Tornadoes and Flash Flood in Texas, May 18, 2025

Area Forecast Discussion
National Weather Service Fort Worth TX
546 AM CDT Sun May 18 2025

...New Aviation, Short Term...

.KEY MESSAGES...

- Scattered (30-40% coverage) strong to severe thunderstorms are
  expected late this afternoon and evening in North Texas with
  primarily threats for damaging winds and large hail.

- Additional severe thunderstorms will develop Monday afternoon
  and evening near and east of I-35. All modes of severe weather
  are possible.

- A cold front on Tuesday will knock temperatures back down to
  near normal for the middle of next work week, with afternoon
  highs in the low to the mid 80s.

&&

.SHORT TERM... /NEW/
Update:
A couple more rounds of severe thunderstorms are forecast to end
the weekend and begin the workweek. Most of this morning's update
focused on refining PoP trends for this afternoon/evening's
convection, and delaying its arrival by a couple of hours compared
to previous forecasts. While high-based showers and isolated
storms are possible from late this morning into the afternoon, the
main time window of concern remains from about 5 to 11 PM when
severe dryline convection from western North Texas and the Big
Country spreads eastward. It still appears this will consist of a
supercellular storm mode, at least initially, with primarily a
large hail threat. However, as discussed previously, the tornado
threat may be slightly higher than the past couple of days owing
to stronger low-level flow/shear. Monday's thunderstorm activity
is still on track to mainly affect areas near and east of I-35 and
north of I-20 which will contain the greatest risk for discrete
supercells and perhaps a couple of tornadoes. However, this will
be dictated by the location of the dryline and how far east it
advances, and this will be the main factor to monitor over the
next 24 hours.

-Stalley

Previous Discussion:
/Through Monday Evening/

Additional rounds of severe thunderstorms are expected today and
Monday, with all severe hazards possible. The main time window of
concern will be from late afternoon into the evening hours both
days.

An upper trough axis presently situated over the Intermountain
West will continue to dig southeastward during the next 36 hours,
with its influences already beginning locally today. In response
to lee cyclogenesis, low-level wind fields will be on the
increase during the next 12 hours, while surface dewpoints
recover into the mid 70s following yesterday evening's convection.
The otherwise oppressive humidity will be offset to a degree by a
steady southerly breeze of 15-20 mph and some gusts up to 30 mph
during the daytime. By early/mid afternoon, a lead disturbance
rippling through southwesterly flow aloft may attempt to ignite
high-based convection rooted at or above 10 kft as a plume of
Pacific moisture arrives within a belt of strong subtropical
westerlies. However, deeper and more robust convection will become
more likely along the dryline boundary positioned farther west
through the Big Country and western North Texas later in the
afternoon (possibly not until as late as 5-6 pm). This activity
(should it be able to overcome weak capping and dry air
entrainment) would likely consist of discrete supercells
initially given the orthogonality of shear vectors to the dryline,
until perhaps some upscale growth in to a small complex occurs
around or after sunset. Unlike yesterday, the stronger low/mid-
level wind fields and therefore stronger bulk shear should aid
with thunderstorm organization and longevity, and may be able to
sustain supercells or a more organized convective cluster later
into the evening or nighttime period. While large hail and
damaging winds will certainly be the primary hazards amid extreme
instability and moderate shear, a slightly higher tornado threat
may exist today compared to the past couple of days, especially
with any initial supercellular activity. This will be due to
stronger low-level flow and hodographs more favorable for right-
moving supercells and tornadogenesis. While most of this activity
should wind down overnight with the nocturnal increase in MLCIN,
broad synoptic scale ascent could continue to support isolated
showers and probably sub-severe thunderstorms overnight in parts
of North Texas.

As the potent upper trough digs closer on Monday, another round of
severe thunderstorms will develop along or ahead of the dryline
during the afternoon and evening. The dryline is likely to advance
a bit farther eastward into parts of North Texas by Monday
afternoon, perhaps bulging as far east as the I-35 corridor during
the peak heating hours. Initiation of scattered supercells should
be the result, with areas roughly along/east of I-35 and
along/north of I-20 at greatest risk for severe weather. This
would likely be a brief window of severe potential, as storms will
be fast-moving given the stronger wind fields in closer proximity
to the upper trough with mean southwesterly steering flow of 50+
kts. While storms may only be isolated/scattered in terms of
coverage, they would have the potential to pose high-impact severe
hazards, including tornadoes. This would be most likely across
parts of East/Northeast Texas during the late afternoon and early
evening hours when 0-1 km shear will increase to 20+ kts and 0-1
km SRH will climb to near 250 m2/s2. These storms will likely
race off to the northeast and out of the forecast area around
sunset.

-Stalley

&&

.LONG TERM... /Issued 216 AM CDT Sun May 18 2025/
/Tuesday through Saturday/

...Tuesday and Tuesday Night...

By Tuesday morning, a cold front is expected to move through the
region from northwest to southeast. By the time thunderstorms
begin to develop along and ahead of the front, it should have
already pushed south of I-20 and east of I-35/35E. While the risk
for severe weather looks to be further east in the Ark-La-Tex and
southern Mississippi River Valley, a storm or two could be on the
stronger side east of a line from Athens to Cameron during the
early afternoon hours, posing the risk for small hail and gusty
winds.

Behind the front, temperatures will peak in the mid 80s before
cooling into the upper 50s/lower 60s overnight.

...Wednesday through Saturday...

While medium range guidance still shows high pressure building
into the region from the north by mid-week this upcoming week,
trends have been to de-amplify the upper-level pattern, resulting
in a less progressive post-cold front airmass. As such, forecast
temperatures have trended warmer owing to models resolving a
weaker cold front on Tuesday, with highs Wednesday and Thursday
ranging from low and mid 80s in northeast Texas, to upper 80s and
low 90s in central Texas. Nighttime lows should still cool to the
low 60s, with upper 50s possible near the Red River. By the end
of this upcoming week into next weekend, the axis of an upper-
level ridge will approach the region from the west, allowing
higher heights and heat to build back into the southern Great
Plains. This will let temperatures climb slightly above average
(into the upper 80s and low 90s) for the end of the forecast
period.

Lastly, surface moisture return will be quicker by the end of this
week owing to the potentially weaker cold front. This coupled with
week disturbances embedded in northwesterly flow aloft will bring
very low (10 to 20%) rain chances each evening and night beginning
Thursday. No severe weather is expected at this time with any of
this activity.

Darrah

&&

.AVIATION... /NEW/
/12z TAFs/

MVFR stratus is in the process of filling in across most of North
and Central Texas as of 11z, and cigs at 1-2 kft can be expected
at all TAF sites through 15-16z before lifting/scattering to VFR.
Southerly winds will be on the increase during the daytime, with
gusts as high as 25-30 kts at times. By late afternoon, the
dryline should become active well to the west of the TAF sites,
but storms will have the potential to spread into D10 between
00-04z with a couple hours of TSRA impacts possible. Most activity
should remain north of the Waco TAF site, and will only include a
brief VCTS mention there. After any convection vacates the TAF
sites late this evening, a lull in thunderstorm activity is
expected the rest of the night before MVFR cigs return heading
into Monday morning. Additional convective development is possible
towards the very end of the valid period early Monday afternoon,
and this may need to be included in subsequent TAFs.

-Stalley

&&

.SPOTTER INFORMATION STATEMENT...
Spotter activation may be requested across North Texas late this
afternoon and evening. Even if activation is not locally
requested, any reports of hazardous weather to the National
Weather Service are appreciated.

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    87  72  85  70  84 /  50  50  60  30   5
Waco                89  73  89  70  86 /  20  20  30  30   5
Paris               84  68  84  68  82 /  40  40  70  60  10
Denton              87  69  86  64  84 /  50  50  60  30   5
McKinney            86  71  84  68  83 /  40  50  70  40   5
Dallas              88  71  86  70  84 /  50  50  60  40   5
Terrell             87  71  84  71  84 /  40  40  60  40  10
Corsicana           89  74  89  73  87 /  20  20  30  30  10
Temple              91  73  93  71  90 /  20   5  20  20  10
Mineral Wells       89  70  90  62  86 /  40  40  40  20   0

&&

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

Special Weather Statement
National Weather Service Fort Worth TX
126 PM CDT Sun May 18 2025

TXZ103-181900-
Denton TX-
126 PM CDT Sun May 18 2025

...A strong thunderstorm will impact portions of northern Denton
County through 200 PM CDT...

At 126 PM CDT, Doppler radar was tracking a strong thunderstorm near
Denton, moving northeast at 45 mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Ray Roberts Park Isle Du Bois, Pilot Point, Denton, Krugerville,
Ponder, Aubrey, Krum, Cross Roads, Lake Ray Roberts, Ray Roberts Park
Johnson Branch, Providence Village, Argyle, Northlake, Celina, and
Lewisville Lake.

This includes the following highways...
 Interstate 35 between mile markers 468 and 475.
 Interstate 35W between mile markers 79 and 85.
 Interstate 35E between mile markers 463 and 466.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3341 9684 3331 9684 3311 9724 3320 9732
      3342 9708
TIME...MOT...LOC 1826Z 229DEG 40KT 3320 9721

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

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