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

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FXUS64 KFWD 050949

Area Forecast Discussion
National Weather Service Fort Worth TX
349 AM CST Tue Dec 5 2017

/Today and Tonight/

A cold front continues to slice southward through Central and
East TX as of 3 AM. This feature will likely continue to generate
showers (though a rumble of thunder or two cannot be completely
ruled out) across the aformentioned geographical area through at
least noon today. There could be a few light rain showers or
sprinkles farther back to the northwest, but widespread rain isn`t
expected today near the I-20 corridor. From mid-morning through
noon, it appears that large scale lift shuts off for much of the
afternoon hours which only supports a low chance for light rain
showers across Central and East TX.

After a day of record warmth for some areas, conditions will be
noticeably cooler today! Mid-level cloud cover in tandem with
northerly winds should keep most highs across most areas in the
50s. A few spots across western and northern zones may only climb
into the upper 40s for high temperatures.

For tonight, isentropic lift along the 310K theta surface should
overspread from the west and southwest. While the lift is
respectable in magnitude, low levels will remain parched, at least
initially. This should mean that much of what falls should be in
the form of virga early in the evening. As the low levels slowly
saturate through the late evening and into the nighttime hours,
the chances for more widespread measurable precipitation
increases. I`ve reflected this thinking in the grids and at this
time it appears as if areas south of I-20 will have the better
probability of measurable rain. Forecast soundings, particularly
for locations near and west of highway 281, do suggest that a few
snowflakes or sleet pellets could mix in with the light rain as
evaporative effects help to cool the column sufficiently.
Currently, no impacts are expected due to recent warmth and
surface temperatures remaining in the mid to upper 30s.



/Wednesday through Tuesday/

Wednesday is likely to be the coldest day this week across North
and Central Texas and could feature some mixed wintry
precipitation across parts of Central Texas through the afternoon.
The cold front that came through last night will be well south of
the area at the start of the day, but extensive cloud cover will
be present with temperatures generally in the mid to upper 30s to
start the day. A broad area of moderate to strong mid level
isentropic ascent will be ongoing from deep south Texas well into
North Texas Wednesday morning. This will result in extensive
northward moisture transport atop the cool air already in place. A
large area of light to moderate precipitation is expected to be
ongoing or in the process of rapidly developing around 12Z
Wednesday across much of Central Texas. Precipitation should
eventually become focused along and east-west oriented band of
strong 700mb frontogenesis by midday. The coarser resolution
models have this band set up generally from Lampasas to
Temple/Killeen and eastward with most of the precipitation
extending from the Waco area southward into Central Texas. The
higher resolution guidance is a little farther north with the
precipitation, however, it is a safe bet that most of the
precipitation will be focused across our southern counties.

As we go through the day Wednesday, an upstream shortwave will
dig through the Central Plains amplifying an already large trough
over all of the eastern CONUS. As it does, a broad area of
stronger forcing for ascent will spread into Central Texas. This
area will also be in a favorable quadrant of an 130 kt upper jet
located across north and northeast Texas. Through the day, thermal
profiles will continue to cool. Initial precipitation during the
morning hours may initially fall into relatively dry air below
800mb but this is expected to saturate fairly quickly by mid to
late morning. Forecast soundings from the Waco area southward
through Bell county and westward to Lampasas and Mills counties
become cold enough by midday to support snowfall production with a
deep saturated layer above 900mb. Surface temperatures are
expected to remain above freezing through the day across the
entire region, and there are some questions as to how cold the
lowest 100mb or so above the surface get, but overall it looks
like a good bet that some areas will see at least a little snow or
sleet mix in with light rain during the day Wednesday. This
favored area would again be from Goldthwaite to Waco and south to
Temple/Killeen and Lampasas.

As far as impacts are concerned...temperatures at the surface are
expected to remain in the mid/upper 30s which will support
melting of any frozen precipitation. At this time, it appears that
no significant impacts would be expected other than some minor
accumulations on grassy surfaces in the coldest areas.
Temperatures are expected to remain in the mid/upper 30s across
our southwest counties on Wednesday and will warm into the 40s and
lower 50s farther north. Areas near the Red River may be the
warmest, especially if the clouds clear faster than currently

Temperatures Thursday through the upcoming weekend will be near
or slightly below climatological normals as a large trough remains
in place across much of the central and eastern U.S. Clouds are
expected to clear Wednesday night and it should remain clear
through the end of the week.



.AVIATION... /Issued 1148 PM CST Mon Dec 4 2017/
The much anticipated cold front had moved south of the Metroplex
TAF sites as of 05Z. Some postfrontal showers will linger across
the Metroplex terminals through about 08Z. A lightning strike or
two will also be possible. The front should reach Waco around 07Z,
bringing showers along with an abrupt wind shift.

Ceilings will remain VFR tonight through Tuesday and generally
between 5000 and 8000 ft.

The passage of the front resulted in some impressive initial wind
gusts this evening with some in excess of 40 knots. Overall,
sustained winds overnight and Tuesday should be in the 15 to 18
knot range with some gusts near or slightly above 30 knots. Wind
speeds will begin to decrease late Tuesday afternoon once surface
high pressure sinks southward into the region. The wind direction
will remain northerly through Tuesday night.

The only other feature of concern is a shortwave which is progged
to drop into the Desert Southwest Tuesday evening, bringing
increasing mid level moisture and some lift to the region. It
appears that most of the precipitation associated with this
feature should remain west and southwest of the TAF sites through
sunrise Wednesday morning.



Dallas-Ft. Worth    54  40  49  35  53 /  10  30  10   0   0
Waco                57  36  37  33  51 /  20  40  60  30  10
Paris               51  37  52  33  47 /  10  10   5   0   0
Denton              53  36  47  32  49 /  10  20   5   0   0
McKinney            53  36  51  33  50 /  10  20   5   0   0
Dallas              54  41  51  35  51 /  10  30  10   0   0
Terrell             53  38  49  34  53 /  10  30  10   5   0
Corsicana           55  40  40  34  54 /  20  40  40  20   5
Temple              56  39  39  34  52 /  30  40  80  40  20
Mineral Wells       51  36  44  30  48 /   5  30  20   5   0




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