm front, which will help set the stage for
more widespread severe weather tomorrow, when the boundary
reverses course as a cold front.

The main weather story in all of this today into tonight will be
the heavy rain, as the Moderate ERO has been expanded into NW LA
to account for this heaviest activity. Widespread 2-4 inches of
rainfall are possible through Monday night, with pockets of 6+
inches certainly not out of the question. In turn, the day shift
flood watch has been expanded in size, and extended in time as
well to account for additional rainfall through Tuesday morning.

The first round of rainfall will exit the region by tonight,
before PoP coverage increases again by Monday afternoon. This
round of heavy rain will be associated with the cold front moving
SE, which will also coincide with the severe weather chances on
Monday. Very little has changed in the thinking with this severe
weather, as large hail and damaging winds remain the main threats.
A very narrow window exists during first initiation in which an
isolated tornado will be possible as well. However, that threat is
almost tertiary in nature given the heavy rainfall.

/44/

&&

.LONG TERM...
(Monday Night through Sunday)
Issued at 156 AM CDT Sun May 12 2024

Rain chances will begin to fade by Tuesday morning, with a very
short "dry period" anticipated through Wednesday night. However,
the next trough will begin moving into the Midwest by Thursday
morning. This will be our next round of heavy rain and potential
severe weather, with another 2-4 inches of rainfall possible in
our southern zones. With that being said, this heavy rainfall
axis may shift south (or north) over the next few days, which
would greatly change the need for another flood watch based on
rainfall here in the short-term. The severe weather threat
continues to look uncertain based on airmass recovery between
heavy rainfall, but there is still plenty of time for that to
change into the weekend as well.

/44/

&&

.AVIATION...
(18Z TAFS)
Issued at 1216 PM CDT Sun May 12 2024

For the 12/18Z TAF update, active weather will continue through
most of the period with VCTS/-TSRA likely to keep MVFR/IFR
vis/cigs through 13/06Z. A lull from precipitation at 13/06Z-14Z
will allow cigs to build in at IFR airspace-wide before the next
batch of VCTS/-TSRA arrives right before the end of the period.
/16/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  67  84  66  84 /  80  40  20  10
MLU  65  85  66  84 /  90  60  40  10
DEQ  62  80  60  80 /  60  50  10  10
TXK  65  82  64  82 /  80  50  10  10
ELD  62  79  63  82 /  90  50  20  10
TYR  67  85  64  84 /  70  20  10   0
GGG  66  85  64  84 /  80  30  10   0
LFK  68  86  64  87 /  70  40  20   0

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...Flood Watch through Tuesday morning for LAZ001-002-010-011-017-
     018.

OK...None.
TX...Flood Watch through Tuesday morning for TXZ124>126-136>138-
     149>153-165>167.

&&

$$

SHORT TERM...15
LONG TERM....15
AVIATION...16