Area Forecast Discussion
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FXUS64 KLUB 210538
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
1138 PM CST Fri Jan 20 2017

.AVIATION...
VFR with CIGs lowering to 4000-6000 ft AGL by daybreak ahead of a
storm system digging into the region. Provided CIGs thin out during
the day, the stage will be set for westerly winds sustained near
30 knots at LBB and lesser at PVW and CDS. Spotty convective
showers at times could enhance these winds which otherwise will
remain very gusty through midnight Sun.

&&

.PREV DISCUSSION... /issued 336 PM CST Fri Jan 20 2017/

SHORT TERM...

A well defined upper level impulse was rotating eastward across the
northern Texas Panhandle this afternoon. Deep mixing and tight
height gradients aloft were resulting in a stiff blow of 30 to 40
mph across the extreme southwest Texas Panhandle. These winds should
be at their peak now, and are expected to taper back gradually in
the next few hours. The Wind Advisory will expire at 600 pm.

Early tonight, we should see the winds continue to back away. But
later tonight, the potent Pacific Jet of around 140+ knots that we
have been eyeing for many days will be driving towards the Rio
Grande in far west Texas. This will quickly re-tighten height and
surface pressure gradients. In addition, we believe there me be at
least some tendency for briefly organized lift mainly after midnight
with a notable increase in mid level moisture pouring into the area.
Some solutions are generating light showers to our southwest within
this zone of lift and streaming the activity to the east mainly over
the southwestern and central South Plains. Lower level moisture will
not improve appreciably, and it will be difficult for meaningful
precipitation to reach the ground. We added isolated showers after
midnight. A bigger deal may be that these showers or virga may have
potential to generate a few stronger wind gusts later in the night.
We trended winds higher as well in the area where showers seem most
likely to occur. Tonight will continue unseasonably mild.

On Saturday, the powerful upper level jet will continue east just to
our south and lead to large scale synoptic lift. Moisture should be
thickening in mid levels and the idea of a slight chance of showers
seems at least somewhat valid. Solutions are mixed on potential
instability. All solutions steepen the 500 to 700 millibar lapse
rate but convective potential energy seems limited to pockets of a
couple hundred joules per kilogram or less. One notable pocket may
be in the southeast Panhandle and northern Rolling Plains by midday
or early afternoon. And we have added isolated thunder mention as
well to this region. Winds should be able to blow owing to the
tightening surface gradient, as well as the height fields aloft, but
cloud cover may limit the mixing depth just a bit. We still are
indicating another day of stiff winds Saturday, favoring our
southwest zones this time. RMcQueen

LONG TERM...

The upper level low responsible for winds on Saturday will be
rotating out of the region overnight with the slight possibility of
some light wraparound moisture rotating into our northeastern
counties. At this time, overnight lows look just warm enough to keep
all precipitation in the liquid form, so opted to keep this forecast
package with just a slight chance of rain. Should precip not develop
during the day on Saturday, optimism for precip during the overnight
hours will not be high as the low levels will not have proven
successful in saturating. As the low pulls away, it will drag a cold
front, and more wind, through the forecast area before winds finally
calm overnight into Monday morning. A quick upper ridge passes the
region on Monday, which could help to quickly raise highs well above
normal. Model guidance has been trending slightly warmer with each
run for Monday, so opted to bump highs a few degrees over the Blend.
As yet another upper level low in this progressive pattern travels
across the Central Plains on Tuesday, it will drag a deep wind max
right through the heart of our forecast area. H700 winds of 50 to 70
kts and H850 in the 35 to 45 kt range should mix down well. Last
feature of interest for this forecast period is a cold front on
Wednesday that will pull us back to winter temperatures, but
thankfully, not to frigid winter.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

93


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