Area Forecast Discussion
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FXUS64 KLUB 211707

Area Forecast Discussion
National Weather Service Lubbock TX
1207 PM CDT Sat Oct 21 2017

VFR expected next 24 hours. A fast moving cold front will barrel
through the region toward 00Z/Sun. There is some risk of BLDU
invof the front. Additionally, high based showers and
thunderstorms may form with an enhanced risk of downburst near
these features. The KCDS terminal has the highest risk of seeing
storms through they can`t entirely be ruled out at KPVW/KLBB.


.PREV DISCUSSION... /issued 954 AM CDT Sat Oct 21 2017/

Updated to insert isolated thunderstorms on the Caprock later
this afternoon. Water vapor imagery and regional RAOBs indicate a
well-defined upper trough axis across central NM complete with
4-5 degrees of mid-level cooling. Although low level convergence
will be minimal west of a surface trough moving into the Rolling
Plains this afternoon, strong low level heating within a thermal
ridge should provide enough buoyancy for high-based storms
once the upper trough arrives. Inverted-V profiles around 7000
feet deep should breed enough downdraft CAPE for some
microburst activity. Else, the forecast remains on track with
comparably better PoPs in the Rolling Plains near the front and
surface trough/dryline intersection.

PREV DISCUSSION... /issued 612 AM CDT Sat Oct 21 2017/

IFR CIGS are anticipated to rapidly dissipate within the next
couple of hours at KLBB and KPVW with MVFR CIGS moving into KCDS.
A strong cold front this evening will push through the region
shifting breezy winds to the north. There is a slight chance of
thunderstorms at KCDS as this front passes through but chances are
too low to mention in the TAF at the moment.

PREV DISCUSSION... /issued 435 AM CDT Sat Oct 21 2017/

Few overall significant changes were made as a sharp upper level
trough was digging on schedule through the Rockies, with a portion
of energy heading into the southern plains by later today. Mid
level height falls already underway will peak late this afternoon
across the Texas South Plains. Veering flow aloft will quickly
erode the early morning stratus deck, and shunt the surface
dryline to near a Benjamin to Aspermont line as strong surface
heating generates surface-based convective energy perhaps
approaching 1500 to 2000 Joules per Kilogram briefly before
shifting east. Better shear will be just north, but ingredients
may line up yet for linear convection either along the dryline, or
related to the Pacific cold front entering the surface trough
about the same time. Model trends have recently retreated the
origins of convection back into the Rolling Plains, and our
forecast will retain a solid chance of thunderstorms for our
eastern row of counties later today.

There also could be an attempt to saturate a high-based cumulus
field back to the west in the drier air, but with inconsistent
model depiction of the instability centered near 600 millibars.
Cannot rule out potential for virga bombs later today - this will
be as a mid level wind mix also sweeps into the area so may have
some potential for locally strong wind gusts. We have nothing in
the gridded forecast for this potential - will readdress if any
need to hype in additional manner.

Otherwise, looking for the continental cold front to sweep
southward also on-schedule late afternoon into northern zones and
early evening southern - with only modest surface pressure rises.
Brief northerly winds near 20-25 mph should back off later in the
evening. A clear and crisp Sunday morning will follow but Sunday
overall still looks stellar - with trends slightly warmer than

Additional warming is expected Monday in advance of the next
continental cold front, perhaps in back-door fashion as the GFS
depicts and arriving Monday afternoon. Minor cooling Tuesday
before zonal-type flow brings decent warming mid week. Solutions
have in-fact considerably sharpened an upper trough coming out of
the western U.S. late next week into the next weekend, but are in
considerable disagreement on how progressive the flow will be in
our area. We have retained dry for next weekend, though we
acknowledge that solutions have trended towards considerable more
amplification that could support the wintry ECMWF. Not ready to
buy into this yet. RMcQueen




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