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FXUS64 KFWD 070906

Area Forecast Discussion
National Weather Service Fort Worth TX
306 AM CST Sat Dec 7 2019

/Today and Tonight/

High pressure continues to build into North Texas this morning
behind yesterday's cold front with light north winds and
temperatures ranging from the mid 30s to the mid 40s. Some high
clouds are passing through the Southern Plains and this will
continue through much of the day as Pacific moisture streams
eastward ahead of a digging trough. Winds will generally be light
and will gradually become more southerly this afternoon with high
temperatures topping out in the upper 50s and lower 60s areawide.

By tonight, southerly winds will increase in response to pressure
falls across the TX/OK panhandles. A modest low level jet will
become established across the region overnight and allow some
better moisture to stream northward. This may result in an
increase in low cloud cover by early Sunday morning mainly east of
I-35. Otherwise, temperatures will be 5 to 10 degrees warmer
tonight with lows in the mid to upper 40s.



/Monday onward/

Synopsis: A return to a more active pattern is forecast for next
week, with near to below normal temperatures and increased
precipitation chances expect. The greatest precipitation chances
will be on Tuesday. Right now, no winter weather or other
widespread hazardous weather is in the official forecast, but
there is a non-zero chance of a brief changeover to a wintry mix
in our far northwestern counties on Tuesday morning.

The next weather-maker for North and Central Texas will be a
strong upper-level trough, poised to approach the area on Monday.
This upper-level trough/low is located near the 130th Meridian
West about 375 miles west of Crescent City, CA at present time. 
Over the next 48 hours, this upper-level low will open up, and 
drop southeast across the Sierra Nevada, Great Basin, and into the
Desert Southwest, reaching the Arizona/New Mexico border by late 
Monday. Strong height falls ahead of this trough will drive a 
surface cold front south across our county warning area. This 
front should enter our northwestern counties on Monday afternoon, 
reach the Metroplex by late afternoon/early evening, and clear our
southeastern counties by mid to late evening. Gusty northerly 
winds, falling temperatures, and increasing rain chances are 
forecast behind this front.

The highest rain chances will begin late Monday night following
the initial frontal passage. The uptick in rain chances will occur
in tandem with the approach of the aforementioned upper-level
trough. With the upper-level cyclonic vorticity maximum forecast
to pass almost directly over our CWA, strong lift will be
realized, resulting in widespread rainfall by late Monday night.
While QPF amounts in the models are not particularly impressive
(on the order of one-quarter to one-half inch), the bigger
forecast challenge will be with respect to (low end) winter 
weather potential. Before we press on, it should be noted that the
official forecast does not show any winter weather at this time, 
nor do we expect ANY winter weather (let alone impactful winter 
weather), so sorry kids, you'll probably still have school on 
Tuesday. With that out of the way, let's continue.

Strong cold air advection will continue through Monday night and
into Tuesday, with temperatures likely to drop very near the
freezing mark northwest of an Eastland to Gainesville line by
Tuesday morning. While the forecast does explicitly show slight
chance to chance PoPs during this timeframe, the current
expectation is that any precipitation should be southeast of this
area by the time temperatures get to/below the freezing mark.
Furthermore, a grand total of zero models (at least their most
recent runs) explicitly show wintry precipitation in North Texas 
on Tuesday. This is a long way of saying our deterministic
forecast is that winter weather is not expected. 

But what about the "reasonable worst case scenario"? The one 
issue that does give us pause from categorically ruling out any 
wintry precipitation is that oftentimes, global models struggle 
in situations involving strong cold air advection within shallow 
cold air intrusions (like this one on Monday/Tuesday). Because of
this, if temperatures were to drop below freezing earlier than 
expected, a quick changeover to sleet or even a rain/snow mix 
cannot be 100% categorically ruled out for our northwestern
counties (read: not in the Metroplex). To stress again however, 
this is not our expectation at this time, and we do not expect any
winter weather, let alone impactful winter weather. We bring this
up merely to put it in the back of your mind, and remind you to 
check the forecast over the next few days...just in case. This is
also a good time to remind our readers to be wary of any forecast
model graphics showing wintry weather that could float around on
social media. Without going into great detail, such graphics are
generated merely using a computer algorithm that attempts (often
poorly) to predict the precipitation type at the surface. If only
winter weather forecasting were so easy...

Rain should come an end late Tuesday across the rest of the CWA,
with Tuesday night likely to be the coldest night of the week. A
freeze appears likely across much of the CWA, even in the urban
core of the Dallas/Fort Worth Metropolitan Area. This is a change
from the last 24 hours, where last night, it was believed any
freezing temperatures would remain north and west of DFW. Forecast
models have trended colder in the last 24 hours, and they could
trend colder still. That said, there's nothing to indicate an
overly severe freeze or extremely cold temperatures, but enough of
one to likely require standard freezing temperature precautions.

Late in the week, another upper-level trough looks to approach
North and Central Texas. This should lead to increasing vertical
ascent late Thursday and into Friday. With moisture largely
scoured out by the Monday/Tuesday cold front however,
precipitation chances look low. The global models generate very
little QPF if any at all during this timeframe. Still, with this
strong of lift, we decided to carry some slight chance PoPs
Thursday and Friday. Temperatures should be warm enough to keep
all precipitation as liquid rain.



.AVIATION... /Issued 1135 PM CST Fri Dec 6 2019/
/06Z TAFs/

A constant feed of Pacific moisture will result in broken to 
overcast high clouds through Saturday evening. We still anticipate
some stratus to work in from the northeast after sunrise Saturday,
possibly resulting in some brief MVFR ceilings, mainly east of the
Metroplex terminals. Any low clouds that do develop will lift and
scatter by late morning with boundary layer mixing. 

A north wind tonight will slowly veer to the east/northeast
Saturday morning, eventually becoming southerly Saturday
afternoon/evening. Wind speeds will remain between 5 and 10 knots
through the TAF cycle. 



Dallas-Ft. Worth    61  48  71  59  71 /   0   0   0   0  10 
Waco                64  46  72  57  77 /   0   0   0   0   5 
Paris               60  44  66  56  68 /   0   0   0   0  20 
Denton              60  45  71  57  69 /   0   0   0   0  20 
McKinney            61  46  69  57  70 /   0   0   0   0  20 
Dallas              63  48  71  60  72 /   0   0   0   0  10 
Terrell             63  46  70  58  73 /   0   0   0   0  10 
Corsicana           65  47  70  59  75 /   0   0   0   0  10 
Temple              66  46  72  57  78 /   0   0   0   0   5 
Mineral Wells       61  44  72  55  69 /   0   0   0   0  10 



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