Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Lubbock Texas
1120 PM CST Friday Feb 27 2015
IFR ceilings have developed at kpvw and kcds...with LIFR ceilings having
recently developed at klbb tonight. Will expect this trend to
persist throughout the night...though computer models hint at ceilings
deteriorating to LIFR category overnight. IFR visible have recently
developed at klbb...with VFR visible at kpvw and kcds...though it is
falling at kpvw. MVFR to IFR visible is plausible throughout the
night...at all three taf sites. -Fzdzsn was impacting klbb and
more so -sn impacting kpvw. -Sn has stopped being reported via
metars at kcds for the last few hours...however this could change
with -fzdzsn being a possibility tomorrow morning into early afternoon
/have inserted a prob30 for this possibility/. -Fzdzsn can not be
ruled out after 15z at klbb and kpvw...though confidence is not
high enough to insert a prevailing or tempo group at this time.
Will of course amend as necessary.
Previous discussion... /issued 353 PM CST Friday Feb 27 2015/
the threat for areas of light snow/flurries will continue late this
afternoon and tonight. An upper wave digging across Arizona into
northern New Mexico will continue to push east...bringing the
initial shot for some light snow to the far southwest Panhandle and
northern South Plains despite the brunt of the lift remaining well
north into the Texas and Oklahoma panhandles. Would expect any
additional accumulation to be confined to less than half an inch as
this wave passes by this evening into tonight.
The larger cyclonic flow responsible for this wave will dig across
the western Continental U.S. And begin to back the local upper flow to more of
a southwesterly component...helping to bring a healthy dose of warm
air advection to the South Plains and rolling plains. The continued
presence of appreciable moisture combined with persistent isentropic
ascent will bring another round of precipitation to the region
overnight into Saturday morning. As temperatures warm...will see a
transition from all snow to freezing rain as a warm nose develops
near h75. Warming aloft will continue from southwest to northeast in
this regime with light ice accumulations of less than one tenth of
an inch taking place from late Saturday night into the afternoon.
Time height and sounding profiles show saturation decreasing to only
encompass lower levels into the afternoon...likely leading to more
of a freezing drizzle event...thus the expected light accumulations.
After record cool high temperatures Friday...temperatures should
warm to near or above freezing late Saturday morning into early-middle
Saturday afternoon from southwest to northeast. Lows Saturday
morning will be quite cold once again...in the teens to low
20s...despite the presence of warm air advection and overcast skies
as the fresh snowpack will dominate the boundary layer.
Given the light amounts of additional precipitation expected...will
forego a Winter Weather Advisory at this time and highlight the
threat of light icing and additional snow in the severe weather potential statement and a Special
we should see a bit of a break in the action Saturday night into
Sunday as the first wave passes off to the east. However...with
isentropic lift expected to continue atop the shallow cold
airmass...areas of freezing drizzle and light freezing rain will
be possible during this period...mainly across the rolling plains.
The temperature forecast on Sunday looks pretty tricky due to timing and
extent of partial clearing during the day...and the timing of the
next cold air surge which is currently expected to pass through
late in the day. We continue to show a pronounced gradient in high
temperatures...from 40s northeast to low 60s southwest.
Meanwhile...off to our west...an upper low will be digging
along the West Coast and we should start to see SW flow aloft
develop across West Texas by Sunday night. This will renew the
isentropic ascent and increase the precipitation chances across the area.
Cold near-surface temperatures may support some freezing rain Sunday
night but temperatures are expected to warm enough that we should see all
liquid during the day Monday and into Monday night...although
precipitation amounts during this period should be on the light side.
The upper low begins to move east Monday and we expect the
remaining cold air to quickly erode in the face of increasing
swerly flow. This should result in fairly mild temperatures by Tuesday
with highs back in the 50s and 60s. Downsloping westerly winds
will begin to shove precipitation chances off to the east despite a sub-
tropical moisture tap continuing aloft. We/ll have to watch to see
how far east the moisture GOES...it is possible that the SW-NE
oriented axis of deeper moisture could hold up across some of the
rolling plains and keep a chance of rain...and possibly T-storms
going during the day Tuesday.
The latest medium-range guidance is in good agreement that the
trough will swing across the Southern Plains on Wednesday. A positive
tilt to the system indicates that the deep moisture will get shunted
to our south and east before the trough moves through...limiting
precipitation chances with the trough/S passage. However...yet another
cold front will sweep through the area on Wednesday...and the
coupled lift might be able to squeeze out some light wintry
precipitation. Seasonably cool temperatures will likely continue on Thursday
followed by a more substantial warm up by Friday.
Preliminary point temps/pops...
Friona 11 38 31 50 / 40 20 10 10
Tulia 11 34 30 52 / 40 30 20 10
Plainview 13 35 30 55 / 40 30 20 10
Levelland 13 40 34 64 / 30 30 10 10
Lubbock 13 37 33 59 / 30 30 20 10
Denver City 16 43 34 68 / 30 20 10 10
Brownfield 15 41 34 64 / 30 30 10 10
Childress 15 32 29 49 / 40 40 30 20
spur 15 33 32 56 / 40 30 20 20
Aspermont 18 35 33 60 / 40 40 30 20