Area Forecast Discussion
Issued by NWS

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FXUS64 KLUB 261732

Area Forecast Discussion
National Weather Service Lubbock TX
1232 PM CDT THU MAY 26 2016

KLBB and KPVW should stay west of the dryline through most, if not
all, of the TAF period. Retreating dryline this evening may make
to near KLBB before push from closed low moving across the plains
sees it march eastward overnight. KCDS will stay in the moisture,
and as a result will have some chance for TS late afternoon
through the evening and stratus near and after sunrise Friday.
Chance of either those too low to insert mention in that TAF right


.PREV DISCUSSION... /issued 1157 AM CDT THU MAY 26 2016/

Do not currently anticipate making significant changes at this
time. Main issue today is how far east the dryline mixes before
stalling, and the chances of convective initiation in large part
directly attributable to that. Of note this morning is a mid level
short wave trough that has spawned showers and a few thunderstorms
across the Permian Basin and southern Rolling Plains earlier this
morning and has now shifted to northwest Texas east of a Quanah to
Haskell line. There was an initial quick mixing of the dryline
eastward on the Caprock in the wake of that trough, and KLBB radar
clearly shows that boundary at 1145 am extending from Quitaque
just east of Lamesa. Eastward momentum appears to have slowed
some, but with the proximity of the short wave trough and its
additional movement away from the area, expect the dryline will
continue to head east. Tend to prefer recent runs of the RAP and
HRRR in this regard that take the dryline to near a Memphis to
Clairemont line before stalling. Subsidence should serve as a
negative regarding convective initiation until late afternoon at
which time there might be some storms develop far eastern parts of
the forecast area. Residence time in the area before departing for
southwest Oklahoma and northwest Texas will limit severe risk
there. Better storm chances appear to be early to mid evening as
storms that form in the eastern Permian Basin and Big Country move
northeastward and encounter moisture return and advection across
the southern Rolling Plains as the dryline retreats westward. Some
of those storms may have a better chance of supporting severe hail
and wind in the forecast area than what may manage to develop late
this afternoon. This forecast obviously would need to be revised
in large part due to dryline positioning. Farther west than
expected would increase risk across the Rolling Plains and a
farther east would almost eliminate the risk.

PREV DISCUSSION... /issued 629 AM CDT THU MAY 26 2016/

VFR conditions are in place at KLBB and KPVW while KCDS is MVFR
thanks to fog. Both KPVW and KLBB could also see MVFR range
visibilities due to fog around sunrise but confidence is not high
enough to include at this time. VFR conditions are expected by
late morning lasting through tonight. There could be storms near
the KCDS terminal area this afternoon and evening but confidence
on timing is too low to have any mention in the TAFs for now. Any
storms should develop well east of the KLBB/KPVW TAF sites. Storms
will dissipate after sunset with VFR conditions in place. Possibly
could see another round of MVFR conditions Friday morning as well
for all three TAF sites but confidence is too low to include now.


PREV DISCUSSION... /issued 323 AM CDT THU MAY 26 2016/

Water vapor satellite loop shows that there is a weak shortwave
moving out across the Big Bend region of Texas early this morning
which is helping to fire off some thunderstorms around midnight
across the western Permian Basin. These storms have since
dissipated with the lone exception of a thunderstorm moving into
the western Concho Valley. We are also seeing some weak mid-level
reflectivity returns that are likely not reaching the ground
across the western South Plains early his morning as well. 00Z
upper-air analysis shows steep lapse rates across the forecast
area extending west across New Mexico all the way into eastern
California, and model forecast soundings show quite a bit of
elevated CAPE available across the region. The forecast for this
morning is going to be tricky as any lift from the shortwave may
result in additional development of showers or storms. Almost all
of the models do not have any precipitation development this
morning and because the chance for precipitation is highly
conditional, we will leave this out of the forecast for now.

The dryline continues to mix northwestward this morning but should
be stalling out shortly before once again making a march to the east
through the day.  As is usually the case, there are differences in
how far east the dryline will make it but all of the models agree
that it should make it into the eastern Rolling Plains.  Very few of
the high-resolution model runs this morning produce any convection
of significance across our forecast/warning area this afternoon and
this evening but the few that do have some pretty robust storms. The
most favored area will be across the southern Rolling Plains where
the best boundary layer moisture will be and cap strength the
weakest.  Shear profiles are favorable for organized convection and
a few supercells but the better chances appear to be outside of the
forecast area to the east and south.  A likely scenario is for
storms to initiate along the dryline in our forecast area and then
move east and strengthen as they do so.  Confidence is not all that
high that we will see severe storms in our area but will leave
mention in the weather grids for now.

Behind the dryline, a dry southwesterly wind will once again help
to bump temperatures up but not quite as warm as yesterday. The
slightly cooler high temperatures are due in part to heights
falling through the day as an upper level low over western Arizona
continues to slowly push east. Models continue to struggle with
how strong wind speeds will be this afternoon with the GFS MOS
guidance in 25 to 35 MPH range out of the southwest with the NAM
MOS 15 to 25 MPH. Deep mixing will take place behind the dryline
allowing some of the higher wind speeds aloft to transfer to the
surface, but not quite as strong as the GFS is suggesting. Models
do not mix the dryline as far west tonight into Friday morning
which will result in cooler morning low temperatures across the
northwestern South Plains and readings fairly close to what have
been reported the last couple of mornings for the remainder of the


The extended will start on the quiet side but will trend toward
the unsettled late this weekend into next week. Initially on
Friday dry air will envelop the South Plains region on breezy
westerly winds south of a storm system emerging across the central
High Plains. Temperatures will moderate back down toward average
as the passing trough provides some cooling. There remains a low
threat a little high-based convection originating over the higher
terrain of New Mexico could make a run toward our northwest zones
late in the day but even if it were to make it amounts would be
spotty and light given the deep and dry sub-cloud layer.

A fine start to the holiday weekend will follow with relatively
light winds and dry conditions beneath relatively flat flow and a
progressive low-amplitude upper ridge. The dry conditions and plenty
of insolation will allow highs to peak around the 90 degree mark for
many spots on Saturday.

The upper flow will quickly transition to southwesterly Saturday
night into Sunday as the next storm system digs toward the Desert
Southwest while low-level moisture rapidly returns from the
center of the state. Under this pattern storm chances will quickly
return to West Texas on Sunday. The current round of NWP
advertises a fairly decent embedded disturbance traversing the
region late Sunday into early Monday complete with widespread and
locally heavy QPF generation. Beyond then, models diverge somewhat
on how things will evolve but they do keep relatively weak but
perturbed flow aloft while low-level moisture and instability
remain in the region. So although there will undoubtedly be lulls
in precipitation, there should also be decent periodic chances of
showers and thunderstorms too. Given this we have accepted the
blend guidance that carries solid chance PoPs through the middle
of next week. As alluded too, the dynamics will be on the weaker
side, but with moderate to strong instability present during the
afternoon and evening hours, occasional robust updrafts will
occur. Additionally, slow storm motions and fairly rich moisture
will support locally heavy rainfall at times. To go along with
the increased moisture and rain chances, temperatures will trend
downward to or even a little below average. All said, the overall
forecast remains on track with only minor adjustments made this


.LUB Watches/Warnings/Advisories...


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