Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 261738 AAB
AFDAMA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
1138 AM CST Sat Nov 26 2016

.AVIATION...
Low clouds in the MVFR range at AMA now should scattered out as we go
through the afternoon. Low clouds in the MVFR range should move back
across AMA and they should also spread across the rest of the TAF
sites overnight. Southwest winds will increase into the 25 to 30
knot range after sunrise on Sunday. There will probably be some rain
showers around Sunday morning with the best chance at GUY, but they
should not be heavy enough to drop conditions below MVFR.

&&

.PREV DISCUSSION... /Issued 546 AM CST Sat Nov 26 2016/

AVIATION...
For the 12Z TAFs, a surface trough of low pressure will organize and
strengthen along the eastern slopes of the Rockies during this fcst
cycle. This will result in an increase in wind speeds later today and
tonight. Some low level moisture will also be transported northward
into the region over the next 24 hours, and have included MVFR cigs
at all terminal sites beginning at 06Z Sunday. Any precipitation
threat will likely occur just beyond this forecast issuance.

Andrade

PREV DISCUSSION... /Issued 451 AM CST Sat Nov 26 2016/

DISCUSSION...
Current upper level analysis places broad ridge over the south-
central CONUS while an upper level trough moves inland over the Pac
NW. Winds aloft over the Panhandles are mostly zonal due to weak
southern stream flow. Upper ridge is progged to break down as large
scale trough establishes itself over the CONUS Sunday into next
week.

One more day of fairly nice weather expected across the Panhandles
today with ridge overhead. Temperatures should top out in the low to
mid 60s with southwest winds increasing some during the afternoon as
a weak lee side trough develops. As the upper wave approaches from
the west...the pressure gradient will increase helping to sustain
southwesterly downsloping winds Saturday night. Clouds will also be
on the increase as mid and high level moisture is drawn up from the
Baja Peninsula region as winds aloft switch to the southwest. This
will help keep low temps well above average going into Sunday
morning with lows in the 40s.

Things get interesting during the day Sunday. Model guidance in
better agreement with evolution of upper low and subsequent leeside
cyclogenesis Sunday afternoon. Shallow low level moisture will
increase enough for some possible drizzle development Sunday
morning as model sounding indicate low level profiles that support.
As the surface low becomes established in NE Colorado...a dryline
is progged to setup over the central Panhandles by late morning
and quickly shift eastward ahead of a Pacific front. This feature
will lead to increasing chances of showers and perhaps a
thunderstorm as mid levels cool enough to get some instability.
Model soundings keep a warm nose in place for most of the
Panhandles keeping any convection elevated and low topped with EL
just above 500 mb. Still...can`t rule out thunder especially with
enough convergence along dryline in the eastern Panhandles Sunday
afternoon where cap is weakest.

Main concern for Sunday will be the strong winds due to tightening
pressure gradient and strong mid and low level jet developing over
the area. Very good mixing will occur after the dryline moves
through the area Sunday afternoon. Would not be surprised to see
Wind Advisory criteria winds for a few hours during the afternoon
behind the dryline across the northwestern half of the CWA based on
strength of jet and momentum transfer expected. Held off issuing for
now based on uncertainty in exact location of jet and how fast the
dryline will move east to allow maximum mixing. Very dry air will
quickly invade the area behind the dryline as the Pacific front
shifts winds from southwest to west into late Sunday. At this time
it looks like T/Td depression will only support elevated fire
criteria Sunday afternoon despite strong winds (See Fire Wx
Discussion).

Beyond Sunday models keep large scale trough over CONUS with a much
cooler and drier air mass in place over the Panhandles. A closed low
over the northern plains will help push an Arctic front into the area
Tuesday into Wednesday. Latest guidance suggest moisture will be
very limited along with the upper level forcing which has lead to a
reduction in the pops for Tuesday. It looks like the next decent shot
at getting some precip will be next weekend as the GFS and Euro are
in decent agreement on cutoff upper low moving out over Baja
Peninsula towards the end of next week and eventually working towards
the southern Plains. The Euro is colder and moves the low into a
more favorable location for winter precip in the Panhandles at
this time. Lots can change over the course of a week so stay
tuned.

Ward

FIRE WEATHER...
Elevated to critical fire weather conditions are expected over
most of the northwestern half of the CWA Sunday afternoon
generally between 12 PM and 6 PM. Winds will be strong with 20
foot winds near 30 to 35 mph during the afternoon. Gusts up to 55
mph can not be ruled out. The RH is the biggest questions mark
depending on how fast the drier air comes in prior to winds
decreasing. At this time min RH is not expected to drop below 18
percent before winds decrease. However...1 or 2 degrees
difference in max temp and/or faster advection of dry air could
lead to critical conditions for a few hours Sunday afternoon. On
the other hand...if showers and thunderstorms are able to
develop along dryline...it may lead to conditions staying below
elevated. With uncertainly as it is...stay tuned for possible
updates.

Ward

&&

.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.

&&

$$

15/89



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