Hail and Damaging Winds in Texas, April 28, 2021

Area Forecast Discussion
National Weather Service Fort Worth TX
309 AM CDT Wed Apr 28 2021

...New Short Term...

.SHORT TERM... /NEW/
Update:
A cluster of vigorous convection has developed over portions of
the Big Country early this morning. The most intense thunderstorm
is located over Jones and Shackelford Counties where one volume
scan from the KDYX WSR-88D indicated Vrot approaching 50 KT. These
thunderstorms are occurring within a robust warm air advection
regime, with low-level wind shear being enhanced by a potent low-
level jet. The KDYX VWP shows 0-1 km SRH of over 200 m2/s2 and
deep layer shear exceeding 70 KT. This environment will continue
to support rotating updraft during the next few hours as this
convection continues east to northeastward. As this convection
moves east, it will encounter an increasingly strong cap that was
evident on the 00Z FWD RAOB, making the tornado threat east of
U.S. Highway 281 somewhat uncertain. Given the vigor of this
convection and strong low-level wind shear however, a Tornado
Watch has been issued to cover this potential threat over western
portions of North TX through the morning hours.

Godwin

Previous Discussion:
/Through Wednesday Night/

Southwesterly flow aloft continues across the south-central CONUS
this morning ahead of an approaching, but slow-moving upper-level
low. This upper-level low was analyzed at 00Z to be located across
northern Baja California, and is moving much slower than was
forecast by global models this time yesterday. In the lower levels
of the troposphere, 850 mb analysis from 00Z reveals an elongated
trough extending from the western Great Lakes region, through the
Central Plains, then southward across the Southern Plains and into
northern Chihuahua. At the surface, a dryline is present across
West TX. Finally, widespread convection is occurring well east of
this dryline across the Red River Valley, some of which has made
its way into northwestern portions of the FWD CWA.

The convection ongoing this morning continues to wane. A few of
the stronger multi-cellular clusters within this convective shield
may have produced small hail earlier (though no reports have been
received), but these thunderstorms are on the decline. Severe
Thunderstorm Watch #115 continues until 3 a.m. CDT, and while it
is possible this watch could be canceled early, with only a
couple hours left to go, the watch will probably be allowed to
continue until its scheduled expiration time. This convection is
forecast to continue eastward slowly through the rest of the
overnight period, but will wane towards daybreak as it struggles
against a still robust EML evident on the 00Z FWD RAOB.

A respite is convective activity is expected during the morning
and early afternoon hours Wednesday, though some isolated to
widely scattered showers and a few thunderstorms will remain
possible. By 00Z, the upper-level low is forecast to move over
southern NM/northern Chihuahua, with a lead shortwave trough
approaching North TX by this time. This lead shortwave trough can
be noted this morning over eastern NM on GOES moisture channel
imagery. Mid-level ascent associated with the approaching lead
shortwave trough should act to weaken the cap across North TX,
allowing for convective development after 21Z. Convection is
likely to initiate along the leading edge of an approaching cold
front across northwestern portions of the FWD CWA to Wichita
Falls.

Near-storm environment forecast soundings from the HRRR indicate
SBCAPE in excess of 2000 J/kg, mid-level lapse rates approaching 7
C/km, and nearly 70 KT of effective bulk shear. These forecast
soundings, as well as HREF neighborhood probability fields for
updraft helicity suggest that some supercellular thunderstorms
will be possible, with large hail and tornadoes being the primary
threats. The tornado threat will be at its highest 00Z-03Z (7-10
p.m.) across western North TX as the LLJ increases. After 03Z,
convection is likely to grow upscale into backward-propagating MCS
as it moves slowly across North TX. While Corfidi upshear
propagation vectors indicate storm motions of 30-40 KT, the
potential for training convection as well as abnormally high PWAT
values for late April suggest a localized potential for flash
flooding. HREF probability-matched mean QPF shows 2-3 inches of
rainfall possible across western North TX (north of a line from
Breckenridge to Decatur to Sherman/Denison). A mitigating factor
will be the recent dry conditions, but even with a D1-D2 drought
in place across these areas, high rainfall rates could still
result in flash flooding in poor-drainage areas and areas near
creeks and streams. Given the localized nature of the threat
however, a Flash Flood Watch is not needed at this time.
Convection will continue eastward overnight, and while the severe
weather threat should diminish after 06Z (1 a.m.), the threat for
localized heavy rainfall/flash flooding will continue.

Godwin

&&

.LONG TERM... /Issued 257 AM CDT Wed Apr 28 2021/
/Thursday through Tuesday/

Numerous showers and thunderstorms will continue Thursday as lift
and moisture associated with a slow moving low pressure system
remains over the region. The good news is that all this activity
will be elevated over a wedge of cooler, post-frontal air near
the surface. Therefore, the potential for severe weather will be
low Thursday but the potential for heavy rain will continue,
especially east of the I-35 corridor where precipitable water
values will remain above 1.5 inches.

The models are coming into better agreement on the fate of the
upper low with the general consensus that it will remain closed
while rotating across Northern Mexico Friday. This solution will
shift most of the rain chances south of the forecast area but we
will linger some low PoPs across our Central Texas zones.

Unfortunately, it is now looking like the weekend will be a little
more unsettled than previously through with the upper low progged
to lift slowly northeast Saturday and Sunday, keeping at least
some low shower/thunderstorm chances. The good news is that the
weekend should not be a total wash and there will still be plenty
of sun with seasonably warm temperatures.

Brief ridging aloft Sunday night through Monday will result in
warm and rain-free weather with highs Monday afternoon from the
mid 80s to the lower 90s. DFW could actually see its first 90
degree day since mid October 2020. The upper ridge will not linger
long across the region with another trough developing over the
Central Rockies Monday afternoon. This trough will move across the
Central and Southern Plains Tuesday allowing a cold front to move
southward through the region. Thunderstorms will likely accompany
the cold front through Tuesday night with the best rain chances
across the eastern half of the region.

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&&

.AVIATION... /Issued 134 AM CDT Wed Apr 28 2021/
/06Z/

CIGs have fallen to MVFR across virtually all of North/Central TX
this morning. IFR CIGs will be possible for a few hours around
12Z, but with gusty S winds across the region, the duration of any
IFR remains uncertain. By mid-afternoon, CIGs may improve to VFR,
but convection is forecast to begin developing northwest of a
KBKD-KLUD-KGYI line. Scattered to numerous SHRA/TSRA with tops to
FL450 will result in significant impacts to the Bowie arrival
gate, and potentially westbound and northbound departures. Expect
SHRA/TSRA to become more widespread just beyond TAF period with
direct impacts at D10 terminals as well as KACT likely after 06Z.

Godwin

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    85  67  76  60  75 /  60  90  70  40  20
Waco                87  68  76  61  74 /  40  80  70  40  20
Paris               82  66  74  58  73 /  50  90  90  40  20
Denton              81  63  74  56  74 /  70  90  70  40  20
McKinney            82  65  75  58  74 /  50  90  80  40  20
Dallas              86  68  77  61  76 /  50  90  70  40  20
Terrell             85  66  76  59  74 /  40  80  80  50  20
Corsicana           87  68  78  61  74 /  30  70  70  40  20
Temple              87  67  78  60  74 /  30  70  60  30  20
Mineral Wells       82  62  74  56  74 /  80  90  60  50  20

&&

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

Hazardous Weather Outlook
National Weather Service Fort Worth TX
320 AM CDT Wed Apr 28 2021

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-290830-
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-
320 AM CDT Wed Apr 28 2021

This Hazardous Weather Outlook is for North and Central Texas.

.DAY ONE...Today and Tonight.
Thunderstorm are possible today and tonight. Some storms may become
severe. Large hail and damaging downburst winds will be the main
hazards, but a few tornadoes can't be ruled out.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.
Thunderstorm chances will continue Thursday. Although a few strong
storms may linger across East Texas, the primary hazard will be from
heavy rainfall.

Isolated to scattered thunderstorms are possible Friday through
Sunday and again on Tuesday.

.SPOTTER INFORMATION STATEMENT...
Spotter activation is possible this morning along and west of U.S 281
and across much of the region this afternoon and evening.

Special Weather Statement
National Weather Service Fort Worth TX
1047 PM CDT Tue Apr 27 2021

TXZ100-280415-
Young TX-
1047 PM CDT Tue Apr 27 2021

...SIGNIFICANT WEATHER ADVISORY FOR YOUNG COUNTY UNTIL 1115 PM CDT...

At 1047 PM CDT, Doppler radar was tracking a strong thunderstorm 9
miles northeast of Crystal Falls, or 15 miles southwest of Graham,
moving east at 40 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

 Locations impacted include...
Graham and Newcastle.

A Severe Thunderstorm Watch remains in effect until 300 AM CDT for
north central Texas.

LAT...LON 3319 9895 3335 9842 3324 9842 3301 9844
      3301 9843 3295 9843 3296 9895
TIME...MOT...LOC 0347Z 250DEG 34KT 3301 9881

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Special Weather Statement
National Weather Service Fort Worth TX
1114 PM CDT Tue Apr 27 2021

TXZ100-101-280445-
Young TX-Jack TX-
1114 PM CDT Tue Apr 27 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN YOUNG AND JACK
COUNTIES UNTIL 1145 PM CDT...

At 1113 PM CDT, Doppler radar was tracking a strong thunderstorm 9
miles north of Graham, moving east at 35 mph.

Pea size hail and winds in excess of 40 mph will be possible with
this storm.

 Locations impacted include...
Graham, Jacksboro, Bryson and Newport.

A Severe Thunderstorm Watch remains in effect until 300 AM CDT for
north central Texas.

LAT...LON 3340 9860 3340 9842 3347 9842 3347 9798
      3324 9792 3306 9863
TIME...MOT...LOC 0413Z 248DEG 29KT 3323 9856

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Special Weather Statement
National Weather Service Fort Worth TX
1157 PM CDT Tue Apr 27 2021

TXZ091-280530-
Montague TX-
1157 PM CDT Tue Apr 27 2021

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL MONTAGUE COUNTY UNTIL
1230 AM CDT...

At 1157 PM CDT, Doppler radar was tracking a strong thunderstorm over
Bellevue, or 9 miles northwest of Bowie, moving northeast at 45 mph.

Pea size hail and winds in excess of 40 mph will be possible with
this storm.

 Locations impacted include...
Bowie, Nocona and Stoneburg.

A Severe Thunderstorm Watch remains in effect until 300 AM CDT for
north central Texas.

LAT...LON 3398 9763 3395 9759 3392 9760 3390 9758
      3391 9748 3385 9748 3367 9766 3351 9798
      3389 9798 3385 9787 3386 9783 3388 9782
      3388 9780 3390 9780 3390 9778 3392 9778
      3391 9776 3394 9776 3394 9773 3399 9768
TIME...MOT...LOC 0457Z 234DEG 44KT 3366 9797

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