Area Forecast Discussion
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FXUS64 KLUB 201740

Area Forecast Discussion
National Weather Service Lubbock TX
1240 PM CDT Thu Apr 20 2017

An MVFR cloud layer that has been lifting and breaking up around
KPVW and KLBB is expected to return by late this afternoon, or
more likely early to mid evening. At that point, the layer should
lower to near IFR levels. Cloud layer unlikely to break up at KCDS
through the day, and will likely lower to near IFR there as well
by early or mid evening. Added light fog all sites for late night
and early Friday, and drizzle as well for KCDS, though there is a
risk for strong thunderstorms as well which we have not included.


.PREV DISCUSSION... /issued 635 AM CDT Thu Apr 20 2017/

A cold front is making its way across the region with some limited
MVFR ceilings that may temporarily affect the KPVW and KLBB
terminals this morning. Winds will eventually swing around from
northerly to northeasterly. Models suggest the potential for MVFR
ceilings especially at KCDS later this morning perhaps sticking
around all day. However, inter-model consistency is low to
moderate thus will side toward less coverage at this point.
Moisture will increase again tonight with a risk of IFR ceilings.

PREV DISCUSSION... /issued 350 AM CDT Thu Apr 20 2017/

Mid level flow will become southwesterly today as the next shortwave
of interest digs out of the Great Basin toward NW Texas with
increasing effect.  A cold front is making its way across the CWFA
early this morning a few hours ahead of schedule from 00Z run
projections.  By mid-day, the front should be through the entire
area with the possible exception of the southeastern Rolling Plains
as the surface boundary will be oriented SW-NE.  This could play
havoc with highs.  Elsewhere to the north and west, winds will be
quite breezy behind the boundary with speeds possibly approaching
advisory level later this morning.  As we`re not quite seeing winds
that strong upstream, will hold off on any advisories for now and
keep an eye as the morning progresses. Also anticipated behind
the front will be the potential of stratus perhaps setting up
around sunrise. How quickly or if the layer will dissipate remains
a point of uncertainty with some guidance holding the clouds in
tight through the day even as far west as Lubbock. Into the
overnight hours, low level moist advection will become re-
invigorated with stratus overspreading the region. Some
thunderstorm risk will exist late tonight--particularly in the
northeast. Interestingly, the TTUWRF does keep us dry and depicts
a evolutionary scenario (based on frontogenetical forcing) not
atypical of this time of year with convection remaining east of
the area. That said, fcst soundings do depict some hefty elevated
cape above the LFC and so any storms could be on the strong side.
However, with a strong near-surface inversion, the primary threat
will likely be hail.

High temps on Friday will be a bit tricky as they will be dependent
upon the timing of the fropa. As of now it looks like the front
should push through our northern zones early enough during the
afternoon to keep temps in the mid to upper 70s. South of the front
temps should be mostly in the mid to upper 80s to around 90. Winds
look like they will be just a bit lighter ahead of the front than
was previously expected (20-25 mph vs. 30-35mph) as the H700
gradient is expected to be more relaxed. Models have also come down
on wind speeds behind the front particulary across our northwestern
zones. Models are still in good agreement with pressure rises around
14-16mb in this area behind the front which would indicate at least
advisory level winds. MOS guidance appears to continue having the
best forecasted wind speeds and will be used for late Friday into
early Saturday. Winds will slowly decrease into Saturday afternoon
as surface high is not expected to settle overhead until closer to
midnight Sunday. The location of the center of the high by Sunday
morning continues to be uncertain with the GFS favoring the eastern
TX Panhandle and the ECMWF favoring the western TX Panhandle. The
final location of the surface high will determine on how much lows
will drop by Sunday morning. The western solution is more consistent
and currently favored for this forecast. Lows as currently
forecasted get as low as 34 across our extreme northwestern counties
with most of the Caprock being in the mid to upper 30s. These temps
along with low dewpoint depressions will allow for a risk of a
late season frost for areas northwest of Lubbock.

High temps will be coolest on Saturday (low to mid 60s) but will
quickly warm back to the upper 80s by Monday and the low 90s by
Tuesday as a thickness ridge makes its home over the region
following the passing of an upper ridge. Models continue to hint at
another fropa by mid week next week, this one being weaker than its
predecessor. Models are also continuing to have a problem with an
upper trough late next week. Model to model runs have suggested deep
meridional troughs all the way to almost zonal flow with a weak
embedded disturbance. Current model runs favor a more meridional
trough with a neutral to slightly negative tilt. This solution would
favor the possibility of some dryline convection. Right now PoPs
will stay on the low side given the forecast time frame and the
inconsistent model runs.




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