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

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304
FXUS64 KFWD 250036 AAA
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
736 PM CDT Tue Apr 24 2018

.AVIATION...
/00Z TAFs/

A cluster of thunderstorms developed within a West Texas surface
low this afternoon. As the complex approaches North Texas,
easterly surface winds will steadily back to the north overnight
though speeds will remain under 10kts. But as the convective
elements separate farther from the instability and convergence
that birthed them, they will gradually diminish in intensity.
However, these storms will continue to disrupt westward departures
well into the evening. But when the activity reaches the
Metroplex after midnight, only elevated showers should remain.

A cold front is advancing south across the Texas Panhandle and
western Oklahoma. While Metroplex winds will already be out of
the north, this will back them further and increase speeds. Such a
scenario should preclude any precipitation along the boundary, but
moisture underneath the frontal inversion will assure MVFR
ceilings throughout the daylight hours Wednesday. The upper trough
now on the High Plains of Nebraska, Wyoming, and Colorado will
arrive from the northwest Wednesday afternoon, resulting in
another round of elevated showers. With more significant forcing
aloft, this batch should contain some embedded thunderstorms. The
current TAFs will carry a more prolonged period of showers, but a
tighter window of thunder may need to be introduced with
subsequent TAF packages.

Due to Waco`s position with respect to the ongoing convection, the
surface winds will likely maintain a southerly component
overnight. The convective complex should remain north of Waco
during the early morning hours, and the frontal passage mid to
late morning Wednesday should be dry. The postfrontal showers/
storms that will affect the Metroplex Wednesday afternoon will
likely not reach Waco until after 00Z Thursday (7pm CDT Wednesday
evening), thus beyond the current TAF.

25

&&

.SHORT TERM... /Issued 327 PM CDT Tue Apr 24 2018/
/This Evening and Tonight/

Showers and thunderstorms are now developing in West Texas near a
dryline and surface low as a weak upper level disturbances ripples
across the area. A few of these storms may become strong or
severe, and the mean flow is expected to drive these storms east.
As this convective activity approaches North Texas this evening,
it will encounter weakening instability and is expected to weaken
in intensity as a result. However, this activity is not expected
to completely dissipate before it moves into western and
northwestern parts of North Texas this evening. Coverage of rain
is expected to diminish through the night as the activity wanes
and have lowered PoPs overnight to reflect this trend. However,
the low PoPs still cover a large area including our eastern
counties due to uncertainty in how far east the rain will progress
before dissipating.

Through the night, generally light east winds are expected with
increasing cloud cover. A cold front will enter the northwestern
corner of the CWA an hour or two before sunrise, but strong warm
air advection is not expected ahead of this front. Overnight lows
will be in the 50s and lower 60s with the cooler temperatures
expected where it rains across our northwestern counties.

JLDunn

&&

.LONG TERM... /Issued 327 PM CDT Tue Apr 24 2018/
/Wednesday through next Tuesday/

Our next cold front will be entering our far northwestern
counties at the start of the period on Wednesday morning with
showers and perhaps an embedded storm or two in the post-frontal
air. This front should arrive across the Metroplex during the
mid-late morning hours, delivering a quick northwest wind shift,
effectively stunting any more warming. As a result, temperatures
should remain steady or slowly fall into the afternoon here.
Locales across parts of Central Texas will remain ahead of the
cold front until later in the afternoon, and this should allow
temperatures to top out in the upper 70s to lower 80s. As a
result, a fairly pronounced gradient in highs is anticipated from
northwest to southeast across the CWA.

For the Wednesday morning hours, we`ve confined the highest (60%)
PoPs roughly north and west of an Eastland to Sherman line where
isentropic ascent will be strongest, quickly tapering to slight
chances from near the Metroplex and south. As the core of a
vigorous shortwave tracks along the Kansas/Oklahoma border
Wednesday afternoon, another area of elevated showers and some
thunderstorms should materialize and track southeastward through
the region. Coverage should be good enough for a quick hit of likely
PoPs roughly north of I-20 during this timeframe. With much of the
area in postfrontal air by the afternoon hours, the threat for
organized severe weather is very low, although an isolated
stronger storm can`t be ruled out as dynamic cooling facilitates
some steepening mid-level lapse rates along with 25-35 kts of
effective deep layer shear. Small hail would be the main threat
with the most robust and overachieving updrafts.

Shower and isolated storm chances will linger into the evening
hours across the southeastern 2/3rds of the region as upglide will
be slow to diminish, but precip-free conditions will return area-
wide Thursday morning. Overall quiescent weather is anticipated
into the upcoming weekend as North and Central Texas remains under
the influence of persistent northwest flow aloft. The one
exception may be Thursday night as another potent vort max
pinwheels across eastern Oklahoma and into Arkansas, dragging
another cold front through the region. While the atmospheric
column should be fairly parched of moisture in the wake of
Wednesday`s cold front, the proximity of the core of the upper-low
warrants an introduction of very low (20%) precipitation chances
north and east of a Decatur to Emory line. Any instability will
be in very short supply, and have limited the wording to just
showers in the official forecast at this time. The parade of cold
fronts will also help hold high temperatures in the low to mid 70s
going into the weekend.

Return flow will commence Saturday night, but the main surge of
Gulf moisture will hold off until Sunday night and into Monday as
the next round of lee cyclogenesis takes place to our north.
Breezy conditions are in store for Monday as the pressure
gradient tightens, helping to pump additional moisture northward.
While most coarse-resolution guidance is painting low amounts of
QPF across our region during this time frame, it looks like any
activity on Monday would just be in the form of hit-or-miss
streamer showers under a strengthening capping inversion.

More widespread showers and thunderstorms could be in store as we
head into the Tuesday-Wednesday timeframe next week ahead of the
next upper-low slated to drop into Arizona/northern Mexico. The
synoptic upper-air pattern depicted by long range ensemble
guidance could become more supportive of typical springtime severe
weather during the middle of next week, but the finer details
obviously remain nebulous at this juncture.

Carlaw

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    60  64  48  74  53 /  30  60  20   5  10
Waco                60  70  50  77  51 /  10  40  40   5  10
Paris               57  61  47  71  50 /  30  70  20   5  20
Denton              56  61  45  74  49 /  30  70  10   5  20
McKinney            57  62  46  73  51 /  30  70  20   5  20
Dallas              61  65  50  75  54 /  30  60  20   5  10
Terrell             59  66  48  75  51 /  30  50  30   5  10
Corsicana           61  69  49  74  53 /  20  40  50   5  10
Temple              61  73  50  77  51 /  10  30  40   5  10
Mineral Wells       57  62  44  75  49 /  40  60  10   5  10

&&

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

$$

25/58



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