Tornadoes and Flash Flooding in Texas, May 21 to 22, 2024

Area Forecast Discussion
National Weather Service Fort Worth TX
558 AM CDT Tue May 21 2024

...New Aviation, Short Term...

.SHORT TERM... /NEW/
Update:
Only minor edits were made to the morning forecast package.
Isolated thunderstorms may develop (~20% chance) late this
afternoon along a dryline across western North Texas and shift
east toward the I-35 corridor this evening. If storms do develop,
they would offer a large hail and damaging wind threat. MOST
locations will remain dry! The time to watch for storms will be
roughly 4pm-9pm this evening. Again, if storms do develop, they
should start to take on a weakening trend as they push toward and
past the I-35 corridor late this evening into the early overnight.

Langfeld

Previous Discussion:
/Through Tuesday Night/

The remainder of the night will feature dry and quiet conditions
as the overhead mid-level ridge exits to the east. Broad troughing
will dig over the western CONUS setting the stage for a few active
weather days during the midweek period. Increasing moisture along
southerly low-level flow will draw stratus northward over North
and Central Texas before sunrise Tuesday morning, lifting and
scattering by midday Tuesday. Expect warm and humid conditions
with temperatures starting in the mid-70s for the Tuesday morning
commute. By Tuesday afternoon, temperatures will rise into the
upper 80s to low 90s across much of the region (potentially
mid-90s across the Big Country). Abundant moisture marked by
surface dewpoints in the low to mid-70s will produce heat index
values in the 95-100 degree range.

A conditional setup for isolated severe thunderstorms will exist
across our western zones late Tuesday afternoon into Tuesday
evening. The greater synoptic-scale ascent will remain far
displaced to the north ahead of a mid-level shortwave passing over
northern Oklahoma/Kansas. However, daytime heating and surface
convergence along a dryline may offer enough support to get a few
isolated thunderstorms going along the dryline as the cap weakens
by 4-5pm Tuesday evening (~20% chance of this occurring). This
dryline will likely be positioned from Bowie-Jacksboro-Cisco
during the time of potential convective initiation. The
environment will support severe weather if thunderstorms do
develop with primarily a large hail and damaging wind threat. The
loss of daytime heating and increasing SBCIN will allow storms to
weaken as they shift east through the evening and early overnight,
likely dissipating as they approach the I-35/35W corridor.

The remainder of Tuesday night will feature warm, humid
conditions with another surge of low-level stratus ahead of a cold
front that will bring the potential for more widespread severe
weather Wednesday.

Langfeld

&&

.LONG TERM... /Issued 240 AM CDT Tue May 21 2024/
/Wednesday Onward/

A cold front will sag south into North Texas on Wednesday as a
shortwave sweeps across the Plains. A few storm clusters may be
ongoing around daybreak Wednesday as the front crosses the Red
River, with activity dissipating mid to late morning as the low
level jet mixes out. The front will likely stall somewhere between
I-20 and the Red River, providing focus for thunderstorm
development Wednesday afternoon as the right entrance region of a
90kt jet approaches from the west. Strong flow aloft (and the
resulting deep layer shear) combined with good instability will
lead to some of these storm becoming severe with large hail and
damaging winds both possible. The presence of the surface front
may also enhance the tornado threat at times, though a persistent
warm layer at 850 to 700mb will hopefully mitigate tornado
development.

Thunderstorms (some severe) will continue into Wednesday evening,
with the best storm chances being along and north of I-20 near
the surface front. PWats near 2 inches will also allow for locally
heavy rain in thunderstorms, and flooding may become an issue
where any training convection may occur. Storms will begin to wind
down around midnight Wednesday night, with activity eventually
dissipating during the overnight hours.

Thunderstorms will redevelop on Thursday as a shortwave trough
passes overhead, with the surface boundary (along with other
possible mesoscale boundaries from Wednesday convection) providing
a focus for development. Shear and instability will be more than
sufficient for severe thunderstorms, with large hail, damaging
winds, and perhaps a few tornadoes possible. Some deterministic
guidance in fact indicates a higher tornado threat for Thursday,
but I would like to see better resolution guidance in the form of
convection allowing models (which will arrive later today through
Wednesday) before ramping up the tornado messaging. The
persistent warm layer could also work against tornado development.
In any case storms will continue into Thursday evening, with the
best rain chances again being along and north of I-20 near the
surface boundary. That being said, any southward shift in the
front itself or in any mesoscale boundary could shift the better
storm chances southward into Central Texas.

Activity will dissipate overnight Thursday night, giving way to a
hot and humid Friday. Dewpoints in the lower 70s and highs in the
lower to middle 90s will yield 100+ degree heat indices Friday
afternoon, with the front having lifted well north of the Red
River by then. The heat will continue through the weekend, with
parts of Central Texas possibly reaching Heat Advisory criteria on
Saturday.

There will be a slight chance of thunderstorms Friday and
Saturday afternoons associated with the dryline. Though storm
coverage may remain isolated, each storm which manages to develop
would likely become severe. A deepening low over the Great Lakes
will send a cold front southward into the region once again on
Monday, providing some relief from the heat along with a slight
chance of storms for Memorial Day. At this time, it looks like the
front will push through the entire region, leading to warm but
drier weather next Tuesday through the midweek period of next
week.

30

&&

.AVIATION... /NEW/
/12Z TAFs/

Widespread MVFR stratus currently overspreads much of North and
Central Texas. We should start to see cig improvements later this
morning, transitioning to VFR status by 16Z-17Z. South flow at
12-16 kts with occasional gusts to 20-25 kts is expected through
much of today.

There is potential for isolated thunderstorms to develop along a
dryline across western North Texas later this afternoon and
evening. If storms do develop, they will likely become severe and would
push toward the I-35 corridor in the 00Z-03Z timeframe. The
latest runs of some high-resolution guidance have been hinting at
thunderstorm activity in the vicinity of the D10 terminals later
this evening. However, with a conditional setup for storms to even
develop, coverage expected to remain quite limited if storms do
develop, and uncertainty in how far east storms maintain, we will
hold off on a VCTS addition in the TAFs for now. We will continue
to monitor this potential through the day, and a VCTS addition may
be needed if high-resolution guidance and trends increase
confidence in impacts to terminals later this evening.

Langfeld

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    90  76  89  74  86 /  10  20  60  40  50
Waco                89  76  89  74  88 /  10  10  20  20  40
Paris               88  73  87  70  84 /  20  20  60  60  50
Denton              90  74  88  72  85 /  20  20  60  50  60
McKinney            89  75  88  72  84 /  10  20  60  50  50
Dallas              91  76  90  74  87 /  10  20  60  40  50
Terrell             89  75  88  72  86 /  10  10  50  40  50
Corsicana           91  76  90  75  89 /  10  10  20  20  40
Temple              90  75  89  74  89 /   5  10  10  10  30
Mineral Wells       92  74  88  71  86 /  20  20  50  40  50

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&

Hazardous Weather Outlook
National Weather Service Fort Worth TX
1112 AM CDT Tue May 21 2024

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-221130-
Montague-Cooke-Grayson-Fannin-Lamar-Young-Jack-Wise-Denton-Collin-
Hunt-Delta-Hopkins-Stephens-Palo Pinto-Parker-Tarrant-Dallas-
Rockwall-Kaufman-Van Zandt-Rains-Eastland-Erath-Hood-Somervell-
Johnson-Ellis-Henderson-Comanche-Mills-Hamilton-Bosque-Hill-Navarro-
Freestone-Anderson-Lampasas-Coryell-Bell-McLennan-Falls-Limestone-
Leon-Milam-Robertson-
1112 AM CDT Tue May 21 2024

This Hazardous Weather Outlook is for North and Central Texas.

.DAY ONE...This Afternoon and Tonight.
A couple of isolated thunderstorms may develop today, primarily along
and west of the I-35 corridor this afternoon and evening. If storms
manage to develop, large hail will be the main threat, with a lower
threat for damaging winds.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.
Thunderstorm chances return Wednesday and continue through Thursday
night. Severe storms will be possible, along with locally heavy
rainfall, which may lead to renewed flooding issues.

There is a low chance for thunderstorms Friday through Sunday,
mainly during the afternoon and evening hours.

.SPOTTER INFORMATION STATEMENT...
Limited spotter activation may be requested this afternoon and
evening for areas generally along and west of I-35/35E.