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

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401
FXUS64 KFWD 271755 AAC
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
1255 PM CDT WED JUL 27 2016

.AVIATION...
/18Z TAFS/

As expected, two areas of convection are being monitored. Both the
HRRR and TTU WRF have been good with initiation of isolated-
scattered showers and storms developing within an are of mid level
deformation and high moisture content west-northeast from DFW
currently. The other area I`m watching is outflow coming up into
central TX. Highest concentration of activity is currently
between Gainesville and Bonham, which should eventually push an
outflow boundary southward toward the DFW terminals between now
and 4 pm. Have carried a 3-hr TEMPO group for MVFR -TSRA and
variable gusty winds to 30 kts or so.

We should see outflow come through before 22Z and push better
convective chances south of DFW with better chances focusing on
central TX and Waco from 22Z through sunset. Confidence is good
on some convection around, but timing or length of time of
persistence of convection is not high. Environmentally, south-
southeast winds will prevail 5-10 kts, with the exception of a
brief outflow surge by 20Z-21Z that should wash out by 00Z over
DFW airports. AWW has been issued current for lightning through
20Z/3 pm cdt.

Beyond nightfall into tonight, deformation area shifts south and
could see latent heat release redevelop pre-dawn convection along
and south of I-20 by sunrise. Confidence here is very iffy, but
have a mention of VCTS at Waco where probabilities are higher for
TSRA with just VCSH at DFW airports for now.

05/

&&

.UPDATE...
Main update this morning was to adjust PoPs/Wx based on current
observations and recent analysis/model output.

Upper air analysis in conjunction with water vapor imagery
revealed a mid-level deformation zone extended from the Concho
Valley back up towards the Ark-La-Tex. Similar to yesterday, this
feature in combination with daytime heating should be enough to
encourage scattered convection late this morning and into the
afternoon hours. The better threat for rain and thus highest PoPs
are confined to an area along the aformentioned deformation axis.
I have nudged PoPs upwards into the likely category for most
areas along the Red River with lower rain chances further south
towards Central TX where WV imagery indicates drier mid-level
air. Despite this mid-level dry air, diurnal sea-breeze activity
and subsequent convective outflows may still support some
scattered convection and I will keep a mention of showers and
storms here. With regards to hazards...the 12 UTC FWD RAOB sampled
an environment characterized by 2" PW values. This combined with
the weak deep layer shear and thus minimal dry air entrainment and
given expected slow storm motions---a heavy rain and a minor
flood threat will likely develop. Given the moist environment,
there does remain some potential for a strong downburst or two due
mainly to precipitation loading. If storms can survive the hostile
environment across the southeastern zones, a slightly higher risk
for downbursts will exist here. Otherwise, heavy rain will be the
main headline for today.

I have cautiously lowered temperatures along the Red River where
cloud cover and rain should keep temperatures in the low to mid
90s here. Given the time of year, however, it will only take a few
hours of sunshine to send temperatures soaring into the mid 90s.

The remainder of the forecast appears to be in great shape and
updated products have been sent.

24-Bain

&&

.PREV DISCUSSION... /ISSUED 347 AM CDT WED JUL 27 2016/

Hot and humid conditions along with scattered showers and
thunderstorms will continue for a couple more days across North
Texas before upper ridging builds back in across the Southern
Plains.

Water vapor imagery shows a weak upper trough centered over
Louisiana this morning. This feature is expected to continue to
slowly move north today. To the northwest of the upper
trough...there is a band of moisture associated with a mid level
deformation axis which extends from southwest Missouri into
central Oklahoma and into North Texas. 00Z upper air analysis at
700mb indicated the presence of rich moisture from near Midland
into North Texas and extending into the Ozarks. Latest RAP
analysis indicates PW values in excess of 2 inches along this axis
and across a good chunk of North Texas. At the surface...there is
some weak troughing noted from south of Lubbock to near Wichita
Falls and into southern Oklahoma. Given these features...think a
good portion of North Texas...especially across the northern half
of the CWA...will see convection develop later this morning into
the afternoon hours...so we have raised PoPs to 40-50%. South of
the I-20 corridor there may be a relative minimum in convective
coverage with the exception of our far southern counties. This
area may see some activity spread north from southeast Texas. All
of this activity should again be diurnally driven with a peak in
coverage late this afternoon and diminishing after sunset.
Conditions will be favorable for isolated strong downburst winds
and locally heavy rainfall.

Later tonight...a second shortwave trough will swing through the
Central Plains and into northern Oklahoma with northerly flow at
500 and 700mb increasing. There is some potential for a complex of
thunderstorms to develop and move south late overnight although
the latest high resolution guidance is less bullish on this
scenario. Nonetheless...will have some 20% PoPs late tonight
mainly along and north of I-20.

The more likely scenario is that this passing shortwave sends a
weak boundary down into North Texas for Thursday. With rich
moisture still in the region...scattered showers and thunderstorms
would likely develop along this boundary during the day Thursday.
Will continue with 30-40% PoPs during this time across much of
North Texas.

Beyond Thursday...upper ridging begins to nudge back eastward into
the area. This will confine PoPs on Friday mainly to the eastern
half of the CWA and only across the far northeast by Saturday.
Temperatures will slowly nudge upwards back to near 100 degrees
during this time with rain chances diminishing to near zero by the
latter half of the weekend. A pair of strong shortwave troughs
will move through the northwest U.S. Sunday and Monday which
should help deepen a surface low east of the Rockies. This will
keep wind speeds up a bit across North Texas so it won`t feel too
oppressive across the region.

Dunn



&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    96  77  96  77  97 /  50  50  30  10  20
Waco                96  77  97  75  99 /  20  20  30  10  20
Paris               96  74  93  73  94 /  50  50  40  20  30
Denton              93  73  94  74  96 /  60  60  30  10  20
McKinney            93  75  94  75  95 /  60  60  30  20  20
Dallas              96  78  96  76  98 /  50  50  30  10  20
Terrell             95  75  94  75  96 /  40  40  40  20  20
Corsicana           95  76  96  76  96 /  20  20  40  20  20
Temple              94  75  96  75  97 /  20  20  30  10  20
Mineral Wells       95  72  95  72  97 /  50  50  30   5  10

&&

.FWD Watches/Warnings/Advisories...
None.
&&

$$

05/24



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