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

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604
FXUS64 KFWD 211802
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1202 PM CST Sat Jan 21 2017

.AVIATION...

Concerns:
- Showers and isolated storms this afternoon
- Wind shift to the west tonight with potential crosswind issues
- Cold front and wind shift Sunday with gusty northwest winds

A deck of mid-level clouds continues to overspread most of the
region with an area of decaying IFR stratus still lingering across
Central TX. Waco is the only TAF site experiencing these IFR
conditions as of 18z, but should see conditions improve in the
next hour. A strengthening upper low digging into NM and the TX
Panhandle will generate showers and isolated storms later this
afternoon across parts of western and North TX. This activity will
move east and is expected to be near the I-35 corridor around
22-02z. Most of this convection will consist of showers rooted
above very dry air in the lowest 8kft. Evaporational cooling from
showers/virga will lead to gusty winds at the surface with any of
this activity as well as turbulence through this atmospheric
layer. Some elevated instability will also exist as lapse rates
steepen with cooling occurring from the strong lift associated
with the approaching upper low. With convection-allowing models
suggesting more robust convection in vicinity of the DFW
Metroplex, have opted to add a brief mention of VCTS centered
around 23 or 00z as isolated lightning strikes will be possible.

Later this evening, rain chances will diminish and winds will
begin to shift to a more westerly direction while increasing in
speed. Expect sustained west winds of 15-20 kts to prevail at all
TAF sites beginning by midnight and lasting into Sunday morning.
These winds may cause some crosswind issues for airports with N-S
oriented runways. A cold front will move through the area later
Sunday morning, around 13-15z at Metroplex airports and a couple
hours later at Waco. Some MVFR stratus will be possible across
North TX in vicinity of the front as moisture wraps around the
surface low, thus have included a mention in the Metroplex TAFs.
Otherwise, winds will shift to the northwest behind the front and
increase to 20 kts or more with gusts up to 35 kts expected
throughout Sunday afternoon.

-Stalley

&&

.UPDATE...
Areas of dense fog formed overnight along and east of a Temple to
Hillsboro to Sulphur Springs line. Visibilities have been
improving during the last hour with only a few sites still
reporting dense fog. Thus the Dense Fog Advisory was allowed to
expire at 10 AM. With an increase in wind speeds expected, the
rest of the fog will dissipate by midday. Have made some minor
adjustments to the hourly temperature trends across the east to
account for the clouds/fog. A few thunderstorms developed during
the last couple of hours near and southwest of Wichita Falls, this
activity will continue to move northeast. Thus have added
isolated thunderstorms in the northwestern zones for late this
morning.

58

&&

.PREV DISCUSSION... /ISSUED 341 AM CST Sat Jan 21 2017/
Our energetic and active weather pattern continues today with
several interesting features to watch. The first is an area of
low clouds and fog which is percolating across the Hill Country
early this morning. Southwesterly winds in the lowest few thousand
feet will continue to advect this into our region over the next
few hours. Have added in patchy fog wording roughly south and east
of a Bonham to Rockwall to Killeen line, and areas of fog south
and east of a Canton to Corsicana to Temple line as this stratus
deck surges northeastward. We`ll be holding off on issuing a dense
fog advisory for the time as it`s still a bit unclear if the 20
kts of flow just off the surface will help keep things
sufficiently mixed enough to preclude widespread dense fog.

Out to our west, pressure falls have commenced across the Texas
Panhandle early this morning, heralding the nascent stages of
surface cyclogenesis as the nose of a 120+ kt jet streak is
overspreading the state. Surface low pressure will rapidly
materialize this afternoon and the race eastward across southern
Oklahoma tonight. As this low progresses eastward, the pressure
gradient will tighten which will result in the development of
breezy west to southwest winds later this morning and afternoon.
In addition, forecast soundings to our west indicate the
development of what should become a very deeply mixed atmosphere.
Momentum transfer output from BUFKIT soundings indicate the
potential for mixing down some 35-40 kts of flow locked up just
above 800 mb by this afternoon. While statistical guidance does
not concur, almost all available high-resolution guidance appears
to be keying in on this signal, indicating strong winds/gusts
materializing this afternoon and evening. It`s possible that cloud
cover ultimately limits the amount of Precip chances will decrease from
west to east late tonight. As this low clears our area on Sunday,
we`ll be left with dry weather through next week.

As this low departs, strong winds are once again in the cards, and
we will likely need another Wind Advisory--this time for much if
not all of the area--late tonight and into Sunday. We will defer
judgment on this to the dayshift, however.  mixing, but given
enough of a signal from guidance, we`ve gone ahead and hoisted a
Wind Advisory for our far western row of counties (Young,
Stephens, Eastland, Comanche, and Mills) from 1 PM to 6 PM.

The next focus is on precipitation chances this afternoon and
tonight. While moisture is in short supply--PWATS are generally
running about a half inch or less--abundant lift from this
approaching system will likely be able to squeeze out whatever
little moisture is available. There may be a few showers this
morning, but better chances will arrive later this afternoon and
this evening. Given the aforementioned deep inverted-V profiles,
any shower/storms will be capable of producing strong and gusty
downburst winds, although widespread severe-caliber wind gusts are
not anticipated at this time. Precip chances will decrease from
west to east late tonight. As this low clears our area on Sunday,
we`ll be left with dry weather through next week.

As this low departs, strong winds are once again in the cards, and
we will likely need another Wind Advisory--this time for much if
not all of the area--late tonight and into Sunday. We will defer
judgment on this to the dayshift, however.

Temperatures will moderate into the 70s on Monday and Tuesday
before a reinforcing cold front sends temperatures back into the
50s on Wednesday where they will likely remain to close out the
rest of the week.

Carlaw



&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    70  48  63  43  67 /  30  30  10   0   0
Waco                73  49  64  40  71 /  30  20   5   0   0
Paris               68  46  60  42  62 /  20  50  20   0   0
Denton              70  46  62  39  66 /  30  30  10   0   0
McKinney            69  47  62  41  65 /  30  40  10   0   0
Dallas              71  48  63  43  68 /  30  30  10   0   0
Terrell             70  47  63  43  66 /  30  40  10   0   0
Corsicana           74  48  64  43  68 /  30  30  10   0   0
Temple              74  49  65  42  72 /  30  20   5   0   0
Mineral Wells       72  46  62  40  71 /  30  20   5   0   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM CST this evening for TXZ100-115-129-141-
142.

&&

$$

26/58



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