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

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266
FXUS64 KFWD 260155 AAB
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
855 PM CDT Tue Apr 25 2017

.UPDATE...
Wind speeds have decreased to 15 to 20 mph this evening, thus the
Wind Advisory that was in effect along and east of the I-35
corridor until midnight has been cancelled.

58

&&

.AVIATION...
/ISSUED 659 PM CDT Tue Apr 25 2017/
Gusty south winds will continue early this evening before abating
somewhat overnight, although a 14-18 kt breeze will linger. A
field of MVFR stratus, presently gathering across the Mid and
Upper-Texas Coast, will surge northward over the next few hours as
winds in the lowest 1-2 kft increase to around 45 kts. At this
time, it appears sufficient amounts of mechanical mixing will be
in place to keep cigs MVFR. The next aviation impact will arrive
Wednesday morning as a cold front sweeps across the TAF sites,
yielding an abrupt and very gusty northwest wind shift. Based on
current analysis and high- resolution trends, bumped this timing
up by an hour at Metroplex sites, although more precise timing
will be added tonight as the front nears the Red River. While a
capping inversion will be in place ahead of the front`s arrival,
it seems plausible that showers may develop southward enough to
graze the northern terminals, and have added in a mention of VCSH
after 26/14Z. Overall, the thunder potential appears too low to
warrant a mention at this time, but DFW and DAL would be the most
susceptible to VCTS between 13-16Z. Either way, impacts to eastern
departures and the Bonham cornerpost appear likely as
thunderstorms congeal into a line during the late- morning.

Brief MVFR cigs should persist behind the front, but anticipate a
return to VFR Wednesday afternoon. Clearing skies and quickly
diminishing winds are then in store as high pressure moves
overhead. DFW may be able to return to south flow as early as
late Wednesday evening.

Carlaw


&&



.PREV DISCUSSION... /ISSUED 343 PM CDT Tue Apr 25 2017/
A warm and breezy day is in progress, but a few changes are on
the way in the next 24 hours. A surface low continues to deepen
across western Oklahoma with strong southerly flow being the
result across much of Texas. A cold front is draped westward
through the TX Panhandle with temperatures in the 50s just north
of this boundary. In addition, a dryline is positioned roughly
from Altus, OK to Abilene, TX. An upper trough continues to dig
southward through NM which is causing additional surface
cyclogenesis through western TX. This trough will continue to make
southeastward progress through Wednesday, driving the cold front
through the forecast area Wednesday morning while delivering a
chance for thunderstorms.

Highs today have climbed into the 80s and 90s area-wide, but
widespread cirrus and lingering cumulus have acted to hold
temperatures a few degrees under previously forecast highs. The
dryline is slowly advecting eastward and will enter our western
counties by this evening. This boundary will not be convectively
active due to the strong cap and lack of supplemental forcing.
Moisture continues to increase as a southerly flow regime advects
ample Gulf moisture into North and Central TX. Surface winds will
remain strong through the evening hours until the surface low
approaches from the northwest; a Wind Advisory remains in effect
until midnight.

After midnight, widespread low stratus is expected to
develop across most of the area as the surge of Gulf moisture
continues. The cold front will begin initiating convection across
central OK as it sinks southward and some of this activity may
approach the Red River between midnight and 6am. Much stronger
upper forcing, including a potent PV anomaly, will near the
region between 6am and noon which will aid in the initiation of
convection along the front by lifting the formidable cap. At this
time, we`re monitoring a brief window for some strong to severe
storms mostly across areas east of I-35 from about 10am-2pm when
the lift will be capable of overcoming the cap immediately along
the front as it encounters the highest moisture content. At this
time, storms are expected to initiate near or just east of I-35
across North TX. The southward extent of convection a few hours
later remains uncertain, but a broken line of storms could stretch
as far south as Palestine by the time it exits our forecast area
to the east by mid afternoon. At this time, instability and shear
parameters imply a threat for storms to produce severe winds
and/or hail, especially if they remain discrete along the front.
The tornado threat is low, yet nonzero, but forecast hodographs
are not terribly supportive of a tornado threat. Behind the front,
a few wrap-around showers will be possible, mostly across areas
near the Red River.

As the cold front clears the area later Wednesday afternoon, much
cooler air will filer into the region causing high temperatures
to hold in the 60s and 70s for many locations, but our
southernmost counties may creep into the 80s before the front
arrives. A cool and tranquil Wednesday night will follow.
Southerly flow will quickly return Thursday along with warmer
temperatures as the front returns northward as a warm front.

Another powerful upper trough will begin deepening across the
western US on Friday. A new surface low will form across West TX
on Friday and a frontal zone will become stalled near the Red
River. A dryline will also develop and sharpen just west of the
forecast area. The warm sector ahead of the dryline will be quite
juicy, characterized by 70F dewpoints and temperatures in the 80s.
These conditions will yield considerable instability, especially
as a plume of steep lapse rates aloft is advected eastward above
the warm sector. This would normally result in a stout capping
inversion, but the cap on Friday is expected to be relatively weak
due to strong large-scale ascent (and therefore adiabatic cooling)
from the vigorous upper trough. As a result, there is the
potential for 2 areas of convection on Friday afternoon/evening:
one along the dryline across our western areas, and another near
the stalled front across North TX and into southern OK. Storm
development during this time will hinge on the degree of lift and
ability to overcome the cap. Given the instability and shear, any
storms that would be able to form during this time would likely
become strong or severe.

The thunderstorm threat will continue into Friday night and
through all of Saturday as the upper trough continues pushing east
and we remain situated within a very high-quality warm sector. A
cold front will slowly move through the area during this time and
numerous thunderstorms are expected across most of the forecast
area. While it`s much too early to delve into the mesoscale
details of the forecast, there will be a chance for strong or
severe storms as well as isolated flash flooding across most of
the forecast area throughout this time. The specific timing and
threat locations will continue to change throughout the coming
days as more information becomes available. Those with outdoor
activities on Friday evening through Saturday are strongly
encouraged to keep an eye on the forecast.

This potent system should be exiting the area by around midday
Sunday with cooler conditions following into early next week. A
couple days of quieter weather are expected to prevail through the
first half of next week before another storm system possibly
affects the region around the Wednesday/Thursday time frame.

-Stalley



&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    70  72  50  82  66 /  20  30   5   0   5
Waco                71  79  49  83  67 /  20  20   0   0   5
Paris               68  69  45  77  60 /  30  70  10   0  10
Denton              66  67  46  78  63 /  20  20  10   0   5
McKinney            68  71  46  77  63 /  20  50  10   0  10
Dallas              71  73  51  83  67 /  20  30  10   0   5
Terrell             70  71  46  80  63 /  20  50  10   0  10
Corsicana           70  77  48  82  66 /  20  40   0   0   5
Temple              70  83  50  84  67 /  20  10   0   0   5
Mineral Wells       64  68  45  85  63 /  10  10   0   0   5

&&

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

$$

90/58



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