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Area forecast discussion...updated
National Weather Service Fort Worth Texas
612 PM CST Sat Dec 7 2019

Aviation...
/00z tafs/

VFR with south flow. Increasing wind speeds on Sunday.

A surface high shifted east of the region this afternoon,
reintroducing south winds that will prevail through Sunday night.
The decoupling boundary layer and proximity of the surface ridge
will keep wind speeds light this evening. Renewed troughing in the
Lee of The Rockies will set up a low-level jet of 30-40kts during
the predawn hours, which may dip below fl020. The upper end of
this range will be primarily west of the metroplex taf sites, but
subsequent taf packages will further assess the need for low level wind shear.

While the stronger winds will be to the west of the airports along
the I-35 corridor, the most intense moist advection will be to the
east. A few puffs of stratocu within the low-level jet may zip
through the Aerodrome, but any MVFR ceilings should be confined to
East Texas. Some of the momentum within the low-level jet will
mix to the surface by mid-morning, and gusty south winds will
prevail the remainder of the day. Deepening Lee troughing will
prevent the nocturnal boundary layer from separating from this
flow Sunday evening, and the gusty winds will continue after dark.

A cold front is scheduled to arrive Monday afternoon, but the
associated rain will be behind the boundary Monday night into
Tuesday.

25

&&

Long term... /issued 221 PM CST Sat Dec 7 2019/
/Sunday night through Saturday/

Warm/moist air advection will increase Sunday night ahead of an
approaching low pressure system and cold front. As a result,
temperatures Sunday night will be very mild for December with
lows generally in the 50s.

Monday will start off mostly cloudy and warm as surface winds
veer to the southwest ahead of the front. The front will enter the
northwest zones Monday afternoon and sweep through the entire
forecast area Monday evening. Some light rain will accompany the
cold front as the upper trough moves east across the state,
increasing large scale lift. The rain will linger through Tuesday
morning, but end from northwest to southeast through the day with
increasing subsidence behind the departing upper trough. The
latest deterministic models continue to indicate temperature
profiles that support only a cold rain and we see no reason to
deviate from that solution based on pattern recognition. If the
upper pattern was not as progressive and the cold air could settle
in well before the upper support arrived, then the potential for
winter weather would be higher. Lows Monday night will be
generally in the middle and upper 30s, except for the northwest
zones which may touch freezing briefly around sunrise (precip
should be over before this occurs). Tuesday will be very cool with
highs generally in the 40s and lows from the upper 20s to the
lower 30s.

Brief riding aloft will occur Wednesday ahead of another
approaching shortwave. Although cold air advection will begin to
decease and ample sun is expected, it will still be cool
Wednesday with highs in the 50s and lows in the 30s.

Another upper low is progged to drop out of The Four Corners
region Wednesday night/Thursday, tracking across the Lone Star
state Thursday night/Friday. Although the system will bring
increasing lift and some elevated moisture, a lack of low level
moisture should limit precipitation potential.

An upper ridge is progged to build in from the west behind the
late week system, bringing warmer and rain-free weather as we head
into mid December. Highs Saturday will likely be in the lower and
middle 60s.

79

&&

Short term... /issued 1024 am CST Sat Dec 7 2019/
/today and tomorrow/

A common saying in some circles of meteorologists is "big bubble,
no trouble." This is a reference to the weather when a dominating
ridge of surface high pressure is directly overhead...today is
one of those days. A ridge of surface high pressure is moving
through the region, keeping the winds light and temperatures near
climo norms for this time of the year--in the low to mid 60s.
Passing mid to upper level clouds should even make for a
picturesque sunset this evening.

The surface ridge axis will shift east overnight as a leeside low
moves east into central Kansas. This will allow southerly flow
with warm/moist advection to take hold of the region tonight. A
30-40 kt nocturnal low level jet will develop aloft this evening, however a
gradually veering profile should prevent the development of
widespread status. We are expecting some stratus to develop east
of I-35 in the early morning hours and persist through the day
tomorrow.

A few hours after sunrise tomorrow, the elevated winds associated
with the low level jet will begin to mix down to the surface. A Stout
shortwave trough will move through the desert SW in the early
morning hours, creating almost purely perpendicular flow overtop
of the southern rockies tomorrow. This will enhance the deepening
of a leeside low over SW Colorado, tightening the pressure
gradient locally. These factors will combine to create breezy
conditions across north and central Texas tomorrow with sustained
winds around 15-20 mph with gusts up to 30 mph. This will elevate
the fire weather concerns west of I-35 with relative humidity values remaining
in the 30s through the afternoon. Temperatures will be noticeably
warmer tomorrow, on average 10-15 degrees warmer than they will be
today. No sensible weather is expected until the next storm
system moves through early next week.

Bonnette

&&

Preliminary point temps/pops...
Dallas-ft. Worth 47 72 59 72 36 / 0 0 0 10 70
Waco 46 74 58 78 36 / 0 0 0 5 70
Paris 45 67 56 69 36 / 0 0 0 20 60
Denton 46 72 58 70 34 / 0 0 0 10 60
McKinney 46 70 59 70 35 / 0 0 0 10 70
Dallas 48 72 60 73 36 / 0 0 0 10 70
Terrell 46 71 59 74 36 / 0 0 0 10 70
Corsicana 47 71 59 76 38 / 0 0 0 10 70
Temple 46 73 58 78 38 / 0 0 0 5 70
Mineral Wells 45 75 56 69 33 / 0 0 0 10 70

&&

Forward watches/warnings/advisories...
none.
&&

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