Area Forecast Discussion
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FXUS64 KLUB 251755
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
1255 PM CDT THU AUG 25 2016

.AVIATION...
Stubborn low clouds will continue to bring MVFR Ceilings to KLBB
and KPVW through at least 19 UTC. Then, concern shifts to
scattered t-storm activity which may affect any or all of the
terminals through mid-evening. KCDS appears to have the best
chances for TSRA impacts. TSRA activity may linger across the area
through the night, and some patchy MFVR ceilings may return
toward Friday morning, however we will keep roughly the second
half of the TAFs VFR for now.

&&

.PREV DISCUSSION... /issued 1129 AM CDT THU AUG 25 2016/

UPDATE...
We have another challenging convective forecast across our
forecast area this afternoon as thick cloud cover will tend to
reduce surface-based instability. Satellite imagery shows an axis
of broken to overcast low-mid level cloud deck stretching from
far southwest Texas to the panhandle, just downstream of the upper
trough axis slowly moving across New Mexico. Although convective
temps are only in the mid 80s, it may be a struggle to reach them
across much of the Caprock. The weak northerly wind shift that
came down through our western counties will continue to slowly
wash out, however the more distinct front sagging south through
the TX Panhandle may eventually reach our northern counties later
this afternoon. The cloud cover currently thins out a bit to the
north and east of Lubbock and this may be the area where we see
the best potential for strong and possible a couple severe storms
late this afternoon and evening. Deep-layer shear will be
strongest across the far southern TX Panhandle and nrn Rolling
Plains, so we are going to add a mention in the HWO for severe
potential in that area.

PREV DISCUSSION... /issued 638 AM CDT THU AUG 25 2016/

AVIATION...
Shower chances will remain not far from KCDS for the time being,
as remnants of the overnight activity hold across the eastern
panhandle and northern Rolling Plains. Chances will shift back
west later today after a period of surface warming and with
surface convergence just ahead of a weakening upper trough. Deep
subtropical moisture will continue today as well. Early today
there are at least shreds of a lower cloud MVFR layer nearby, but
not yet compelling reasons to expect a solid ceiling. RMcQueen

PREV DISCUSSION... /issued 430 AM CDT THU AUG 25 2016/

SHORT TERM...

The early morning shower and thunder activity was edging slowly to
the east in line with low level jet and the old outflow boundary
that has been steadily advancing eastward through the night. We
will retain best chance of showers this morning favoring northern
and eastern areas. The upper trough also has been very slowly
approaching through the southern Rockies and continues to pull high
precipitable water values of 1.0 to 1.5 inches into the area, though
this morning around 1.75 inches from the eastern South Plains into
the Rolling Plains. Thus fairly efficient and productive showers
have been the rule. Activity expected to wane by mid to late morning
over eastern areas, then shift back to the west.

A frontal boundary edging through the Panhandle was very near its
expected most southern extent, but still could creep into northwest
zones at least briefly this morning before pulling back north during
the afternoon. Low level convergence should be focused in our west
and northwest by later today and will be a decent place to look for
shower and thunder development as that upper trough continues edging
east towards the state line. Somewhat similar to yesterday, surface
heating later today may be hampered by lingering opaque mid and high
level clouds within the subtropical moisture plume, but with
relatively high dewpoints would not take a lot of heating to conjure
up a thousand joules or more per kilogram of available convective
energy. And even though the 500 millibar upper trough will be losing
definition into the night, the trough will remain capable enough at
300 millibar to hold deep moist flow and a good chance of thunder
once more overnight in tandem with the diurnal increase in low level
southerly flow. Small changes all in all, though with nearby fronts
such as this, a lot could easily change with a slightly better shove
to the south. RMcQueen

LONG TERM...

We end the week with the models in good agreement on a shift to the
east of the Bermuda High and the development of weak troughing to
almost more zonal flow to the west. The GFS suggests the best
moisture will be pinched off and left stranded south of the Rio
Grande, and with the trend that has been developing on water vapor
imagery, am inclined to believe this scenario. Therefore, backed off
on PoPs for the first half of the weekend. By Sunday afternoon, a
return of moisture and a shortwave may be just enough to fire off
convection in the afternoon to overnight hours. We may see the same
scenario for Monday, but as the week wears on, ridging building into
the west will start to push our rain chances out and our
temperatures up. Beginning with the Tuesday PoPs, started to shrink
the Blend downward each day as it seemed to be producing PoPs that
were too hefty for a 591 high. Also keeping an eye on the Gulf of
Mexico for any tropical development late next week. Subsidence from
a system that makes it too far west would only add to our warming
and drying, though that is still well out in the future.

&&

.LUB Watches/Warnings/Advisories...
None.
&&

$$

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