Area Forecast Discussion
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FXUS64 KLUB 230439

Area Forecast Discussion
National Weather Service Lubbock TX
1039 PM CST Thu Feb 22 2018

It`s a difficult aviation forecast for KLBB and KPVW overnight as
there is potential for low ceilings, but indications are mixed. We
will keep the forecast VFR for now but include a TEMPO that
suggests category reductions are possible. If low stratus does
develop, ceilings could quickly drop to IFR or even LIFR. KCDS
should remain socked in through the night. Areas of fog may also
produce VSBY reductions at times. Conditions should improve from
west to east during the day Friday but it is uncertain whether or
not KCDS will return to VFR.


We`ve added a mention of patchy fog overnight for all but the
northwest counties. Temperatures in some areas will be near or
slightly below freezing but we do not think freezing fog will
result in much ice deposition except perhaps on elevated surface
like bridges and overpasses.


.PREV DISCUSSION... /issued 548 PM CST Thu Feb 22 2018/

The main aviation problem tonight is the potential for low
stratus at KLBB and KPVW, with KCDS expected to remain socked in
for most of the period. Confidence is not good for the timing and
extent of ceilings reductions at KLBB and KPVW, so we`ve kept the
TAFs VFR for now. Some fog is also possible around KCDS. Friday
morning, scattered light -SHRA moving north through the Rolling
Plains could affect KCDS. VFR conditions should return area-wide
by mid to late morning.

PREV DISCUSSION... /issued 332 PM CST Thu Feb 22 2018/


Not a lot of changes for this forecast package. Clouds have been
slowly clearing from west to east today, though we`ll see somewhat
of a resurgence of some high clouds from the southeast overnight
predominately across the eastern 2/3 of the forecast area. This
moisture could produce some very light drizzle across the far
southeast, but more importantly, it will keep us from drying out too
much tomorrow.

Our main feature of interest for this forecast period is an upper
trough passing to our north on Saturday. Early Saturday morning, the
dryline will race eastward from the TX/NM line to OK, causing
dewpoints to crater behind it. As the H5 feature passes across SRN
CO/KS Saturday afternoon, the brunt of the winds will be dragged
across the South Plains. Bolstering these winds will be a max of 700
mb winds of 50-65 mph passing right over our forecast area, and
plenty of mixing is expected. At the surface, westerly winds of 25-
35 mph with gusts to 50 can be expected, and RH values will fall
well into the teens, even some single digits. Even with a Pacific
front pushing through to keep temperatures slightly lower, all other
factors point towards a critical fire danger day, and therefore, a
Fire Weather Watch has been hoisted for Saturday. With great mixing,
blowing dust will also be an issue for most of the forecast area,
more so on the Caprock.

Sunday may prove to be slightly breezy with the passage of another
upper level trough, though this one looks much more tame. We look to
settle down and warm up for a few days after that, as we find
ourselves in between systems. Models show a new deep trough gearing
up across the deep southwest by next Wednesday, but there is too
much uncertainty with the strength and track of this system attm.
Therefore, kept most mentions of PoPs out of this package.


As mentioned above, winds on Saturday are expected to kick up out
of the west at 25 to 35 mph with gusts to 50. The dryline will be
well east of the region, meaning RH values will plummet into the
teens and even single digits for all Lubbock forecast counties.
All told, RFTI numbers on the Caprock are looking to high 5-6, and
for the rest of the area, we are looking at a solid 4. Even with
the moisture we just saw, persistent drought conditions will
likely favor the more critical fire weather danger for Saturday.
Therefore, a Fire Weather Watch is in effect on Saturday from 16Z
to 0Z for the entire Lubbock forecast area.


Fire Weather Watch from Saturday morning through Saturday
afternoon for TXZ021>044.



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