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

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FXUS64 KFWD 091110

Area Forecast Discussion
National Weather Service Fort Worth TX
510 AM CST Tue Mar 9 2021

...New Short Term, Aviation...

/Through Tonight/

Models are now showing slightly more veered low level winds just
above the surface that should allow a little more sunshine and
insolation for most by mid-late afternoon, especially our
northwest counties. I did warm up highs to between 75-80 degrees
northwest of a Cisco, to Jacksboro, to Bowie/Nocona line this
afternoon due to that area seeing more hours of sun versus other

Otherwise, the rest of a mostly cloudy, warm, and windy forecast
looks on track from my earlier discussion below.


Previous Discussion:
/Through Tuesday Night/

A strong 40-50kt LLJ will bring stratus northward through much of
the CWA by, or shortly after sunrise. Moisture within the
925-850mb layer should be deep enough to keep low level
stratocumulus around a good part of the day, though I can`t rule
out a few brief hours mid-late afternoon of some partial sunshine.
Spurts of denser mid-high clouds will also be present within the
fast zonal flow aloft, as periodic, fast-moving impulses lift east
across the Central/Southern Plains. Look for the cloudiness to
keep temperatures in check somewhat with high temps continuing
5-7 degrees above seasonal normals that are usually in the mid
60s. A strong southerly pressure gradient and partial mixing of
the strong 925mb winds will result in south winds 15 to 25 mph
with a few gusts in excess of 30 mph by midday.

Partly-mostly cloudy and breezy conditions continue tonight, as a
another south-southwest 45kt+ LLJ develops by mid evening over
the Southern Plains. Another stratus surge just after midnight
will result in cloudy conditions through daybreak Wednesday. The
mostly cloudy and breezy conditions will work in conjunction with
surface dew point temperatures s rising into the 50s for a little
warmer and more humid night Tuesday night. Lows Wednesday morning
will range from the mid 50s across East Texas to the upper
50s/lower 60s elsewhere. Though a sprinkle or two can`t be ruled
out late during the pre-dawn hours Wednesday morning.



.LONG TERM... /Issued 313 AM CST Tue Mar 9 2021/
/Wednesday through Monday/

A typical springtime pattern appears to be taking shape for the
mid and latter part of the week featuring breezy conditions, warm
overnight lows and periodic cloud cover, along with increasing
storm chances by Friday into the weekend. A well established low
level warm advection regime will be in place on Wednesday with
morning cloud cover giving way to some afternoon sunshine, pushing
high temperatures into the upper 70s and lower 80s. A shortwave
trough spreading into the Great Lakes region will help drag a cold
front into the Central Plains by Wednesday afternoon. This front
should remain well north of our area, but low/mid level flow will
veer ahead of this feature helping to advect a deep elevated mixed
layer over North Texas. This should effectively cap the region to
any deep convection through at least early Friday. We`ll have
some low rain chances across our far northeast counties on
Thursday where low level warm advection may lead to some showers
beneath the capping inversion.

Meanwhile, a deep upper low over the Southwest U.S. will become
pinched off on Friday between a trough over Eastern Canada and
another upstream trough approaching the Pacific Northwest. This
feature won`t stall out completely given the expected nudge it
should receive from the Pacific Northwest trough, but it will slow
it enough to create some timing uncertainty with respect to
rain/storm chances across North Texas into the weekend.

On Friday, continued southerly flow will lead to a very warm start
to the day. Morning lows may not fall much below 70s in urban
areas and it should remain cloudy most of the day. A deepening
moist layer beneath the cap should lead to an increase in
scattered showers through the day so we`ll have increasing PoPs
by afternoon with the best chances north of I-20. The old frontal
boundary will still be draped across Oklahoma on Friday, and this
is where the better chances for thunderstorms should occur.

Uncertainty starts to increase with respect to timing and severe
weather potential for Saturday into Sunday. Our upper trough to
the west will spread across the 4-corners region on Saturday with
a more typical spring time severe weather setup taking shape. The
old cold front to our north will begin to retreat as a warm front
through Oklahoma while a dryline will sharpen and move east
through West Texas by Saturday afternoon. Forecast soundings
continue to indicate a fairly stout capping inversion will remain
in place through most of Saturday, with some potential for
thunderstorms to develop along the dryline to our west. We`ll have
fairly high PoPs west of I-35 for Saturday afternoon, but right
now I`m inclined to think most of this activity will be showers
beneath the cap, with more robust convection off to our northwest
closer to the warm front/dryline intersection and in proximity to
the better upper forcing.

As the upper trough spreads into the Plains late Saturday night
into Sunday, it will take on more of a negative tilt with
impressive shear profiles. Flow at 500 mb strengthens to near
100 kt which almost certainly suggests a significant severe
weather threat in the presence of modest surface based
instability. However, most of the model guidance is quite bearish
on instability, likely owing to the overnight timing and eastward
surging Pacific front. Both the GFS and EC ensemble probabilities
of at least 500 J/kg of CAPE across North Texas are below 30%
through this time period, which doesn`t bode well for severe
weather prospects. Nonetheless, with such strong wind fields
associated with this upper trough and the potential for timing
errors in the forecast, we`ll continue to mention a severe weather
threat late Saturday into Sunday. The highest PoPs for this
forecast will be early Sunday morning with the system moving east
by late in the day. Drier weather and the potential for increasing
fire weather concerns can be expected by early next week.



/12z TAFs/

Concerns remain the same as the 06z TAF discussion below.

Despite having 40-50 knot SSW flow 1-2 kft above the surface,
surface winds 10-15 knots with occasional gusts in excess above 20
knots should keep the LLWS speed shear minimized enough for no
mention in the 12z TAFs.

With the LLJ expected to continue to veer after 13z, I did make
some adjustments to add a TEMPO group for IFR/BKN009 for the SE
D10 terminals of KGKY/KDAL before 15z. Otherwise, it appears
western D10 terminals KFTW/KAFW may not see MVFR cigs until after
14z...even possibly 15z if CONSHORT/GLAMP data were to be
believed. Otherwise, I sped up improvement to VFR cigs to 18z per
latest guidance, with a return to MVFR cigs by/after 06z Wednesday
tonight once again as a 50-60 knot LLJ is expected to develop
after 03z Wednesday.

Otherwise, wind trends for sustained and gusts remain the same as
in the 06z discussion below.


Previous Discussion:
/06z TAFs/

Challenges: MVFR stratus, with possible brief IFR at Waco this
morning. Return of MVFR stratus late tonight(after 06z Wed).

VFR conditions with FEW-SCT Cu and BKN250 will continue through
09z-11z this Tuesday morning, as 40-50kt 925mb winds help draw
stratus northward. All terminals should see low MVFR cigs by
12z-13z, before rapidly warming surface temps help raise cigs into
high MVFR late this morning.

Cigs will continue to lift into low VFR by 20z and continue VFR
through the evening hours. 45-55kt southerly winds just above the
surface by mid evening should help draw MVFR cigs back north a
little faster tonight with arrival just after 06z Wednesday.

A continued strong southerly surface pressure gradient and mixing
should result in gusty south-southeast winds 15-20 knots with
gusts 25-30 knots. The gusty winds will continue tonight as the
surface temperatures remain mild and keep the surface-boundary
layer semi-coupled with the strong LLJ noted previously.



Dallas-Ft. Worth    73  60  78  66  79 /   0   0   5   0  10
Waco                74  58  80  64  80 /   0   5   0   0  10
Paris               70  55  75  62  75 /   5   0  10  10  30
Denton              73  59  78  64  80 /   0   0   5   5  10
McKinney            73  59  78  64  78 /   0   0   5   5  20
Dallas              74  61  79  66  79 /   0   0   5   0  10
Terrell             74  57  79  64  79 /   5   0   5   0  20
Corsicana           74  57  79  65  79 /   5   0   0   0  10
Temple              75  58  80  64  80 /   5   0   0   0   5
Mineral Wells       74  58  79  61  81 /   0   0   0   5   5



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