Area Forecast Discussion
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836
FXUS64 KLUB 220533 AAB
AFDLUB

Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
1133 PM CST Sat Jan 21 2017

.AVIATION...
MVFR ceilings are in place at KPVW but these should be short-
lived along with brief showers that are not lasting long enough to
meet TEMPO criteria. May see these ceilings spread into KCDS
through the early morning hours. Biggest uncertainty in this TAF
cycle is how high wind speeds will get as observations are not
matching up with model output. Wind speeds have remain in the 20
to 30 knot range at KLBB and KPVW but have not ramped up at KCDS
yet. Still expecting to see wind shift to the north to northwest
at all three TAF sites in the next 2-3 hours, then a gradual
decrease in speed through the day Sunday. Wind should go light and
variable Sunday evening after sunset with VFR conditions expected.

Jordan

&&

.PREV DISCUSSION... /issued 532 PM CST Sat Jan 21 2017/

AVIATION...
Aviation Weather Warning for KLBB will be allowed to expire at 00
UTC/6 PM CST as wind speeds have fallen below 30 knots sustained,
although occasional gusts to 30 knots will still be possible for
the next hour or two.

VFR conditions are in place at all TAF sites in our area but
there will still be brief periods where MVFR visibilities could
develop due to blowing dust. Window for these occurrences are
very narrow and should last less than 5 to 10 minutes. Wind speeds
will remain up through sunset and then briefly drop before ramping
up again around or shortly after midnight local time. Wind
direction will gradually shift to the north to northwest as a
strong mid- level storm system passes north of the region. There
could be a few wrap around showers affecting KCDS in the early
morning hours Sunday but confidence on timing is not high enough
to include any mention in that TAF for now. Wind speeds will ramp
back up into the 20 to 30 knot range through Sunday morning with a
gradual decrease into the 15 to 25 knot range by Sunday afternoon.
This may require another Aviation Weather Warning for KLBB Sunday
morning and will evaluate as we head through the overnight hours
to narrow down if one will be needed or not.

Jordan

PREV DISCUSSION... /issued 327 PM CST Sat Jan 21 2017/

SHORT TERM...
Surface pressure gradient has been tightening this afternoon in
response to an approaching upper level low exiting the Four Corners.
As such, wind speeds on the Caprock have generally been in the 30 to
40 mph range with gusts as high as 56 mph at Denver City (as of this
writing). As we head towards sunset, the winds will begin to taper
slightly for a brief period of time. Light shower activity this
morning resulted in mostly virga activity, though we did see a
whopping three drops appear on our tower cam at the office around 10
AM. With the approach of better lift this afternoon, we have seen
slightly heavier shower activity with a few embedded thunderstorms
begin to develop across the southern TX Panhandle and South Plains,
all moving to the east/northeast fairly rapidly. So far, this
activity has resulted in mostly just a few hundredths of an inch to
just over a tenth of an inch with the heavier activity. This squally
activity should continue the rest of the afternoon but taper quickly
after sunset.

The low is progged to quickly pass over the TX Panhandle this
evening, relaxing the winds slightly, however, as the low pulls away
to the east, winds will begin to pick up once again as a cold front
is dragged through the forecast area. Winds in the H850-700 layer,
on average, will range from 45 to 55 KT which should mix well to the
surface. Therefore, opted to continue the Wind Advisory through 12Z
on Sunday. Past this, winds should begin to slowly relax, and
finally, we may see a calm evening of winds ahead for Sunday
evening. As for overnight precipitation, models continue to lean
towards moisture wrapping around the backside of this low and
producing at least a small amount of precip across our northern
zones. One change, however, from previous packages, was the precip
type. Model thermo soundings have warmed sufficiently to give enough
confidence to keep precip as all liquid through the night. Surface
temperatures will certainly be warm enough, but the freezing level
has risen significantly across several models to around three or
four thousand (or more) feet above the ground. This poses a mighty
feat for even the heartiest of snowflakes.

Otherwise, clouds should clear quickly from west to east with winds
slowly subsiding as the day goes on...lots of bright yellow sun to
see, so find yourself a field of green, throw the pigskin around,
and enjoy the day!

LONG TERM...
An active flow pattern is expected for the coming week, with an
upper level ridge axis passing early Monday, followed by an upper
trough Wednesday night. A brief flattening late Thursday and
Friday will be followed by another trough next Saturday and then
northerly flow loft afterwards. Dry air will dominate. Solutions
are in reasonable agreement in our area. Blends were followed,
except we leaned more towards combined MOS wind output for Monday
and much of Tuesday. And we also sided with warmer solutions both
Monday and Tuesday, though high clouds as always will have
potential to limit warming.

Height fields will tighten late Monday reaching their maximum
as the strongest core passes early Tuesday. This nocturnal passage
may allow us to miss out on the strongest winds, but expect wind
speeds will elevate fairly quickly mid to late Tuesday morning
before subsiding again late in the day. Significant wind speeds
are possible - to near wind advisory levels anyway - and Tuesday
would seem the peak day for that.

Monday should be the warmest day coming up, with height falls and
a Pacific Front dropping highs a fair amount Tuesday. Additional
cooling to below normal is expected Wednesday into next Saturday.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 AM CST Sunday for TXZ021>023-027>031-
033>044.

&&

$$

14/93/14



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