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Area forecast discussion 
National Weather Service Lubbock Texas
1222 PM CDT Friday Aug 29 2014

the MVFR fog at both taf sites diminished earlier this
morning...though MVFR cloud decks were slow to scour out at kcds
early this afternoon. Computer models show VFR decks at kcds by
late afternoon. Otherwise...VFR conditions expected throughout the
remainder of the taf period. This is slight chance for light
VFR/MVFR fog to develop again overnight...though computer models
show atmospheric conditions to be slightly drier at the surface than
the previous night. Will hold off on inserting a mention
at this time...but will of course amend as necessary. Light and variable
winds will veer to the west-southwest tomorrow morning. There are
hints of light -shra/-tsra nearing kcds tomorrow afternoon...but
confidence is not high enough to insert a mention at this time.


Previous discussion... /issued 414 am CDT Friday Aug 29 2014/

Short term...
as of 08z...convection stretched from central Kansas southward
through central and eastern Oklahoma into North Texas...then bent
south and westward into the Big Country and Concho Valley. This
widespread precipitation was associated with a weakening shortwave
trough /formerly a closed low/ that was shearing out as it was
accelerating eastward through the plains states on its way to be
absorbed by the westerlies. Water vapor imagery shows this
well...with much drier middle/upper level air invading from the west
behind the passing disturbance. The upper trough axis will take a
little longer to exit the eastern zones...and given this have
decided to maintain a minimal storm mention in the rolling plains
through this morning though a bulk...if not all...of the activity
will probably remain to the south and southeast. Behind the
trough...a period of northwesterly flow aloft will follow this
afternoon into tonight...though no obvious upstream disturbance
until perhaps a minor wave on Saturday.

At the surface...a poorly defined/weak cold front was taking its
time sagging southward into the County Warning Area...but it is prognosticated to stall
later this afternoon somewhere across the area. In advance of the
front...very moist conditions were in place...and with clearing
skies and light winds it has promoted the development of low clouds
and pockets of fog this morning. Any lingering fog should lift by
mid-morning...but it may take until midday or even early afternoon
for all of the low clouds to scatter out...particularly out east.
Much drier air should advect into at least the northwest zones
behind the stalling front this afternoon...but abundant moisture
will linger in the rolling plains. Although large-scale support will
be lacking this afternoon /and perhaps even a little on the negative
side/...if enough heating can occur the quasi-stationary front could
be the focus for isolated to widely scattered thunderstorm
development late this afternoon. Most nwp is rather sparse with quantitative precipitation forecast
locally and generally favor the southeast third to half of the
County Warning Area...should it occur. Given this...we have trended probability of precipitation
downward...but did maintain a slight chance mention along and east
of a Brownfield to Lubbock to Memphis line. If/where storms do
develop...deep layer shear will be down a notch from yesterday...
but modest instability could exist along with precipitable waters near 1.5
inches...which in concert could support a strong storm or two with
locally heavy rainfall. Should storms develop...would expect them to
quickly diminish this evening with the loss of heating. Attention
will then turn to the northwest as mountain convection may attempt
to propagate this way though limited moisture/instability and
effective inflow will temper chances of convection making into the
forecast area tonight.

Temperatures will be cooler today with the front in the area and a
considerable amount of cloud cover. Generally favored highs near
guidance...though did trim off a couple of degrees where the heavier
rain fell yesterday. Tonight will be mild with lows mostly in the
60s...perhaps a few lower 70s east.

Long term...
a weak shortwave will move out of The Rockies appears
slightly sharper and more energetic in the WRF-NAM than the
GFS...and results in a period of relatively swift northwest flow aloft
over wtx. The NAM generates T-storm activity across the panhandles
and carries it southeast across northern portions of the County Warning Area Sat afternoon and
evening. The sref is not as bullish as the NAM but does indicate
some activity across the western and southern Texas Panhandle. We have added a
slight chance in our northern zones. A moderate ulj will enhance deep
layer shear and is suggestive of a potential for strong/marginally
severe storms...but coverage is expected to be isolated. The middle-
level flow becomes more zonal Sunday into Monday as a shallow and
broad trough migrates from the Pacific northwest into the northern plains. A
cold front will be pushed south through the plains by this wave
but the latest forecasts stall it out across the okla or northern Texas
panhandles. Some jet energy will spread over northwest Texas late Sunday but
current indications are that the cap will hold south of the
front...something to keep an eye on though.

Beyond Monday....sprawling subtropical ridge over the southeast will expand
westward and should bring US a period of dry and warm weather. The
circulation around the high will gradually support a return of
sub-tropical moisture back into nm and the resulting diurnal
convection could eventually edge eastward toward wtx late in the
week...but the signal is too weak to add any probability of precipitation at this time.

For should get pretty toasty Sunday into Monday as
tightening gradients lead to stronger S-SW flow. High temperatures are
expected to be in the middle 90s on the cap to near 100 in the Low
Rolling Plains. Then...heights and thickness values show a gradual
declining trend for the remainder of the week...but high temperatures still
are likely to remain warmer than average...mainly in the lower to
middle 90s.


Preliminary point temps/pops...
Friona 62 89 64 94 63 / 10 20 10 10 10
Tulia 64 90 67 95 68 / 10 20 10 10 10
Plainview 65 91 68 95 68 / 10 20 10 10 10
Levelland 65 92 67 95 67 / 10 10 10 10 10
Lubbock 68 93 70 96 71 / 20 10 10 10 10
Denver City 67 93 67 96 67 / 10 10 10 10 10
Brownfield 67 93 68 96 68 / 20 10 10 10 10
Childress 69 95 72 98 75 / 20 10 10 10 10
spur 68 94 71 97 73 / 20 10 10 10 10
Aspermont 72 96 74 98 75 / 20 20 10 10 10


Lub watches/warnings/advisories...



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