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

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377
FXUS64 KFWD 250543 AAB
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
1243 AM CDT Mon Mar 25 2019


.MESOSCALE UPDATE...
Strong to severe thunderstorms continue at this hour across North
Texas along a cold front and numerous convective outflow
boundaries. Discerning the cold front is a little difficult due to
the convective outflows, but 925mb data from regional VWP appears
to paint the picture a bit better. This data suggests that the
true cold front was located near and along a line from Fort Smith,
AR, to Denton to near San Angelo. Storms to the south of this
feature will have the potential to remain surface based and will
pose the greatest large hail and damaging wind potential. Where
low level flow has not veered associated with the low level
pressure/height trough, an environment slightly more conducive to
tornadoes has developed...and this is mainly across East Texas
(our far eastern counties south of I-30). With time, low level
flow should veer and diminish this threat. Storms rooted along or
just above the surface cold front will likely pose mainly a large
hail threat, though if convective downdrafts can penetrate the low
level stable layer, a damaging wind threat may continue.

The overnight period presents a challenge with regards to
additional convective development. With a sharp cold front
plowing into an airmass characterized by low to mid 60 degree
dewpoints, additional development is possible. With deep layer
shear plentiful (40-50 knots) and MUCAPE near 1000 J/kg...the
severe weather potential could continue over the next 2-4 hours.
As such, SVR Thunderstorm Watch 33 has been extended in time
through 4 AM. Alterations to the watch are possible, including
extensions in area.

Bain

&&


.AVIATION... /Issued 1140 PM CDT Sun Mar 24 2019/
/06z TAFs/

Challenges: Slower FROPA timing until shortwave can pass east of
here, residual linger VCTS with that in mind, and stratus/MVFR
cigs at Waco between 09z-15z Monday.

A surface cold front continues straddling the DFW Metro airports
from NE-SW with the front between KDFW-KAFW attm. As a shortwave
continues to move across through 09z, some CAMs are still showing
at least isolated TS develop in/near DFW airports through 07z-08z,
so out of caution, will continue VCTS wording til then. True FROPA
should occur at all DFW airports by 09z and after, as subsidence
in behind the departing shortwave helps support a southward
movement of the cold FROPA. Otherwise, cigs to remain VFR
throughout.

At Waco, prevailing SSW winds around 10 knots will continue
through 09z-10z, before a gradual cold FROPA occurs through 12z.
Best forcing for TS should remain east of Waco Regional and will
maintain a VCSH wording with MVFR cigs ABV FL020 through 14z-15z.
VFR returns after 15z Monday.

Winds behind the initial FROPA will be NW less than 10 knots,
before low level cold advection helps drive northerly winds 10-15
knots after 12z Monday.

05/

&&

.SHORT TERM... /Issued 331 PM CDT Sun Mar 24 2019/
/Through Tonight/

Thunderstorms are expected to accompany a cold frontal passage
tonight, the bulk of the activity east of the I-35 corridor. Some
of the storms may be severe, with large hail and damaging winds
the primary hazards.

The cold front has made only slow southward progress this
afternoon, with both parallel flow above the boundary and
insolation in the cold sector impeding its movement. A narrow
corridor of westerly flow between the front and the more humid air
to the southeast has diminished the thermal discontinuity at the
edge of the better moisture, and the veered flow ahead of this
dryline continues to negate any potential convergence. The
downslope winds within the humid air have warmed temperatures
into the 80s, the thin boundary layer moisture yielding only some
innocuous cumulus clouds. The more favorable instability is deeper
into the warm sector, along the I-35 corridor, where MLCAPE
values have topped 1000 J/kg. However, newly reinvigorated
westerly flow has re-established a weak cap that should prevent
any ambitious thermals from reaching their convective potential
this afternoon.

Our focus instead will remain farther east along the boundary,
specifically from Lake Texoma into southeastern Oklahoma, where
deeper moisture should allow for the initial precipitation-
producing convective elements. These discrete cells will intensify
quickly, initially posing a hail threat. The proximity of the
surface boundary may enhance the sub-cloud helicity, but the
veered flow and cloud bases near 3000 ft should limit the
tornadic potential. With increasing storm duration, there will
also be an attendant wind threat. Into the evening hours, the
resulting outflow will enhance the frontal boundary, and a steady
transition to a linear MCS should occur as the activity passes
south of the I-20 corridor. The maintenance of this cold pool will
allow the complex to survive well beyond its separation from the
upper support (that will remain primarily north of the Red River
and into the Ark-La-Tex). Backbuilding will increase as the line
moves south into the deeper moisture, potentially impacting areas
west of the I-35 corridor (particularly those areas that are also
south of I-20), but the western reaches of the line may struggle
to maintain their intensity. Although the severe potential will
diminish during the early morning hours, the line may continue to
pose a damaging wind threat into the predawn hours in our
southeast zones.

25

&&

.LONG TERM... /Issued 331 PM CDT Sun Mar 24 2019/
/This Week into Next Weekend/

Following our bout of strong to severe storms across parts of the
region tonight, conditions will clear across North and Central
Texas on Monday. A few lingering showers and isolated storms may
affect the Brazos Valley through mid-morning, but with a front
continuing south, precipitation should be clear of our southern
counties by mid-day. While a strong storm or two cannot be ruled
out during the early morning hours, the severe threat will most
likely have diminished.

Surface ridging will build across much of Texas through Tuesday,
bringing near to slightly below normal temperatures during the
first half of the week. Skies should be considerably clearer than
prior days as well. However, we may have to watch the potential
of some lower-level cloud cover sneaking into the Red River Valley
and East Texas Monday and Tuesday, associated with cold-air
advection trailing weak impulses in cyclonic flow aloft.

Heights build over Texas mid-week and beyond, yielding a low-level
return flow regime and increasing moisture/multi-layered clouds
through the end of the week. A weak impulse and an uptick in
warm-air advection may promote a few showers Thursday, but chances
appear quite low and thunder seems unlikely, with only shallow
convective processes at work.

Rain and thunderstorm chances increase Friday into Saturday as
parcel buoyancy builds and the region remains under the influence
of west/southwesterly flow aloft. However, deterministic/ensemble
guidance still exhibit wide spread in the evolution of a sharp
impulse over the central Plains, the amplification of the
northern stream, and how amplified/active the southern stream
remains upstream of us. Regardless, the interaction of all these
features should allow a stout cold front to drive south across our
area late Friday into early Saturday, and this is generally when
the highest PoPs are forecast to exist. There is a possibility of
stronger storms, but widespread severe weather remains far from
certain (or even likely), as robust deep-layer ascent could very
well remain north of our area. This would lead to shallow frontal
ascent within a somewhat capped environment, which would likely
favor more anafrontal development. Still, the severe-weather
potential bears watching.

Temperatures fall noticeably behind the cold front next weekend,
and highs are expected to be several degrees below normal.

Picca

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    48  69  49  71  57 /   0   0   0   0   0
Waco                48  70  48  72  55 /   0   0   0   0   0
Paris               45  66  44  67  52 /   0   0   0   0   5
Denton              45  69  48  70  56 /   0   0   0   0   5
McKinney            45  67  47  69  55 /   0   0   0   0   0
Dallas              48  69  49  71  57 /   0   0   0   0   0
Terrell             46  69  46  70  54 /   0   0   0   0   0
Corsicana           48  67  47  69  54 /   0   0   0   0   0
Temple              49  70  48  71  56 /   0   0   0   0   0
Mineral Wells       44  69  47  72  56 /   0   0   0   5   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

24/05



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