Area Forecast Discussion
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FXUS64 KLUB 181105

Area Forecast Discussion
National Weather Service Lubbock TX
505 AM CST Sun Feb 18 2018

A quick bout of MVFR ceilings should affect CDS around 10 AM or
so, with the west edge possibly grazing LBB around 11 AM or so.
Else, expect VFR with SW winds increasing to 20 knots with
frequent gusts over 30 knots at LBB and PVW. Such gusts usually
stir up some dust at LBB, but visibilities should hold at or above
six miles.


.PREV DISCUSSION... /issued 352 AM CST Sun Feb 18 2018/

The main issue with this forecast is how the models are handling
boundary layer moisture through the week and struggle with how
precipitation may develop. For today, all models are quite
aggressive with pulling low-level moisture across the area through
the day. By noon, global-scale models bring low 50F dewpoints
into the southern Rolling Plains while the regional and high-
resolution runs keep dewpoints lower until around sunset when they
pulls the low 50F dewpoints across all of the Rolling Plains. A
few models break out light precipitation mainly east of I-27/US 87
at various points but this is likely to be artifacts of the strong
warm-air advection regime. Cannot rule out some light rain or
drizzle across the southern Rolling Plains after sunset as weak
isentropic lift develops under a decent low-level jet across this
area, but amounts should be light and generally under one tenth of
an inch.

Monday looks to be breezy to borderline windy as a tight pressure
gradient develops across the region under southwesterly flow
aloft. Low-level moisture will mix east through the day but we
should still see low to mid 30 dewpoints remain in place across
the forecast area. The biggest impact from this will be keeping
minimum RH values between 20 to 25 percent which will keep
critical fire weather conditions from developing. Wind speeds
remain tricky as MOS guidance has come in ranging with speeds
between 20 to 30 knots while most of the operational model
guidance is between 15 to 25 knots. A wind advisory may be needed
Monday afternoon if the higher MOS guidance is realized but it
does appear that the higher RH values should keep the fire danger
in the elevated range.

Moisture kicks further east Tuesday as as a weak Pacific front
moves across the area dropping high temperatures Tuesday into the
upper 50s in the far southwestern Texas Panhandle to mid 70s over
the Rolling Plains. Wind speeds will decrease through the day and
dewpoints will drop into the teens to low 20s ahead of a stronger
Canadian front that will arrive overnight Tuesday into Wednesday
morning. This will further drop highs generally into the 40s for
Wednesday afternoon with a few areas in the northern Rolling
Plains struggling to get out of the upper 30s. The last two days
of this forecast become a bit messy as the GFS and ECMWF differ on
how low-level moisture will move across the Southern Plains. The
ECMWF is trying to generate quite a bit of precipitation Wednesday
afternoon across the Rolling Plains into Oklahoma which none of
the other models are showing. This continues into Thursday night
into Friday but the GFS has more precipitation coverage compared
to the ECMWF. After that, the models struggle with when the
dryline will push east drying us back out and whether there will
be any precipitation along the dryline. Opted to lower pops in the
last three periods below what the model blend was putting in due
to the differences between the models for now.





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