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Area forecast discussion 
National Weather Service Amarillo Texas
1253 PM CDT Wednesday Aug 27 2014

Aviation...
18z tafs...scattered thunderstorms are expected to redevelop this
afternoon. The most favorable period currently looks to be somewhere
in the 19-02z timeframe depending on the site. Will cover with thunderstorms in the vicinity
remarks for now...and amend as necessary as the storms evolve this
afternoon and evening. Showers and storms may linger over parts of
the area overnight...but confidence in these impacting the terminals
is too low to include any additional mention at this time. MVFR or IFR
conditions and brief gusty winds to around 45 kts will be possible if
any stronger storms directly impact a terminal. VFR conditions are
expected outside of the showers and thunderstorms. Southerly winds
will gust to around 20 kts this afternoon. A cold front will slide
through kdht and kguy Thursday morning...turning winds to the
northwest...and will be nearing kama at the end of this forecast
period.

Kb

&&

Previous discussion... /issued 1207 PM CDT Wednesday Aug 27 2014/

Update...
increased precipitation chances for parts of the area this
afternoon...mainly to expand chance/scattered probability of precipitation farther east
across most of the forecast area. Plume of healthy middle/upper-level
moisture with a feed from Hurricane Marie remains across the
area...with rich low-level moisture in place as well /sfc dewpoints
60s to lower 70s/. Despite lingering cloud cover across the
area...believe we/ll see enough breaks to allow for sufficient
diurnal heating in the presence of weak broad scale forcing ahead of
the upper low over Utah /and minimal convective inhibition/ to trigger
scattered thunderstorms this afternoon. Also lowered high temperatures for
this afternoon in areas of thicker cloud cover.

Kb

Previous discussion... /issued 459 am CDT Wednesday Aug 27 2014/

Discussion...
an active weather pattern is evolving over the southern High Plains
of West Texas. This as moisture aloft originating near Hurricane
Marie in the eastern Pacific streams northeastward within the
western periphery of the subtropical ridge and in advance of an
approaching shortwave trough now nearing The Four Corners. Concerns
include increasing risks of flash flooding...with activity peaking
late Thursday.

Currently...regional radar shows multiple waves of convection extending
from central New Mexico eastward to the northeastern panhandles. Localized
rainfall rates this morning upwards of 3 to 4 inches/hour have been
observed near Booker /Lipscomb County/. A lull in convection is likely
by late morning/midday...but forcing for ascent and atmospheric moisture
content will only increase through the next 48 hours. Convection may
remain isolated/widely scattered enough late today to preclude a widespread
organized flash flood threat...but instability appears to increase upwards
of 1000 j/kg...which may support a few pulse-type storms capable of
localized/brief damaging winds and heavy rainfall.

The most likely timeframe for an organized heavy rainfall threat is
expected to occur late Thursday/early Friday as the shortwave trough
ejects over the Southern Plains and a weak frontal boundary pushes
south across the panhandles. SBCAPE values will approach 2000 j/kg
and deep layer shear will increase sufficiently to support loosely
organized convection and warrant a threat of a few severe storms.
Model forecast soundings additionally indicate precipitable water values in excess
of 2 Standard deviations as early as this evening...but values
approaching 2 inches over the eastern Texas Panhandle by Thursday
night. Flash flood watches may become necessary if signaled trends
for more widespread storms/rains continue.

Few changes to the forecast/grids for the Saturday through Tuesday
timeframe. Conditions appear to dry/warm up by the weekend. Medium
range guidance struggles to rebuild the subtropical ridge this far
north through the remainder of the period...but Lee troughing will
deepen and promote hot temperatures beneath modest near zonal flow.

Lindley

&&

Ama watches/warnings/advisories...
Texas...none.
OK...none.

&&

$$

08/05

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