Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Lubbock Texas
1125 PM CST sun Dec 28 2014
VFR expected through much of Monday though outlook in the last 6
hours of this cycle become a bit more cloudy. Winds should shift
northwesterly for much of the day before strong cold front pours
a cold airmass into the region. Post frontal cloudiness will
eventually bring about worsening conditions through Monday night
and beyond. Bottom line...if you want to fly VFR this week...its
best to get it done Monday.
Previous discussion... /issued 331 PM CST sun Dec 28 2014/
a cool and breezy day was underway across the South Plains and
rolling plains of West Texas this afternoon. The NAM remains
overdone on the amount of forecast snow cover on the ground. As a
result...the NAM shows fog developing directly near the non-existent
snowpack which in reality is unlikely tonight. We can expect another
cool day on Monday before the Arctic air plunge engulfs the region.
A pre frontal trough will make its way through by late Monday
morning shifting winds to the north but the colder air will hold off
until the evening.
pattern ahead still favors well below normal temperatures Tuesday and new
years evening accompanied by light wintry precipitation...before dynamic
forcing for ascent improves later in the week ahead of a still
undeveloped upper low. The fact this trough is just in its
formative stage over the Canadian rockies this afternoon implies
the window remains wide open for departures to the late week
forecast. As this trough dives south into the Great Basin by
Tuesday...an impressive 1055 mb Arctic high will be dislodged
south to near the Red River by New Years Day...albeit much weaker
than its prognosticated 1060 mb (!) Peak intensity on Tuesday.
Model soundings continue to favor a freezing drizzle scenario as
soon as Tuesday morning mainly on The Caprock where sub-cloud moisture
deficits are lower than farther east. Lift from steady isentropic
upglide and east-northeasterly upslope flow will be the driving forces for this
light drizzle...but by late Tuesday into Wednesday middle and upper saturation
are prognosticated to increase as winds back more southwesterly downstream of a
burgeoning upper cyclone in the Great Basin. This process could
easily allow for some seeder feeder opportunities culminating with
better chances for light snow...but ascent overall appears quite
subdued so wintry accums including freezing drizzle appear minor
at this time.
As temporary short wave ridging unfolds overhead new years evening night...a
warm nose is shown to sharpen over the region in the 300-305k
layer. This Stout warm nose still looks to deepen and quickly
overwhelm much of the lower thermodynamic profile of all wintry
precipitation by late Thursday into early Friday even as height falls and deeper
ascent unfold ahead of the upper low. Models and ensembles are
reasonably clustered with the track of this low across the County Warning Area by
Friday night...however the 12z GFS is less eager to fill/decay the
low compared to the 12z ecm. This raises concern about the
duration of enhanced lift and subsequent precipitation amounts. But since
this low has yet to even develop...we see no reason for any
serious adjustments to late week probability of precipitation which still match well with
current MOS data.
Maximum temperatures were nudged lower Tuesday and Wednesday with overnight lows still
favoring close to MOS given abundant stratus. An easy overturning
of this modified Arctic air still appears feasible by Thursday...but am
skeptical of the strong warming prognosticated by MOS given thick clouds.
Opted for a blend of the cooler GFS and ecm raw numbers for now.
Preliminary point temps/pops...
Friona 19 45 14 23 10 / 0 0 10 20 30
Tulia 19 46 15 23 12 / 0 0 10 20 30
Plainview 22 48 16 24 13 / 0 0 10 20 30
Levelland 26 51 18 26 15 / 0 0 0 20 30
Lubbock 24 50 19 26 15 / 0 0 0 20 30
Denver City 24 51 20 27 18 / 0 0 0 10 30
Brownfield 25 52 19 27 17 / 0 0 0 20 30
Childress 22 48 20 28 15 / 0 0 0 10 20
spur 26 53 21 29 17 / 0 0 0 10 30
Aspermont 27 55 23 31 19 / 0 0 0 10 20