Severe Thunderstorm Warning 134, NWS Fort Worth, TX

Area Forecast Discussion
National Weather Service Fort Worth TX
1118 PM CDT Thu Apr 20 2017

.AVIATION...
Convection has erupted and will continue to erupt across Oklahoma
overnight as a mid level shortwave moves into the Southern Plains.
Storms will be focused mainly in the vicinity of a stationary
front, which should remain draped across northwest Texas and
Oklahoma for the rest of the night. A couple of right-moving
supercells have the potential to cross the Red River in the next
few hours, but these storms should still remain north of TAF
locations during the overnight hours. As the shortwave moves
farther east on Friday, the front will surge south, bringing with
it a round of showers and storms in the DFW area likely in the
02-04 Z time frame Friday evening. Activity will attempt to
backbuild southwest towards the Waco area, which may lead to an
isolated storm or two near KACT after 22/06Z.

Ahead of the system, we should see another round of MVFR stratus
develop and spread quickly north across the area. MVFR conditions
first thing Friday morning will gradually improve throughout the
day, becoming VFR by mid Friday afternoon.

30

&&

.UPDATE...

At 9pm a surface frontal boundary was nearly stationary to the
northwest of Wichita Falls and draped across southern Oklahoma.
There were a few convective attempts to the south of the front
earlier this evening, but capping and insufficient forcing led to
their quick demise. Since then, as stronger forcing for ascent has
spread into the Southern Plains ahead of a shortwave trough, and
strengthening low level warm advection spreads north, there has
been a marked increase in elevated showers and thunderstorms
across Oklahoma, north of the frontal boundary. This activity
should continue for much of the nighttime hours, with most of the
activity remaining north of the Red River through Friday morning.
For the remainder of tonight, we have lowered PoPs across our
northwest counties and confined rain/storm chances to the
immediate Red River area after midnight. Lapse rates will steepen
through the nighttime hours as temperatures cool aloft with the
approaching trough. This will support a severe hail threat with
any storms. Other than some minor changes to PoPs for tonight, no
other changes needed to the current forecast.

Dunn

&&

.PREV DISCUSSION... /ISSUED 345 PM CDT Thu Apr 20 2017/
At mid afternoon, a frontal boundary extended southeast of a line
from Rogers, Arkansas to Muskogee, Oklahoma to Frederick,
Oklahoma to Big Spring, Texas. Scattered showers and thunderstorms
so far today has been across eastern part of this front from
Central Oklahoma northeastward. How far south this boundary moves
is dependent on the convection that develops along the front. For
now, have indicated that this front will become stationary
southeast of a McAlester, Oklahoma to Wichita Falls line late this
evening before it then start to lift back to the north. A few
storms may reach areas north of a Cisco to Denton to Paris line
tonight. If these storms occur, they will have the potential to
become severe producing one inch hail and 60 mph wind gusts.

Low clouds will overspread much of the forecast area again
overnight tonight. Lows will be in the 60s. After morning low
clouds, skies will become partly sunny Friday and highs will once
again be well above normal with 80s expected area wide. There
will be low chances of showers and thunderstorms Friday morning
through mid afternoon mainly near the Red River. As a shortwave
moves out into the Plains Friday afternoon, the cold front move
southeast and thunderstorms chances will increase late Friday
afternoon along and north of the I-20 corridor. Some severe
thunderstorms will be possible with large hail and damaging winds
as well as heavy rain and cloud to ground lightning. The storms
are expected to develop into a squall line Friday night which will
then sweep across much of the forecast area. The threat for
damaging winds, locally heavy rain and cloud to ground lightning
will continue through the night. Thunderstorm chances will linger
southeast of a Killeen to Sulphur Springs line into early Saturday
morning but the severe threat should be ending around daybreak as
the cold front clears the region.

Skies will clear from northwest to southeast during the day
Saturday. It will be breezy and cool Saturday behind the front
with highs in the 60s to lower 70s. Wind speeds will decrease
to 5 to 10 mph toward sunset. With clear skies and these lighter
winds, temperatures will fall into the 40s area wide by daybreak
Sunday.

Upper level ridging will occur Sunday and Monday in the wake of
the departing upper level trough. The upper flow will become more
zonal by Tuesday as shortwaves move across the northern and
central Plains. This will result in dry weather through
this period with warming trend starting during the day Sunday.
Highs will be in the upper 60s to mid 70s Sunday, mid 70s to lower
80s Monday, and 80s to lower 90s Tuesday and Wednesday. Lows will
still be cool Sunday night with lows mostly in the 40s, but will
moderate Monday and Tuesday nights with mid 50s to lower 60s
Monday night and 60s area wide Tuesday night.

An upper level trough is expected to move out into northern and
central Plains on Thursday, this should drive a cold front
southward toward North Texas. Although the GFS, ECMWF and Canadian
differ on their solutions, shower and thunderstorm chances should
return on Thursday.

58

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    69  82  55  67  47 /   5  20  60  10   0
Waco                67  82  56  67  45 /   5   5  40  10   0
Paris               64  80  53  64  44 /  10  20  70  10   0
Denton              66  82  52  67  45 /   5  30  60   5   0
McKinney            67  81  54  65  46 /   5  20  60  10   0
Dallas              69  83  56  68  49 /   5  20  60  10   0
Terrell             66  81  55  67  46 /   5   5  50  10   5
Corsicana           66  82  57  67  46 /   5   5  50  20   5
Temple              66  83  57  68  48 /   5   5  40  10   0
Mineral Wells       64  85  51  67  43 /   5  20  40   5   0

&&

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

30/91

Hazardous Weather Outlook
National Weather Service Fort Worth TX
244 PM CDT Thu Apr 20 2017

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-211200-
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-
244 PM CDT Thu Apr 20 2017

This Hazardous Weather Outlook is for North and Central Texas.

.DAY ONE...Tonight.

A chance of thunderstorms exists mainly north/northwest of a
Breckenridge to Decatur to Sherman line. An isolated storm may
briefly produce hail up to one inch and strong gusty winds

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Storm chances will once again increase late Friday afternoon into
Saturday as a cold front moves south from Oklahoma into North and
Central Texas. As storms initially develop, there will be a chance of
large hail and damaging winds. The storms are expected to grow
upscale and eventually form into a line which will move southeast
into North Texas. Once a line of storms develops, the main threats
will be damaging winds and heavy rain.

As the cold front continues to move southward, severe storms will
continue to be possible early Saturday morning, especially southeast
of a Sulphur Springs to Corsicana to Killeen line.

.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected at this time.