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

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FXUS64 KFWD 140616

Area Forecast Discussion
National Weather Service Fort Worth TX
116 AM CDT Wed Apr 14 2021

...New Short Term, Aviation...

/Overnight through Wednesday night/

Isentropic lift is increasing over the region now as one upper
level disturbance ripples through in the zonal flow aloft. Weak
elevated instability behind a stationary frontal boundary draped
across the eastern and southeastern zones is allowing for
scattered showers to develop. The better instability will be
confined to the region near and to the east of the front and
a few thunderstorms are likely in this area before daybreak.
Can`t rule out a couple severe storms in the far southeast zones
ahead of the front where surface based instability exists.
Otherwise, cloud cover is extensive and cold advection currently
weak behind the front, and have raised overnight lows a few
degrees from previous forecast...which means the central and
southeast zones will see temps stall in the low to mid 60s.

This current episode of isentropic lift will wane and shift east
of the CWA around daybreak and therefore just some low PoPs for
scattered showers and isolated storms will exist over the eastern
zones through mid morning. Most of the region will be dry through
the day. The frontal boundary will dissipate in its current SW to
NE configuration, and set up in a more W to E configuration south
of the CWA during the course of the day as northerly surface flow
increases as a high pressure cell in the Plains expands southward.
The combination of increasing (weak) cold advection and cloud
cover will result highs stuck in the mid 60s along the Red River.
But upper 70s are forecast across the far southern zones where
cold advection will be delayed and some brief clearing may occur
early this afternoon.

The next upper level wave will move across the region this
evening, and this means isentropic lift will once again increase
late this afternoon across the western zones leading to a few
showers or storms. This elevated activity will shift eastward
across the remainder of the CWA tonight and again end over all but
the eastern zones by daybreak. Elevated instability will be
limited and therefore just mainly showers and a few storms are
expected with no severe weather threat. Best chances of rain and
storms will be over the southeast zones, and PoPs will range from
likely there to just a generic chance in the west. QPF will again
be light, averaging 1/10 of an inch, meaning some locations will
see no rain but others may see over a 1/4 inch. Lows tonight will
fall into the 50s areawide as northerly winds continue to bring
some cooler air into the region from the Plains.



.LONG TERM... /Issued 350 PM CDT Tue Apr 13 2021/
/Late Wednesday through the Weekend/

The weather pattern appears active through the end of the week
with rain chances through Friday. The weekend appears dry at the
moment, but there could be some caveats to the latest forecast.
What does appear likely is that it`ll remain cooler than normal
especially as we head into the weekend.

Isentropic ascent along the 300K theta surface is expected to
ensue and this should yield a broad area of showers and embedded
thunderstorms late Wednesday into early Thursday. The greatest
concentration will likely be near/west of Hamilton to Mineral
wells to Gainesville line. MUCAPE values of around 750-1000 J/kg,
deep layer shear in excess of 40 knots, and 700-500mb lapse rates
approaching 6.5-7 C/km may support a low-end severe hail risk.
These storms are expected to be elevated so the damaging wind and
tornado threat will be near zero. The greatest rain chances will
shift south and eastward through sunrise Thursday with potentially
a slight lull for most areas through the early afternoon hours.
Cloudy skies in tandem with northeast to east winds will equate to
daytime highs in the low 60s across the Big Country to upper 60s
down toward eastern Central Texas (Brazos Valley).

Rain and isolated storm chances will increase again late Thursday
afternoon into the day on Friday as strong warm air advection
commences as a 300mb 100 knot jet streak approaching the Great
Plains induces cyclogenesis across the southern Texas panhandle.
PoPs remain greater than 50% near and northeast of a Hearne to
Waco to Graham line. The surface low should track along the
low-level baroclinic zone. Unfortunately, there is some
uncertainty with how far north the boundary will get. On one hand,
widespread precipitation may halt just how far north the surface
front can travel and this appears to be supported by simulations
from the NAM/ECMWF/Canadian. This will keep the surface low
farther south and thus the risk for strong low level WAA and
cooler conditions. The GFS, however, induces much more rigorous
cyclogenesis and lifts the surface front nearly to the Red River
which would place more of the area in the warm sector (and current
daytime highs would be too low). At present time, I`m inclined to
go with the model consensus given that I have greater than 60
PoPs northeast of the surface front and the warmer airmass will
likely encounter substantial inertia to overcome the cooler/denser
air to the north. I do think that areas near/along the I-14 and
US HWY 79 corridors will have a chance for warm frontal passage
and I`ve nudged Friday`s high temperatures upward a few degrees
from the previous forecast/NBM.

As the aformentioned jet streak exits eastward, there should be a
tremendous amount of CAA with a dry continental airmass plunging
southward in its wake. I`ll end just about all precipitation
chances as even 75th percentile NBM QPF suggest little to no
threat for lingering post-frontal precipitation. The GFS and to
some degree the ECMWF do suggest a potential for a few potent
upper level shortwave troughs to ripple through the southwesterly
flow aloft. However, forecast soundings only suggest virga with
maybe a shot of a few sprinkles. The official forecast will remain
rain-free this weekend, but we`ll keep an eye on this. Rapid
pressure rises will mean very blustery conditions post-FROPA late
Friday and into most of the day on Saturday. Overnight lows into
Saturday morning will remain elevated with values in the 40s to
near 50 degrees. However, it`ll likely feel cooler with the stiff
north wind.

Saturday will see widespread low to mid 60s across the region as
widespread post-frontal stratus will likely be in place. If cloud
cover, however, is a little thinner then the mid-April sun may
warm us a little more than expected. Breeziness will continue into
Sunday morning, but overnight lows are still expected to fall into
the low to mid 40s. A few of the isolated/sheltered spots west of
I-35, may see the thermometer dip into the upper 30s. Cool
conditions will linger into Sunday, though partly sunny skies
may allow temperatures to increase a little more than Saturday`s
highs. Sunday night into Monday morning may feature a larger area
of sub-40 degree temperatures (but still above 32 degrees) across
the Big Country as high pressure settles in across the area. I
wouldn`t doubt some patchy frost either west of I-35 and
near/north of I-20, but we`ll refine this forecast as we get



/6z TAFs/

A few showers will stream across the TAF sites during the next few
hours. Have removed the mention of thunder from the Metroplex TAF
sites as the best instability should remain east, but will need
to monitor the convective trends closely. Brief visibility
reductions are possible in the core of the showers, but otherwise
VFR will prevail. For Waco the chance of vicinity storms is a
little higher and will advertise that threat from 8 to 10z. Most
of the rain activity should push east of all TAF sites after 10z
with a dry morning/day expected. Another round of showers and a
few storms will be possible this evening and have brought VCTS
into the forecast after 4z.

CIGs are currently VFR but should lower to MVFR around 9-10z.
Given the latest trends have sided with MET MOS guidance which
means this forecast will back off on forecasting IFR this morning
and keep CIGs in the low MVFR category instead. These MVFR CIGs
will persist through the evening hours, and may lower to IFR early
Thursday morning.

Winds are light northerly now, but will increase to 10-15kt during
the day as a central Plains high pressure cell begins to spreads



Dallas-Ft. Worth    55  65  56  63  48 /  50  10  70  70  20
Waco                57  66  58  69  49 /  50  40  50  50  20
Paris               50  66  52  57  47 /  50  30  70  80  20
Denton              50  64  52  62  43 /  50  10  70  70  20
McKinney            52  65  53  61  46 /  50  20  70  70  20
Dallas              55  66  57  64  50 /  50  20  70  70  20
Terrell             52  66  54  62  46 /  50  40  70  70  20
Corsicana           55  67  56  65  48 /  60  50  60  70  20
Temple              56  66  57  73  48 /  50  50  40  40  20
Mineral Wells       52  63  54  67  44 /  40  20  50  60  20



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