Area Forecast Discussion
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000
FXUS64 KLUB 300442
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
1142 PM CDT Sat Apr 29 2017

.AVIATION...
The aviation concerns will be low ceilings for the first few hours
of the forecast followed by strong low-level winds for much of
the day Sunday. Ceilings may have a period of rising and falling
before becoming all VFR by about 09 or 10 UTC. Surface winds may
reach 30 kts at all terminals by late morning Sunday and this may
require an Airport Weather Warning for the KLBB terminal. Wind
speeds will diminish around 00 UTC.


&&

.PREV DISCUSSION... /issued 1019 PM CDT Sat Apr 29 2017/

UPDATE...
The accumulating snow has tapered off over the far southwest Texas
Panhandle and northwest South Plains as the main deformation snow
band has pivoted northward with the upper low. A few flurries or
light snow showers will remain possible through the overnight
hours over the far northwestern zones, but the accumulating snow
has shifting further to the north across the central and northern
Texas Panhandle. Thus we have canceled the winter weather advisory
a little ahead of schedule. We have also dropped PoPs for all but
the eastern most zones where the last band of light rain will
quickly shift east over the next hour or so. No other changes were
made to the forecast at this point with the freeze warning
continuing for points north and west of Lubbock through 9 am
Sunday.

PREV DISCUSSION... /issued 753 PM CDT Sat Apr 29 2017/

UPDATE...
We have decided to issue a short-fused winter weather advisory for
the far southwest Texas Panhandle and northwest South Plains
(Parmer, Bailey, Castro and Lamb Counties) until midnight.

Calls to local PD in Friona and Muleshoe confirmed moderate
snowfall with snow beginning to accumulate on grassy surfaces,
with even a little snow trying to accumulate on roads in Muleshoe.
This area of snow is associated with the deformation region of an
upper low that will quickly lift from east-central NM near the
TX/NM line this evening into the northeast TX Panhandle by 06-09Z.
This will keep the window for accumulating snow relatively short
over our northwestern zones...to the next few hours...though
light snow and/or flurries could linger there through early
Sunday morning. Given temperatures right at or just above the
freezing mark, we don`t anticipate any big problems on the
roadways, aside from slushy accumulations during the heaviest
snow. Snow totals up to an inch will be most likely with perhaps
localized 2 inch amounts. Aside from the snow, a light freeze
still appears on track for many spots generally north and west of
Lubbock and we will maintain the freeze warning for this area
until 9 am Sunday.

The grids have also been adjusted to represent likely rain chances
north and east of Lubbock through the remainder of the evening
hours as the last thrust of lift coupled with sufficient moisture
moves through this area. Beyond that Sunday will be dry, but it
will come with strong northwesterly winds and temperatures still
well below average.

PREV DISCUSSION... /issued 640 PM CDT Sat Apr 29 2017/

AVIATION...
-SHRA and low stratus will affect the terminals this evening.
Ceilings should be mainly in the IFR to MVFR range. The ceilings
may begin to lift around 04-05 UTC but confidence in timing is
very low. VFR conditions will return Sunday morning, and strong
northwest surface winds will develop, possibly sustained around 30
kts at all terminals through much of the daytime.

PREV DISCUSSION... /issued 344 PM CDT Sat Apr 29 2017/

SHORT TERM...
Midday water vapor imagery captured a twin-lobed upper cyclone
across NM, and a modest warm conveyor belt of clouds and light rain
from the northern Panhandle south to the western Permian Basin. This
axis of lift was collocated along sharp 500mb thermal packing ahead
of a robust cold pocket. Despite this satellite presentation, IR
data showed cloud top temps within the warm conveyor were steadily
warming as confirmed by a gradual shrinking/decay of precip and rain
rates.

As the upper low tracks from near Ft Sumner, NM to Perryton, TX by
daybreak Sunday, mid-level drying will envelop more of the South
Plains and Rolling Plains behind the current axis of light rain.
Farther NW near the upper low and deformation zone, precipitation
should prove more definitive in both time and space. Thermal
profiles here are likely to resume all snow toward sunset as modest
insolation ceases. However, marginal ground temps and mostly light
snowfall rates do not bode well for causing public travel impacts,
so we have opted to leave winter wx advisory headlines stored in the
attic for now. After midnight, abundant stratus will begin to lose
ground to increasing subsidence from SW-NE, so despite breezy NW
winds all night the stage is still set for a light freeze for the
western South Plains northeast into much of our southern Panhandle.

Northwest gradient flow will sharpen considerably by Sun morning as
the upper low deepens about 130 meters in 9 hours. Subsequent
northerly LLJ of about 50 knots will focus across our NE zones by
Sun morning, so wind advisory speeds are a good bet. Midnight
forecast shift will have a better idea of how much real estate these
30+ mph winds will affect, so a wind advisory will be delayed until
then. Otherwise, chilly NW flow under full sun still looks to keep
temps well below normal with generally lower 60s on tap.

LONG TERM...
By Sunday evening, the upper low responsible for this weekends cool-
down should be positioned near the Kansas City Metro area leaving NW
flow aloft West Texas.  The first of a series of embedded shortwaves
approaches on Tuesday followed by a sharper shortwave into
Wednesday.  Guidance now suggests that this second trough will
strengthen into a full fledged low along the western Gulf Coast.  As
this occurs late this week, a high amplitude ridge will build along
the Rockies drifting to the central Plains on Sunday.

Windy conditions on Sunday will taper during the evening hours with
Westerly winds returning on Monday.  Thanks to the aforementioned
disturbance, a weak cold front should move at least part-way through
the area on Tuesday followed by a stronger front on Wednesday
morning.  While there may be some regional rain/thunder, by in large
most of the guidance (and climatology) points to the best chances to
our north and east.  The northerly flow behind the front should
persist into early Friday morning thanks in part to the
cyclogenesis well to our east before southerly flow returns for
the weekend.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Freeze Warning until 9 AM CDT Sunday for TXZ021>024-027>029-033-
034-039.

&&

$$

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