NWS Area Forecast Discussion

FXUS64 KFWD 200450

Area Forecast Discussion
National Weather Service Fort Worth TX
1150 PM CDT Sat Jun 19 2021

...New Short Term, Aviation...

/Overnight through Monday/

Another clear and warm night will occur across North and Central
Texas as we remain primarily under the influence of strong ridging
centered to our west. Overnight lows will only fall into the mid
70s across most of the region. Weak mid tropospheric flow has
generally been unable to tap into appreciable moisture and a
relatively dry boundary layer has left most of the region warm but
lacking the higher humidity we saw earlier in the week. That will
begin to change on Sunday as our ridge axis shifts westward to
some extent and a shortwave trough digs into the Northern Plains
and Great Lakes region. This will send a cold front southward
through the Plains and induce a poleward mass response across
Texas due to falling pressures in the Plains. These southerly
winds will tap into a moisture rich western Gulf of Mexico where
buoy and oil platform observations indicate dewpoints in the upper
70s. This higher moisture is already spreading into Deep South
Texas and the Coastal Bend and will gradually spread northward
into our southeastern counties through the day Sunday.  Sunday
should be precipitation free across the region although some
scattered storms may develop across Southeast Texas during the
afternoon. It`ll be hot with high temps in the mid/upper 90s and
heat indices in the 99-102 degree range.

Boundary layer moisture will continue to increase particularly
east of I-35 Sunday night into early Monday as the cold front
moves through Oklahoma and approaches our northern counties during
the late morning hours. There continues to be a fairly
significant timing difference between the global guidance and the
higher resolution models with respect to the front. This will
clearly have implications on the temperature forecast as a slower
front will allow temperatures to quickly climb ahead of FROPA.
Latest forecast will trend toward the NAM/TTU WRF with respect to
timing (newest NBM guidance is slower now too) and we`ll keep
high temperatures in the lower 90s across most of the region with
mid/upper 90s across our southern counties. As the front moves
into an increasingly unstable airmass, thunderstorms should
develop and increase in coverage through the late afternoon and
evening hours particularly along and north of I-20. Meager lapse
rates and weak flow through 700 mb should limit the severe threat,
but we still can`t rule out a few severe wind gusts given the
strong instability. Storm chances will continue into Monday
evening as the front pushes into Central Texas.



.LONG TERM... /Issued 200 PM CDT Sat Jun 19 2021/
/Sunday night through next Saturday/

The big weather story in the longer-term part of the forecast
revolves around the cold front expected to sweep across the area
Monday afternoon and evening, bringing a round of scattered to
numerous showers and thunderstorms to the region. The rest of the
period features a return to hot, dry conditions with perhaps a
small chance of thunderstorms in the northern counties next

As noted in previous discussions, there continues to be noticeable
differences in the timing of this front between the faster GFS and
ECMWF solutions and the slower evolution offered by the NAM. Opted
to adhere closely to the NBM solution for the wind fields Monday,
which leans toward the faster timing of the two global models.
This would put the cold front along the Red River around 18z,
penetrating the counties north of I-20 during the afternoon, then
sweeping across the remainder of the forecast area between 00z-06z
Tuesday (Monday evening).

The large, stout mid-level shortwave trough accompanying this
cold front will be sliding through Kansas, Oklahoma and North
Texas during the afternoon hours, providing decent synoptic-scale
forcing for ascent. A few showers and thunderstorms should start
to break out across our northeastern counties during the early/mid
afternoon, become more widespread across much of the area from
mid/late afternoon into the early evening. MUCAPE values from the
GFS are advertised to exceed 3500 J/kg across much of the area.
While wind shear will be light, the presence of a robust cold
front in June implies at least some potential for a few strong to
severe thunderstorms during the afternoon and early evening, with
damaging wind being the main threat.

Painted the highest PoPs - generally in the 50-70% range - across
areas east of I-35 where deep layer forcing and CAPE will be a
little better. Did, however, hold onto chance PoPs across the
remaining northern and western counties, where enough forcing
along the front may be present to kick off at least scattered
activity during the afternoon. The bulk of the precipitation
should be exiting the southeastern portion of our forecast area by
06-09z, but did hold onto low PoPs across our extreme south for
the early morning hours Tuesday.

This cold front will temporarily usher in a period of cooler and
slightly drier conditions to North and Central Texas on Tuesday.
Under partly cloudy skies and with a nice northeasterly flow
regime, highs Tuesday should remain in the 80s areawide, which
will be a welcome relief from the 90s of recent days. This
interlude will be brief, however, as another upper level ridge
building episode commences over northern Mexico, Texas and
Oklahoma Wednesday and continues through Friday. Highs will
quickly recover into the mid and upper 90s across the forecast
area, and with southerly flow returning, dew points will climb
into the 70s over much of the region. Resultant heat indices will
likely penetrate the century mark by Thursday and Friday, and
renewed attention to heat safety rules will become necessary.

Another mid-level shortwave may flatten the ridge somewhat by
Saturday, and may also deliver another cold front near the
vicinity of the Red River during the latter half of next weekend.
Held onto small PoPs in the northern counties to account for
this, though believe the odds of precipitation  are actually
pretty low at this point.



/6Z TAFs/

VFR will continue through the period with southerly winds
increasing to 15 to 20 Sunday afternoon. In the 24-30 hr portion
of the DFW TAF, MVFR cigs are expected to overspread the region
late Sunday night into Monday morning and we`ll indicate this
around 8Z Monday.



Dallas-Ft. Worth    76  97  78  93  68 /   0   0   0  70  50
Waco                73  95  77  96  69 /   0   0   0  40  60
Paris               71  93  75  89  64 /   0   0   0  90  50
Denton              73  95  76  91  64 /   0   0   0  70  40
McKinney            73  95  77  90  65 /   0   0   0  80  50
Dallas              77  97  79  93  69 /   0   0   0  70  50
Terrell             73  94  76  92  66 /   0   0   0  70  60
Corsicana           74  95  77  93  70 /   0   0   0  50  60
Temple              72  95  76  95  69 /   0   0   0  30  60
Mineral Wells       71  96  75  91  64 /   0   0   0  60  40




NWS FWD Office Area Forecast Discussion