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

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FXUS64 KFWD 141604 AAA
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
1104 AM CDT Sat Oct 14 2017


.UPDATE...
Main update to the forecast was to remove the mention of fog and
tweak sky and temperature trends to better match observations.
Otherwise, the forecast is in very good shape.

Low level moisture streamed northward this morning and supported
some patchy fog mainly across Central TX. With heating and mixing,
fog has lifted into a broken stratocumulus cloud deck. With most
sites reporting visibility greater than 5 miles, I went ahead and
removed the mention of patchy fog from the forecast. Southerly
breezes at 10 to 20 MPH will continue today with perhaps some
gusts to near 30 MPH as the surface pressure gradient remains
tight. This should allow it to feel a bit more tolerable outside,
but it`ll still remain unseasonably hot with temperatures in the
low to mid 90s area-wide. We`ll continue to examine the latest
model guidance on frontal timing and rain chances for late tonight
and into Sunday morning for parts of the area.

Other than tweaking sky and temperature trends, the remainder of
the forecast remains unchanged. Updated products have been
transmitted.


24-Bain

&&


.AVIATION... /Issued 717 AM CDT Sat Oct 14 2017/
/12Z TAFs/

Concerns will be the broken IFR/LIFR stratus deck and patchy
BR/FG moving northward across Central TX and toward the Waco area.
I do not do not think this deck will maintain this far north into
DFW airports with expected mixing and strong heating by 14z-15z
this morning. FROPA timing and SHRA/VCTS timing is the other
concern after 06Z Sun.

Broken IFR/LIFR stratus continues to ride southerly 25-30 knot
flow in the boundary layer toward Waco Regional Airport this
morning and though it didn`t happen Friday morning, pretty
confident the airport will at least see TEMPO IFR conditions
between 13z-15z this morning. Will carry scattered stratus near or
just below FL020 at DFW, but have them remain VFR for now, as I
do not have confidence these will reach DFW with expected
increases in southerly wind speeds and rapid warming.

All airports will see VFR with south winds sustained at or just
below 15 knots. Could see a few gusts in excess of 20 knots, but
did not mention this in TAFs. These conditions will persist
through the evening hours, then we see a vigorous shortwave over
the Rockies exit out across the High Plains, helping to shunt the
surface low quickly into IA/WI by 06z Sun. This will help drag the
strong cold front across the Red River between 06z-08z Sun a.m.
-- with FROPA noted at DFW TAFs between 0830-0930z Sun a.m. per
timing on high-res models --then at Waco between 11z- 12z Sun a.m.


The cold front will be outrunning the stronger mid level ascent
further north and will quickly undercut showers and storms before
daybreak Sun. With an unimpressive thermodynamic environment and
speed of FROPA through the area, will only carry 2 hours of VCTS
at DFW airports between 08z-10z, then maintain VCSH at all Metro
airports through mid morning with MVFR cigs below FL020. Did not
introduce VCTS at Waco just before 12z with FROPA, as the cold
front will continue moving into a more stable environment.

A deepening and drying frontal inversion by late morning or
midday Sunday should allow for the return of VFR conditions at DFW
airports, likely delayed until early afternoon at Waco.

05/

&&

.SHORT TERM... /Issued 322 AM CDT Sat Oct 14 2017/
/Today & Tonight/

A cold front was draped from Eastern Colorado, northeast into
Nebraska, and Iowa early this morning. A weak surface low was
noted across Southeast Colorado. A broad longwave trough was
draped across the Rockies and Great Basin with a vigorous shortwave
trough moving east across Idaho, Western Montana, and Northern
Utah. Southerly winds 5 to 10 mph were the rule across North-
Central Texas with surface dew point temperatures in the mid to
upper 60s with a more muggy feel to the morning than previous 3-5
days. Stratus was forming from the Texas Hill Country eastward
into parts of Southeast Texas.

After dissecting the latest 00Z runs the past few hours of
several models, only minor tweaks were needed to the ongoing
forecast through tonight with models all having a good handle and
consistency with both features aloft and at the surface. As the
strong Northern Rockies shortwave trough moves east over the the
Central and Norther High Plains by this afternoon, the surface low
over Southeast Colorado will lift progressively into Eastern Iowa
and Southwest Wisconsin by this evening, supporting a good push
to the current stagnant surface frontal boundary situated over the
Heartland early this morning. Ahead of these features will be
breezy south winds 15 to 20 mph and very warm temperatures over
North-Central Texas with a very warm low level thermal ridge ahead
of the cold front right over our area. I have gone slightly
warmer than guidance by a degree or two with highs between 90 and
95 degrees once again. With the cold front delayed until late
tonight, the breezy south winds, and not much in the way of
veering or compressional warming, this appears to be the most
reasonable scenario for today. Do not see wind speeds being strong
enough for any advisory issuance and record highs today at both
Waco and DFW in the upper 90s look to be safe.

The cold front will move readily into the Texas/Oklahoma
Panhandles and into Kansas early this evening with good mid level
support. Scattered to numerous showers and thunderstorms will
evolve both along and behind the cold front through the evening
hours, as the vigorous mid level energy lags back to the northwest
and trudges eastward over the Central Plains. The cold front is
still expected to make its entrance into the Red River Valley
around or shortly after midnight. With a weak EML (or cap) in the
850-700mb layer and a relatively shallow moisture initially this
evening, it`ll likely take the lift from both the front and
approach of the shortwave trough to moisten the environment for
numerous showers and a few non-severe thunderstorms. The cold
front will outrun the mid level support with an unimpressive
thermodynamic environment across our area.

The gusty post-frontal winds will actually be more impressive
than any winds thunderstorms along the cold front would produce.
Strong cold advection and a strong pressure gradient will result
in gusty north winds 15 to 25 mph with temperatures rapidly
falling off into the 50s and lower 60s across the northwest half
of the area by daybreak Sunday morning. No heavy rainfall is
expected at any one location, due the speed of the cold front and
with the better mid level support remaining much further north.
However, brief heavy downpours cannot be ruled out. Central Texas
areas will likely remain muggy and warm overnight with lows 65 to
70, as the cold front`s arrival holds off until after sunrise
Sunday.

05/

&&

.LONG TERM... /Issued 322 AM CDT Sat Oct 14 2017/
/From Daybreak Sunday/

The cold front should be nearly through the forecast area by
sunrise Sunday morning. Convective activity will be on the
downtrend by this time with a thin band of showers and storms
located along or just behind the frontal zone. All activity will
be falling apart rather quickly throughout the morning hours as
the cold front outruns the upper-level forcing for ascent.
Lingering light stratiform rain within the frontal inversion layer
will persist across areas well north of the surface front through
mid morning before very dry air arrives and shuts down
precipitation area-wide. By mid afternoon, all showers should be
long gone and skies will begin clearing from north to south.
Substantial cold advection aided by strong northerly low-level
winds will hold temperatures in the 60s and 70s Sunday afternoon;
surface winds will hold around 15-25 mph throughout most of the
day.

Dry and pleasant weather will be the story heading into early next
week with a few days of seasonable fall temperatures and low
humidity. On Tuesday, we should see the coolest morning in quite
some time with most of the forecast area expected to dip into the
40s. A gradual warming trend will ensue through midweek as winds
come back around to the south with surface high pressure shifting
eastward and relatively zonal flow aloft. Highs will be back in
the upper 70s and 80s by Wednesday and these conditions will
persist through the end of the week.

By Friday, a broad trough should take shape across the Western US
and a few upper disturbances will eject eastward into the Plains.
This will aid in moisture return through North Texas and possibly
a few showers or storms Friday afternoon if a disturbance is
potent enough. Have decided to introduced some low PoPs for this
time frame. Models are all over the map for next weekend`s
forecast, but the ECMWF has been hinting that a deep upper low
could develop across the Southern Plains and send another cold
front toward the region by next Sunday or Monday. While the
operational GFS keeps these features weaker and farther north, a
few GEFS members are in very good agreement with the ECMWF
solution. Have included some low PoPs for next weekend since there
should be sufficient moisture for a few showers or storms whether
the lift is from another front or just from a weaker upper
disturbance pivoting through.

-Stalley

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    93  63  70  50  74 /   0  80  30   5   0
Waco                93  66  74  51  74 /   0  40  40   5   0
Paris               91  61  68  48  71 /   0  80  30   5   0
Denton              93  60  69  47  72 /   0  80  20   5   0
McKinney            92  60  68  47  71 /   0  80  30   5   0
Dallas              93  64  71  52  74 /   0  80  30   5   0
Terrell             93  63  70  48  73 /   0  60  30   5   0
Corsicana           91  66  72  50  73 /   0  30  40   5   0
Temple              91  65  73  52  73 /   0  20  40   5   0
Mineral Wells       93  58  68  45  72 /   0  80  20   5   0

&&

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

$$

24/82



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