Area Forecast Discussion
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FXUS64 KLUB 272037

Area Forecast Discussion
National Weather Service Lubbock TX
337 PM CDT Thu Apr 27 2017

Despite a strong mid-level jet moving over West Texas, winds at the
surface have been a bit slow to come up today. At 230 pm, West Texas
Mesonet observations showed wind speeds across the forecast area
were generally in the 20 to 30 mph range with gusts up to the lower
40s - with the strongest winds located across the southwest Texas
Panhandle. A surface low pressure trough deepening from the Okla.
Panhandle southwest into east-central NM may be partially
responsible for keeping a relatively slack gradient across our
western counties. In addition, the thicker cloud cover across
central and northern portions of the Caprock may be inhibiting
mixing to some extent. But with some strengthening of the wind
expected in the next couple hours, we will maintain the wind
advisory, although at this point it looks like it will be on the
lower bound of windy conditions. Short-range guidance is still
spitting out some very light qpf across our nrn counties through
this evening as a mid-level cold pocket brings steeper-lapse rates
across the Texas Panhandle, skirting our northern counties, mainly
along and just east of the Caprock where there is slightly more low-
level moisture. At this time we don`t think the narrow-layer
saturation will produce more than a few sprinkles and perhaps some
stronger downdraft wind gusts.

The winds should diminish pretty quickly evening as a weak cold
front moves through and brings a wind shift to the north. The front
will wash out during the day Friday with winds returning to south
and picking back up on the Caprock by early afternoon.  Low-level
moisture will be moving back into the eastern Rolling Plains on
easterly winds but forecast soundings at Childress suggest that area
will remain capped through the day. Farther west, falling heights
aloft and a cold front will edge toward the southwest Panhandle late
in the afternoon, but moisture will be lacking in this area. The
lift may force some high-based shower and t-storm activity capable
of producing strong downdrafts in our northwest counties.

Biggest change to the long term forecast was to lower temps
considerably during the day on Saturday as all models sharpen cold
advection through the otherwise traditional peak heating. In fact,
some models prog record cold highs for Lubbock on Saturday.

Otherwise, an abrupt pattern change is still on track beginning
Friday evening as modified Cp air drains south in advance of a
developing upper low over the Four Corners. During cold FROPA
Friday night, heights will remain neutral as the flow backs more
SW ahead of the low digging towards Albuquerque by Sat morning.
Forecast vertical profiles locally are largely uninspiring for precip
both along and following the front, but saturated isentropic
ascent will improve steadily through the night from N-S. Opted to
keep highest PoPs Fri night across our northern zones closer to
the upper jet core, but a second maximum may unfold off the
Caprock where the back edge of Gulf moisture should be edging
W-SW ahead of the front. A couple potent storms may erupt in this
environment even as instability becomes increasingly elevated
behind the front.

As the low tracks along or just south of I-40 in eastern NM on
Saturday, dry slotting will envelop much of the CWA despite low
clouds prevailing under strong cold air advection and temps
falling through the 40s and even 30s in our NW zones. This loss of
deeper saturation should keep morning PoPs on the low side for
the most part until the mid-level cold pocket rotates east through
the afternoon. Alone, this improved cooling aloft is not looking
to get the job done for a second round of precip, so PoPs remain
less than stellar outside of our NW zones where these moisture
woes should be much less nearer the low. Precip type is still
likely to favor some snow in the SW Panhandle and adjacent South
Plains by late Saturday and Sat night along the deformation zone
axis, but marginal ground temps should keep light accumulations
tied to grass or any areas that see steadier snow rates. Deepening
of the upper low during this time could foster a well defined
deformation zone precip shield, but provided the upper low tracks
no farther south, our area should dodge any impacts from snow.

Gradual erosion of low clouds from W-E Sat night through early Sun
could still aid in a light freeze for areas on the Caprock including
Lubbock. Opted to keep min temps on par with the colder
NationalBlend guidance which is certainly the route more of the
recent MOS guidance is headed. Dry, cyclonic NW flow following the
upper low will then sharpen by the start of May and likely send a
strong cold front all the way to the Yucatan, effectively nixing Gulf
moisture for some time to come. This FROPA and parent trough could
garner some PoPs o/a Tue and Wed, but confidence in this is low.

Gusty west-southwest winds and RH values around 10-15 percent will
create elevated fire weather conditions across the western portions
of the Caprock this afternoon and early evening. A Fire Danger
Statement is in effect for this area through 8 pm CDT.


Wind Advisory until 8 PM CDT this evening for TXZ021-022-027-028-



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