Severe Thunderstorm Warning 223, NWS Fort Worth, TX

Area Forecast Discussion
National Weather Service Fort Worth TX
301 PM CDT Tue Aug 17 2021

...New Long Term...

.SHORT TERM... /Issued 153 PM CDT Tue Aug 17 2021/
/Through Wednesday/

Widespread convection is ongoing across northern and western
portions of the FWD CWA this afternoon. This convection is
occurring ahead of a mid-level shortwave trough which is moving
across the Southern Plains presently as seen on GOES-E water vapor
channel imagery. An outflow boundary at the surface leftover from
overnight convection is acting as a focus across North TX. The
12Z FWD RAOB indicated PWAT values near 1.80", nearly moist
adiabatic mid-level lapse rates, and a warm cloud depth of more
than 14,000 ft. This profile will support warm rain processes and
therefore make any thunderstorms capable of producing very heavy
rainfall rates. Indeed, some flooding has already been reported
across parts of Wise County with over 3.50" of rain reported in
Bridgeport over the last three hours.

A Flash Flood Watch was considered, but given the expected spotty
nature of the heaviest rains, opted not to issue a watch at this
time. A more widespread threat is typically warranted before
issuing a Flash Flood Watch. As detailed above however, some
isolated instances of flash flooding will be possible,
particularly as the convection moves east into urban areas more
prone to flooding.

The strong synoptic-scale ascent will maintain at least low-end
shower/thunderstorm chances overnight with the greatest chances
expected over Central TX near the nose of a burgeoning low-level
jet. Convection will become more widespread towards daybreak and
into Wednesday morning as another mid-level shortwave trough
overspreads the region. Once again, heavy rainfall and flash
flooding will be the primary hazard.

Godwin

&&

.LONG TERM... /NEW/
/Wednesday night through Tuesday/

Humid and somewhat unsettled weather will remain in place across
North and Central Texas Wednesday night through the end of the
week as an upper trough moves slowly from the Rockies to the
Central Plains. Although the best large scale forcing for ascent
will reside north of the region, there will be enough lift and
moisture to produce scattered showers and thunderstorms, especially
Thursday. Of course, the best chances will come during the heat
of the day when the atmosphere is the most unstable. The primary
threat from any of these storms will continue to be heavy rainfall
due to precipitable water values above 2 inches and relatively
light steering winds. Although temperatures will not be
excessively hot for mid August (Highs in the upper 80s to lower
90s), the humidity will be quite high with dew points remaining
in the 70s. This will keep afternoon heat index values both
Thursday and Friday very near 100.

High pressure will begin to build back over the Lower Mississippi
Valley and the Southern Plains on the weekend, increasing large
scale subsidence across the region. Building heights and more
abundant sunshine will yield warmer temperatures with highs
Saturday through Tuesday generally in the middle 90s. Since low
level moisture will remain quite high (dew points in the 70s),
heat index values will reach or slightly exceed 100 each
afternoon. A few locations may approach Heat Advisory Criteria
early next week.

Looking ahead, it does appear that the ridge axis will shift
westward through next week with some possible rain chances
returning to North and Central Texas for the last weekend of
August.

79

&&

.AVIATION... /Issued 153 PM CDT Tue Aug 17 2021/
/18Z TAFs/

Widespread SHRA/TSRA occurring across much of North TX will
overspread the D10 TRACON during the next couple of hours.
Expecting major impacts at all terminals through at least 00Z. Any
TSRA that move over airfields will be capable of producing wind
gusts to 30 KT, frequent CG, and +RA reducing vsby to AOB 4SM at
times. Convection may diminish somewhat overnight, but expecting
at least isolated to scattered coverage through the night, with
the higher coverage anticipated across Central TX. SHRA/TSRA will
redevelop towards 12Z with CIGs falling to MVFR. Brief IFR CIGs
may be possible as well, though confidence is low in this
scenario. Regardless, TSRA will be the primary concern during the
period 12Z Wed to 00Z Thu.

Godwin

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    75  88  76  92  77 /  70  60  40  50  10
Waco                75  90  77  94  77 /  70  60  30  30   5
Paris               72  84  74  87  75 /  70  70  40  70  10
Denton              73  88  75  92  76 /  70  60  40  60  10
McKinney            73  87  75  90  76 /  70  60  40  60  10
Dallas              75  88  78  91  78 /  70  60  40  50   5
Terrell             73  87  75  89  76 /  70  60  30  50   5
Corsicana           74  89  77  92  77 /  70  60  30  40   5
Temple              74  90  75  93  76 /  60  60  30  20   5
Mineral Wells       70  86  74  90  73 /  60  70  40  50  10

&&

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

Hazardous Weather Outlook
National Weather Service Fort Worth TX
611 PM CDT Tue Aug 17 2021

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-181130-
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-
611 PM CDT Tue Aug 17 2021

This Hazardous Weather Outlook is for North and Central Texas.

.DAY ONE...Tonight.

Scattered showers and thunderstorms will continue into the late
evening hours mainly east of I-35 with additional shower and storm
development expected overnight. Heavy rainfall and lightning will be
the main threats with these storms.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Scattered thunderstorms are expected across the region through
Thursday evening with isolated storms possible Friday. Gusty winds,
frequent lightning, and heavy rain with localized flooding will be
the primary hazards.

Hot, humid, and rain-free weather is expected this weekend through
early next week. Afternoon heat index values will approach 105,
mainly across the eastern portions of North and Central Texas.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Special Weather Statement
National Weather Service Fort Worth TX
514 PM CDT Tue Aug 17 2021

TXZ134-146-172245-
Ellis TX-Navarro TX-
514 PM CDT Tue Aug 17 2021

...A strong thunderstorm will impact portions of Ellis and
northwestern Navarro Counties through 545 PM CDT...

At 512 PM CDT, Doppler radar was tracking a strong thunderstorm near
Italy, or 11 miles south of Waxahachie, moving northeast at 20 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Waxahachie, Ennis, Ferris, Palmer, Italy, Blooming Grove, Bardwell,
Alma, Rice, Garrett, Milford, Frost and Emhouse.

This includes the following highways...
 Interstate 35E between mile markers 380 and 398.
 Interstate 45 between mile markers 237 and 264.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3212 9656 3207 9689 3207 9692 3222 9701
      3247 9678 3255 9659 3255 9653 3253 9651
      3245 9650 3241 9644 3235 9645 3233 9643
      3233 9639 3230 9633 3230 9630 3228 9628
TIME...MOT...LOC 2212Z 221DEG 19KT 3225 9681

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

Stalley

Special Weather Statement
National Weather Service Fort Worth TX
630 PM CDT Tue Aug 17 2021

TXZ122-180015-
Van Zandt TX-
630 PM CDT Tue Aug 17 2021

...A strong thunderstorm will impact portions of southern Van Zandt
County through 715 PM CDT...

At 629 PM CDT, Doppler radar was tracking a strong thunderstorm near
Canton, moving east at 20 mph.

HAZARD...Wind gusts of 50 to 55 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Canton, Grand Saline, Van and Edom.

This includes Interstate 20 between mile markers 521 and 542.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3235 9556 3236 9595 3259 9599 3271 9561
      3268 9559 3248 9560 3242 9552 3242 9551
      3239 9550 3237 9547 3237 9546 3236 9545
TIME...MOT...LOC 2329Z 248DEG 19KT 3247 9580

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

Stalley