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

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000
FXUS64 KFWD 111144
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
544 AM CST Mon Dec 11 2017


.AVIATION...
12 UTC TAF Cycle

Concerns---FROPA timing. Otherwise, VFR will prevail.

VFR is expected to continue over the next 30 hours at all North
and Central TX terminals. West winds will increase a few hours
after sunrise, with peak speeds of around 10-12 knots. A few gusts
to 15 knots are possible, but significant crosswinds on north-
south oriented runways are NOT expected. FROPA is expected around
0200 UTC for Metroplex terminals with a couple of hours later at
Waco. Breezy northerly winds of around 10 to 15 knots appear
probable after FROPA. Outside of some high clouds around FL300,
significant obstructions to ceilings or visibility are not
anticipated through the entire TAF cycle.

24-Bain

&&


.SHORT TERM... /Issued 316 AM CST Mon Dec 11 2017/
/Today and Tonight/

An unseasonably warm day is forecast to begin the week with near-
record highs expected. Winds will remain out of the west today so
downsloping combined with weak warm advection will allow the very
dry airmass in place to heat up quickly. Temperatures may climb a
bit higher than advertised considering some compressional warming
will occur ahead of an approaching cold front that will move into
the area this evening. Although the current forecast calls mostly
for upper 70s, would not be shocked at all if DFW sets a record
high (80F in 1938 and 1996) although the record may be more
difficult to achieve at Waco (82F in 1949). These near-record
temperatures along with very dry air (RHs 10-20%) will once again
set the stage for elevated fire danger as west winds increase to
10-15 mph. Any activities that could ignite wildfires are strongly
discouraged as fuels become more and more favorable for their
ignition/spread.

By late afternoon and early evening, a dry cold front will move
into the area. This front is associated with the fast-moving
shortwave located over Minnesota as of 3 AM. A reinforcing shot of
cooler air will arrive with the frontal passage and it will also
prevent any moisture recovery from occurring while holding
dewpoints in the 20s through tomorrow. Winds behind the front will
be breezy (15-20 mph) overnight and into Tuesday morning.

-Stalley

&&

.LONG TERM... /Issued 316 AM CST Mon Dec 11 2017/
/Tuesday through Sunday/

The main theme in the long term period will be large daily
temperature swings courtesy of a few cold fronts and the dry
airmass in place. The dryness combined with above normal warmth on
a few afternoons this week will result in an elevated fire
weather threat, especially on Wednesday and Saturday. Rain chances
this weekend continue to look rather unimpressive and I`ve
maintained a precipitation-free forecast throughout the long term
outlook.

Tuesday and Wednesday---Tuesday will be noticeably cooler and
blustery (compared to Monday) as a cold front will have crashed
southward through all of North and Central TX by daybreak. I`ve
cautiously kept temperatures towards the cooler end of the
guidance spectrum as surface-925mb temperature advection in the
morning hours are progged to be quite impressive. The stiff north
wind of 15 to 20 MPH will likely make it feel even colder. That
being said, daytime heating courtesy of full insolation will still
allow temperatures to approach seasonal norms. If the latest NAM
is to verify, however, it`s possible that temperatures may fall
into the low 50s across all of the area. Winds should relax with
time as surface pressure tendencies become neutral during the late
afternoon and nighttime hours. With the boundary layer likely to
decouple, Tuesday night into Wednesday morning will be cold,
especially across rural and sheltered areas. In general overnight
low temperatures are forecast to fall into the 20s and 30s.

Conditions quickly moderate on Wednesday as winds respond to the
next approaching upper trough across the Midwest. The surface
pressure gradient will become tight and should allow south to
southwest winds to approach the 10 to 20 MPH range. Stronger wind
gusts closer to the 25-30 MPH range will also be possible. The
southwest flow at the surface combined with low level mixing
should allow afternoon dewpoints to fall quickly into in the
the 20s and 30s and I`ve undercut blended model guidance
dewpoints by a few degrees. The southwest flow will also allow
temperatures to soar about 10 to 15 degrees above normal. These
factors combined will likely yield an elevated to near-critical
fire weather threat across much of North and Central TX on
Wednesday. The limiting factor, however, may be the magnitude of
the surface winds, so we will keep a close eye on this crucial
component of the fire weather forecast over the next day or so.
Regardless, we urge individuals to take care and avoid activities
that could result in starting grassfires. Wednesday night into
Thursday night should be a tad milder as the boundary layer may
stay a bit more well- mixed with the approach and passage of the
front.

Thursday and Friday---Breezy northerly winds in the wake of the
aformentioned front will overspread much of the area on Thursday.
While temperatures may only be a few degrees above seasonal
normals, a lingering fire weather threat may materialize due to 10
to 15 MPH north winds and the dry conditions associated with
FROPA. Similar to Tuesday, it`ll feel a little cooler than actual
temperature readings due to the north wind. The breezy conditions
should subside after sundown. Another ideal radiational cooling
night will be on tap Thursday night into Friday as clear skies and
light winds are anticipated.

Conditions on Friday are expected to moderate as flow quickly
switches to the south and southwest. At this time, I`m a little
hesitant to warm things up dramatically as surface winds may not
attain the necessary westerly component to allow temperatures to
really soar due to downsloping. Regardless, above normal
temperatures should occur with breezy conditions continuing.

Saturday and Sunday---Saturday has the potential to be an active
day with regards to fire weather based on the latest model
projections. Blended model guidance actually outputs near advisory
level wind speeds across the area as a strong pressure gradient
induces 40-50 knot winds just above the surface. Mixing should
occur readily, but the potential fly-in-the-ointment will be
possible mid/high level dense cirrus. It does look like that
temperatures will still warm almost 10 to 15 degrees above normal
and with south to southwest winds in the 20 to 25 mph range, the
threat for rapid fire spread will increase on Saturday afternoon.

Unfortunately, it appears that there is a strong model consensus
on little hopes of any rainfall late Saturday into Sunday. This
time yesterday, the 00 UTC deterministic GFS and its ensembles
were the lone outliers and painted QPF across eastern and
southeastern zones. The latest deterministic GFS has started to
shift towards the drier model consensus comprised of
deterministic and ensemble European and Canadian model output.
I`ve maintained a dry forecast as a result and at this point in
time, it`s possible that the next meaningful rain chances may not
appear until the middle of the following week.

24-Bain

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    79  40  57  37  74 /   0   0   0   0   0
Waco                78  38  60  28  70 /   0   0   0   0   0
Paris               75  37  52  33  67 /   0   0   0   0   0
Denton              77  36  56  29  71 /   0   0   0   0   0
McKinney            76  37  55  30  71 /   0   0   0   0   0
Dallas              78  41  57  38  75 /   0   0   0   0   0
Terrell             77  39  55  32  70 /   0   0   0   0   0
Corsicana           77  41  58  36  67 /   0   0   0   0   0
Temple              78  38  60  33  71 /   0   0   0   0   0
Mineral Wells       79  36  57  27  73 /   0   0   0   0   0

&&

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

$$

24/26



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