Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 281737

Area Forecast Discussion
National Weather Service Amarillo TX
1237 PM CDT SAT MAY 28 2016

Light surface winds will trend to south and southeast as zonal mid-
level flow induces development of lee-side trof.  Expect to see some
high-based cumulus clouds this afternoon.  Low-level jet develops
overnight, strengthening before sunrise, with significant moisture
return commencing.  Warm air advection will support stratus cloud
development.  Timing of onset of MVFR ceilings remains uncertain at
this time, but this forecast calls for occurrence at or before 12z
Sunday at KAMA and KGUY.  Conditions expected to deteriorate further
beyond time frame of this forecast, with scattered to numerous
thunderstorms developing Sunday afternoon.



.Prev Discussion... /Issued 551 AM CDT SAT MAY 28 2016/

Aviation... /For the 12z TAFs/
Light northwest winds will become southeast later today and increase
slightly. VFR conditions are expected to continue although low
stratus could reduce ceilings to MVFR especially at Amarillo. If this
occurs it would be near the end of the TAF period.


Prev Discussion... /Issued 440 AM CDT SAT MAY 28 2016/

Short Term...
Weak ridging will build in today resulting in warmer temperatures
and generally dry conditions. The exception will be in the western
Oklahoma Panhandle and the far northwest Texas Panhandle where we
have retained low precipitation probabilities late this afternoon
and evening. Forecast soundings suggest deep mixing and small MLCAPE
values supportive of isolated convection, primarily focused near the
Raton Ridge. This activity will move east affecting the above
mentioned areas by late afternoon or early evening. Dry sub-cloud
layer is probably extensive enough for mostly virga except with the
most robust convection. Even then amounts will be light.

A surge of low level moisture is expected late tonight as
southeasterly winds strengthen in response to the approach of the
next system. Adjusted cloud cover upward late tonight through
tomorrow morning to account for stratus that will likely develop
with moisture advection. By afternoon, warming of a more moist
boundary layer should contribute to a fairly unstable environment.
Most models show CIN eroding by mid day or early afternoon and
convection should develop by then. Mid level flow is not
particularly strong and although storm depth shear may be enough for
at least weak storm organization, storm motions should be fairly
slow. Cold pool formation may ultimately drive/accelerate
propagation east or southeastward. Spatial and temporal detail in
how this will evolve is not completely clear at this point with
varying model solutions. Large hail and damaging winds will be
threats with storms that form Sunday afternoon, probably weighted
toward large hail initially and then evolving into more of a wind
threat as cold pool matures. Heavy rain will also be a threat given
increasingly deep moisture and slow storm motions. Activity should
shift east into Oklahoma overnight but kept low probabilities in for
the entire area the whole night given proximity of upper trough
still to our west and presence of at least weak ascent.

Long Term...
The Panhandles remain under southwest flow aloft on Monday. An
embedded shortwave trough is shown to lift through this southwest
flow during the afternoon hours as a dryline works it`s way across
the Panhandles. There is some uncertainty as to how far east the
dryline will make it, but given earlier precip, there is an argument
for the further west position displayed by a few medium range
models. The further west placement means a greater part of the area
would be opened up for thunderstorm activity during the afternoon
hours. Models show a fair amount of available instability for any
storms to work with but the limiting factor could be weak shear of
20kt to 30kt. Strong to severe storms are possible with hail and
damaging wind being the primary hazards. There could also be a
locally heavy rain threat across the southeastern Texas Panhandle
with forecast PWATS near the 1.5 inch mark.

On Tuesday, we will have a cold front moving towards the area but
this frontal passage is expected after peak heating. The result is a
surface feature for convection to initiate along across the
Panhandles. Mixed layer instability is shown to be in the 1500-2000
J/kg range, but the difference from Monday is that deep layer shear
is expected to be far better. This results in hail, damaging wind,
and a tornado or two being possible. The tornado threat appears to
be limited to a brief window during the evening hours as surface
winds back slightly to increase the low level helicity. Any heavy
rain threat continues to be targeted at the southeastern Texas
Panhandle where PWATS are forecast in the 1.5 to 1.75 inch range.

A few lingering showers and thunderstorms are possible Wednesday
morning before clearing as upper level ridging builds in from the
west. As the ridge continues to builds in, we should stay fairly dry
on Thursday. On Friday there is a chance mountain convection across
northeastern New Mexico could sneak into the far northwestern corner
of the combined Panhandles but these storms would diminish quickly
after entering the Panhandles.


.AMA Watches/Warnings/Advisories...



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