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

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018
FXUS64 KFWD 260853
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
353 AM CDT Wed Apr 26 2017

.DISCUSSION...
A busy day ahead as a strong surface cold front moving into the
Wichita Falls/Abilene areas moves toward the I-35 corridor
through sunrise this morning. The well-advertised, vigorous upper
trough responsible for severe weather across Eastern Oklahoma this
morning will continue to swing quickly east across the Southern
Plains today. A plume of surface dew points of 65-70 degrees was
surging northward just ahead of the cold front and north up
through the I-35 corridor and points east. This is maintaining
good surface instability despite the non-favorable time of day. In
addition, very strong large-scale ascent will arrive by/after
sunrise to help lift/moisten the modest EML/capping inversion
through mid morning. This should allow for a broken line of strong
to severe storms to develop along or just east of I-35 after 6-7
am CDT, then move east with the cold front through the morning
hours, before exiting our far eastern counties early-mid
afternoon. Mid level lapse rates on the order of 7-8 deg/C and
40-50 knot southwest effective shear will likely result in severe
storms across especially the eastern third of the CWA. Large hail,
damaging winds, and frequent lighting will be the primary
hazards. Though the tornado threat is non-zero, 0-1km winds and
shear are already veering southwesterly as well with the more
significant threat for tornadoes to be east/northeast of our area
later today.

In addition to the severe weather threat with the cold front,
strong CAA for this late in the season and a very dynamic, strong
pressure gradient will likely result in windy conditions with
very gusty west-northwest winds 20 to 25 mph, with a few gusts
between 35 to 40 mph during the afternoon hours. Winds should
rapidly decouple after dark with surface high pressure settling in
quickly for the overnight. Lows Thursday morning will range from
the lower 40s along the Red River to around 50 degrees within
immediate urban areas and across Central Texas. Downright chilly
for the last week of April! Dry near zonal or dampened cyclonic
flow aloft will result in mostly sunny skies Thursday, as a return
of south breezes and low WAA allow for a range of high
temperatures of 75-80 degrees in the east, to 85-90 degrees in the
west. It will be fairly breezy again during the afternoon hours
and lasting into Thursday night.

Gulf moisture returns rapidly northward Thursday night and Friday
morning, as a surface warm front lifts readily northward back
into the area. Return stratus clouds, breezy conditions, and the
low level moisture will result in much warmer morning on Friday.
With mid level heights rising (or weak mid level ridging), it
appears the warm front will stall somewhere west and north of
I-20, with a surface dryline nudging into our far W/SW counties.
While all this is occurring, another upper level system is
deepening across the Southern Rockies, with a lead shortwave
ejecting eastward across the Southern and Central High Plains. A
low "conditional" chance for thunderstorms will be possible near
the dryline and old frontal boundary draped somewhere across the
far N/NW counties. With SW flow aloft over the area and some
EML/cap expected, if a storm or two does develop, it would likely
become severe with the strong winds aloft and very high SBCAPE
values and mid level lapse rates at 8 deg C/km or higher. These
would likely be supercells with very large hail, damaging winds,
and could potentially be tornado along and just north of where the
stalled front sets up. Again, this very "conditional", but worth
monitoring.

Otherwise, have held to increasing convective chances, north of
I-20/I-30 Friday Night within the nose of the strongest WAA, then
across most of the area Saturday into Saturday evening, as the
upper system rotates across the area and brings substantial large-
scale ascent across the area, along with a cold front late
Saturday into Saturday night. All modes of severe weather will be
possible on Saturday, with potential for flash flooding along and
east of I-35 and north of I-20 where rainfall totals by Sunday
morning may reach between 2-4 inches. Definitely worth noting
along with the severe weather threat.

Much cooler and brisk conditions arrive after daybreak Sunday
with convective chances shifting east away from the area. Strong
CAA arrives in wake of yet another strong late season cold front
with highs hard pressed to get out of the 60s most areas. Cyclonic
flow aloft will transition to zonal or even weak ridging, which
will result in dry conditions with gradual moderating temperatures
each day early next week. Another upper trough possibly affects
the area again mid-late next week, but as of right now, models as
expected are struggling on specifics of organization, speed, and
track of features.

05/

&&

.AVIATION...
/ISSUED 1140 PM CDT Tue Apr 25 2017/
Breezy south winds will persist overnight with occasional gusts
to around 25 kts or so, and MVFR cigs will prevail at all sites. A
nocturnal bore feature can be seen entering the region on radar
imagery, and recent surface observations from KRPH indicate that a
northwest wind shift accompanies this feature. Should this
move across the Metroplex sites, any wind shift would be brief,
with a quick return to breezy southerly winds.

The main change from the 00Z TAFs was to introduce a mention of
VCTS at all Metroplex sites as it seems likely sufficient lifting
will occur to erode the lingering capping inversion as the main
cold front arrives. Waco looks to remain far enough removed from
the better forcing to preclude an explicit mention of thunder, but
have inserted a brief window of VCSH to account for southwestward
precip development. An abrupt northwest wind shift will accompany
the front, which should arrive between 13-14Z at western sites,
and 14-15Z across the eastern Metroplex sites and Waco.
Convective chances will quickly come to an end by 15-16Z as cooler
and drier air filters in. Cloud bases will then begin to rise,
eventually to VFR Wednesday afternoon.

Winds will then slacken as high pressure builds in overhead, and
airports will likely be able to return to south flow late
Wednesday evening. As winds go nearly calm, there is some
potential for a shallow layer of fog to materialize, but this
potential is too low to include in the TAFs at this time.

Carlaw


&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    73  50  81  65  86 /  40   0   0   0  20
Waco                77  48  83  66  88 /  20   0   0   0  10
Paris               69  45  75  59  82 /  80  10   0   5  30
Denton              67  46  81  62  85 /  40   0   0   5  20
McKinney            71  46  78  62  84 /  60   0   0   0  20
Dallas              75  51  81  66  87 /  40   0   0   0  20
Terrell             71  46  80  62  85 /  60   0   0   0  20
Corsicana           77  48  79  65  87 /  40   0   0   0  10
Temple              83  50  83  66  88 /  10   0   0   0  10
Mineral Wells       68  45  86  62  88 /  10   0   0   0  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from noon today to 7 PM CDT this evening for
TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175.

&&

$$

/05



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