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

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FXUS64 KFWD 131805
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1205 PM CST Sat Jan 13 2018


.AVIATION...
VFR will prevail with generally clear skies aside from a few high
clouds. Winds will be northerly near 10kt today, but become light
northeasterly after sunset and light southeasterly by sunrise.
South winds will increase to near 10kt Sunday afternoon. TR.92

&&

.SHORT TERM... /Issued 317 AM CST Sat Jan 13 2018/
/Today and tonight/

Water vapor satellite imagery shows a shortwave moving southeast
across Oklahoma into North Texas this morning. Some mid-level
clouds that are associated with this feature can be seen on IR
satellite imagery from south of Wichita Falls to Sulphur Springs
line as of 3 AM. This shortwave will quickly move through the
region today. There will be some brief cloudiness especially
across the northeastern third to half of the forecast area this
morning as the shortwave moves across; otherwise, skies will be
mostly sunny today. It will be another cold day with temperatures
rising from the 20s area wide at daybreak to the upper 30s
northeast to the mid 40s south this afternoon. Winds will be
northerly at 5 to 15 mph.

A surface ridge currently extends from North Dakota southward
into Texas. As this ridge moves to the east this afternoon into
tonight, winds will come around to the northeast by late
afternoon, to the east this evening and then to the southeast by
daybreak Sunday. Lows will be in the 20s under mostly clear skies.

58

&&

.LONG TERM... /Issued 317 AM CST Sat Jan 13 2018/
/Sunday through next weekend/

The cold airmass currently in place will begin to modify on Sunday
as the surface ridge works its way east into the Ohio and
Mississippi River Valleys. High temperatures will reach the 40s
and 50s Sunday afternoon. Weak return flow and the subsequent
dewpoint increase will keep low temperatures generally in the 30s
for Sunday night, though a few spots near the Red River may see
upper 20s.

On Monday, the axis of an upper level trough (extending southwest
from a deepening low over the Great Lakes) will swing southeast
through the central part of the CONUS, sending another strong
surge of arctic air southward through the Southern Plains.
High temperatures ahead of the cold front will range from the
upper 40s along the Red River to the upper 50s across the southern
counties. The cold front will approach the Red River around noon,
then surge quickly south through the forecast area Monday
afternoon and evening.

A period of isentropic lift will develop behind the front as the
axis of the upper trough approaches, leading to a broad region of
stratiform precipitation above the frontal layer. Precipitation
will begin across the northern third of the region Monday
afternoon, and should initially be in all liquid form. As
temperatures drop to and below freezing Monday evening, a
changeover to a wintry mix can be expected. The timing of the
changeover is dependent on how fast temperatures can fall below
freezing. Models are agreeing on this being a particularly cold
airmass, so just about all of the forecast area will see at least
a chance of wintry precipitation, due to the expectation that all
zones will fall below freezing prior to precipitation coming to an
end.

Model soundings indicate that a warm layer will remain overhead
during the early evening hours, but this layer will likely erode
late evening and overnight due to height falls associated with the
approaching trough and evaporative cooling processes. Rather than
try to be too specific with timing this early on, there is merely one
messy grid (00-06Z Tuesday) where a mix of all winter precip
types will be possible. After 06Z, the feeling is that precip will
be snow along and north of I-20, with sleet changing to snow
south of I-20.

The question then becomes, how much and where? At this time it
appears that ice accumulations would be fairly minor, and if
there are any significant accumulations, it would be in the form
of sleet/snow. There are still variation in model data with
regard to available moisture and it is still too early to
accurately predict accumulations. The NAM remains the dry outlier,
and if verifies, would mean little or no accumulations. But with
the GFS and ECMWF indicating more moisture, there is increasing
confidence that accumulation`s significant enough to affect travel
will occur somewhere. More will be known later this weekend when
we get into the range of the more high-resolution model runs.

Subsidence will spread in during the day Tuesday, bringing an end
to precipitation by midday. Bitterly cold conditions are then
expected with teens and lower 20s expected for Tuesday night lows.
A gradual warming trend will commence late Wednesday and Thursday
ahead of a fast-moving upper low. This next system will bring a
slight chance of rain, possibly mixed with snow, Thursday and
Thursday night.

30

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    26  49  35  52  22 /   0   0   0  20  50
Waco                23  51  34  56  25 /   0   0   0  10  50
Paris               22  44  29  49  20 /   0   0   0  30  40
Denton              23  49  32  50  20 /   0   0   0  20  40
McKinney            21  46  32  50  20 /   0   0   0  20  50
Dallas              26  49  35  52  23 /   0   0   0  20  50
Terrell             24  47  31  52  22 /   0   0   0  20  50
Corsicana           26  48  33  54  24 /   0   0   0  10  50
Temple              25  52  35  57  26 /   0   0   0  10  50
Mineral Wells       22  52  32  52  20 /   0   0   0  20  50

&&

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

$$



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