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

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FXUS64 KFWD 162015

Area Forecast Discussion
National Weather Service Fort Worth TX
315 PM CDT Mon Oct 16 2017

Following a glorious day across the region, a seasonably cool night
is expected. Wind speeds this evening will drop to 5 mph or less for
the remainder of the night. With clear skies, dry air in place, and
light winds through the lower to mid levels of the atmosphere, good
radiational cooling is expected. Overnight lows will fall into the
40s with some readings in the upper 30s possible in our west and
northwest counties. It is possible some isolated areas of frost may
occur where temperatures dip into the 30s.



/Tuesday through Sunday/

Rain-free conditions are anticipated through a majority of the
work week, before unsettled weather possibly returns sometime this
weekend. In the meantime, dry conditions will prevail due in part
to little to no low level moisture and no real big upper
perturbations for lift. The rain-free forecast looks to end as we
head into the latter part of the week and into the weekend. While
temperatures will moderate back above normal values this week, it
appears that there will be another shot of cooler air towards the
end of the weekend as well.

For Tuesday and Wednesday---After what should be a cool start to
the day, temperatures will rebound quite nicely thanks to the dry
airmass in place. Surface high pressure will gradually slide
towards the east beneath modest northwest flow aloft. I won`t
nudge temperatures too far above guidance given the weak, but cool
1000-500mb thickness advection evidenced in model progs. That
being said---it`ll still be a nice, warm day with temperatures in
the 70s and 80s as northeasterly winds become east to
southeasterly. Tuesday night into Wednesday morning should feature
moderating, but cool conditions with mostly clear skies.
Wednesday should be a few degrees warmer than Tuesday as southerly
winds return in full force.

For Thursday and Friday---Low level moisture advection will
commence on Thursday and into Friday as the subtropical jet arcs
around the northern periphery of the east Pacific ridge. There may
be some patchy fog/low stratus on Thursday morning across Central
TX as this low level moisture lifts northward over a slightly
cooler airmass. The upper jet feature should serve to increase
upper level cloudiness as well as help carve out a broader trough
to the west. In response, southerly flow will ramp up and help to
lift low level moisture northward. The initial surge of moisture,
coupled with the lack of large scale ascent (minus some WAA)
should be insufficient at generating precipitation on Thursday.
GEFS accumulated precipitation products appear to support this and
as a result, I`ll maintain a rain-free forecast on Thursday.

On Friday, better rain chances look to return as a deeper and
richer plume of moisture is pulled northward by the west coast
trough. Large scale ascent should also increase with this feature
and the trough looks to cross through North and Central TX. I`ll
maintain slight chance to chance PoPs mainly across Central TX
where the moisture looks to be the richest. I`ve extended PoPs
northward back towards western zones as they`ll be in closer
proximity to the center of the upper forcing. There does appear to
be sufficient instability, so I`ll go with a mention of
thunderstorms on Friday. There is some shear in the forecast GFS
profiles with magnitudes on the order of 20 to 25 knots,
suggesting some organized convective modes. Lapse rates, however,
remain somewhat poor and as a result, I`ll abstain from the
mention of any strong or severe storms on Friday. Rain chances
look to dwindle during the overnight hours into Saturday as the
upper trough exits to the east.

For Saturday and Beyond---Low rain chances may linger on Saturday
mainly across the eastern two-thirds of North and Central TX, but
forecast soundings indicate some decent warming in the 700-850mb
layer. This may prevent precipitation from developing through much
of the daylight hours. For now, I`ll maintain low PoPs (around 20
percent) with low confidence of rain/thunder occurring. If the
capping is weaker than projected, it`s possible that isolated to
scattered convection could develop given the increasing low level
moisture and diabatic heating.

Late Saturday into Sunday looks to be the best time period for
more widespread rainfall in the extended forecast. The operational
GFS and ECMWF have come somewhat into better agreement and both
models deepen an upper trough down through west TX late Saturday
and into Sunday. The associated cold front will crash southward
into what should be an unstable airmass with 1,000 to 2,000 J/kg
of CAPE. Deep layer shear is still forecast to remain on the lower
side of things and at this time, it appears that the best lift
won`t overspread the area until the overnight hours, potentially
limiting optimal instability. That being said, it looks like there
may still be enough of a shear, instability and lift combo to
support some risk for strong storms across the area. We`ll keep
monitoring this over the next several days.

Both models do bring the front through the area by the end of
Sunday, though the GFS advertises some post-frontal convection
through at least midday. Thereafter, the models diverge
significantly, with the ECMWF cutting and closing off the upper
low over the Ark-La-Tex which would result in continued cool
weather and widespread cloud cover for our area. The operational
GFS on the other hand remains progressive and pushes the upper low
and closes it off across South TX---resulting in more insolation.
For now, will maintain a low confidence forecast with generally
cooler conditions and some cloud cover.



.AVIATION... /Issued 1218 PM CDT Mon Oct 16 2017/
/18Z TAFs/


VFR conditions will prevail through the period under clear skies.
Generally northeast winds between 5-10 kts will occur today with
occasional wind gusts near 15 kts, more likely occurring at KACT.
The winds overnight will become light and variable or light
easterly, and then are expected to gradually turn to the
southeast on Tuesday as the surface high moves east of the region.



Dallas-Ft. Worth    46  77  51  83  56 /   0   0   0   0   0
Waco                42  79  44  84  53 /   0   0   0   0   0
Paris               43  73  46  79  51 /   0   0   0   0   0
Denton              40  76  43  82  52 /   0   0   0   0   0
McKinney            41  76  43  80  51 /   0   0   0   0   0
Dallas              47  77  54  83  57 /   0   0   0   0   0
Terrell             41  75  44  82  52 /   0   0   0   0   0
Corsicana           46  78  48  81  55 /   0   0   0   0   0
Temple              44  79  46  83  56 /   0   0   0   0   5
Mineral Wells       41  79  48  83  51 /   0   0   0   0   0




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