Area Forecast Discussion
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596
FXUS64 KLUB 201530 AAA
AFDLUB

Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
1030 AM CDT Fri Oct 20 2017

.UPDATE...
Quick update to remove measurable rain chances today as a decaying
upper low exits the Rolling Plains. Current precip echoes across
our northeastern counties are largely virga with some sprinkles.
Given mean subsidence behind this wave, firm capping, and minimal
surface convergence today, additional precip should be hard-pressed
to materialize.

&&

.PREV DISCUSSION... /issued 615 AM CDT Fri Oct 20 2017/

AVIATION...
MVFR CIGS are looking less likely for the terminals this morning
with lowered CIGS remaining southeast of the region. Very light
rain showers remained from early morning activity but is expected
to have minimal impact on the terminals. Otherwise, strong
southerly winds are expected this afternoon with a strengthening
surface pressure trough to the west of the region.

PREV DISCUSSION... /issued 330 AM CDT Fri Oct 20 2017/

DISCUSSION...
A weakening mid and upper level low pressure trough was slowly
lifting northeast through the area this morning. Overall seeing
infrared cloud warming and weak shower depiction on RADAR.
However, a few cooler IR clouds remained so we will hold on to a
slight chance of thunder for the eastern 5/6 of the area this
morning, then mainly over the Rolling Plains later today with
drying expected to spread in behind this trough. As a result, we
will see a little better warming than yesterday, especially on
the Caprock by this afternoon.

A stronger upper trough crossing the northwest coast this morning
will translate eastward over the Rockies into the high plains by
late Saturday. The bulk of energy appears directed to our north,
but we still are expecting a portion to drop southeast into the
southern plains eventually pinching a low off over the lower
Mississippi Valley far to our east as this pattern should remain
quite progressive. This will allow us one decent period of height
falls and lift late Saturday. But moisture will be compromised
with veering aloft following todays weak trough. So we are not
expecting a whole lot of moisture left for potential thunderstorm
development on the west end of the cold front or near the surface
dry-line mainly over the Rolling Plains. Solutions have generally
trended a little drier still with this model package, and we are
holding on very low thunder mention Saturday over the Rolling
Plains. GFS attempts to convect in the drier air on the Caprock
late Saturday, but a dry lower atmosphere should preclude thunder
mention at least at this point. Would expect virga at most.

The cold front will slide southward Saturday evening with Sunday
dawning clear and cool - sided with sub-guidance lows by morning
on the Caprock per usual in this situation. Surface pressure
gradient behind this front appears much weaker than the previous -
so perhaps a period of 15-20 mph winds, but should drop off fairly
quickly early Sunday.

The upper pattern to begin the new week appears will be fairly
high amplitude with western NA ridge/eastern NA trough. A sharp
clipper-type wave digging through the Great Lakes will send a
notable cold front southward into our area by late Monday. So,
brief warming Monday with another cool day Tuesday. The remnants
of this western ridge will then flatten and pass overhead late
Tuesday and Wednesday with another brief warmup. And the next
version of western NA ridge appears a little more offshore, so the
next upper trough and associated cold front arriving late week -
potentially late Thursday with current agreement on both the GFS
and ECMWF - may prove to dig further with later model runs. We`ll
see. Anyway, looks dry for the week ahead. No precipitation
mention beyond Saturday evening. RMcQueen

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

93



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