Area Forecast Discussion
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FXUS64 KLUB 131709

Area Forecast Discussion
National Weather Service Lubbock TX
1109 AM CST Tue Feb 13 2018

Modest low level southerly flow and increasing high level moisture
will be the dominating features in the coming 24 hours. Low clouds
still in the KCDS area for another couple hours before being
shunted to the east early this afternoon. Low level flow for the
most part will be more veered but still a slim chance of near
surface saturation at KCDS early Wednesday - below mentionable
limits at this point. Also, a 35-40 knot low level jet appears
will set up over the western Panhandle tonight - not enough flow
to consider a low level wind shear remark. RMcQueen


.PREV DISCUSSION... /issued 534 AM CST Tue Feb 13 2018/

The main aviation concern is the development of IFR ceilings this
morning as a low stratus deck across central TX moves/expands to
the north and west. The highest confidence in IFR conditions is at
KCDS with lower confidence at KLBB and especially at KPVW. IFR
conditions, if any, should be short-lived at KLBB and KPVW but may
linger until 18 UTC or so at KCDS. VFR conditions are then
expected for the remainder of the TAF period.

PREV DISCUSSION... /issued 409 AM CST Tue Feb 13 2018/

It is another dry and chilly start to the day with 09Z temperatures
again in the teens and 20s. However, southerly flow just off the
deck was carrying moisture northward with an expansive area of
stratus now spreading over the Concho Valley and Big Country. These
low clouds will likely spread into at least the eastern zones later
this morning, with some question remaining how far west the low
clouds can expand. Regardless, the stratus should scatter/clear
from west to east later in the day, though it could suppress
heating somewhat off the Caprock where temperatures may not make
it out of the lower to middle 50s. On the other side of the CWA,
plenty of filtered sun along with drier downslope flow will propel
highs into the lower and middle 60s near the TX/NM line.
Increased moisture tonight will help secure milder temperatures,
with a risk of patchy fog development out east where the low-level
flow is last to veer.

Breezy southwesterly winds will follow on Wednesday as pressures
fall in the lee of the Rockies under southwesterly flow aloft. This
will result in a warm day, though an increase in mid/upper level
moisture and cloud cover could temper heating and the wind magnitude
a bit. Even so, temperatures will still warm well into the 70s, and
with relatively dry breezes this will elevate the fire danger.

Attention will then turn to the upper level low currently spinning
southward through central California. This low is expected to
meander off southern California later today through Wednesday
before quickly opening and ejecting northeastward Wednesday night
into Thursday. The disturbance will quickly lose definition as it
is absorbed into a northern stream trough, but it will quickly be
replaced by additional energy moving into the Great Basin. This
pattern will keep a steady stream of sub-tropical moisture flowing
off the eastern Pacific and up over the region. Unfortunately,
relatively dry and warm downsloping low-level flow Wednesday and
Thursday will keep rain chances low, with elevated fire weather a
greater concern. However, the northern stream trough will send a
cold front southward into the South Plains late Thursday night.
The latest NWP has trended a little slower with the front and not
as cold as what was indicated 24 hours ago. As the front interacts
with the Pacific moisture and the approaching southwestern
trough, NWP is now more favorable in showing top down moistening
yielding a period of light precipitation from late Thursday night
through Friday and perhaps lingering into Saturday (if the slower
and more coherent vort max depicted in the ECMWF prevails). Given
this, we have accepted the blended guidance which now reflects
solid chance PoPs across the central and southern zones Friday
into Friday night. If the ECMWF is correct, any precipitation
would fall as a cool rain, but the GFS is still cold enough that
there is a risk of a wintry mix. We have warmed temperatures a few
degrees, but still have maintained a wintry mix over much of the
CWA Friday night.

Regardless, after highs in the 70s and even 80s Thursday,
temperatures will likely be stuck in the 40s Friday. Warmer and
drier conditions will then follow the departing wave, particularly
by late weekend when highs will recover into the 60s and 70s.




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