Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Lubbock Texas
633 PM CDT Wed Oct 23 2019
VFR conditions expected through tonight before deterioriating
conditions with the passage of a strong cold front and the
approach of an upper level disturbance. Gusty north/NE winds to
develop late tonight with the frontal passage. MVFR ceilings are
expected to develop several hours later with a good chance of IFR
ceilings and some drizzle or light rain during Thursday afternoon.
Previous discussion... /issued 327 PM CDT Wed Oct 23 2019/
it is another fine afternoon with temperatures in the 70s and lower
80s and mostly sunny conditions. However, this will change quickly
tonight into Thursday as much colder air and a risk of wintry
weather enters the picture. At this point, it appears the southern
Texas Panhandle and adjacent northern South Plains, on The Caprock,
will have the best chance of seeing accumulating snowfall. Snow
totals of 1 to 3 inches are looking increasingly likely across our
northwestern counties, falling primarily Thursday afternoon into the
early evening hours.
Before jumping to more winter-like conditions tomorrow, we were
seeing a surface trough roughly bisecting the County Warning Area this afternoon.
The northerly wind shift behind the trough has little to no cooling
associated with it, but a surge of colder air will follow late
tonight, after midnight, and continue to build into the region on
Thursday. In addition to dropping temperatures through the day
Thursday, northerly winds sustained at 20 to 30 mph will make it
feel down right blustery.
Isentropic upglide above the frontal zone will cause clouds and
light precipitation (drizzle and/or very light rain) to develop
across the region Thursday morning ahead of a developing upper
level storm system. A strong upper level jet currently diving
southward through the northern rockies will carve out a sharp
trough that may eventually cut off a small upper low over the
Texas Panhandle late tomorrow before shifting east of the area
early Friday. This is somewhat of a compromise from the faster
open wave solutions and deeper closed low solutions that have been
advertised (and at odds with each other) the past several days.
This evolution will provide increasing upper level support,
peaking across the Texas Panhandle between the 18z-00z. This lift,
combined with an area of elevated f-gen and fairly steep mid-
level lapse rates, are expected to force a band of precipitation
to develop Thursday morning (between 15-18z). This band will be
oriented from southwest to northeast and may clip at least our
northwest and/or north-central zones. There remains some
uncertainty on exactly where this band will form. Regardless,
model soundings suggest the precipitation could start out as a
cold rain, but should mix with and change to wet snow within the
band by mid-late morning. Within the band, a quick 1 to 3 inches
of wet snow will be possible. We continue to advertise this
possibility in a Special Weather Statement, and will let the next
shift take one more look at things before potentially pulling the
trigger on a Winter Weather Advisory...hopefully after gaining
higher confidence on where this snow band will develop.
Further southward, into the central and southern South Plains, as
well as most spots off The Caprock, drizzle/light rain could
briefly mix with or change to snow late Thursday afternoon or
evening, but little to no accumulation is expected. Assuming the
more progressive solutions are correct, any precipitation will
quickly diminish from west to east Thursday evening/night. We have
followed this trend and have removed mentionable pops completely
after 12z Friday. Winds will decrease behind this system and most
spots will fall too or below freezing by early Friday. We may have
to entertain freeze headlines for those select locations (mostly
off the caprock) that have yet to experience a freeze this season.
Temperatures will moderate moving into the weekend, but questions
remain about our next upper level storm system and cold front(s).
Similar to our impending storm system, it is unclear whether the
slow/deeper Camp or the faster/less amplified Camp will prevail.
Given this and the attention to the shorter term forecast, we have
generally accepted the blended guidance in the long term.