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

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000
FXUS64 KFWD 180445
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1145 PM CDT WED AUG 17 2016

.AVIATION...
No major changes from previous TAFs other than to increase the
amount of time that IFR cigs should prevail overnight. DFW
Metroplex airports have been alternating between SCT/BKN clouds
right around FL010 and these should gradually turn onto persistent
IFR cigs in the next few hours. Waco has already been carrying
MVFR/IFR cigs for the better part of the evening and would expect
IFR cigs to prevail overnight as well. Sky conditions should
gradually improve by mid-morning with MVFR/VFR conditions
possible by midday.

The other concern for this set of TAFs is the rain/thunder
potential at all sites on Thursday. Scattered showers and isolated
storms should begin redeveloping in the morning with coverage
increasing by early afternoon. Have included VCSH through most of
the forecast as well as a short period of RA with reduced vsbys on
Thursday afternoon when impacts to airports seem to be the most
likely. Once again there will be sufficient instability for
isolated thunderstorms, but as activity is expected to be
scattered with infrequent lightning, it is not worthy of a mention
in the TAFs at this time. Activity should trend downward Thursday
evening as MVFR cigs redevelop again late Thursday night.

-Stalley

&&



.PREV DISCUSSION... /ISSUED 347 PM CDT WED AUG 17 2016/
With North Central Texas remaining under troughy upper level flow
and devoid of any major ridging influences through the middle
of next week, our uncharacteristically mild and wet pattern will
continue.

TONIGHT: A distinctive Mesoscale Convective Vortex (MCV) tracked
across the I-35 corridor S of DFW today, bringing widespread
showers/isolated thunderstorms to most areas S of I-30. Some
localized 2-4 inch totals did occur earlier, prompting a Flash
Flood Watch (and several warnings) for a number of our Central TX
counties. Despite the fact that the MCV and its associated rain
shield have moved east of the FFA area, have decided to keep the
watch going at least into the evening hours given the additional
convection that has developed to its SW this afternoon. Much of
this activity likely formed due to differential heating along the
periphery of the MCV cloud shield, and should drop off in
coverage/intensity by late evening. Through the late afternoon and
evening, however, some isolated 1 to 2 inch rains may still be
possible in the watch area, where soils remain pretty moist.

Otherwise tonight, we`re going with likely pops generally along
and east of I-35 and south of I-30, where the MCV remnants are
located or advancing eastward. These PoPs MAY turn out to be a
bit overdone, unfortunately, if subsidence on the backside of the
decaying MCV takes hold over the area. This will be something to
watch out for, and could yield another short-term rain bust for
much of the Metroplex tonight. We`ll show somewhat lower PoPs
elsewhere across the area, where organized convection will be less
prevalent.

THURSDAY/FRIDAY: Much of North Central Texas remains under moist
southwesterly flow, with a band of higher moisture and 850 Theta E
oriented SW-NE across the region. Both the GFS and Euro persist in
advertising a decent amount of coverage both days, so have kept
good chance to likely PoPs in place.

SATURDAY THROUGH WEDNESDAY: The next significant change will
occur Friday night through Saturday as a pronounced upper level
shortwave drops out of the Central High Plains across Oklahoma and
North Texas. In conjunction with this shortwave and its associated
forcing for ascent, another cold front will move into North Texas
by midday Saturday. It`s hard to gauge exactly how far south this
boundary will penetrate, but given the strength of the shortwave,
am inclined to think the front will reach our southern forecast
area by Saturday afternoon. The main upshot of this boundary and
shortwave will be yet another enhanced potential for rainfall
across the area in the Saturday/Sunday timeframe. Went with likely
PoPs both days, though it`s difficult at this time to tell which
areas may be more favored. This will depend on the final resting
place of the front and associated outflow boundaries.

A split flow pattern develops across the middle part of the
country by Monday, and both the Euro and GFS bring yet another
vigorous shortwave (by August standards) out of NM/W TX across our
region by Tuesday morning. Though model solutions are fairly
consistent, was a bit hesitant to bite off on the widespread QPF
offered with this feature this far out, especially considering
we`ve been hitting PoPs hard with this system already.
Nevertheless, we did depict 50% PoPs across the SW half of our
area for Monday afternoon ahead of this NM shortwave, with chance
PoPs lingering elsewhere Monday and Tuesday.

A ridge does attempt to develop along the Gulf Coast in the
Wed/Thurs timeframe, but the active split flow pattern persists
over our area and to the W and N of us. As a result, another wave
does exit the Southern Rockies late Wednesday into Thursday, thus
maintaining the potential for scattered showers and thunderstorms
into the end of next week.

With extensive cloudiness persisting across the area, coupled with
episodic precipitation, daytime temperatures will remain
considerably below seasonal norms this week, weekend, and all
next week. This really is an interesting counterbalance to the
much warmer and drier regime that held sway over North Texas
through most of the first half of the month. What a difference!

Bradshaw

66



&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    74  85  74  88  76 /  50  60  40  40  30
Waco                73  86  74  90  76 /  60  60  40  20  20
Paris               70  83  71  87  72 /  50  70  40  50  40
Denton              72  84  72  86  73 /  50  60  40  50  40
McKinney            72  84  73  87  74 /  60  60  40  50  40
Dallas              74  85  75  88  76 /  60  60  40  40  30
Terrell             73  85  73  88  74 /  60  60  40  40  30
Corsicana           73  85  73  89  75 /  60  60  40  30  30
Temple              72  86  73  90  75 /  50  50  40  20  20
Mineral Wells       72  85  71  87  72 /  50  60  40  40  40

&&

.FWD Watches/Warnings/Advisories...
Flash Flood Watch until 7 AM CDT Thursday for TXZ133-134-144>146-
156>161-174.

&&

$$

26/25



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