Area Forecast Discussion
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FXUS64 KLUB 200905

Area Forecast Discussion
National Weather Service Lubbock TX
405 AM CDT FRI MAY 20 2016

Unlike the past few nights the radar scope was quiet tonight as the
upper level system that aided in producing the recent wet stretch
was now pulling away from the region via the central plains. Upper
ridging will follow today downstream of a broad upper low sinking
slowly southward over the western states. At the surface, light and
moist southerly flow along with the moist ground was supporting the
rapid development of low clouds and areas of fog, locally dense, as
of 08Z. The lows clouds and fog should fully fill in over the CWA
over the next couple of hours before gradually lifting and
scattering from west to east through the morning and early afternoon
hours. The far northeast zones around Childress could see clouds
hang on until well into the afternoon which will temper warming
somewhat. Not too confident regarding how widespread or dense the
fog will be this morning, with KCDS recently dropping down to 1/4
mile. At this point the dense fog appears rather spotty, but we will
continue to monitor and if it becomes more widespread a dense fog
advisory will be issued. Any fog concerns will quickly fade by 14-
15Z, and with sunshine gradually returning from west to east and
building temperatures/heights aloft, we will see afternoon
temperatures jump into the upper 70s and lower 80s. A dryline will
attempt to sharpen across the central zones this afternoon, but
relatively weak convergence along it coupled with subsidence aloft
beneath the ridge will likely keep deep moist convection at bay. A
more seasonably mild night will follow tonight as southerly breezes
continue and we could see another round of low clouds and/or fog
develop after 06Z.

...Severe weather possible Saturday and Sunday...

Low-level moisture should be banked against the higher terrain of
New Mexico Saturday morning, while flow aloft over West Texas transitions
to southwesterly downstream of a large upper trough moving into
the western states. This increasing southwesterly flow should
encourage a dryline to develop somewhere in the vicinity of the
TX and NM state line Saturday afternoon. The airmass to the east
of the dryline should become moderately unstable as temps rise
into the middle 80s with progged MLCAPES on the order of 1500 to
2500 J/kg. However, with the upper trough well to the west, it
appears that upper forcing for ascent will be rather weak, relying
on a weak ripple or two moving through the sw flow. Despite this,
most of the available guidance does develop at least some QPF in
the vicinity of the dryline by 00 UTC. Deep-layer shear, although
not particularly strong, should be sufficient for multi-cell storm
organization and perhaps a supercell or two, and the attendant
threats for large hail and damaging wind gusts. The storms may
congeal into a small cluster or two in the Rolling Plains Saturday

On Sunday, a shortwave trough will eject northeastward across the
southern Rockies. This will bring stronger westerly momentum
across our area and help increase deep-layer shear and push the
dryline a little farther east while sharpening it further. How
far east is still in question but the latest indications suggest
it may be located somewhere in the vicinity of the I-27/Highway 87
corridor by late afternoon. Continued rich moisture feed from the
Gulf of Mexico will result in higher CAPE values, while stronger
large-scale ascent is expected with the ejecting trough,
especially across our northern counties. Thus the severe weather
potential appears to be even higher on Sunday. T-storm activity is likely
to continue well into the evening across the Rolling Plains.

We should see a period of subsidence behind the exiting shortwave
early Monday, but already by Monday evening, lift may be renewed
as an upper-level jet approaches from the southwest. Deep moisture
may be confined to the eastern and southern Rolling Plains by that
point and we`ve upped PoPs in that area. Significant differences
in the GFS and ECMWF crop up Tue through Thu as the GFS keeps the
deep-layer flow veered sufficiently to prevent adequate moisture
from returning anywhere other than a sliver across the southern
Rolling Plains. The ECMWF however is deeper with the trough across
the southwest which allows moisture to flow back farther west and
support precip. chances at least across most of the Rolling
Plains, and perhaps some of the Caprock as well. Late May dryline
climatology favors the ECMWF depiction and we have included a
mention of t-storm chances for portions of the Rolling Plains
through Thursday.


.LUB Watches/Warnings/Advisories...


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