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

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FXUS64 KFWD 091758

Area Forecast Discussion
National Weather Service Fort Worth TX
1158 AM CST Fri Dec 9 2016

A thin deck of mid-level clouds overspreads much of the region
with a few breaks across Central TX where some weak subsidence is
occurring. These cigs, currently at FL060, should lower to around
FL045 this evening. As surface high pressure shifts eastward,
winds will continue veering to the east and southeast by late
afternoon/evening and remain less than 10 kts.

Southerly flow will strengthen tonight resulting in increasing
low-level moisture through Saturday. Cigs will continue lowering
to near MVFR (around FL030) initially at Waco Saturday morning,
and then spread northward toward the DFW Metroplex around midday.
Have only included this mention for borderline MVFR cigs in the
Waco TAF and the extended DFW TAF for now as the better potential
resides just outside of the current 24-hour TAF period. Wind
speeds will increase to around 15 kts by midday as stronger low-
level winds mix down to the surface.



Visible satellite imagery shows some decrease in cloud cover over
the last hour primarily south of Interstate 20. Very weak
isentropic ascent continues this morning but will diminish a bit
through the afternoon. The morning sounding shows that the
moisture responsible for the cloud cover is only about 50mb deep
so as this ascent weakens...clouds should begin to thin out a bit.
Some areas will become mostly sunny by afternoon while others will
have lingering cloud cover. Temperatures will be affected strongly
by cloud cover but most areas should warm into the lower 40s by
late afternoon. Only made some minor tweaks to hourly temperatures
through mid afternoon and adjusted cloud cover a bit. significant changes are needed at this time.



.PREV DISCUSSION... /ISSUED 345 AM CST Fri Dec 9 2016/
It`s definitely a cold morning out there now as a strong 1040 mb
arctic anticyclone is settling in just to our northeast, although
perhaps not quite as bone chilling as we were anticipating a few
days ago. Temperatures this hour are generally running in the
lower 20s to near 30 degrees with a light northerly breeze
resulting in wind chills in the teens for many. Expansive low-
level cloudiness is spreading eastward this hour, and will likely
envelop most of our region today as residual moisture in the
850-750 mb layer is resupplied by increasing southwesterly flow
aloft. Given the potential for this cloud cover today, sided with
the cooler temperature guidance and even knocked a degree or two
off of that. Thankfully, wind speeds will be greatly diminished
from what we experienced yesterday.

High pressure slides east of the region on Saturday, which will
result in the return of southerly/southwesterly low-level flow and
swiftly increasing moisture. By Saturday evening, forecast
soundings reveal a saturated, or a near-saturated airmass in the
lowest 5000 feet or so, with very dry air above. This should set
the stage for the development of drizzle/light rain showers across
a good chunk of the CWA Saturday night. That said, the likelihood
of measurable precip looks pretty low at this time, and will cap
PoPs at 30 percent during this time frame. As a shortwave and
associated cold front approach the region on Sunday, shower
chances should steadily push east of the I-35 corridor before
chances come to an end Sunday evening. As all of the saturated air
seems to be relegated below 850 mb and well above 0C, the
potential for thunder appears very low at this time, and have left
it out of the worded forecast on Sunday afternoon.

Cooler and drier air will filter into the region on Monday behind
this aformentioned front resulting in a nice, seasonable start to
the work week. The moderating temperatures will be short-lived,
however, as yet another arctic airmass will be intruding into the
northern CONUS on Tuesday. The leading edge of this rejuvenated
cold airmass should move through North and Central Texas somewhere
during the Tuesday night into Wednesday morning time frame, but
substantial model spread and run-to-run consistency issues are
plaguing this portion of the forecast. The GFS, which has
struggled mightily over the past few days with the timing of this
arctic front has largely been ignored in this forecast package
given its very tardy frontal timing on Wednesday afternoon.
Instead, a blend of the notably faster 09/00Z ECMWF and GFS
Ensemble mean seems more reasonable, and matches up a bit better
with the 09/00Z Canadian as well. Moisture profiles look very
meager during the frontal passage, and as a result, we`ve
maintained the dry forecast during the middle of the week.

Temperatures behind the front on Wednesday and Thursday should not
be quite as cold as what we experienced this week, but will
nonetheless be about 10 to 15 degrees below average. As the cold
high pressure center migrates east of the region on Friday, return
flow and an approaching disturbance may bring about renewed
chances of showers towards the end of the week.



Dallas-Ft. Worth    43  31  51  47  70 /   0   0   5  20  10
Waco                43  31  50  48  70 /   0   0  10  20  10
Paris               41  27  48  44  65 /   0   0   5  30  40
Denton              41  28  50  46  70 /   0   0   5  20  10
McKinney            42  28  49  45  68 /   0   0   5  30  20
Dallas              43  32  50  48  70 /   0   0   5  30  20
Terrell             42  29  49  47  68 /   0   0  10  30  30
Corsicana           43  32  50  48  68 /   0   0  10  30  20
Temple              42  31  50  48  69 /   0   0  10  30  10
Mineral Wells       41  28  53  47  71 /   0   0   5  10   5




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