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

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FXUS64 KFWD 181142
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
642 AM CDT Wed Apr 18 2018


.AVIATION...
/12z TAFs/

A cold front is entering the DFW Metroplex as of 1130z causing
winds to turn to the northwest. This northerly wind shift will
occur at all Metroplex airports within the next hour, but in the
meantime, they have veered to the west and weakened slightly. A
thin band of MVFR cigs exists immediately along the front, and
have tempo`d these conditions at DAL where cigs could last 30-60
minutes. They`ll be too short-lived at the other TAF sites to
warrant a mention. Ahead of the front, MVFR stratus exists near
Waco and points southeastward. MVFR cigs could occur
intermittently at Waco prior to the front`s arrival, but will be
quickly scoured by the boundary as it moves through around 15z.
In wake of the front, breezy north winds with gusts around 25 kts
will occur into the afternoon.

By this evening, wind speeds will decrease, but remain light out
of the north overnight. VFR conditions will prevail into Thursday with
passing high cirrus.

-Stalley

&&


.SHORT TERM... /Issued 233 AM CDT Wed Apr 18 2018/
/Today and Tonight/

A formidable cold front is on our doorstep this morning which
will be the main focus through the short term forecast. Ahead of
this front, breezy south winds with gusts of 20-30 mph continue.
Very shallow Gulf moisture has been pulled northward within a
stout nocturnal low-level jet resulting in a swath of low stratus
developing across parts of Central Texas. As the front sweeps
through this morning, winds will abruptly shift to the northwest
with gusts up to 35 mph possible, although these stronger winds
will be confined immediately along and behind the front. Speeds
will lessen a bit through the day with winds of 15-25 mph
persisting through sunset. Approximate frontal passage timing
is expected to be 5-6am in the Metroplex, 8-9am at Waco, and
exiting the forecast area to the southeast around noon. Any low
clouds will be immediately scoured by the dry air arriving with
the front.

While there is not an abundance of cool air behind this front, it
will be noticeably cooler and drier with high temperatures only
expected to reach the 70s and low 80s rather than the 80s and 90s
experienced yesterday. Dewpoints will fall from the low 60s into
the upper 30s and 40s as drier air scours what little moisture is
in place. By the time the front reaches our far southeastern
counties, it may encounter enough moisture to squeeze out a rain
shower or two, although this potential is too low to justify more
than a silent 10% PoP at this point. Otherwise, the onset of
strong northwest winds through the lowest ~2km could usher in
haze/smoke from fires in western Oklahoma which may be detectable
either visually or olfactorily.

Later this evening, we`ll finally get a reprieve from the gusty
winds as they diminish below 10 mph after sunset. While some
cirrus will continue streaming across Central Texas, much of
North Texas will be clear and calm overnight. Temperatures should
fall quickly, especially in areas deprived of high cloudiness,
and low temperatures will be about 15-20 degrees cooler than this
morning.

-Stalley

&&

.LONG TERM... /Issued 233 AM CDT Wed Apr 18 2018/
/Thursday through Wednesday/

The main highlight of the extended portion of the forecast
continues to be the upper level trough that will bring rain to
much of the region this weekend. The severe weather threat on
Saturday still appears limited but should not be discounted.

A reinforcing surface ridge will push across the region on
Thursday, and temperatures are expected to be near and slightly
below normal. East and east-southeast winds will prevail through
Friday, which will limit moisture return before the upper level
trough arrives on Saturday.

The upper level trough will cross the Four Corners region on
Friday and continue moving east into West Texas on Saturday.
Moisture from the Gulf of Mexico will be transported around the
western periphery of the surface ridge; across South Texas and
then north into New Mexico. Showers and thunderstorms will form
along the dryline in New Mexico on Friday as the upper level
trough impinges on the boundary. This line of convection is
expected to progress east, and may expand in size as it crosses
the Big Country Friday night, aided by continued height falls
crossing the state and an increasing low level jet. By daybreak
Saturday morning, this convection could be moving into our western
counties, but the dryline is expected to still be well to our
west near the TX/NM border. Our surface winds will finally turn to
the south Saturday morning, drawing dewpoints in the 50s and
lower 60s north during the day.

As the upper level trough continues moving east during the day on
Saturday, the dryline will also move east. Ahead of the dryline,
widespread showers and storms are expected to continue moving
across the region due to lift from the upper level trough. The
ECMWF is significantly slower with the speed of the dryline and
never brings it into our western counties before it is overtaken
by the cold front that night. The GFS has the dryline in our
western counties by late afternoon. However, the way it`s looking
right now, too much rain ahead of the dryline could severely
limit instability. The environment ahead of the dryline is what we
will be monitoring, and the area for any possible severe storm
threat still appears to be across Central Texas, in particular
west of I-35. This area has the potential for up to 1000 J/kg of
CAPE with shear values of 50-60 kts, but this CAPE may not be
realized if the atmosphere is too worked over from earlier
convection.

In general, Saturday will be a rainy day for most areas and many
locations may receive over an inch of rain. Some heavy rain may
occur across the eastern half of the CWA resulting in minor flood
issues. A cold front will sweep across the region Saturday night,
ending most of the rain, but some post-frontal rain may linger in
our eastern counties Sunday morning. A weak upper level ridge
will build to our west through the middle of next week, keeping
northwest flow aloft across the region. Under this influence
another front may sweep across the region around the middle of
next week. Cool conditions are expected Sunday and Monday with a
slow warm-up ahead of the next front. Looking at the pattern
through the rest of the month, it looks like we could finish April
with below normal temperatures.

JLDunn

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    79  49  75  51  73 /   5   0   0   5  10
Waco                81  47  76  51  74 /   5   0   0   5  10
Paris               75  43  71  47  70 /   0   0   0   0   5
Denton              76  43  75  49  72 /   0   0   0   5  10
McKinney            76  42  73  48  71 /   0   0   0   5  10
Dallas              78  51  76  52  73 /   5   0   0   5  10
Terrell             78  45  75  49  72 /   5   0   0   5  10
Corsicana           81  46  74  50  72 /   5   0   0   5  10
Temple              82  50  76  52  73 /  10   0   0   5  10
Mineral Wells       76  43  76  48  73 /   0   0   0  10  10

&&

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

$$

26/82



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