116
FXUS64 KLUB 221800
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
100 PM CDT Sun Apr 22 2018

.AVIATION...
Moisture layer remains around 3500 feet above the ground amounting
mostly to scattered cloud layer but may briefly go broken as a
very weak surface north-northeasterly wind surge was pressing
southward from the Panhandle. Wind speeds also may elevate just
briefly - perhaps near 15 knots - but in general remaining around
11 knots we think. VFR with clear skies and lighter winds will
dominate overnight. Flow will return to southeast then southerly
Monday which we have not shown - as winds at least through 18z
likely to remain 10 knots or less. Also will see a slight increase
in mid and high level moisture on Monday, probably amounting to
scattered layers, but not significant to indicate in a change
group this far out. RMcQueen

&&

.PREV DISCUSSION... /issued 631 AM CDT Sun Apr 22 2018/

AVIATION...
Patchy BR and cigs could bring periods of MVFR conditions to the
terminals for the next few hours before VFR becomes dominate for
the remainder of the TAF cycle. Northerly winds may be a little
breezy at KCDS through the day, with light but somewhat variable
winds tonight.

PREV DISCUSSION... /issued 315 AM CDT Sun Apr 22 2018/

DISCUSSION...
Water vapor imagery shows the upper low over SE KS/NE OK, moving
east toward the Miss. Valley. Northwest flow aloft and northerly
flow at the surface in the wake of this system has brought a
cooler and somewhat drier airmass to the forecast area early
Sunday morning. 2 am West Texas Mesonet temperatures show 30s
across much of the far southwest Texas Panhandle and western South
Plains, and we expect a few locations to record a light freeze
this morning. There was still sufficient moisture remaining in a
shallow layer for areas of low status and perhaps even some
pockets of light drizzle and/or fog across the far southern Texas
Panhandle into the northern South Plains and Rolling Plains early
this morning.

Otherwise, the northerly winds will gradually relax through the
afternoon and temperatures should max out in the 60s to low 70s
across the area, still a bit on the cool side for this time of
year. Also, some sub-tropical moisture getting drawn up ahead of a
weak low latitude system moving into the Desert SW will supply
some high clouds coming in from the southwest today.

Shortwave ridging aloft and surface winds returning to a
southerly fetch on Monday should result in a nice rebound in
temperatures with highs expected to be in the middle to upper 70s.

An upper-level shortwave or upper-low moving southeast from the
Rockies into the Central Plains will send a cold front racing
south on Tuesday. Timing differences are narrowing with the front
and we expect it to pass through our forecast area during the
day. The northerly winds could get a little gusty with this FROPA,
but right now they don`t appear to be quite at advisory level. If
the front isn`t too quick, there is some potential for a triple-
point to develop somewhere over the central or southern Rolling
Plains Tuesday afternoon, where there could be sufficient moisture
pooling for the lift with the front and approaching wave to
generate t-storms...a potential that is suggested in the latest
GFS and NAM progs. Otherwise, much of the guidance is generating
widespread post-frontal QPF late Tuesday into early Wednesday,
despite strong low-level cold and dry advection. In this pattern,
we suspect this QPF signal is a little overdone, at least for
western portions of the forecast area, and have trimmed PoPs and
QPF grids down a bit. Skies should clear out late Wed but it
should remain on the cool side with highs in the 50s and 60s.

GFS and ECMWF really begin to diverge beyond Tuesday`s system. The
ECMWF brings a similar system and front across the region late
Thursday/Friday, while the GFS does still show a weaker front, it
carries the upper-wave well off to our north and east.

Then, heading into the weekend, the ECMWF brings a large low into
the Pacific NW, with solid ridging over the southern plains
bringing warm & dry weather. The GFS on the other hand brings the
upper low farther south into central and southern California,
pushing the ridge east of West Texas and generating quite a bit of
t-storm activity to our west as Gulf moisture is drawn toward the
approaching system. For now we will stick with an ensemble blend
approach which does mention a chance of t-storms with mild temps.

&&

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

$$

99/05/99