Forecast Discussion for Dallas/Ft. Worth, Texas

FXUS64 KFWD 112101

Area Forecast Discussion
National Weather Service Fort Worth TX
401 PM CDT Tue May 11 2021

...New Long Term...

.SHORT TERM... /Issued 1218 PM CDT Tue May 11 2021/
/Through Wednesday/

A persistent and deep upper-level trough remains anchored over
much of the CONUS this morning. At the surface, a 1005 mb low is
centered near Truth or Consequences with a stationary front
extending from this low across the Trans-Pecos to near San
Antonio, then eastward across the TX/LA coastal plains. The warm
sector south of the stationary front is characterized by
temperatures in the lower 80s and dewpoints in the lower 70s. The
cool sector north of the stationary front consists of temperatures
in the upper 50s and dewpoints in the lower 50s.

Through the rest of the afternoon, widespread showers and
thunderstorms are expected across much of the FWD CWA, with these
thunderstorms occurring within two regimes:

1. Ongoing convection across western North TX being driven by an
approaching upper-level shortwave trough.

2. Developing convection across Central TX near the stationary

The first of these two regimes, as noted above, is being driven by
an approaching upper-level shortwave trough evident on GOES-E
water vapor channel imagery. This convection is rooted above the
boundary layer owing to the sharp frontal inversion noted on the
12Z FWD RAOB. Despite the elevated nature of this convection, it
is nevertheless able to tap into MUCAPE values in excess of 1,000
J/kg given the exceptionally steep mid-level lapse rates. Some of
the stronger cores within the widespread precipitation shield may
be capable of producing large and severe hail.

The second convective regime, developing across Central TX, is
being driven by convergence along the stationary front. GOES-E
visible channel imagery already shows agitated Cu near the
stationary front with IR channel imagery showing cooling cloud
tops. Some surface-based instability does exist in the vicinity of
the stationary front with LAPS analysis indicating 1,000+ J/kg
SBCAPE just south of the front. While thunderstorms that form just
north of the front are unlikely to be surface-based, parcels will
likely be rooted fairly low in the troposphere and will have
access to more than 2,000 J/kg MUCAPE. This will mean severe hail
will be possible in these areas well. Perhaps more significantly,
the large CAPE profiles and PWAT values approaching 1.75" will
support heavy rainfall, especially if convection begins to train
near the stationary front. This potential certainly exists as
backward-propagating Corfidi vectors are oriented nearly parallel
to the stationary front. HREF probability-matched mean QPF shows a
potential for 3-5 inches of rainfall possible near the stationary
front. For this reason, the Flash Flood Watch will continue
through 12Z (0700 CDT) Wednesday. In addition to the flash flood
potential, there will be a possibility of minor river flooding
within the Trinity River basin below Trinidad, with minor to
moderate flooding possible within the Neches basin.

Convection should end from northwest to southeast late tonight as
the axis of the upper-level trough begins to move east of the
region. Cloudy and seasonably cool conditions will persist through
Wednesday however, with some light rain showers likely continuing
across parts of Central TX.



/Late Week Into Early Next Week/

Dry northwest flow will evolve over the Southern Plains late this
week in response to our rapidly departing and dampening trough
and increasing shortwave ridging across the Southwest U.S. Surface
high pressure building in behind Wednesday`s cold front will
result in mostly sunny and mild conditions Thursday with highs in
the upper 60s to lower 70s. As the surface ridge shifts east on
Friday and lee side cyclogenesis deepens across E CO/W KS, breezy
southeasterly winds will slowly draw modified moisture back
northward from the Gulf of Mexico with a slight increase in
humidity. High temperatures will warm to near 80 degrees across
parts of Central Texas and western North Texas. Flow aloft will
dampen with brief shortwave ridging aloft occurring Friday night
and early Saturday, before a weak mid level impulse arrives across
the area Saturday afternoon and night.

Breezy southerly winds 15 to 20 mph will continue to pull rich
surface moisture up from the Gulf with surface dew points in the
60s across the CWA. This rich moisture will combine with highs
warming well into the 80s to increase instability across the area
on Saturday. Isolated to scattered showers and thunderstorms are
expected to increase across the southwest half of the area in the
afternoon, then continue Saturday night with the addition of
strong warm advection within the 925mb-850mb layer. Though better
surface-based instability will remain across the Permian Basin,
West-Central Texas and the Big Country, mid level lapse rates
of around 7 deg C/km are forecast across the western counties.
This may lead to a few strong storms with hail and gusty winds. A
stronger, but progressive mid level wave arrives on Sunday with
continued warm temperatures in the lower-mid 80s and plenty of
Gulf moisture around within the surface-boundary layer. Though
details are very difficult to determine 5 days out, this sneaky
system could provide a risk for a few strong to severe storms
across at least the western half of the area where models are
currently forecasting steep mid level lapse rates and plenty of
surface-based instability. The one mitigating factor will be the
very marginal deep layer flow and shear being advertised by the
GFS/European models only 25-35 knots from the northwest. This
would likely result in a low coverage severe weather threat on
Sunday and Sunday night.

The longwave mid level pattern early next week does appear to
show a fairly wet and stormy signal for Monday and Tuesday, but
details remain very murky and uncertain. The deterministic
European model and its ensemble are much deeper with an
approaching mean longwave trough over the Rockies and Great Basin,
while the GFS is much more progressive, open, and less amplified.
Anytime I see such discrepancies, I tend to lean toward the
European model for its recognition of deeper energy within the
mid-upper levels and its better track record in the Day 5-7
period. This has me leaning toward the wetter NBM and WPC PoPs for
the early part of next week with seasonably warm and humid
conditions continuing. Being we`re in one of our two peak wet
seasons, this isn`t anything out of the ordinary. Any severe
weather threat will remain uncertain considering precise environmental
analysis is very difficult this far out, though the lift and
kinematics are present. What is more certain may be the potential
for rounds of heavier rainfall and potential flooding, as soil
moisture continues to remain elevated. We`ll continue to expound
on these extended periods in more detail as model confidence
becomes higher with subsequent sampling with future upper air runs
as we move through the end of the week into next week. Stay



.AVIATION... /Issued 1218 PM CDT Tue May 11 2021/
/18Z TAFs/

Widespread TSRA expected to impact the D10 TRACON shortly. For
this reason...TSRA will be prevailed at D10 TAF sites through the
next few hours. TSRA will then begin to shift east and away from
D10 TAF sites later this evening with impacts continuing to the
Bonham and Cedar Creek arrival gates as well as eastbound
departures. IFR will prevail through the TAF period with
intermittent LIFR CIGs possible during SHRA/TSRA. N-NE winds 10-13
KT will continue. Convective impacts will begin to diminish after

Convective timing is a bit more uncertain at KACT, but at least
intermittent TSRA can be expected through the evening. Amendments
may be required as the convective evolution across Central TX
becomes more clear. IFR will continue through the TAF period with
LIFR CIGs likely by Wednesday morning. Winds will be N-NE 8-11 KT.



Dallas-Ft. Worth    55  65  54  73  56 /  40  10  10   0   0
Waco                58  65  55  73  54 /  60  20  10   0   0
Paris               54  64  50  71  51 /  50  10  10   0   0
Denton              52  64  51  72  53 /  30  10  10   0   0
McKinney            54  65  51  73  53 /  40  10  10   0   0
Dallas              57  65  55  74  57 /  40  10  10   0   0
Terrell             54  65  52  73  53 /  60  20  10   0   0
Corsicana           57  65  55  73  54 /  70  20  10   0   0
Temple              58  65  55  73  54 /  70  30  10   0   0
Mineral Wells       53  63  53  71  53 /  30  20   5   0   0


Flash Flood Watch through Wednesday morning for TXZ095-105>107-



NWS FWD Office Area Forecast Discussion