Area Forecast Discussion
Issued by NWS

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FXUS64 KLUB 011110

Area Forecast Discussion
National Weather Service Lubbock TX
510 AM CST Thu Dec 1 2016

Kept the TAFs simple this morning as VFR is expected next 24
hours. Winds will come around to the east or southeast this
evening though speeds should remain under 10 kts. Looking ahead
into Friday, increasing mid and upper level clouds will move in
this evening before rain chances increase tomorrow night.


.PREV DISCUSSION... /issued 434 AM CST Thu Dec 1 2016/

Zonal upper level flow will rapidly become southwesterly in
orientation today as trough digs into the desert southwest.  Over
the next 24 hours, a split flow regime will become established
bringing to a start the weather system which will bring a shot of
precipitation this weekend.  More about that, however, in the
extended discussion.  After a sunny day today, high cloudiness will
be the first indications of the approaching storm system.  However,
it appears that the clouds shouldn`t make it overhead until after
sunset this evening.  This should help moderate overnight lows
especially in the NW overnight lows cratered last night.  This
morning, wind speeds have increased since about 1am leading to a 10
degree temp jump in the last 2 hours.

During the day surface moisture advection should remain to our east
though by 12Z Friday, deeper surface moisture will finally make its
way to our southern zones.  Bottom line is that we`ll have one more
pleasant day.

Most recent NWP guidance has shifted the track of the upper level
system set to influence our weather for the weekend, setting a
trajectory farther north and farther west. Blended guidance is now
showing a notable influence of the NAM solution which seems
reasonable at this point.

We`ll see clouds increase from southeast to northwest over the
course of the day as steady moisture advection sourced from the
Gulf works its way across West texas into eastern New Mexico.
Precipitation chances increase through the day as well as isentropic
lift increases out ahead of the deepening upper level low working
ESE across the Baja. Any precipitation occurring in the CWA
during daylight hours Friday will be in liquid form. After sunset
and after cooler air works its way south across the SW Texas
Panhandle and NW South Plains, we`ll likely see some of that rain
change over to snow. Further lift from omega values peaking across
our NW counties late Friday night into the early Saturday could
result with snow accumulations around 1-3 inches by early

Beyond Saturday morning there is still some uncertainty on how the
system evolves between operational models. The NAM is most
agressive for QPF and cooler temps working farther south into our
area while the ECMWF favors QPF across our southern half in the
form of rain on Saturday. The NAM also seems to be over doing
precip on the north side of the low as it approaches late
Saturday into Sunday. Which could add to snow totals there if
verified but for now leaning toward blend that dries quicker which
goes along with the GFS/ECMWF. Overall the blended solutions seem
to have good handle on shifting best precip chances on Sunday to
the south and east after the first wave late Friday and Saturday.

Monday precip chances will be dictated by how the Low begins to
exit to the east and northeast on Monday. The ECMWF would leave us
mostly dry with a more progressive shift than the slower GFS.
Beyond Monday we`ll see broad troughing with cooler air work in
from the north but any fronts look to be dry at this point from
middle of next week onward.




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