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

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FXUS64 KFWD 221821
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
121 PM CDT Sat Jun 22 2019


.AVIATION...
/18z TAFS/

Decaying MCV just west of Stephenville at 18z will continue to
drift northward this afternoon and evening, with scattered
showers/isolated thunderstorms concentrated near its center. CAPE
is relatively low and convective inhibition is relatively high
near and north of this MCV center, and believe additional
development around the core will be limited through 00z. On the
other hand, higher CAPEs exist along the eastern outer periphery
of this feature, generally along a Austin-Palestine-Paris axis.
Believe scattered convection will form through the afternoon
within this nearly uncapped warm sector, where insolation is
better.

The DFW-area TAF sites are on the fringe of this better convective
potential across eastern N TX, and wouldn`t be surprised to see
scattered showers/isolated storms break out by 20z. However, think
the cloud canopy associated with the MCV will retard significant
storm formation this afternoon. Have elected - for now - to
forego VCTS mention at any of the DFW TAF sites or at KACT.
Otherwise, sky conditions should remain VFR into the evening
hours.

Short-term convective allowing models are struggling to develop
any organized activity south of the Red River, and show little
more than isolated activity prior to daybreak Sunday. Am inclined
to buy this scenario for now, given the better forcing for ascent
associated with the large shortwave exiting the Rockies will
remain focused from the TX Panhandle eastward into OK. As a
result, have not gone beyond a mention of VCSH through 18Z Sunday.
We`ll really need to watch how this setup unfolds, however, as any
unforeseen convective complexes that do form over OK/NW TX may
have favorable propagation characteristics that will take it into
N TX after 06z tonight. While unlikely, this could lead to a
band of strong/severe storms tracking across the DFW TAF sites
prior to daybreak Sunday.

With decent moist isentropic lift continuing over the area, expect
a return of MVFR ceilings at all TAF sites in the 07-09z
timeframe, eventually mixing to VFR conditions by 15-16z Sunday.
A healthy southerly windflow will persist throughout the forecast
period, gusting at times this afternoon in the 24-28knot range.

Bradshaw

&&


.SHORT TERM... /Issued 310 AM CDT Sat Jun 22 2019/
/Through Tonight/

Relatively low predictability exists regarding convective chances
over the next 24 hours. Those with outdoor activities today
through tonight should have methods of monitoring the weather
with the potential for scattered strong storms throughout this
time period. Increased cloud cover should keep temperatures a
couple degrees lower than yesterday, preventing heat indices from
climbing above 105 for most locations, thus no heat headlines are
advertised.

Similar to the past several days, an open warm sector with 70+
degree dewpoints will exist across the region, with temperatures
expected to climb into the upper 80s and 90s. Steep lapse rates
exist through the mid levels, which will yield very strong
instability through the peak heating hours as surface based
inhibition erodes. The main question mark through the day will be
the lifting mechanisms, and whether they will be sufficient to
initiate and sustain deep moist convection. A subtle upstream
shortwave exists across West Texas which will pivot over the area
today. In addition, there is some indication that a convectively
induced vorticity lobe from ongoing convection across southwest
Texas (or perhaps a smaller scale MCV feature) may join with the
larger scale impulse within southwesterly flow aloft. Should this
occur, these features could allow for scattered convective
initiation attempts through the afternoon hours today, although
they would be highly disorganized without a the presence of a
focusing surface boundary. Given the magnitude of instability but
modest shear, a localized threat for borderline strong/severe
multicellular storms could exist, with a potential for hail and
downburst winds. Confidence in coverage, placement, and timing are
all rather low through this afternoon/evening, so modest broad
PoPs have been advertised. A plausible alternate scenario through
the afternoon is that no convection is able to develop at all if
lift is more absent compared to what guidance currently indicates.

Regardless of how things unfold this afternoon, additional
convective chances may exist this evening and tonight, as
convection to our northwest grows upscale into an MCS. While a
complex in this environment should exhibit elements of both
upwind and downwind propagation, its unclear which may be favored
at this point. Upwind propagation would favor a more southeastward
motion, possibly steering the complex into North Texas late this
evening and overnight, while downwind propagation would keep most
activity to the north in Oklahoma. There could at least be a
lower-end strong/severe wind threat, especially near the Red
River should a complex remain robust into the overnight hours.
Areas south of I-20 are largely expected to be dry tonight, unless
a complex maintains much better organization than currently
anticipated.

-Stalley

&&

.LONG TERM... /Issued 310 AM CDT Sat Jun 22 2019/
/Sunday through Next Weekend/

Overnight convection should exit to the east Sunday morning. We
will then shift our focus back to the northwest where an
unseasonably deep upper trough will be making its way out of the
Rockies and into the Plains. At the surface, a front will extend
from a low pressure center near Kansas City southwestward across
Oklahoma and into Northwest Texas. A second low will develop
Sunday afternoon between Wichita Falls and Childress, with a
dryline extending southward from the low.

Thunderstorms will initiate along the front and the dryline by
late afternoon to the west and northwest of the region as dynamic
forcing from the upper trough arrives. Convective initiation will
occur in an area where CAPE on the order of 5000 j/kg will exist,
allowing storms to quickly become strong to severe with large hail
the initial primary threat. 25 KT of unidirectional deep layer
shear will likely result in activity quickly evolving into a
linear complex while entering the northwest zones, with damaging
winds becoming the primary severe weather concern.

A 40-50 MPH low level jet should help maintain the MCS as it
propagates southeastward across the region Sunday night. There is
still some uncertainty regarding the exact timing, but a rough
estimate would be the northwest half of the region prior to
midnight, then the southeast half after midnight, but is subject
to change depending on the mesoscale environment and subsequently
when/where initiation occurs. Along with damaging winds, localized
flash flooding will be possible, particularly within the southern
portion of the complex where west-east training of storms will be
most likely.

The storm complex should continue to work its way south through
Central Texas Monday morning. It is possible that activity
dissipates before exiting to the southeast. If so, redevelopment
Monday afternoon would be likely, and chance POPs have been kept
across the southern counties to account for this possibility.

Heights will be on the rise again by Tuesday as the upper trough
heads for the East Coast and a ridge builds in from the
southwest, with 590+ DAM 500mb heights overhead by midweek.
Normally the expectation would be hot and rain-free weather as a
result. In this case, however, the ridge axis will be centered to
the west of the area, allowing weak ripples in the northwest flow
to generate mainly diurnally driven convection. This warrants the
continuation of chance POPs for both Tuesday and Wednesday.

By Thursday, the ridge axis back away even farther to the west
while an easterly wave moves in from the Mississippi Valley.
Forcing for ascent will be modest at best, so at this time POPs
will only be in the slight chance category and mainly east of I-35
Thursday through next weekend. Otherwise, outside of
thunderstorms, temperatures should be near seasonal normals
through the end of the period.

30

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    92  76  92  72  89 /  20  40  30  70  20
Waco                93  77  90  75  89 /  20  20  20  70  30
Paris               90  75  87  68  85 /  20  50  40  80  50
Denton              90  75  90  70  89 /  30  40  40  70  10
McKinney            91  75  89  71  87 /  20  40  30  70  20
Dallas              93  77  92  73  89 /  20  40  30  70  20
Terrell             92  77  89  72  87 /  20  30  30  60  30
Corsicana           93  76  90  74  87 /  20  20  20  70  40
Temple              93  77  91  75  89 /  30  20  20  60  40
Mineral Wells       90  75  90  70  88 /  30  40  60  70  10

&&

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

$$

66



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