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

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639
FXUS64 KFWD 060852
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
252 AM CST Tue Dec 6 2016

.DISCUSSION...
A challenging forecast expected today, especially this morning as
areas of fog, some dense have formed well out ahead of a cold
front that is now moving into Northwest TX and Southwest OK
currently. A Dense Fog Advisory currently exists until 8 a.m. CST
for all but some of our far western and northeast counties. Per
BUFKIT and high-resolution model guidance, along with trends on
fog infrared imagery of moisture building southwestward ahead of
the cold front, I have included all BUT Mills and Lampasas
counties in the southwest, and Lamar, Delta, and Hopkins county in
the northeast. Tracking the front, I have extended the Dense Fog
Advisory across our Central Texas counties through late morning.

One caveat here with the fog is the strong westerly 925mb winds
via WSR-88D VWPs just to the west and south of the CWA. The strong
westerly 925mb component could likely result in any dense fog
lasting only an hour or two across my far west/southwest counties.
We will have to continuously monitor the fog through the morning
hours and adjust as needed. Once the cold front passes through
much of the area by midday with help from a shortwave transversing
east across the Central Plains, expect some patchy lingering
drizzle through the afternoon hours. BUFKIT RAP/NAM forecast
sounding analysis indicates some buoyancy and low level laspe
rates continuing through much of the afternoon within the stratus
layer. Any drizzle will be light and patchy and not expected to affect
visibility behind the cold front. The cold front will stall across
South-Central and Southeast TX, before lifting slowly north as a
weak warm front into our CWA late tonight into Wednesday. As such,
moisture will not get scoured completely out and the airmass will
not cool down too much. A shortwave will transition eastward
across the state late Wednesday into Wednesday evening and have
continued low rain chances across mostly the eastern half of the
CWA. Moisture isn`t overly rich, so do not expect rainfall to
total more than a tenth of an inch, if even that.

The larger scale Central CONUS upper trough deepens over the
Plains for the latter half of the week, which support our first
arctic cold front and airmass intrusion of the season Thursday and
Friday. As has been noted recently, this will be the coldest
airmass our area has seen in two years. It is highly recommended
you cover outdoor faucets and pipes, as well as make sure you
check on people who may not have adequate heating. Outdoor pets
should also be prepped for the frigid weather expected the latter
half of the week. We will not reach our official hard freeze
criteria of 10 degrees or less for any highlights. That said, with
the warm growing season having lingered longer than expected this
year, it`s a good idea to take necessary precautions now. Highs on
Thursday will be hard pressed to get out of the 30s, with lows
Friday morning ranging from the mid teens northwest to the mid 20s
across parts of Central Texas. Some gradual modification of the
airmass will occur Friday, as the broad surface high and colder
air shift gradually east. However, I still undercut guidance
temperatures by several degrees and may still be too warm on
Friday. Models do have a tendency to scour out dense arctic
airmasses too quickly and the better low level warm advection
looks to hold off until late in the day Friday and Friday night.

We will see a rapid modification to the arctic airmass this
weekend, as the main Central U.S. longwave trough lifts northeast
into eastern Canada and heights rise over the Southern Plains with
a strong zonal flow in place. This pattern usually leads to strong
lee surface cyclogenesis to our northwest with a return breezy
southerly winds. After a chilly start, highs Saturday should
rebound into the 50s most places. A shortwave will move east
across the Plains with best moisture flux occurring from E TX into
the Ark-LA-TX and Lower Mississippi Valley moving into the latter
half of the weekend. I see enough instability aloft and low level
warm advection above the shallow frontal inversion to maintain a
low chance of showers and thunderstorms across areas east of I-35,
with a few lingering showers across the east moving into early
next week. Highs will briefly modify into the 60s Sunday, before
another cold front, not of arctic nature, drops high temperatures
slightly to between 55 and 65 degrees.

05/

&&

.AVIATION...
/ISSUED 1146 PM CST Mon Dec 5 2016/
/6Z TAFS/

Conditions continue to deteriorate late tonight across North Texas
as low clouds and dense fog are settling in. The main upper trough
is moving off to the northeast and in its wake is much drier air
above the surface. Near the surface...extensive moisture is still
in place and will linger into Tuesday morning before a front moves
through. With light winds and ample moisture...expect visibilities
to continue to fall through morning. Will prevail IFR conditions
through the overnight hours...although some brief scattering is
possible over the next few hours. From 3-7am...will have a tempo
for 1/2SM and FG across most areas. Conditions should improve
through the morning as northerly winds increase to 10-15 kt. Low
clouds may linger well into the afternoon before we see VFR cigs
into the evening hours.

Dunn


&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    53  41  55  29  37 /  10   5   5  20   5
Waco                54  41  59  32  39 /  10   5   5  20  10
Paris               51  39  50  27  36 /  10   5  20  20   5
Denton              51  37  53  26  36 /  10   5   5  10   0
McKinney            51  39  53  28  36 /  10   5  10  20   0
Dallas              52  42  55  30  37 /  10   5   5  20   5
Terrell             54  41  55  30  37 /  10   5  10  20   5
Corsicana           57  44  57  33  38 /  10   5   5  20  10
Temple              56  43  59  33  39 /  10   5  10  20  10
Mineral Wells       49  35  54  27  36 /  10   5   5  10   5

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 11 AM CST this morning for TXZ121-122-
129>135-141-143>148-157>162-174-175.

Dense Fog Advisory until 8 AM CST this morning for TXZ091>094-
100>105-115>120-123.

&&

$$

05/



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