Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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056
FXUS64 KFWD 211035
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
435 AM CST Sun Jan 21 2018

.SHORT TERM...
An upper trough will move east from the Four Corners region today
and reach the Central Plains by this evening. Strong low level
warm air advection will continue over the region today ahead of
this system which will result in warm, breezy and humid conditions
with afternoon highs in the upper 60s to lower 70s. Wind speeds
will approach wind advisory criteria this afternoon across the
central and western zones but only for a brief time.

Some light showers will be possible this morning as large scale
upward vertical motion slowly increases, but most locations will
not see any measurable rainfall through midday. More vigorous
large scale lift and the arrival of a dryline will bring better
precipitation chances this afternoon. All models (including the
high res solutions) continue to indicate that a somewhat organized
line of storms will develop on the dryline mid to late afternoon
just to the east of the I-35 corridor. This line is progged to
intensify as it moves east into slightly more moist and unstable
air. There is still a potential for some strong to severe storms
due to ample wind shear and sufficient moisture but a limiting
factor will be meager instability. There is at least some
potential for an isolated supercell or two to develop ahead of the
main line of storms across the southeast zones late this
afternoon with a low tornado potential. The more likely mode of
convection will be a thin squall line with straight line winds as
the primary hazard. Even though we will have high PoPs across the
east, expected rainfall will be low (generally < 1/4 inch) since
the squall line will be thin and fast moving.

All storms will move east during the evening and should exit the
CWA before midnight as a cold front overtakes the dryline.

There will still be a high wildfire threat this afternoon/early
evening across the western zones due to the dry, windy and warm
conditions expected behind the dryline. Therefore, we will keep a
Red Flag Warning in place along and west of a line from Jacksboro
to Stephenville from 1 PM until 9 PM. Locations just to the west
of the warning area will see an elevated threat for grass fires
this afternoon, but minimum relative humdities should be generally
above 30 percent and winds speeds will be slightly lower.

79

&&

.LONG TERM...
/Monday through Saturday/

Breezy conditions will continue on Monday in the wake of a Pacific
cold front. The deepening cyclone and surface cyclogenesis in the
Central Plains should intensify the flow, which should exceed
40kts at 925mb early Monday morning. After daylight, some of this
momentum will reach the surface, and sustained speeds at the
surface may approach wind advisory criteria from late morning
through mid-afternoon. Despite a chilly start to the day and the
brisk winds, the downslope component to the wind may push
temperatures to near 60F by midday. Veering winds Monday
afternoon will gradually enhance the cold advection and should
cap high temperatures near seasonal normals.

Though maritime by definition, these Pacific air masses typically
go through a thorough dessication as they pass over the high
terrain of the Southwest. This is no exception, and dew points
will likely fall into the teens Monday afternoon in our western
zones. With little chance for significant rainfall today, the
parched vegetation in our west will remain conducive to fire
initiation. Although the cooler temperatures may somewhat
mitigate the fire weather concerns, relative humidity values
dipping below 20 percent will enhance the potential for fire
initiation, and the gusty winds will promote the spread of any
wildfires that do develop. As a result, we have issued a Fire
Weather Watch for Monday afternoon for those areas along and west
of a line from Comanche to Granbury to Nocona. Elsewhere,
Sunday`s rainfall may preclude fire weather issues, but everyone
across North and Central Texas should remain vigilant about fire
usage. Avoid open flames near dry vegetation, and assure all coals
and embers are fully extinguished.

Both Monday and Tuesday night, winds will be light with low
humidity and mostly clear skies. In low-lying and/or outlying
areas, freezing temperatures are likely both Tuesday and
Wednesday morning. Significant warm advection won`t ensue until
late in the week, and the warming trend will be slow.

As a longwave trough makes landfall on the West Coast, the flow
will back. Considerable cloudiness will prevent temperatures from
exceeding the 60s on Friday, but deep moist advection in
destabilizing southwest flow aloft will result in some showers
and isolated thunderstorms in advance of the next cold front.
Unsurprisingly several days out, there is some disparity in the
timing of the front, but the GFS/CMC consensus is for a Saturday
morning FROPA. This would bring an end to the rain chances and
result in a breezy and seasonally cool weekend.

25

&&

.AVIATION... /Issued 1140 PM CST Sat Jan 20 2018/
/06Z TAFs/

MVFR cigs continue to expand across North and Central Texas this
evening, but temporary breaks of nearly clear skies may occur for
the next few hours due to holes in the cloud cover. IFR ceilings
may also occur for a little bit at KACT between 06-10Z. Ceilings
are expected to lift at all TAF sites to MVFR around midday, with
VFR and then clearing skies in the late afternoon and evening
hours.

Breezy south winds will continue tonight, and then the winds will
shift to a more southwesterly direction Sunday afternoon as an
upper level system and dryline approach. At the Metroplex
airports, winds of 15-20 kts gusting 25-30 kts from a 200-220
direction are expected between 20Z-23Z, and this is expected to
result in crosswind issues on north-south and diagonal runways.
After 23Z, the wind speeds will subside a little as the dryline
approaches, and then they will shift to the west in the evening
and eventually northwest overnight. However, overnight wind speeds
will remain at 15-20 kts. The winds at KACT are expected to
remain in a southwest direction for much of the evening hours with
speeds of 10-15 kts, but the winds may turn more westerly near
the end of the valid TAF period.

Some showers still remain possible near the TAF sites Sunday
afternoon, and have kept a few hours mention of VCSH. A broken
line of showers and storms should develop east of the airports
during the late afternoon hours, and this may affect arrivals and
departs from northeast to southeast directions. KACT and KDAL
have a better chance of a shower occurring at the airport. In
addition, there`s a low chance KACT could be impacted by a
thunderstorm late in the afternoon depending on where the broken
line of storms develops and the speed of the dryline.

JLDunn

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    72  44  60  35  60 /  40  10   0   0   0
Waco                72  42  62  31  63 /  50  20   0   0   0
Paris               68  42  57  34  58 /  70  70   0   0   0
Denton              71  40  59  31  59 /  30   5   0   0   0
McKinney            69  42  59  32  59 /  40  20   0   0   0
Dallas              70  44  59  37  60 /  40  10   0   0   0
Terrell             71  43  59  34  59 /  60  30   0   0   0
Corsicana           71  43  61  35  62 /  60  40   0   0   0
Temple              71  41  63  32  63 /  50  20   0   0   0
Mineral Wells       73  39  60  30  62 /  10   0   0   0   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM this afternoon to 9 PM CST this
evening for TXZ100-101-115-116-129-130-141.

Fire Weather Watch Monday afternoon for TXZ091-100>102-115>117-
129>131-141.

&&

$$

25/79



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