Area Forecast Discussion
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FXUS64 KLUB 210443
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
1143 PM CDT SAT AUG 20 2016

.AVIATION...
MVFR cigs appear more possible for at least KLBB and KPVW by
daybreak Sunday as short term solutions have trended with more
saturation near the 1500-2500 foot AGL layer with slightly
stronger easterly upslope component. We have added this risk to
the 06Z TAF set with conditions possible much of the morning
before lifting into a low scattered cumulus cloud layer during the
afternoon. The RAP solution also is indicating possibility of
patchy fog on the Caprock, which we are not yet adding but
mentioning here since we will be watching for it overnight. Less
likely for a broken layer at KCDS though certainly possible here
as well. RMcQueen

&&

.PREV DISCUSSION... /issued 642 PM CDT SAT AUG 20 2016/

AVIATION...
Relatively moist and cool airmass will cover the area overnight
with a surface high pressure ridge nosing in, but with minimal
upslope wind components. And solutions are not indicating any
significant low clouds or fog formation. But of course we will be
keeping an eye for lower layers especially as the clouds near
5000 to 6000 feet gradually dissipate overnight. Shower chances
also to remain south and west of the area over the next 24 hours.
RMcQueen

PREV DISCUSSION... /issued 312 PM CDT SAT AUG 20 2016/

SHORT TERM...
After a bout of beneficial rain for some spots last night and early
today, primarily off the Caprock, much quieter weather has settled
in over the South Plains region this afternoon. This as a surface
ridge was nosing into the area behind an impressive early day summer
FROPA. The combination of cold air advection and plenty of cloud
cover have temperatures sitting mostly in the 70s across the CWA as
of 1930Z. Of note, the high in Lubbock so far has only been 74
degrees. This may climb through the late afternoon hours as
additional breaks in the clouds form, but we will have a shot at the
record low maximum for the day. The current record low maximum
for August 20th is 78 degrees, set back in 1956.

Aside from the nice and cool late summer conditions, the frontal
zone and precipitation has shifted southward as more stable air
spills into northwest Texas. The lower theta-e air will likely keep
the FA dry tonight into much of Sunday. However, we will have to
watch closely to see if any activity forming over the higher terrain
of central/southern New Mexico can make a run toward the far western
zones this evening or again Sunday afternoon/evening. Given the
unfavorable thermodynamics and minimal upper support prospects do not
look good tonight, though they may improve slightly by late Sunday
and we have maintained a low thunder mention near the TX/NM line
Sunday afternoon.

Before then, cool light upslope flow tonight may be just moist
enough to support the risk of low cloud and/or patchy fog
development on the Caprock early Sunday. However, there may be
enough mid/upper level cloud cover drifting in from the west to
mitigate this potential, and with NWP shying away from the low
cloud/fog scenario we have left it out of the forecast for now. What
is more certain is a pleasantly cool night with lows by morning in
the upper 50s and lower 60s fairly common. Cloud cover should be
less abundant than today on Sunday, especially across the
northeastern half of the CWA as drier air advects in, so we expect a
modest warming trend. Even so, it will remain cool by August
standards, with highs primarily in the lower to middle 80s.

LONG TERM...
Forecast hasn`t cleared up any with the 12z model runs. Weak
cyclonic curvature progged to persist over the southern high
plains through much of the upcoming week. Embedded short wave
troughs, dew point temperatures in the 60s through much of the
period, and a cold front all point to some potential for
precipitation. Models tend to overdo extent of precipitation, and
this may not be much different. Looking at things on a daily
basis, Monday still looks to have a good shot at scattered storms
mainly east with a subtle short wave trough moving across the
South Plains and Panhandle while increasing southerly low level
flow brings pretty rich moisture into the area, especially off the
Caprock, which is where best rain chances are anticipated. Tuesday
is looking dry on some models such as the GFS but at least
isolated to scattered storms possible per the WRF-NAM and ECMWF.
Speed of the next, sharper short wave trough will drive timing of
this next batch of precip. This trough will be slow to cross the
plains bringing rain chances again Wednesday. The cold front is
progged into the area Wednesday night enhancing rain chances.
After that the precip forecast becomes more complicated. Models
have been too far north with where the last two fronts have
stalled, the result being they have too wet in what turned out to
be a post-frontal environment. This midweek certainly has the
potential to do the same, but until there is stronger evidence,
and with additional short wave energy back to the west will keep
rain chances going into the weekend, although toned back from
model blend toward the lower objective guidance. Model blend for
temperatures look fine at this time, although will likely need
fine tuning for Thursday and Friday depending on frontal movement.

&&

.LUB Watches/Warnings/Advisories...
None.
&&

$$

99/99/05



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