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

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FXUS64 KFWD 150926

Area Forecast Discussion
National Weather Service Fort Worth TX
326 AM CST Mon Jan 15 2018

/Today and Tonight/

An arctic cold front extended from a low over southwestern
Wisconsin southwest through central Missouri to south of Wichita,
Kansas to just north of Clayton, New Mexico at 3 AM. This front
will continue to move southward reaching a Paris to Graham line by
noon, the I-20 corridor by 3 PM, and through the southern zones
early this evening. South winds 5 to 10 mph this morning will
become south southwest ahead of the front and then shift to the
north at 15 to 25 mph with gusts over 35 mph with frontal passage.
Clouds will be on the increase from the southwest today and there
will be a slight chance of light rain this afternoon. Highs today
will range from the upper 40s along the Red River to the lower
60s across parts of Central Texas but temperatures will steadily
fall behind the front. By sunset, temperatures north of the I-20
corridor will be in the 30s and they will fall into the 40s north
of a Goldthwaite to Athens line.

Strong cold advection will continue tonight and the transition to
wintry precipitation will occur from northwest to southeast.
Light rain should initially change over to a wintry mix of
freezing rain, sleet and snow and as the atmospheric column cools,
the precipitation will switch over to a sleet-snow mix before
switching over to all light snow. There was not much of a change
in the latest model runs and it looks like the worst of the
weather will be across areas along and southeast of a Goldthwaite
to Hillsboro to Sulphur Springs line while areas along and north
of a Graham to Denton to Sherman line will likely only get very
light amounts. Thus have left the Winter Weather Advisory that
starts at 6 PM as is. In those areas, generally total ice, sleet,
and snow accumulations of up to a half inch are expected. Areas
farther to the southeast appear to have higher amounts of QPF.
Given the expected transition to freezing rain and sleet and
finally over to snow before daybreak. Have decided to upgrade the
Winter Storm Watch to a Winter Storm Warning as those areas will
have the potential to have a light glaze of ice and total sleet
and snow accumulations of a half inch to over 1 inch. By
daybreak, temperatures are expected to fall into the teens across
the north to the mid 20s across Central Texas.



/Tuesday through the weekend/

Light snow will linger across the southern half of the region
through midday Tuesday. Precipitation will come to an end Tuesday
afternoon as the upper trough axis heads for the Gulf Coast
Region and subsidence spreads over North and Central Texas in its
wake. Bitterly cold conditions will remain across the area on
Tuesday as a 1045MB arctic high settles over North Texas and the
Southern Plains, and high temperatures are expected to remain
below freezing across the entire region. The subfreezing airmass
means that travel will likely remain rather hazardous well after
precipitation comes to an end, particularly across the southern
half of the region where the higher sleet/snow totals are

In addition to travel issues, dangerously cold weather is
expected Tuesday night and Wednesday morning. Even though arctic
airmasses do not radiate as efficiently as continental airmasses,
the clearing skies will be sufficient to allow temperatures to
drop from the 20s into the teens overnight, with single digit
readings not out of the question. Hard Freeze Warning criteria
for North and Central Texas is 10 degrees and below, which will be
attainable for the northern and northwestern counties, and a Hard
Freeze Watch has therefore been issued for areas along and north
of a line from Paris to Denton to Cisco from 10 PM Tuesday until 8
AM Wednesday.

Temperatures will begin to moderate late Wednesday and Thursday as
the arctic ridge shifts to the east, with Wednesday`s high temps
clawing their way to just above freezing, followed by lower 40s on

A shortwave trough moving across Central and South Texas will
provide a slight chance of a rain/sleet mix to the southern and
southeast counties on Thursday and Thursday night (no
accumulations expected).

A stronger upper trough is still progged to move east across the
Four Corners Region Saturday, then into the Southern Plains on
Sunday. Good warm and moist air advection is being advertised in
advance of this system, leading to much warmer weather Friday
through the weekend. Moisture and instability will be sufficient
for scattered convection when combined with the strong lift that
the trough will provide, and thunder has been added to the
Saturday night/Sunday grids. A Pacific front will bring seasonably
cool and dry conditions as the storm system heads east into the
Mississippi Valley early next week.



.AVIATION... /Issued 1131 PM CST Sun Jan 14 2018/
/06Z TAFS/

Trends to 00z TAFs (see discussion immediately below) remain
similar with regard to challenges through 21z Monday. However,
925mb winds continue to remain weak and it appears outside of the
possibility of MVFR vsbys between 12z-15z at all airports, only
spotty low stratus is expected on Monday.

A cold FROPA still expected at DFW Metro airports by 21z with the
possibility of MVFR cigs with a rapidly deepening frontal
inversion. North winds around 15 knots will increase and become
quickly gusty by the evening hours at 15-20 knots with gusts
between 35-30 knots. By early evening, we expect a wintry mixture
as the column aloft rapidly cools. However, surface temperatures
will remain above freezing through 04z-05z and do not believe -FZRA
will be an issue. By that time, however the entire atmospheric
column will have cool to or below 0 deg C with a transition to
light now, as cigs rise into VFR AOB FL040. The reasoning for less
restrictions is there will be much drier low level air below
925mb (initially arriving into the area), thus kept intensities
of precipitation light during the evening hours with only MVFR
vsby restrictions. Outside of limited flight approaches from light
wintry precipitation after 02z, the gusty north winds will also
make approaches within the Bonham and Bowie cornerposts very
limited as well.

At Waco Regional, similar MVFR vsby restrictions are possible, but
otherwise VFR conditions through much of the day with spotty -RA
developing in the late afternoon just ahead of the cold front. The
cold FROPA and the transition to gusty north winds 15-20 knots
with higher gusts will arrive by 00z and after. A cold rain will
develop with isentropic ascent over the shallow frontal boundary,
however, temps won`t fall below freezing til midnight or after
across Central Texas, so like DFW airports, no -FZRA is expected
at this time. Sounding analysis indicates a transition to a
rain/sleep mix after 03z Tuesday. Any mixture with, or transition
to light snow will likely occur just beyond the 06z TAF forecast
and after 06z.



.AVIATION... /Issued 614 PM CST Sun Jan 14 2018/
/00Z TAFs/

Quiet conditions are expected tonight with no aviation concerns
expected. South-southeast winds around 10 knots or less will
continue with VFR conditions underneath northwest flow aloft
continuing through 12z Monday. Challenges increase on Monday with
low cigs arriving after sunrise, then with timing the cold FROPA
and precipitation development mid afternoon Monday and beyond.

MVFR cigs will surge north from the Hill County and over Waco
Regional shortly after 12z Monday, with a brief potential for IFR
cigs through 15z. These cigs should arrive northward to the I-20
corridor and DFW Metro airports by, or shortly after 18z. Up until
cold FROPA arrives into the I-20 corridor and DFW area between
20z-22z, enough near surface warming may occur for brief low VFR
cigs BLO FL040 before cold FROPA. Cold FROPA will arrive a few
hours later at Waco Regional, or between 23z-00z. North-northeast
winds 10-15 knots will occur initially post FROPA, then back
northerly at 15-25 knots once strong cold advection arrives and
the frontal inversion deepens after 00z Tuesday.

A strong cold front was currently moving into the Central Plains
and through the Midwest. As noted above, this cold front arrives
in the mid-late afternoon period Monday for our region. The tricky
part of the extended forecast is timing any light developing
precipitation and any conversion over to a wintry mixture as the
vertical thermal profile cools Monday evening. Better frontogenetical
and isentropic ascent above the boundary layer will be delayed a
good 3-6 hours after the cold front. All precipitation should be
in the form of a cold -RA at all sites through 00z Tuesday, as we
await the stronger cold advection underneath the deepening inversion.
In addition, sub freezing surface temperatures will likely hold
off til mid-evening and after. As such, I have remained conservative
with the 24-30 hour forecast at DFW with low confidence on how all
these processes evolve. I have added a 02z Tuesday period with a
light -RA/SN mix and MVFR cigs above FL020 for and until better
confidence on transitioning thermal profiles and precipitation
development become more clear as we move into Monday night.



Dallas-Ft. Worth    54  23  29  14  33 /  20  40  20   0   0
Waco                58  25  30  13  36 /  30  70  30   0   0
Paris               48  18  25  10  33 /  20  40  20   0   0
Denton              50  20  28   9  34 /  20  30  10   0   0
McKinney            52  21  27   9  32 /  20  40  20   0   0
Dallas              54  23  28  15  33 /  20  40  20   0   0
Terrell             54  22  27  11  34 /  30  60  20   0   0
Corsicana           57  24  27  14  33 /  30  70  30   0   0
Temple              61  25  29  15  36 /  20  80  40   5   0
Mineral Wells       54  20  30   9  35 /  20  30  10   0   0


Winter Weather Advisory from 6 PM this evening to noon CST
Tuesday for TXZ094-095-104>106-115>120-129>133-141.

Winter Storm Warning from midnight tonight to 6 PM CST Tuesday
for TXZ107-121>123-134-135-142>148-156>162-174-175.

Hard Freeze Watch from Tuesday evening through Wednesday morning
for TXZ091>095-100>104-115>117-129.



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