Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
FXUS64 KLUB 282113

Area Forecast Discussion
National Weather Service Lubbock TX
313 PM CST Mon Nov 28 2016

Breezy conditions remain in place across the forecast area this
afternoon. This is in response to a tight surface pressure gradient
at the surface and being between a departing and approaching
shortwave troughs aloft.  A few stations across the area have
flirted with wind advisory speeds but not for any length of time and
expect to see wind speeds decrease as we head through the afternoon
into tonight.  After a clear start to the day, high clouds continue
to increase ahead of the next trough approaching the region and this
is starting to hold temperatures in check after rising faster than
expected in the morning forecast.  We may still climb a degree or
two with the strong westerly wind component but for the most part,
temperatures will remain in the mid to upper 50s across the western
South Plains to the upper 60s and possibly lower 70s for the Rolling
Plains.  Once the boundary layer decouples after sunset, wind speeds
will continue to come back down under 20 mph but will remain in the
10 to 20 mph range through the overnight hours.  This along with the
increased high cloud cover should help min temperatures from
dropping too far; low 30s can be expected across the northwestern
South Plains to the mid 40s across the Rolling Plains.

Wind speeds will try to pick up again Tuesday afternoon ahead of a
cold front that will arrive into the northern counties of the
forecast area around noon.  The west wind ahead of the front will
try to help boost temperatures again ahead of the front and by how
much will depend on where the front stalls out.  The latest model
runs show the front sagging to near a Morton, Lubbock, to Paducah
line by late afternoon before finally sagging south after sunset.
High temperatures will also depend on how much mid or high cloud
cover will still be in place through the day as well so forecasted
highs for tomorrow could go a few degrees either way from the
current forecast package has.


Confidence is high in a pattern shift toward much cooler and
unsettled weather by the end of the week, but how cold and whether
this translates into wintry precip is another matter altogether.
Until then, cyclonic upper flow from recent days will flatten with
very little sensible weather from Tue night through Thu night.
Changes then take grasp on Friday as a modified Cp airmass wedges
south through the southern High Plains. The source region of this
airmass is not particularly robust in terms of cold, even for this
time of year. Add to this a fair amount of airmass modification
expected given a void of snow cover from here to the Canadian border
and there is opportunity for temps to end up milder Fri-Sun than
some of the coldest data suggest.

Temps aside, a far greater concern will be how vigorous troughing
currently in the Gulf of Alaska evolves in the coming days. We are
siding with WPC`s assessment of this energy digging west of the
Continental Divide and cutting off in the Baja vicinity by Friday,
before ejecting in a much weaker format by Monday or so. Although
the ECMWF has shown less run-to-run continuity with this wave as
compared to the more consistent GFS, GEFS, GEM, and DGEX, this
system could remain more phased with northern stream troughing and
end up very progressive - ultimately preventing a deep closed low
solution from occurring. However, healthy upper jets diving south
along the Pacific Coast tend to be a good precursor of deep and
slow moving lows this far south.

PoPs were left largely unchanged from Friday and beyond as the first
(and perhaps most efficient) surge of isentropic ascent unfolds late
Friday, with some lull expected by Sun under rising heights well
ahead of the low, before resuming a more muted round of precip on
Mon as the filling/decaying low lifts across West TX. Dynamic
cooling from height falls are not a factor with this setup for our
CWA, so precip type does appear to be more rain than snow
especially if the warm nose proves more robust than models
indicate - which is often the case with these systems. Still,
we have retained a rain and snow mix from Fri night-early Sat for
all but our SE zones to allow for some latitude with thermal
profile changes in the coming 4-5 days. Even with the modified Cp
airmass, max temps under thick clouds should reside well below
normal before moderating nicely early next week.




14/93 is the U.S. government's official web portal to all federal, state and local government web resources and services.