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

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FXUS64 KFWD 270825
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
325 AM CDT Thu Apr 27 2017

.DISCUSSION...
A much quieter early morning compared to 24 hours ago, as our
first sharp shortwave trough and associated cold front have raced
east past the Mississippi River and are affecting the Deep South
and Southeast States. Surface high pressure pressure, light winds,
and clear skies are going to result to a fairly chilly morning
for the last week of April, as the entire area starts off in the
40s. The chill won`t last long, however, as dampened, to near
zonal flow aloft happens overhead with low level WAA returning in
earnest this afternoon and tonight. Highs today will return to
pleasant readings between 75 and 85 degrees with breezy south-
southeast winds. Though we could see localized gusty conditions by
afternoon into tonight, I do not feel a Wind Advisory is needed
for a third day in a row.

Gulf moisture and stratus will return readily to especially the
southeast half of the region which will lend to much milder low
temperatures Friday morning in the 60s most areas. A warm front
moving up through the area will likely hang up somewhere across
the far northwest counties Friday afternoon, while a surface
dryline nudges toward the far west/southwest counties. Aloft, a
broad large-scale upper trough/low over the Western U.S. and
Rockies will be strengthening, with a lead shortwave lifting
northeast across the Central/Southern High Plains later in the
afternoon and evening. High temperatures will push the lower 90s
near the intersection of the surface dryline and stalled frontal
boundary across our northwest counties. The EML/capping inversion
will be slowly increasing, but not so strong that if the tail end
of the ascent from the shortwave to the northwest and daytime
heating can work in unison to possibly and conditionally convect a
few supercellular storms mainly west-north of the DFW Metro.
Confidence is not high here, but not high enough to remove from
the forecast either. With high SBCAPE values and steep lapse
rates aloft, large hail, damaging RFD winds, and a tornado or two
could not be ruled out. This will bear watching as we monitor our
sounding environment and EML/cap strength the next 24-48 hours.

Some fairly significant changes were made to the forecast Friday
night into at least Saturday morning, if not extending into early
Saturday afternoon. As is usually the case, the med range models
of past days underestimated the embedded energy of an upper low
organizing across the Four Corners and Southern Rockies, with a
much deeper and slow solution being agreed upon by the models. As
such, our warming and deep southwest flow aloft Friday night into
the early Saturday will really be enhancing our EML/cap across our
area. Sure, it will be breezy to windy with increasing humidity
with another widespread stratus intrusion. A few sprinkles or
isolated light showers can`t be ruled out under the EML moving
into Saturday morning. A complex of storms will be moving readily
east across the Panhandles into Oklahoma/Western Arkansas. I will
have a tight gradient for modest convective chances along the Red
River, to a slight chance near I-20/I-30 corridors, with nothing
across Central Texas.

The deep upper low will track slowly across New Mexico early
Saturday and lift east across the Panhandles by Saturday evening.
As such, WAA and isentropic ascent will combine with increasing
large-scale ascent to lift and moisten the capping inversion with
a line of showers and storms developing near or just west of
I-35/35W corridors. Activity will lift east progressively
Saturday Night with a surface trough, before a cold front
overtakes the surface trough overnight into early Sunday, with
showers and storms ending from west to east. SPC`s risk areas look
on target with our thinking for the Saturday afternoon into early
Sunday morning period, with all modes of severe weather,
including a few tornadoes possible with any discrete storms ahead
of the line or meso-lows along the line. In addition, localized
heavier rains of 1-3 inches east of I-35, with isolated higher
amounts across the far northeast counties likely will cause some
localized flash flooding issues and possibly mainstream river
issues from the lower Trinity River basin east to the Sabine,
Sulphur, and Navasota River basins.

The upper trough and cold front gradually end all rain chances
from west to east by midday Sunday. With such a deep upper low
over the Central and Southern Plains for late April and cold
850-500mb temperatures, it will be another cool and blustery day
on Sunday afternoon with highs struggling to warm into the 60s.
Early next week will start off with yet another chilly morning
Monday and lows falling into the 40s as high pressure settles in.
Depending on rainfall, this may be a good set up for radiation fog
development with wet soils and cool surface conditions. This
should become more clear as we approach the end of the weekend.

Otherwise, the deep upper cyclone will lift readily northeast
Monday and Monday Night with rising mid level heights across the
Southern Plains and a gradual modified warm up on Monday and
Tuesday with dry weather. Highs will average in the 70s northeast
to the 80s elsewhere with most of the rest of the week relatively
quiet as the Continental Shelf across the Northwest Gulf of
Mexico becomes scoured quite a bit. Any moisture return mid-late
next week will be modified, though some low chances return briefly
next Wednesday, as progressive, less-amplified trough moves east
across the plains with yet another strong cold front arriving and
cooler temperatures uncharacteristic of early May around these
parts.

05/

&&

.AVIATION...
/ISSUED 1144 PM CDT Wed Apr 26 2017/
High pressure is cresting overhead at this hour, with the surface
center near KMNZ. Winds will remain light and variable tonight as
this surface anticyclone slides east of the region. Dewpoint
depressions are currently in the 1-3 F range at our typically
cooler TAF sites (AFW, GKY, and ACT), and with continued
radiational cooling overnight, it`s possible some slight vsby
reduction occur towards dawn. Based on data from our evening`s
balloon, this residual moisture layer is quite thin, and the
vertical transport of drier air from just off the surface should
keep and vsby reductions from really tanking late tonight.

A southerly breeze will get going tomorrow thanks to cyclogenesis
to our north. A passing disturbance may throw some addition mid-
level cloud cover our way, but nothing more. In the DFW extended
TAF, MVFR stratus will surge northward as a potent low-level jet
gets cranking towards Friday morning. Low cigs will also make a
run at Waco, but these should hold off until just after the
current TAF window.

Carlaw


&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    78  66  88  73  80 /   0   0  20  20  50
Waco                81  68  89  75  82 /   0   0  10  10  30
Paris               74  59  82  69  76 /   0   5  30  30  80
Denton              78  65  85  70  77 /   0   5  20  40  60
McKinney            76  64  84  71  77 /   0   0  20  30  70
Dallas              79  66  87  73  81 /   0   0  20  20  50
Terrell             78  63  85  72  80 /   0   0  20  10  60
Corsicana           79  65  87  74  82 /   0   0  10  10  40
Temple              81  68  88  75  82 /   0   0  10  10  20
Mineral Wells       83  64  88  68  79 /   0   0  20  30  30

&&

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

$$

05/



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