Severe Thunderstorm Warning 71, NWS Fort Worth, TX

838 
WWUS54 KFWD 132021
SVSFWD

Severe Weather Statement
National Weather Service Fort Worth TX
321 PM CDT FRI APR 13 2018

TXC097-132029-
/O.CAN.KFWD.SV.W.0071.000000T0000Z-180413T2100Z/
Cooke TX-
321 PM CDT FRI APR 13 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN COOKE COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled for 
northeastern Cooke County. A Severe Thunderstorm Warning continues 
for southeastern Cooke County.

A Tornado Watch remains in effect until 1000 PM CDT for north central
Texas.

LAT...LON 3395 9691 3387 9689 3385 9686 3385 9684
      3387 9684 3387 9680 3382 9676 3384 9669
      3392 9667 3389 9663 3389 9658 3385 9663
      3382 9655 3369 9694 3395 9694 3396 9693
TIME...MOT...LOC 2019Z 239DEG 29KT 3384 9686 

$$

TXC181-132100-
/O.CON.KFWD.SV.W.0071.000000T0000Z-180413T2100Z/
Grayson TX-
321 PM CDT FRI APR 13 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM CDT
FOR NORTHWESTERN GRAYSON COUNTY...

At 319 PM CDT, a severe thunderstorm was located near Willis, or 12
miles north of Whitesboro, moving northeast at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Pottsboro, Eisenhower State Park and southern Lake Texoma. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection stay inside a sturdy structure and keep away from
windows.

If on or near Lake Texoma, get off the water and move indoors or 
inside a vehicle. Do not be caught on the water in a thunderstorm.

&&

A Tornado Watch remains in effect until 1000 PM CDT for north central
Texas.

LAT...LON 3395 9691 3387 9689 3385 9686 3385 9684
      3387 9684 3387 9680 3382 9676 3384 9669
      3392 9667 3389 9663 3389 9658 3385 9663
      3382 9655 3369 9694 3395 9694 3396 9693
TIME...MOT...LOC 2019Z 239DEG 29KT 3384 9686 

HAIL...1.00IN
WIND...60MPH
 
$$

Godwin

736 
WWUS54 KFWD 132048
SVSFWD

Severe Weather Statement
National Weather Service Fort Worth TX
348 PM CDT FRI APR 13 2018

TXC181-132058-
/O.CAN.KFWD.SV.W.0071.000000T0000Z-180413T2100Z/
Grayson TX-
348 PM CDT FRI APR 13 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN GRAYSON COUNTY IS
CANCELLED...
        
The storm which prompted the warning has moved out of the area.
Therefore the warning has been cancelled.

A Tornado Watch remains in effect until 1000 PM CDT for north central
Texas.

LAT...LON 3395 9691 3387 9689 3385 9686 3385 9684
      3387 9684 3387 9680 3382 9676 3384 9669
      3392 9667 3389 9663 3389 9658 3385 9663
      3382 9655 3369 9694 3395 9694 3396 9693
TIME...MOT...LOC 2046Z 233DEG 39KT 3403 9656 

$$

Godwin

Area Forecast Discussion
National Weather Service Fort Worth TX
100 PM CDT Fri Apr 13 2018

.AVIATION...
/18Z TAFS/

GOES-R satellite imagery shows the deck of MVFR moving northeast
and, resulting in some passing high clouds. Surface observations
show the dryline along a Jacksboro to Stephenville line.

The main concern for the Metroplex airports during the forecast
period is the development of thunderstorms along a dryline. Based
the current location of the dryline, thunderstorm development
will likely begin west of the Metroplex and impact most, if not
all, TAF sites. High res guidance attempts to initiate
thunderstorms around 19Z for AFW and FTW, with storms exiting the
Metroplex around 0Z or 1Z. I added a TEMPO group for TSRA for at
least 2 hours with VCTS prevailing to include for any timing
discrepancies. Any thunderstorms that do develop will have the
potential to become severe with a hail and wind threat.

The second concern will be the arrival of west winds behind the
dryline, as well as northwest winds behind a cold front that will
move into the region later this evening and overnight. Winds
should decrease to around 15 knots. Otherwise, VFR should prevail
for the remainder of the forecast period.

For Waco, VFR should prevail through the forecast period. The main
concern for this evening will be the shift to westerly winds
associated with the dryline, and then northwesterly winds behind
the cold front overnight.

Villanueva

&&

.MESOSCALE UPDATE... /Issued 1217 PM CDT Fri Apr 13 2018/
The elevated convection that began during the predawn hours will
douse areas east of I-35 early this afternoon hours before pushing
into East Texas. While this may appear to disrupt the potential
for more intense convection later in the day, rest assured that
gusty south winds and the warm/moist advection they will impart
will effectively destabilize the boundary layer this afternoon --
even where rainfall is currently ongoing. In western portions of
North Texas, sunshine has begun to bake the ground ahead of an
advancing dryline, and temperatures have soared into the 80s
before midday. Another slug of mid-level forcing is swinging
through behind the morning activity, resulting in a renewed batch
of elevated showers and storms, but this too should do little to
impede the convective potential later this afternoon. Both of
these areas of convection are rooted above 10,000ft AGL, beneath
which a deep layer of dry air (800-600mb) has so far capped the
surface layer. With steep mid-level lapse rates, some hail cores
will be possible within this activity, but this potential should
move into Oklahoma with the associated forcing for ascent. This
lift will attempt to erode the cap, but with 21C at 5000ft AGL on
the 12Z KFWD RAOB, the morning activity in our western zones is
unlikely to make the transition to surface-based convection this
afternoon.

A strongly amplified upper trough is emerging from the Rockies and
deepening on the High Plains. This has aided in the eastward
propagation of a dryline, which KDYX radar imagery shows is near the
western edge of our CWA at midday. Winds within the critical dryline-
steering levels in the vicinity of the boundary may approach 50kts,
and the ongoing surge should continue the next few hours. But as the
upper trough in the Central Plains slows its eastward progress,
these winds will veer and weaken later this afternoon. KDYX VWP data
show that the post-dryline winds are already exhibiting this
evolution. Although the surface winds are strongly veered in advance
of the boundary, which will impede the mechanical forcing that could
help erode the lingering inversion, MLCAPE values have already
topped 2500J/kg in the unstable air just ahead of the dryline. With
temperatures in the mid 80s from Breckenridge to Graham, surface
heating may be the impetus for the initiation of surface-based
convection this afternoon, and a CU field has already begun to
develop in advance of the dryline. Guidance varies considerably as
to where initiation will occur, but as the dryline slows as it
approaches the I-35 corridor, the potential has increased for
thunderstorms to develop west of the Metroplex.

Initially, these will be discrete cells with rapidly intensifying
updrafts that will quickly support very large hail. Intense precip-
loading aloft and dry air remaining in the mid-levels will enhance
the threat for damaging downburst winds. The strong westerly flow
should guide these storms quickly to the east, and the window for
strong/severe storms will be small at any given location. As the
next impulse arrives late in the day, the ongoing activity will
likely intensify east of the I-35 corridor. These convective
elements will ingest increasingly unstable boundary layer parcels,
and the updrafts will enter a zone of intense lapse rates in
excess of 9C/km. While the activity should orient itself into a
line, cell separation may be maintained, and the rotating updrafts
within these cells will be capable of very large hail. Across
East Texas, the surface winds will be less prone to veering, and
the 0-1km shear beneath these strong, rotating updrafts may allow
for a few tornadic supercells before the activity moves into the
Ark-La-Tex.

With better forcing to the north and lingering capping to the south,
the southern extent of the afternoon convection will likely be
within our CWA. However, east of the I-35 corridor, an
extraordinarily unstable boundary layer may be able to overcome
these limitations, and the line could develop southward between the
I-35 and I-45 corridors late this afternoon and into the evening
hours. Even if the Ark-La-Tex complex has already moved on, renewed
development should occur this evening in our southeast zones as a
cold front overtakes the dryline, lifting the surface layer into a
new line of strong/severe storms. This could maintain a severe
weather threat within our CWA past midnight before the activity
finally exits the region.

25

&&

.SHORT TERM... /Issued 436 AM CDT Fri Apr 13 2018/
/Today and Tonight/

Several various weather elements plague the short term portion of
the forecast including morning rain, windy conditions, a dryline
that brings fire weather concerns and a severe storm threat, very
warm temperatures, and a cold front. For more details on today's
fire weather concerns, please see the added section below.

This morning's surface features that we will be tracking today
include 1) a dryline that currently lies across western Oklahoma
and West Texas, 2) an upper level trough that currently stretches
meridionally just west of the Rockies, with the base of the trough
moving east across New Mexico, and 3) a strong surface low
currently in western Kansas.

The wind is one of the main highlights this morning, and we have
decided to expand the Advisory south to Waco, and extend the time
through 10 am. Regardless if locations are technically in/out or
meeting Wind Advisory criteria this morning, breezy conditions
will persist not only this morning, but into the afternoon hours
ahead of the dryline. Behind the dryline, a new Wind Advisory has
been issued from Noon until 7 pm for west winds of 25-30 mph with
gusts approaching 40-45 mph in some of our far western counties.
The strongest winds this afternoon are expected across nearly the
same area where a Red Flag Warning has been issued.

Also this morning, we expect to see a blossom of scattered to
widespread precipitation on radar as warm air advection increases
above the cap layer. Most of this development will likely be
based above ~650 mb, and the rain will be falling into a pretty
dry layer just below. Initially, very little to no rain may reach
the surface, but with steep lapse rates above the cap, any
thunderstorms this morning should be able to generate better
amounts of precipitation that can reach the ground, and maybe even
some small hail. However, as the rain shifts east with the
shifting low level jet late this morning into the early afternoon
hours, better moistening of the lower levels in our eastern
counties will likely allow for more rain to reach the ground. Thus
have kept higher rain chances east of Interstate 45 and Highway
75. The forecast soundings still indicate this area may recover
for storms later in the day, but it could be a negating factor for
a severe weather threat across the eastern half of the CWA.

With the upper level trough progressing east this morning, and the
surface low also tracking east, the dryline should also steadily
progress east this morning, and will likely be crossing our
western border around 10-11 AM. I expect it will continue to move
east, but slow down or stall in the mid afternoon hours. This is
a slower progression than the previous forecast, and my reasoning
is 1) forecast models stall the surface low over western Kansas in
the afternoon and 2) the speed of the 850-700 mb winds actually
decrease behind the dryline as it moves across our the western
half of the CWA. The HRRR and RAP are both showing this slow down
as the dryline approaches the I-35 corridor, but their locations
vary by 1-2 counties with the HRRR slightly farther east. For
this forecast, have sided with the RAP and slow the front along a
line from Sherman to DFW to Killeen. The location of the dryline
will be critical to where storms may develop this afternoon.

Model guidance tonight has been hesitant to develop too many
storms along the dryline later today, and there are a few factors
that will need to be monitored that may inhibit storm development
and/or severe storm development. Notably, the strongest low level
winds shift east of the region in the mid afternoon hours, before
the best forcing arrives, and surface-925 mb winds ahead of the
dryline are expected to veer more towards a south-southwest
direction that could limit convergence along the dryline. However,
this is a strong trough arriving that may be able to overcome
these limitations, resulting in strong, rapid updrafts.

There does appear to be a similar signal in the model fields that
initiation will be in the 19-21Z time frame along and north of
Interstate 20. Depending on the location of the dryline, this will
likely include at least the eastern portions of the DFW Metroplex.
These initial storms are expected to move northeast. With MUCAPE
values over 2000 J/kg, shear values nearing 50 kts, and decent
lapse rates in the mid levels, these storms could be severe with
a threat for large hail and damaging winds. Although not zero, the
tornado threat appears low due to the veered southwest winds
ahead of the dryline.

None of the models are unzipping storms along the dryline north of
I-20, but 1-2 CAM models that developing isolated storms and then
a line of storms in the late afternoon and/or early evening hours
across parts of Central Texas. This development is a little
quizzical as this area appears to be farther removed from the
better upper level forcing. Still, it's hard to ignore this signal
in the models and have maintained rain chances and a mention of
severe storms along and east of I-35 and south of I-20 through the
evening hours.

The cold front will quickly sweep across the region this evening
and overnight, overtaking the dryline, and pushing any storms
associated with the dryline out of North and Central Texas. Have
maintained some low rain chances across our southeastern counties
overnight as some light rain may develop in this area when the
upper level trough arrives.

JLDunn

&&

.FIRE WEATHER... /Issued 436 AM CDT Fri Apr 13 2018/
/Today/

Critical and elevated fire weather conditions are expected this
afternoon across our western counties behind a dryline. Along
and west of I-35, humidity values will fall into the teens and 20s
with strong west winds of 25-35 mph and gusts between 30-45 mph.
Temperatures will warm into the mid and upper 80s, and ERC values
are only near or slightly above normal. Discussions with our fire
weather partners on Thursday revealed a decent green-up has
occurring across our western counties from earlier rains. This
green-up will likely prevent any fire starts from quickly
spreading, but given the concerning fire weather conditions, we
decided to issue a Red Flag Warning where conditions will be most
critical with the strongest winds and lowest RHs. This is along
and west of a line from Montague to Erath to Mills County where
sustained winds of 25-30 mph and gusts up to 45 mph will combine
with RH values between 10-15 percent. East of this area, to the
I-35 corridor, near-critical fire weather conditions will still
exist but fuel moisture and green-up is better. However, even
though the Red Flag Warning does not extend to I-35, burning is
still not recommended anywhere west of the Interstate.

JLDunn

&&

.LONG TERM... /Issued 436 AM CDT Fri Apr 13 2018/
/Saturday through the end of next week/

A Pacific cold front and associated convection will extend from
the Texas coastal waters northeastward through the Mississippi
Valley early Saturday. Northwest winds will bring a cooler and
drier airmass across North and Central Texas behind the front.
Wind speeds of 20 to 30 MPH will coincide with minimum RH values
in the 20 to 25 percent range to produce elevated to near-critical
fire weather conditions once again across the western-most
counties Saturday afternoon. The mitigating factor will be
temperatures, which should be 10 to 15 degrees below normal for
April, so a Fire Weather watch is not planned at this time.

After a cool weekend, a warm-up will begin on Monday as south
winds return and an upper level ridge develops overhead. The ridge
will weaken late Tuesday and Wednesday as a shortwave trough
moves quickly eastward through the Central Plains. This will send
a weak cold front through North Texas on Wednesday. Little in the
way of a cool-down is expected behind the Wednesday front due to a
re-strengthening of the upper ridge.

Model guidance is consistent in showing a deep upper low
transitioning across the Southern Plains late next week and the
following weekend. Chances for showers and thunderstorms will
return by next Friday and continue into Saturday. Though still a
ways out, the time of year and strength of the upper level system
will likely bring at least a low-end potential of severe weather
to the area around day 8.

30

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    87  49  62  39  64 /  40  20   5   5   5
Waco                86  49  65  38  65 /  40  20  10   5   0
Paris               81  46  57  35  57 /  50  40  10  10   5
Denton              84  46  61  35  63 /  40  10   5   5   5
McKinney            85  46  59  36  61 /  40  20   5  10   5
Dallas              87  50  62  40  64 /  40  20   5   5   5
Terrell             84  48  62  36  62 /  40  30  10  10   5
Corsicana           83  50  61  37  62 /  40  30  10  10   0
Temple              85  52  65  39  67 /  40  20  10   0   0
Mineral Wells       87  44  62  34  65 /  30   5   0   0   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 10 PM CDT this evening for TXZ091-100-101-
115-116-129-130-141-142.

Wind Advisory until 7 PM CDT this evening for TXZ091-100>102-
115>117-129>132-141>143.

&&

22/25

Hazardous Weather Outlook
National Weather Service Fort Worth TX
241 PM CDT Fri Apr 13 2018

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-141200-
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-
241 PM CDT Fri Apr 13 2018

This Hazardous Weather Outlook is for North and Central Texas.

.DAY ONE...This Afternoon and Tonight.

Scattered thunderstorms will continue this afternoon and evening
along and east of a dryline. This feature will be generally around
I-35 and areas east through this evening. Some storms will be severe
with very large hail and damaging winds. There will also be a threat
for a tornado or two through the evening.

Gusty west winds behind the dryline will continue through this
evening. There will be a threat for rapidly spreading grass fires
west of the dryline. A Red Flag Warning is in effect through late
evening.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

There will be an elevated threat of grass fires west of I-35 on
Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed this afternoon and evening.

Dunn

Special Weather Statement
National Weather Service Fort Worth TX
101 PM CDT FRI APR 13 2018

TXZ105>107-123-131830-
Hunt TX-Hopkins TX-Rains TX-Delta TX-
101 PM CDT FRI APR 13 2018

...SIGNIFICANT WEATHER ADVISORY FOR EASTERN HUNT...NORTHWESTERN
HOPKINS...NORTHWESTERN RAINS AND SOUTHWESTERN DELTA COUNTIES UNTIL
130 PM CDT...

At 100 PM CDT, Doppler radar was tracking a strong thunderstorm near
Campbell, or 7 miles southeast of Greenville, moving northeast at 55
mph.

Dime size hail will be possible with this storm.

Locations impacted include...
Greenville, Commerce, Cumby, Campbell, Cooper Lake Park South
Sulphur, Lone Oak, Tira and Neylandville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so closely monitor for additional
information or possible warnings from the National Weather Service.

&&

LAT...LON 3293 9594 3302 9613 3341 9589 3341 9587
      3342 9586 3328 9555
TIME...MOT...LOC 1800Z 212DEG 49KT 3305 9599

Godwin

Special Weather Statement
National Weather Service Fort Worth TX
110 PM CDT FRI APR 13 2018

TXZ091-131845-
Montague TX-
110 PM CDT FRI APR 13 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL MONTAGUE COUNTY
UNTIL 145 PM CDT...

At 110 PM CDT, Doppler radar was tracking a strong thunderstorm near
Oscar, or 13 miles north of Nocona, moving northeast at 45 mph.

Dime size hail will be possible with this storm.

This storm will remain over mainly rural areas of north central
Montague County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so closely monitor for additional
information or possible warnings from the National Weather Service.

&&

LAT...LON 3398 9763 3395 9759 3393 9759 3392 9760
      3391 9759 3385 9768 3391 9776 3393 9776
      3394 9773 3399 9769 3399 9766
TIME...MOT...LOC 1810Z 225DEG 39KT 3397 9769

Godwin