River Flood Warning 5, NWS Fort Worth, TX

Area Forecast Discussion
National Weather Service Fort Worth TX
634 PM CST Tue Feb 20 2018

.MESOSCALE UPDATE...

A strong cold front continues to make southward progress and is
located roughly from Comanche to Paris as of 6pm. Initially, some
drying should occur farther behind the front while showers and
thunderstorms continue immediately along and behind it. Areas
from Graham to Bowie have seen a marked decrease in rain coverage
in the last hour and this should generally be the trend for
locations more than ~50 miles behind the front. Temperatures in
these locations, however, have fallen to near freezing as shallow
arctic air continues to funnel down the southern Plains. At this
point, the current forecast temperatures and Advisory
configuration for potential freeing rain overnight still are on
track. We'll continue to assess temperature trends in guidance
through the next several hours, but at this time, there is no
indication the Advisory needs to be expanded southeastward. After
about midnight, a stronger wave of ascent should pivot through
the upper trough to our west. Isentropic lift within the 650-750mb
layer along with steepening lapse rates of as much as 6-7 C/km
should support some convective rain showers where temperatures
will have fallen to near or perhaps just below freezing. With
100-300 J/kg of MUCAPE available in this area, can't rule out some
thunder occurring as well. If convective freezing rain occurs
with temperatures in the upper 20s, bridges and overpasses will
quickly deteriorate overnight and into Wednesday morning.

To the east and south of the current Winter Weather Advisory,
temperatures are expected to remain just above freezing overnight.
The cold front will have cleared our southeastern counties by
midnight or shortly after. However, the threat for heavy rain and
some flooding will continue in these areas as activity
intensifies with the aforementioned wave of ascent. Much of the
forecast area has already received 1-2" of rain with isolated
spots closer to 3-4". As continued waves of rainfall arrive into
Wednesday, the threshold for flooding will be decreased due to
soils becoming saturated. Additional river flooding and isolated
instances of flash flooding will be the primary concern for these
areas.

-Stalley

&&

.AVIATION... /Issued 602 PM CST Tue Feb 20 2018/
/00Z TAFs/

Concerns...Shower and thunderstorm threat continues through the
period with low MVFR and IFR cigs. Potential for freezing rain in
the Metroplex overnight being closely monitored.

A cold front is blasting through the region, already having moved
through DFW and is on its way to Waco. Strong north winds of 15-20
kts with gusts up to 25 kts will continue through the day on
Wednesday, but should diminish late Wednesday afternoon.

A combination of ceilings between 500-1200 feet prevails across
the region. All locations are expected to prevail at these
ceilings through the night, with IFR expected for most of
Wednesday. After the front passes, the potential for thunder
diminishes but showers are expected to continue. There will
likely be temporary breaks overnight, but the chances for rain
remain high through the night. On Wednesday, another wave of
showers, potentially with isolated thunderstorms, is expected to
occur, but the extent of precipitation should be diminishing by
the late afternoon hours.

The Metroplex airports are currently outside of a Winter Weather
Advisory to the west and northwest of them, but with temperatures
potentially falling to 30-35 degrees, freezing rain may become a
threat late tonight and Wednesday morning. Outlying airports such
at KAFW may fall to 30-32 degrees by daybreak Wednesday. We are
closely monitoring temperatures behind the front now, and upcoming
TAFs may need a mention of -FZRA overnight into Wednesday
morning. IF freezing rain does occur, ice accumulations up to
0.10" may be possible, and overnight rainfall rates are likely to
vary between a tenth and quarter inch per hour.

JLDunn

&&

.SHORT TERM... /Issued 251 PM CST Tue Feb 20 2018/
/Tonight/

Multiple shortwaves continue to work their way around a parent
trough located across the Rockies, generating enough lift to
produce numerous showers and storms across the North and Central
Texas. The axis of heavier precipitation has thus far remained
over the western two-thirds of the forecast area. Convection is
currently beginning to become focused along a cold front currently
making its way into the northwestern zones. The axis of heavier
precipitation will shift to the southeast tonight as the front
pushes southeast through the forecast area. A few strong to
marginally severe storms will remain possible due to good shear
and modest instability, but the focus will shift to heavy rain and
possible flooding over the next 24 hours.

Another issue that we have been monitoring over the past few days
is the amount of cold air present behind the front. Judging by
upstream observations, it is one again appearing that the NAM has
done a better job depicting the cold air within the shallow arctic
airmass. The latest temperature forecast has leaned toward the
colder NAM, which indicates sub-freezing temperatures across the
northwest counties overnight and through most of the day
tomorrow. The threat for a switch-over to freezing rain is
looking more likely overnight and Wednesday for areas to the west
and northwest of the Dallas-Fort Worth Metroplex. A Winter Weather
Advisory has been issued for areas along and northwest of a line
from Gainesville to Weatherford to Eastland, where freezing rain
accumulations between a hundredth and a tenth of an inch will be
possible late tonight through Wednesday.

&&

.LONG TERM... /Issued 251 PM CST Tue Feb 20 2018/
/Wednesday through early next week/

Travel west on I-20, northwest on Highway 287 and north on
Interstate 35 could become difficult at times by midday Wednesday.
The advisory is set to expire at 6 PM Wednesday, but may need to
be extended if future trends suggest that cold air and precipitation
will linger beyond that time. In addition, if later guidance
trends colder farther south, we may see some minor impacts creep
into the Metroplex during the morning hours Wednesday. Will leave
it to the evening and overnight shifts to monitor temperatures
and adjust the advisory area if it becomes necessary.

Meanwhile, the cold front will continue sagging southeast,
reaching the southeastern counties by Wednesday afternoon. The
focus for the heaviest precipitation will likewise shift east of
I-35 and south of I-30. It may become necessary to remove western
counties from the Flash Flood Watch as the heavier precipitation
moves east. However, due to the presence of strong ascent
associated with the Rockies trough, moderate rain from elevated
convection will remain possible, and at this time the Watch is
set to continue for all counties along and east of a line from
Gainesville to Stephenville to Goldthwaite.

The Flood Watch is set to expire at midnight Wednesday night
after one of the stronger shortwaves lifts northeast of the
region. The cold front will have briefly become stationary over
southeast Texas, but should begin to lift northwest as a stronger
shortwave swings down through the Desert Southwest and a lee-side
surface cyclone develops. So after a lull in precipitation
Wednesday night and Thursday, showers and storms will ramp up
again Thursday night and Friday as strong lift arrives from the
west. The surface boundary will again provide added focus for
development, and some locally heavy rainfall may again be a
possibility. We will likely need to look into the possibility of
another Flood Watch sometime between late Thursday and late
Saturday.

The main trough axis is progged to finally move east across the
Plains over the weekend. Precipitation will come to an end from
west to east late Saturday or Sunday. A few days of dry and
seasonable weather is likely Sunday and Monday, followed by
another system approaching around the middle of next week.

30

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    35  36  36  51  47 /  80  90  50  70  80
Waco                42  42  39  52  48 /  90  90  40  60  70
Paris               39  42  42  55  50 /  90  90  70  70  90
Denton              34  35  35  50  44 /  70  80  50  70  80
McKinney            36  36  36  51  47 /  80  90  50  70  80
Dallas              37  37  37  52  48 /  80  90  50  70  80
Terrell             40  40  40  55  49 /  90  90  60  60  80
Corsicana           41  42  41  55  51 /  90 100  60  60  80
Temple              42  44  39  53  49 /  90  90  40  60  70
Mineral Wells       31  33  32  47  40 /  60  80  40  70  60

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Wednesday evening for TXZ092>095-102>107-
116>123-130>135-143>148-157-159>161.

Winter Weather Advisory until 6 PM CST Wednesday for TXZ091-092-
100>102-115>117-129.

&&

Hazardous Weather Outlook
National Weather Service Fort Worth TX
328 PM CST Tue Feb 20 2018

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-211300-
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-
328 PM CST Tue Feb 20 2018

This Hazardous Weather Outlook is for North and Central Texas.

.DAY ONE...This Afternoon and Tonight.
There is a chance of thunderstorms across all of North and Central
Texas through tonight. A few severe storms are possible through this
evening along and southeast of a line from Sherman to Comanche. The
weather hazards from the severe storms include large hail and
damaging winds as well as an isolated tornado or two. Cloud to ground
lightning and heavy rainfall that could lead to flooding will be a
threat with any of the thunderstorms.

Temperatures behind a cold front will drop below freezing this
evening and overnight across northwest counties, causing rain to
switch over to freezing rain. A Winter Weather Advisory goes into
effect tonight for areas along and north of a line from Gainesville
to Weatherford to Eastland.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.
The Winter Weather Advisory will continue Wednesday. Areas in the
advisory could receive ice accumulations up to a tenth of an inch,
which will cause dangerous driving conditions.

Chances of thunderstorms are expected to continue into Wednesday. The
threat of heavy rain should shift to east of I-35/I-35E by Wednesday
afternoon.

Thunderstorm chances return late Thursday and continue through
Saturday. Severe weather is not expected at this time, but
additional heavy rainfall could cause additional instances of
flooding.

.SPOTTER INFORMATION STATEMENT...
Limited spotter activation may be requested late this afternoon into
the evening hours along and southeast of a Sherman to Comanche line.

Special Weather Statement
National Weather Service Fort Worth TX
403 PM CST TUE FEB 20 2018

TXZ130-202230-
Erath TX-
403 PM CST TUE FEB 20 2018

...SIGNIFICANT WEATHER ADVISORY FOR EASTERN ERATH COUNTY UNTIL 430 PM
CST...

At 359 PM CST, Doppler radar was tracking a strong thunderstorm near
Stephenville, moving northeast at 35 mph.

Half-inch hail and winds in excess of 40 mph will be possible with
this storm. The storm will primarily impact areas south of Highway
377 and north of Highway 67.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rain will also accompany the storm and may lead to localized
flooding.

The storm is moving into a less favorable environment and is
unlikely to intensify, but continue to closely monitor the situation
for additional information or possible warnings from the National
Weather Service.

&&

LAT...LON 3248 9806 3215 9790 3204 9822 3221 9831
TIME...MOT...LOC 2159Z 231DEG 31KT 3219 9816

25

Special Weather Statement
National Weather Service Fort Worth TX
425 PM CST TUE FEB 20 2018

TXZ130-131-202300-
Hood TX-Erath TX-
425 PM CST TUE FEB 20 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN ERATH AND HOOD
COUNTIES UNTIL 500 PM CST...

At 422 PM CST, Doppler radar was tracking a strong thunderstorm near
Bluff Dale, or 13 miles southwest of Granbury, moving northeast at
35 mph.

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

This strong thunderstorm will be near...
  Oak Trail Shores around 445 PM CST.
  Granbury and Pecan Plantation around 450 PM CST.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rain will also accompany the storm and may lead to localized
flooding.

The storm is moving into a less favorable environment and is
unlikely to intensify, but continue to closely monitor the situation
for additional information or possible warnings from the National
Weather Service.

&&

LAT...LON 3256 9795 3255 9762 3237 9762 3232 9778
      3219 9802 3239 9816
TIME...MOT...LOC 2222Z 231DEG 31KT 3232 9798

25

Special Weather Statement
National Weather Service Fort Worth TX
519 PM CST TUE FEB 20 2018

TXZ141-142-202345-
Mills TX-Comanche TX-
519 PM CST TUE FEB 20 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN MILLS AND CENTRAL
COMANCHE COUNTIES UNTIL 545 PM CST...

At 514 PM CST, Doppler radar was tracking strong thunderstorms along
the Mills/Brown county line and into far southwestern Comanche
County. Movement was north at 20 mph.

The strongest storm, in far eastern Brown County, will be capable of
half-inch hail and winds in excess of 40 mph will be possible with
these storms.

On their current track, these thunderstorms will be near...
  Comanche around 545 PM CST.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Each storm will take the same path, resulting in heavy rainfall.
Combined with rainfall from earlier storms, some flooding issues
may result. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3148 9899 3161 9878 3169 9876 3170 9867
      3188 9879 3216 9861 3204 9840 3202 9838
      3141 9883 3142 9886 3144 9887 3143 9893
      3146 9894 3144 9896 3144 9897 3145 9896
      3147 9900
TIME...MOT...LOC 2314Z 198DEG 15KT 3180 9869 3146 9892

25

Special Weather Statement
National Weather Service Fort Worth TX
600 PM CST TUE FEB 20 2018

TXZ141-142-210030-
Mills TX-Comanche TX-
600 PM CST TUE FEB 20 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL MILLS AND
SOUTHWESTERN COMANCHE COUNTIES UNTIL 630 PM CST...

At 558 PM CST, Doppler radar was tracking a strong thunderstorm 7
miles east of Zephyr, or 14 miles south of Comanche, near the
confluence of Mills, Comanche, and Brown counties. The storm is
moving northeast at 30 mph.

Dime size hail and winds in excess of 45 mph will be possible with
this storm.

This strong thunderstorm will be near...
  Comanche around 625 PM CST.
  Gustine around 630 PM CST.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with this storm. Combined with
rainfall from earlier storms, some flooding issues may result. Do
not drive your vehicle through flooded roadways.

&&

LAT...LON 3165 9877 3169 9876 3170 9867 3183 9876
      3196 9872 3190 9844 3180 9837 3160 9870
      3164 9878
TIME...MOT...LOC 2358Z 226DEG 28KT 3169 9867

25

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FORT WORTH TX
713 PM CST TUE FEB 20 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0610 PM     FLASH FLOOD      4 ESE IRVING            32.84N 96.91W
02/20/2018                   DALLAS             TX   DEPT OF HIGHWAYS

            THREE LANES OF LOOP 12 AFFECTED BY HIGH
            WATER NEAR THE SH183 INTERSECTION.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FORT WORTH TX
726 PM CST TUE FEB 20 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0724 PM     FLASH FLOOD      3 E SACHSE              32.98N 96.53W
02/20/2018                   DALLAS             TX   TRAINED SPOTTER

            SPOTTER REPORT OF HIGH WATER NEAR
            NEIGHBORHOODS IN EAST SACHSE / SOUTH WYLIE.

&&