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

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FXUS64 KFWD 260455

Area Forecast Discussion
National Weather Service Fort Worth TX
1155 PM CDT Tue Sep 25 2018


The cold front front has now moved into the Bowie cornerpost, and
will continue advancing to the southeast through the early morning
hours. There has been no convection associated with the cold
front, except for the storms across far West Texas. A few showers
have developed east of Interstate 35, but given slightly drier
environment across the DFW Metroplex, current thinking is that
those showers will remain east of the region.

Much of the guidance now suggests there will be little in the way
of precipitation associated with the leading edge of the cold
front. The upper level shortwave is still across New Mexico,
unable to provide the large scale lift for shower/storm
development. Having said that, given slightly more moist air is
sliding northward into North Texas, the front may provide just
enough lift for a few showers on its leading edge.

As the shortwave slides eastward through the morning, rain chances
will be increasing behind the front. For that reason, have added a
TEMPO group beginning at 12Z for the DFW Metroplex TAF sites and
at 15Z for Waco signifying the highest potential for rain showers.

The main forcing for ascent will remain north of the Red River,
keeping North and Central Texas from continuous rain chances.
Given the shallow nature of the "cold" air, MVFR conditions will
move in behind the front and likely persist through the remainder
of this TAF period.

Sustained winds behind the front will also pick up to around 15
mph with higher gusts. Taking a look at observations behind the
front, Sheppard AFB in Wichita Falls has reported sustained winds
between 15-20 mph, with higher gusts. The higher gusts are
expected to subside by midday, leaving sustained winds between
10-15 mph.

A few of the models are hinting at the possibility of another
round of showers Wednesday afternoon as the front aloft passes
through North Texas. Given the uncertainty in this precipitation
potential, will forgo adding it to the TAF, but will need to be
revisited in case more guidance latches on to the development of
this precipitation.



.UPDATE... /Issued 1058 PM CDT Tue Sep 25 2018/

A few showers have managed to develop mainly across North Texas
east of Interstate 35. The area in which these showers have
developed does have a bit more moisture compared to the rest of
the region, with generally 1.5-1.8 inch PWATs. A slight weakness
in heights also dominates across the east due to a departing
shortwave that had surged out of the Gulf of Mexico.

On the western front, the much anticipated cold front is now
moving into Young and Montague counties. Behind the front, winds
will pick up to around 15 mph, gusting up to 25 mph. This front
will continue moving to the southeast through the night into the
early morning hours. It continues to lack enough moisture for
shower/storm development, with the only ongoing convection
remaining across West Texas. With the upper level support lagging
behind to the west, the better chances for precipitation will
likely occur after the cold front has come through. Still can`t
rule out the development of showers and isolated storms, but given
the main shortwave is still across New Mexico, latest thinking is
that the rain will be slightly delayed behind the front.

The main changes were made to the PoPs to account for observed
radar trends as well as forecast trends. Temperatures were changed
by a degree or two depending on the placement of the cold front,
as well as adjusted the wind field to account for the latest
thinking on FROPA timing.



.SHORT TERM... /Issued 402 PM CDT Tue Sep 25 2018/

A shortwave trough can be seen on satellite moving across the
Central and Northern Plains this afternoon. The system is
accompanied by a cold front, which stretches from Northwest Texas
to Missouri and will push southeast overnight as the upper level
system moves east. The front will enter the northwest counties
this evening before crossing the I-20 corridor during the overnight
hours. Little in the way of forcing aloft will be present due to
the displacement of the upper level feature well to the north of
the region, but there should still be enough lift to generate
scattered showers and perhaps an isolated thunderstorm or two
tonight in the vicinity of the front. A shift to north winds and
cooler weather can be expected behind the cold front, with
Wednesday morning lows ranging from near 60 across the northwest
to the mid and upper 60s along the I-20 corridor. Areas to the
south will remain in the 70s prior to the arrival of the front
later Wednesday morning.



.LONG TERM... /Issued 402 PM CDT Tue Sep 25 2018/
As the cold front plunges through the region on Wednesday,
refreshing north winds will steadily reduce the humidity. In areas
north and west of the Dallas/Fort Worth Metroplex, daytime
temperatures may remain in the 60s. But the late arrival of the
cooler air into Central and East Texas means temperatures may
still reach the 80s Wednesday afternoon, despite persistent cloud
cover. Scattered showers will be possible regionwide, including
areas well behind the surface front, but there will be two primary
focus areas for precipitation, for which we will highlight likely
PoPs on Wednesday. One will be in our southeastern zones,
associated with the frontal forcing, near and just behind the
surface boundary. The other will be in the northwest where a
complex of postfrontal showers (and perhaps embedded
thunderstorms), linked with a mid-level disturbance, will
approach from the west. Both of these areas will remain focal
points for rainfall Wednesday night.

As the upper trough axis approaches Wednesday night, the low-
level cold advection will wane. But despite the reduced surface
winds, lingering cloud cover will prevent temperatures from
reaching their full radiational cooling potential. Even so, the
cool start to the night in the northwest means Thursday morning`s
lows will still fall in the lower 50s (and maybe in the upper
40s), the coolest temperatures since early May. The sun will
gradually emerge Thursday, but first in the cooler northwest,
assuring the entire region peaks in the 70s.

The return of southerly winds Thursday night and Friday will begin
the warming trend that will push temperatures back to normal by
the upcoming weekend. After a break in the rain chances on
Thursday, Gulf moisture will surge back into the region. Late-
season ridging will attempt to re-establish itself in the Desert
Southwest and in the Southeast, leaving Texas underneath a poorly
defined weakness aloft. With abundant bounday layer moisture and
little to impede diurnal convection, scattered showers and storms
may occur Friday through Monday, particularly across Central and
East Texas. Without any focus for initiation or any well-defined
upper support, this would be largely disorganized activity. Severe
weather is not anticipated, but isolated thunderstorms may disrupt
weekend plans.



Dallas-Ft. Worth    68  71  60  78  64 /  20  40  20  10   5
Waco                74  79  60  79  64 /  20  40  20  10  10
Paris               65  73  59  77  61 /  20  40  20  10   5
Denton              64  68  55  76  62 /  30  40  20  10   5
McKinney            64  71  57  77  62 /  20  40  20  10   5
Dallas              69  72  61  78  64 /  20  40  20  10   5
Terrell             66  76  60  78  65 /  20  40  20  10   5
Corsicana           71  79  62  80  64 /  20  40  20  10  10
Temple              74  81  61  78  65 /  30  40  20  20  10
Mineral Wells       63  65  55  75  60 /  30  50  20  10   5




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