Area Forecast Discussion
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FXUS64 KLUB 252353

Area Forecast Discussion
National Weather Service Lubbock TX
653 PM CDT THU AUG 25 2016

Biggest concerns revolve around possible storm impacts at the
terminals this evening into early Friday. KPVW and KCDS could see
storms kicking off the TAF cycle with boundaries converging on
KPVW and convection immediately upstream of KCDS. The best chances
at KLBB may hold off for another couple hours before peaking mid-
late evening. Have covered the best thunder chances with TEMPO
groups, though storms could linger beyond their window, so will
watch closely and amend as necessary. The strongest storms will be
capable of dropping very heavy rain, producing gusty and erratic
winds and even small hail, with periods of MVFR to IFR conditions
also likely. Outside of the storm influences, VFR should generally
prevail. By Friday morning, there is a chance of sub-VFR cigs,
though confidence is not overly high and it has been omitted from
the forecast for now. Additionally a few storms may be possible
by Friday afternoon, though coverage is expected to be more
limited than today.


.PREV DISCUSSION... /issued 321 PM CDT THU AUG 25 2016/

At 230 pm, the cold front was located roughly from near Clovis NM to
near Wellington TX. T-storm activity was beginning to increase along
an axis from the northern Permian Basin into the southeast Texas
Panhandle, within a broad corridor of about 2000 J/kg of MLCAPE and
25 to 35 kts of deep layer shear - supporting potential for some
storm organization and a threat of severe hail and wind gusts. Water
vapor imagery shows the base of the upper trough to the southwest of
El Paso. As the trough slowly advances east this evening it will
provide large-scale ascent while maintaining the deep-layer
transport of moisture across West Texas. The front has stalled
out for the most part, however we do anticipate that developing
thunderstorm outflows will likely push the effective front
southward some this evening. The best storm chances will be
located across our northern tier of counties, with the lowest
chances in the southeast - farthest removed from the forcing
mechanisms. Precip. water values running around 1.2 to 1.4 inches,
the focus of the front, and mean storm motion roughly aligned with
the moisture transport vector suggest some potential for locally
heavy downpours and training of storm cells. Thunderstorm activity
may continue continue through midnight or so, especially in the
vicinity of the front/outflow boundary, then begin to wind down
early Friday morning - although some showers could linger into the
morning hours as the weakening trough crosses the area. Friday
should be warmer and drier as we see drying occur in the mid-
levels. However, weak troughing will linger over the region and
NWP suggests scattered convection will develop with another
impulse moving into central NM - some of that activity could move
into the western South Plains late in the day.

Steady height rises begin Friday night and continue through the
weekend as a zonal upper ridge sprawls westward over all of the
southern Great Plains. Subsidence will be most prevalent over the
eastern half of the CWA during this time while remaining areas enjoy
comparably better lapse rates aloft and sporadic lift along the
periphery of the ridge. As a result, PoPs most days through next
week have been refined even further to show much lower rain chances
off the Caprock. The one exception to this is Sunday which still
features enhanced rain chances of 30-40% over all of the area
despite some recent misgivings in QPF between the GFS and ECMWF.
Even with the ridge axis firmly atop the region, models do prog a
temporary uptick in PWATs as 850-700 mb winds back from SW to SE.
How well this actually translates into better rain chances is fuzzy
as the overall pattern would suggest much lower PoPs, but will give
more of a nod to the higher Superblend values for now. Otherwise,
the center of the ridge should only draw closer through midweek
while serving to lower PWATs and effectively suppress additional
storm chances. High temps were also bumped up even further by Tue
and Wed closer to the hotter Euro MOS guidance more fitting of the
pattern by that point.


.LUB Watches/Warnings/Advisories...


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