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

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745
FXUS64 KFWD 251123
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
623 AM CDT Tue Apr 25 2017

.AVIATION...
Strong low level flow will be the rule today in advance of a
deepening upper trough and a cold front. A 50 to 60 KT southerly low
level jet should partially mix to the surface later this morning,
resulting in surface winds mainly in the 20 to 30 KT range.
Meanwhile, a strip of low clouds has developed south of the
Metroplex, which will need to be watched. The current thinking is
that veering flow just off the deck should shunt the MVFR deck to
the east of TAF locations, though we may want to place a scattered
layer in the first few hours to the KACT and KDAL forecasts. It
does look like stratus will be more widespread as we head into
tonight, and cigs have been added to the 26/06Z time and beyond
(04Z for KACT).

Otherwise, a shift to northwest winds can be expected with FROPA
Wednesday morning, and has been added to the extended DFW TAF
accordingly. A stray shower along the front cannot be ruled out,
but it looks like convection will hold off until later in the day
when the front is well east of the TAF locations.

30

&&


.PREV DISCUSSION... /ISSUED 402 AM CDT Tue Apr 25 2017/
Several challenges the rest of the week into weekend, as we deal
with two separate strong upper level systems and surface
boundaries. Today will continue to see our first vigorous upper
trough deepening across the Rockies and into far Northern Mexico,
with strong southwest flow aloft likely continuing to keep our
elevated mixed layer (EML/capping inversion) very strong over
North and Central Texas. As this system deepens and slides
eastward toward the Plains States, a deep surface low will shift
east across Southwest Kansas and the Oklahoma/Texas Panhandles
this morning, thus allowing for a dryline to surge east into into
at least the U.S. 281 corridor, if not to between that highway and
I-35/35W. The WSR-88D profiler network indicates a pre-dawn LLJ
50-60 kts in the boundary layer. The expected warming
temperatures, strong pressure gradient, and unidirectional nature
of the south flow just above the surface will likely induce south
winds 20 to 25 mph with gusts up to 35 mph east of the dryline. A
Wind Advisory has been hoisted from late morning through midnight
tonight, as the boundary layer should remain semi-coupled even
past dark, with winds diminishing with the approach of a cold
front overnight and early Wednesday morning. In addition to the
winds, breezy and hot temperatures will occur both just behind and
ahead of the surface dryline this afternoon. Highs reaching the
lower-mid 90s and low humidity values will result in an elevated
fire danger across Western North Texas this afternoon. Luckily,
greening of small vegetation and grasses should limit any critical
conditions and explosive grass fire growth.

After a windy/breezy Tuesday night, the first upper level trough
will move east progressively over the Central/Southern Plains on
Wednesday, before exiting quickly to the east of our area
Wednesday Night and Thursday. A pre-frontal surface trough and
cold front will move quickly through much of the area and into our
eastern counties by midday. The EML/capping inversion will be key
to timing of strong-severe thunderstorm development across mainly
far northeast and eastern counties by late morning/midday
Wednesday. A few isolated/elevated storms could occur beforehand
across the immediate Red River Valley, but think our far eastern
counties, mainly north of I-20 will be the initiation area. We
believe this area will see a 2-3 hour window for rapid development
of strong-severe storm at midday, before the upper level system
and cold front readily shift a broken line of severe storms east
of the CWA by mid-late afternoon. Main severe weather risk will be
large hail and damaging winds, but in these cases the tornado
threat is not zero. Brisk northwest winds 15-25 mph and gusty are
expected behind the cold front late Wednesday with quite the
temperatures difference of 65-75 degrees northwest areas to the
lower-mid 80s across Central Texas.

Winds will diminish readily after nightfall Wednesday evening, as
the cooler and dry airmass helps to decouple the surface to
boundary layer, along with surface high pressure settling across
the region readily overnight into Thursday morning. Thursday low
temperatures will fall into the 40s outside of immediate urban
areas of the DFW Metro and possibly Waco as light winds become
light southeast by sunrise Thursday. The cool/dry weather will be
short-lived however, as the very progressive weather pattern
continues and lifts the old cold front back rapidly as a warm
front into Southern Oklahoma and Northwest Texas. In its` wake,
breezy south winds will allow highs warming back into the 80s for
all but the immediate Red River Valley and northeast counties.
The breezy and mild conditions will continue Thursday Night and
Friday with surface dew points returning back north quickly in
advance of our next system over the Great Basin and Four Corners
region of the Southern Rockies.

The increasing southwest flow aloft will once again strengthen
the EML/capping inversion and make for a very tricky forecast
convection-wise later in the day Friday. A surface dryline will
move into, or near our far western counties, while the old surface
warm front wavers on either side of the immediate Red River and
northwest counties. Have maintained very low convective chances
near these boundaries, as a lead shortwave lifts northeast across
the Oklahoma/Texas Panhandles late in the day. If, and that`s a
big "if" lift can break the cap in these areas, it`s likely
isolated and discrete strong-severe storms could erupt north of
I-20 and near the immediate dryline out west by late afternoon and
evening. This will be HIGHLY CONDITIONAL based on the cap in
place.

As this second, deeper upper low/trough swings out of the
Southern Rockies/High Plains Friday Night into Saturday, large-
scale ascent will weaken the cap, especially across areas along
and north of I-20 for scattered-numerous showers and storms, with
likely a threat for strong to severe storms containing hail and
gusty/ damaging winds, along with some localized heavier rains
across the northern counties. A pre-frontal trough will arrive
into our far western counties by Saturday afternoon, with a cold
front overtaking this feature by Saturday night with the upper
trough swinging readily east across the Southern Plains. This will
likely end the severe weather threat from west to east by
midnight Saturday night into Sunday morning with brisk and cooler
conditions in the front`s wake. Sunday will see cooler conditions
with winds diminishing with surface high pressure settling in. A
few showers may linger, but should be dry for the most part with
highs Sunday afternoon in the 60s north, lower 70s south. Otherwise,
the topsy-turvy pattern continues with dry conditions Sunday
Night into the first half of next week. Breezy south winds return
by Tuesday with highs pushing back into the 80s once again.

05/

&&



.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    89  70  75  50  80 /  10  10  20   0   0
Waco                88  71  83  49  82 /  10  10  10   0   0
Paris               84  68  72  45  75 /  10  20  60   5   0
Denton              89  66  73  46  78 /  10  10  20   0   0
McKinney            86  68  75  46  77 /  10  20  20   0   0
Dallas              88  71  76  51  80 /  10  20  20   0   0
Terrell             85  70  77  46  79 /  10  20  30   0   0
Corsicana           86  70  81  48  81 /  10  20  20   0   0
Temple              87  70  84  50  83 /  10  20  10   0   0
Mineral Wells       93  64  73  45  83 /   5  10  10   0   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 AM this morning to midnight CDT tonight
for TXZ092>095-103>107-118>123-133>135-145>148-158>162-174-175.

&&

$$

30/05



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