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

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FXUS64 KFWD 201146 AAA

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
546 AM CST Mon Nov 20 2017

/12z TAFs/

The only real challenge on this forecast set will be possible
VSBY restrictions at Waco Regional both early this morning and
again Tuesday morning, with DFW Metro airports seeing VFR

Waco Regional Airport... Stronger radiational cooling and very
weak south-southwest flow has resulted in some moisture flux off
nearby Lake Waco for a brief TEMPO period of possible MVFR VSBYs
early this morning. VFR conditions with south winds around 10
knots are expected by this afternoon and through the evening
hours. A vigorous shortwave passing through this morning will only
bring spotty dense cirrus this morning, before clearing occurs
this afternoon in wake of the upper disturbance passing through.

Late tonight brings a challenge as 925mb flow veers and advects a
very shallow, near surface layer of moisture from the Gulf of
Mexico across the airport after midnight. I have introduced MVFR
VSBYS for now with scattered stratus at AOB FL010. This weak warm
advection just above the surface should allow for spotty BR, or
possibly FG formation at or near the airport after midnight and
through mid morning Tuesday. IFR cigs are being shown by WRF and
NAM forecast soundings, but not the GFS. For now will introduce an
optimistic 4SM BR/SCT008 after midnight. Later forecasts should
have more confidence on whether IFR conditions and/or any BR/FG
occurs late tonight.

DFW Metro Airports... VFR conditions and increasing south winds
of 10-15 knots are expected through tonight. A passing shortwave
this morning will result in scattered-broken cirrus that will be
shunted east of the area this afternoon. As noted in the Waco
Regional discussion, any modified warm advection and moisture flux
should remain confined over Central Texas as 925mb flow veers in
advance of a cold FROPA expected later on Tuesday.



.SHORT TERM... /Issued 345 AM CST Mon Nov 20 2017/
/Today and Tonight/

A well-defined shortwave disturbance aloft will track east across
the region through this evening. Due to a very dry atmospheric
column as noted by the 0.24 inches of PWAT on the the 00z FWD
sounding, the only thing we`ll see from this system is the
continuation of some high clouds today. At the surface, the
departure of our cool surface high will continue to enhance
southerly winds today with slightly warmer temperatures from what
the area experienced on Sunday. Highs will range from the lower
60s east to the mid-upper 60s west. I wouldn`t be surprised to see
a rogue 70 degree reading across the far western counties if the
high cloudiness disperses quickly enough.

For tonight, the aformentioned shortwave disturbance will move
away from the area with clearing skies. Southerly winds of 10-15
mph will continue across the western counties as lee side pressure
falls continue. Wind speeds less than 10 mph will occur farther
east and thus, these areas will see the cooler temperatures. Lows
will be primarily in upper 40s, though protected areas across
Central Texas counties east of I-35 could see values fall into the
lower-mid 40s. 925mb flow on the order of 25-30 kts will veer
southwest and help surge modified moisture across our Central
Texas during the pre-dawn hours and have inserted some patchy fog
for those areas near river valleys and bodies of water.
Otherwise, quiet sensible weather is expected due to the dry
airmass in place and subsidence expected behind the departing



.LONG TERM... /Issued 345 AM CST Mon Nov 20 2017/
/Tuesday through Sunday/

Quiet and generally rain-free conditions are expected through the
entire outlook period, despite the passage of a few frontal
boundaries through the region. The one caveat to these rain-free
conditions may be on Tuesday across far southeastern zones where
there remains a very low chance for a few sprinkles. Otherwise,
expect large swings between high and low temperatures on most days
given the dry airmass in place.

Low level moisture will continue to lift northward on Tuesday as a
compact, but potent shortwave trough dives southward in the
meridional flow aloft across the region. Forecast soundings the
past few days have shown a saturated near-surface layer across
Central TX and with a favorable hydrolapse, I can`t rule out some
patchy fog down across this area. Strong winds just above the
surface may prove to be a negating factor to this development and
its possible that only a low stratus deck develops. For now, will
increase cloud cover and continue a mention of patchy fog beyond
12 UTC on Tuesday. Any fog should disperse by mid to late morning.
Mid and upper level cloud cover will be on the increase through
the day as a 100 knot 300mb jet overspreads the area from the

As noted the past few days, there will be a decent amount of
ascent ahead of the aformentioned shortwave trough. However,
moisture in the free atmosphere just above the surface, but below
the mid-levels remains very low. I`ll maintain a silent 10-15 PoP
given this strong lift, but the very dry air precludes mentioning
sprinkles or light rain in the worded forecast at this time.
Temperatures on Tuesday are a tad tricky as weak compressional
warming ahead of the front will be pitted against increasing mid
and high level clouds. At this time, I believe that the northern
two-thirds of the forecast area will climb into the 60s to near
70. Across Central TX south of a Lampasas to Temple/Killeen to
Palestine line, temperatures may climb into the mid 70s as low
level flow remains veered through peak heating and mid/high level
cloud cover thins.

Despite FROPA, conditions Tuesday night into Wednesday morning
will be a tad warmer than the previous night due to stronger
northerly nocturnal breezes. Overnight temperatures will only fall
into the mid to upper 30s along the Red River and across
northwest zones to 40s elsewhere. Mid and upper level clouds will
begin to clear from west to east. Wednesday will be cooler as
north winds, albeit a tad lighter, persist. Highs will likely
only climb into the upper 50s along the Red River to low to mid
60s elsewhere. Wednesday night into Thursday morning will be on
the chilly side as clear skies, light/variable winds and a dry
airmass will promote ideal radiational cooling. Very light
northerly winds may keep eastern sections colder than central and
western zones where southerly winds are expected to return.

Thanksgiving Day (Thursday) should be a very pleasant day across
much of the area as temperatures rebound. There is a hint in model
wind, temperature and pressure fields that a weak frontal boundary
may slide southward towards the area. The broad surface low
associated with this feature may be enough to veer winds such that
winds become westerly. This would favor warmer conditions and I`ve
started to trend towards European MOS output with highs in the
upper 60s to low 70s. The diffuse boundary does appear as if it`ll
slide southward through the area on Thursday, resulting in a brief
wind shift to the north Thursday evening.

By Friday, southerly winds return in response to a deepening
surface low to the northwest. The increase in winds aloft on
Friday morning should limit the ability of the boundary layer to
completely decouple and overnight low temperatures will be 5 to 8
degrees greater than Thursday morning. Afternoon high temperatures
will be above seasonal norms with readings in the 70s. A few sites
out west may climb into the mid to upper 70s thanks to
southwesterly flow at the surface.

The third front for this week looks to arrive through the day on
Saturday across North and Central TX. Models have started to
cluster near this solution and this yields a bit higher
confidence in FROPA timing compared to 24 hours ago. With the
front likely not making it to I-20 by midday, a majority of the FA
will still experience above normal temperatures. In fact, areas
along the Red River may only fall into the upper 70s. The
remainder of North and Central TX should climb into the mid to
upper 70s. The best low level moisture will still remain south of
the area and so at this time, I`ve continued with a rain-free
forecast in the extended.



Dallas-Ft. Worth    66  49  67  42  61 /   0   0   5   5   0
Waco                67  48  70  44  63 /   0   5  10  10   0
Paris               63  44  65  37  58 /   0   5   0   0   0
Denton              65  46  68  37  61 /   0   0   0   0   0
McKinney            64  46  66  40  59 /   0   0   5   5   0
Dallas              66  50  67  43  61 /   0   0   5   5   0
Terrell             65  47  68  42  61 /   0   5  10   5   0
Corsicana           66  47  68  44  60 /   0   5  10  10   5
Temple              67  47  73  44  64 /   0   5  10  10   0
Mineral Wells       67  43  68  37  61 /   0   0   0   0   0




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