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

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FXUS64 KFWD 220037 AAA

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
737 PM CDT Sat Apr 21 2018

/00Z TAFs/

What began as a lone supercell in western North Texas near the
center of a surface low transitioned into a meso-beta convective
complex as the associated cold front approached the I-35 corridor.
At 00Z (7pm CDT), the Dallas/Fort Worth Metroplex was near the
north end of the advancing system, which stretched from the
surface low southward along the cold front. Although the
convective elements are ingesting rather stable surface parcels,
the mechanical lift along the frontal boundary and the further
enhancement of forcing resulting from the surface low has allowed
the complex to maintain its intensity. Although it has now passed
east of the Metroplex TAF sites, the tail end will affect Waco
01-02Z (8-9pm CDT). This is not expected to be severe, but small
hail and gusty winds may impact the airfield.

After the convective activity ends this evening, north flow will
dominate the remainder of the TAF periods. Some gusts will exceed
30kts during the daylight hours of Sunday morning.

Ceilings below FL020 will prevail until early afternoon. Moisture
will remain trapped in the postfrontal layer under FL010, and
during the early morning hours Sunday, a prolonged period of IFR
ceilings will likely result. This layer will lift as the
postfrontal layer deepens, but a VFR cloud deck may remain much of
the day Sunday, particularly across Central Texas.



.SHORT TERM... /Issued 340 PM CDT Sat Apr 21 2018/
A large scale upper level low pressure center will continue
eastward into the Southern Plains this evening while its
attendant surface low and cold front work their way across North
and Central Texas. After one round of showers and storms earlier
today, a second round of convection accompanying the surface low
can be seen on RADAR across the northwestern part of the forecast
area. Storms had been struggling to survive, but with surface
heating storms will increase in coverage and intensity as they
approach the I-35 corridor late afternoon/early evening.

Visible satellite imagery reveals an area of good insolation over
the western third of the region, and it will be interesting to see
how things evolve over the next few hours as storms move into the
area of increasing instability. Being that good deep layer shear
values are already in place, the current thinking is that a few
storms will become capable of producing large hail and damaging
winds as a surface based CAPE approaches 1000 J/KG. This threat
will not be wide-spread, but will likely affect areas along I-20
including the DFW Metroplex this evening. A low-end severe threat
will continue later into the evening as storms push east of
I-35/35E and south of I-20. The severe threat would most likely
shift primarily to damaging wind gusts as storms evolve into a
linear mode.

Precipitation will quickly push east and south of the forecast
area around midnight along with the cold front. Breezy conditions
can be expected during the overnight hours as northwest winds
usher in a cooler and drier airmass behind the front. Low
temperatures tonight should range from the mid 40s in the
northwest to mid 50s in the southeast.



.LONG TERM... /Issued 340 PM CDT Sat Apr 21 2018/
/Sunday through Friday/

The upper level low that is currently over western Kansas will
have moved to just south of Fort Smith, Arkansas by 7 AM Sunday.
Clouds will decrease from southwest to the northeast during the
day but the northeastern zones will remain mostly cloudy past
sunset due to wrap around moisture from the upper level low. It
will be breezy and cool. Winds will be northwesterly at 10 to 20
mph with some gusts over 25 mph. Highs will range from the lower
60s northeast to the lower 70s across Central Texas.

Wind speeds will decrease to 5 to 10 mph Sunday night. The upper
level low will have moved across Arkansas during the day Sunday
will into the Tennessee River Valley by daybreak Monday.  Skies
across North and Central Texas will be mostly clear across all
but the northeastern zones where some wrap-around moisture from
the upper low will remain. Lows will be in the mid 40s to lower

Dry and warmer weather is expected Monday and Tuesday with mostly
sunny skies expected area wide. Highs will be in the upper 60s
northeast to the upper 70s southwest Monday and expect mid 70s
northeast to mid 80s southwest Tuesday.

A northern stream shortwave is forecast to move southeast
through the Northern and Central Plains Tuesday and Tuesday
night through the Arklatex by sunset Wednesday. The moisture
return will not be great with this shortwave, but with a cold
front expected to move into the forecast area Tuesday night and
lift above the frontal boundary Wednesday, we will have 30-50
percent PoPs for Tuesday night and Wednesday. With the increased
cloud cover and chances of precipitation, it will be cooler
Wednesday with highs in the mid 60s north to the lower 70s across
Central Texas.

The model solutions really diverge on the possibility for a late
week system. Given the low confidence have just placed 20 to 30
percent PoPs for Thursday night and Friday.



Dallas-Ft. Worth    51  69  51  75  55 /  60   0   0   0   0
Waco                52  71  49  77  52 /  50   0   0   0   0
Paris               51  62  52  69  51 /  70   5   5   5   0
Denton              48  67  49  73  51 /  50   0   0   0   0
McKinney            50  66  50  72  51 /  60   0   0   0   0
Dallas              50  69  53  75  55 /  60   0   0   0   0
Terrell             51  68  51  74  52 /  70   0   0   0   0
Corsicana           53  69  50  74  53 /  60   0   0   0   0
Temple              52  72  50  77  53 /  40   0   0   0   0
Mineral Wells       47  68  47  75  51 /  30   0   0   0   0




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