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

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FXUS64 KFWD 151203 AAA
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
703 AM CDT Tue Aug 15 2017


.AVIATION...
An overnight thunderstorm complex continues to weaken and move off
into Oklahoma early this morning as the low-level flow has veered.
A well defined outflow/undular bore can be seen on area radars
(and satellite) from near a KGZN-KRPH-K0F2 line, and this
continues to move towards the southeast. Winds are now only meekly
turning out of the west/northwest behind this feature, indicating
it`s beginning to lose forward momentum. With the onset of
mixing this morning, any additional forward progress is expected
to be stunted. As a result, don`t believe a northwest wind shift
is in the cards this morning at the Metroplex TAF sites.

A few warm advection showers appear to be falling out from the
extensive mid-level deck which stretches from the Concho Valley,
northeastward into the Metroplex. As the low-level jet weakens
this morning, these too should come to an end with minimal
aviation impacts. A breezy south to southeast wind will be the
norm today and tonight, and an occasional gust to 20 kts can be
expected. Another thunderstorm complex is forecast to develop
across far West Texas this evening, but is expected to remain
north and west of our TAF sites tonight/Wednesday morning.

Veered low-level flow looks to keep the brunt of MVFR cigs south
and east of the Waco airfield this morning. As additional moisture
is pumped in from the south tonight, MVFR cigs are expected to
build across the Waco TAF site on Wednesday morning, but look to
remain just south and east of the Metroplex sites.

Carlaw

&&


.DISCUSSION... /Issued 337 AM CDT Tue Aug 15 2017/
Rain chances don`t completely leave the forecast this week with
most of the rain chances along and north of Interstate 20, but the
heat later in the week will make it feel more like the August we
are accustomed to.

A complex of storms in NW Texas continues to make steady progress
east and southeast with aid from a low level jet around 30 kts.
On its current track, this complex would likely move into our
western counties before daybreak. Some gusty winds and brief heavy
rain would be the main hazards. The low level jet will continue
to veer southwest and weaken after daybreak, and we expect the
complex will dissipate by mid morning. Ahead of the complex, some
weak showers and maybe an isolated thunderstorm may occur as
isentropic lift and warm air advection occur with the low level
jet. However, our chances for rain won`t completely be done for
the day for more than one reason. One, this complex may leave an
outflow boundary in the region that could be a focus for
additional showers and storms later today. Two, diurnally driven
convection may occur as a disturbance currently over the TX
Panhandle moves into the Central Plains. With the upper level
ridge centered to our southeast and ample moisture still in place
across the region, most model guidance indicates isolated activity
across the northern half of the region and will keep low PoPs in
that area this afternoon. Temperatures today are likely to remain
near normal values across most of the region (in the mid to upper
90s), but will remain slightly cooler in our northeast counties
that have been inundated with rain over the past few days.

This evening and tonight, our upper level flow pattern will shift
to southwest winds aloft as an upper level trough crosses the
Rockies. Disturbances embedded within this flow are expected to
aid in the development of an MCS across western portions of the
state. Overnight, this complex is projected to move northeast and
east, aided by a 30-40 kt low level jet, bringing rain to our
western counties before daybreak. Severe weather is not expected
but gusty winds and heavy rain will again be possible. Once again
this complex will likely dissipate over northwestern portions of
the CWA, but may bring rain to areas as far east as I-35/35W. Low
rain chances will remain across roughly the northern half of the
region during the day on Wednesday for very similar reasons as
today.

On Wednesday night, as the upper level trough moves across the
Plains, another complex of storms will likely form to our north
along a southward moving front. This front isn`t expected to move
into North Texas, but the complex may and have increased PoPs
north of Interstate 20. A moisture-laden low level jet of 30-40
kts will likely help move the MCS south, but the southern extent
of its track is still challenging and will likely be based on
mesoscale properties of the outflow. Best guess at this time is
this complex will be weakening as it moves into North Texas early
Thursday morning. Low rain chances continue Thursday, and then
another complex of storms may make a run at the region Thursday
night/Friday morning, from the northwest, as another disturbance
moves through the Plains.

Starting Thursday, the upper level ridge will build back west over
the region. Even with the continued rain chances this week, the
heat will make a significant return, and a Heat Advisory may be
needed for parts of the region for several days this week. A
handful of scattered locations may see heat index values of 105 to
106 today, but heat indices will increase starting Wednesday in
our southeast zones where southerly winds will continue to
transport moisture rich air. As the upper level ridge builds back
in and temperatures rise into the upper 90s and around 100
degrees, heat index values of 105 to 110 are possible over much of
the eastern half of the region. Across our western zones, better
afternoon dewpoint mixing is expected, and we will monitor each
day how far east the dewpoints will mix under the influence of the
ridge.

JLDunn

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    96  78  96  79  95 /  20  10  20  20  20
Waco                98  79  99  79  99 /  10  10  10  10  10
Paris               89  73  91  73  90 /  20  10  20  40  30
Denton              95  77  96  77  94 /  20  20  20  20  20
McKinney            93  77  94  77  93 /  20  10  20  20  30
Dallas              96  78  96  79  95 /  20  10  20  20  20
Terrell             94  78  95  77  95 /  20  10  20  10  20
Corsicana           95  78  97  78  97 /  10  10  10  10  10
Temple              98  77  99  78  99 /  10  10  10  10  10
Mineral Wells       95  76  95  76  95 /  20  20  20  20  20

&&

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

$$

90/82



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