Area Forecast Discussion
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FXUS64 KLUB 131147

Area Forecast Discussion
National Weather Service Lubbock TX
547 AM CST Fri Jan 13 2017

Low CIGS will continue to slowly lower this morning as moisture
makes its way to the surface. This will also be accompanied by
freezing drizzle with temperatures near or below freezing at all
TAF sites. Temperatures are expected to rise above freezing at
KLBB and KPVW later this morning shifting precipitation to rain.
However, freezing drizzle or freezing rain may remain at KCDS for
much of the day and overnight. Flight conditions will likely
further deteriorate during the overnight hours.


.PREV DISCUSSION... /issued 420 AM CST Fri Jan 13 2017/

We are eagerly awaiting the onset of drizzle early this morning to
start off the event. Lift over the next 24 hours or so will
primarily be driven by moist isentropic upglide. This lift will
generally be weak but persistent through the period. There may be
some period where lift will be strong enough to get rain showers but
drizzle or freezing drizzle would likely be the primary
precipitation mode. Furthermore, an area of enhanced lift will move
into the southern Panhandle through western South Plains associated
with a low level layer of frontogenetical forcing.

Before any meaningful precipitation begins, a strong mid level dry
layer would need to saturate. Also, the very low levels of the
atmosphere will need to saturate since dew point depressions are
very high at the moment. The lower levels will eventually saturate
later today as isentropic lift continues to increase. The mid level
dry layer will slowly moisten through the day and overnight but may
not completely saturate until Saturday morning. The precipitation
type forecast still remains tricky through the period. There will be
a very small diurnal range today through tonight. The surface wet
bulb temperature will increase today across much of the area but
will continue to hover around 0C in the southeastern Panhandle and
adjacent South Plains regions. Surface cooling will be minimal
tonight but would likely be enough to bring freezing rain to the
aforementioned areas. Ice accumulations will likely be light but
enough to cause problems in the southeastern Panhandle and
northeastern South Plains.

Mid and upper level flow will back and moisten Saturday in
advance of a potent upper level low pressure system that should be
near the Baja Spur early Saturday, poised to approach the area
Saturday night and Sunday. Moistening will be very impressive for
mid January, forecast to reach some of the richest precipitable
water levels ever recorded in this part of West Texas for mid
January. The lower levels also will warm, especially just above
the surface, further scouring out the remaining sub-freezing air
anyway that may still persist across the Rolling Plains by mid or
late Saturday. Strong warm advection in the increasing moist
airmass should lead to periods of rain or widespread rainfall on
Saturday. And we also expect increasing low levels of instability
perhaps enough for at least isolated thunder mention by late
Saturday. We have trimmed the freezing rain mention Saturday
morning just a little further north. Lingering freezing rain early
Saturday may tack on a few more hundredths still in the northern
Rolling Plains and southeast Panhandle, in particular, but should
be waning.

Further backing mid and upper flow with approaching jet forcing,
along with the lower and mid level warm advection, will improve
overall lift Saturday night. Instability should continue to stream
northward mainly across the western half of the area. Thermal
gradients will gradually tighten and we expect to see at least
some level of convective organization developing, though hard to
imagine too much in the way of discrete cells given night-time,
January, etc; more likely to remain at least somewhat elevated.
But, we may very well see core intensity improve as freezing
levels start to lower perhaps leading to hail stone development.

The primary forcing across our area will be on Sunday as the upper
low transits north-northeast through our western counties. Exact
track still not yet known, but we expect widespread rain and
thunder spreading through the area. Rainfall totals Saturday night
and Sunday generally are expected to be near an inch or two, which
would be amazing for mid January. And thunder intensity could be
strong enough yet for a few marginally severe hail storms. System
should pull north of the area late Sunday night with drier air
slotting in from the west and southwest; wrap around potential
remains across our northwest zones late Sunday night with mid and
lower level temperatures remaining just marginal enough for a
snow mention but we will not be too concerned of significant
snowfall given limited residency time and particular path.

Brief anticyclonic curvature Monday will be followed by a trailing
upper trough Tuesday/Wednesday. Still very limited moisture, and
highly questionable lift given uncertain path of primary energy so
we are retaining a dry forecast. Temperatures should gradually
rebound with the drying airmass reaching peak temperatures by
Thursday in advance of a possibly significant upper trough that
has potential to impact the area next weekend. RMcQueen


Freezing Rain Advisory until 6 PM CST this evening for



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