Of course, after I post, the National weather service says:
An arctic front will surge south through all of North and Central
Texas Friday night, bringing much colder weather for the holiday
weekend into next week. Confidence is still high that dangerously
cold weather will be in place for multiple days beginning Saturday
night, with lows in the teens and 20s along with wind chills in
the single digits and teens. A Cold Weather Advisory will likely
be needed at some point starting sometime this weekend. It is
possible that temperatures do not climb above freezing in some
locations for a few days, particularly Monday and Tuesday
following a reinforcing shot of arctic air. On Monday for
instance, areas along and north of Highway 380 and along/west of
I-35 have the highest probability of max temperature at or below
32 (around 70-80%). Either way, high temperatures will remain in
the 30s areawide Sunday through Tuesday, which even for January
is 20 degrees below normal.
As important as all of that is, the more frequently asked
question focuses on winter precipitation probabilities and the
potential for travel impacts. Anytime North and Central Texas
becomes enveloped in an airmass this cold, even modest amounts of
available moisture can produce enough light precipitation to cause
impacts. The upper level feature of interest at this juncture
continues to be a positive-tilt shortwave, which is progged to
drop southeast around the southwest flank of a longwave trough
entrenched over the center of the CONUS at the start of next week.
Model guidance has been struggling with consistency regarding the
strength of the isentropic lift out ahead of the shortwave and
amount of available moisture. If the ascent is strong enough, the
upper level system typically can find enough moisture to produce
precip, and consequently higher moisture content can often
overcome weak lift. Due to a lack of any significant changes in
guidance since yesterday, will stick somewhat close to persistence
for this forecast package, indicating a chance of light snow along
with minor to no accumulations.
One thing to note is that last night`s National Blended Model has
increased POPs compared to previous runs, perhaps attributed to
slightly more aggressive (with QPF) ECMWF members. Will therefore
increase POPs slightly, and extend the slight chance POPs farther
north to near the Red River, both based on the latest NBM numbers.
That being said, due to the presence of such a dry airmass,
accumulations will be kept in the "minor to none" category for
now. There continues to be a lot of uncertainty regarding QPF,
however, so the forecast could still shift to higher accumulations
(or none) depending on how the upstream shortwave evolves. Much
more will become known over the weekend when better resolution
model guidance comes into play. Whatever the case, temperatures
should finally start to modify during the latter half of next week
as the longwave trough weakens and shifts east. Temperatures may
even approach near-normal values by Thursday or Friday of next
week.
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