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

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FXUS64 KFWD 222032
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
332 PM CDT THU SEP 22 2016

.DISCUSSION...
The first day of astronomical fall certainly doesn`t feel like
it. Temperatures this hour are running in the lower to middle 90s,
some 6 to 9 degrees above our climatological norms for this time
of year. It`ll start feeling more like fall in a few days,
however. More on that below. For the rest of this afternoon and
into the early evening, I`ve decided to add in a small sliver of
isolated thunder (10%) wording across our southeastern most
counties (Milam, Robertson, and Leon) where the cumulus field is
showing a bit more in the way of vertical development. This lines
up with recent objective analysis, which shows MLCAPE steadily
increasing as dewpoints in the 70s are being ushered into the
region. Any activity that manages to sneak into our CWA will
dissipate around sunset. We`ve also added in some patchy fog to
the forecast, roughly south and east of an Athens to Cameron line,
overnight and into tomorrow morning as moisture advection
continues and temperatures cool.

Tomorrow, a robust trough and associated upper-level low
currently diving into the Great Basin will emerge out onto the
High Plains. Stout upper divergence in association with the exit
region of a 100 kt jetstreak will encourage lee cyclogenesis
during this time, which will act to further increase the northward
transport of moisture across our region. Large-scale forcing for
ascent will, however, remain displaced well to the north and west
of North Central Texas tomorrow, so any showers and storms should
remain diurnally driven and isolated to scattered in coverage.
I`ve expanded some low 20% PoPs northward across our western
counties to coincide with progged deeper low-level moisture. A
well-mixed boundary layer with DCAPE values pushing above 1000
J/kg will mean any of the stronger storms will be capable of
producing some gusty downburst winds during the afternoon and
evening hours.

The upper-trough will nudge slowly eastward on Saturday and a cold
front will begin dropping southeastward across Kansas. Several
weak mid-level perturbations may graze our western zones and weak
warm advection/isentropic ascent will act to produce scattered
convection across our region. The highest PoPs (50%) are painted
across roughly the western half of the CWA, coincident with the
best upper-level dynamics and moisture content. Some strong storms
will be possible during the afternoon on Saturday, primarily
across our northwestern counties, where wind shear will be
maximized.

The forecast from Sunday and beyond remains in a state of flux,
with considerable uncertainties regarding the pertinent large-
scale features. That said, recent runs of ensemble systems from
the NAEFS (a combination of the GEFS and Canadian ensembles) to
the EPS (ECMWF ensemble) seem to be locking onto a scenario in
which a low cuts off from the mean flow and hangs back across the
Desert Southwest/northern Mexico as the main trough continues
east across the Upper Midwest. Given enough support from the
ensemble systems, we`ve started to trend the forecast gradually
towards the Euro`s cutoff solution in this afternoon`s forecast
package. As a result, the highest PoPs are painted during the
Sunday through Monday period, coincident with the arrival of a
surface cold front. I`ve then continued at least low-end chance
PoPs now through Tuesday as the frontal boundary may linger across
our CWA. If trends continue, these chances may need to be raised
in subsequent forecasts.

While we`re not prepared to bite off wholesale on the ECMWF
solution at this point, the potential exists for a fairly drawn-
out episode of wet weather across the region into next week. With
PWAT values approaching +2 SD and individual cell motions largely
paralleling the surface front, flooding--at least on a localized
basis--will be a concern from Sunday into Monday, and potentially
lingering through Wednesday. Along with the rain, much cooler
temperatures look to arrive this weekend and next week.

Carlaw

&&

.AVIATION...
/ISSUED 1150 AM CDT THU SEP 22 2016/
An upper level ridge will continue to dominate the Metroplex and
ACT TAF sites through Friday with drier air and subsidence
producing VFR conditions today.

Low level moisture from the Gulf of Mexico will return to the
region overnight. MVFR ceilings are expected to develop after
midnight around the ACT TAF site and slowly move north toward the
Metroplex TAF sites before sunrise Friday. MVFR ceilings should
be short lived giving way to VFR conditions between 16-17Z.

50


&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    76  93  76  91  75 /   5  10  10  40  50
Waco                74  94  76  90  74 /   5  20  10  50  40
Paris               71  92  73  90  72 /   0  10  10  30  50
Denton              71  92  74  89  73 /   0  10  10  40  60
McKinney            72  92  74  90  73 /   0  10  10  40  50
Dallas              76  94  77  91  75 /   5  10  10  40  50
Terrell             73  93  74  91  73 /   5  10  10  40  40
Corsicana           74  93  75  90  74 /   5  20  10  40  40
Temple              74  92  74  89  74 /  10  30  10  50  40
Mineral Wells       71  92  73  89  71 /   5  20  10  50  60

&&

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

$$

50/90



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