Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 130111 AAA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
711 PM CST Tue Dec 12 2017

For the 00Z TAFs, a cold front will move across the terminal sites
Wednesday morning with gusty north winds in its wake from mid to
late Wednesday morning through much of the afternoon hours. There
may be a brief period of local wind shear on the order of 35 knots
at around 1000 feet at the TAF sites immediately preceding the
cold frontal passage. However, it should not last very long, and
did not include in this fcst cycle.



.PREV DISCUSSION... /Issued 315 PM CST Tue Dec 12 2017/

The demise of the persistent Rex block to our west is underway.
The closed mid-level ridge over Nevada is expected to slowly fill
and migrate west.  This is brought on by a shortwave trof over
Alberta which will dive quickly southeast.  Meanwhile the closed
mid-level low will remain over the northern Gulf of California
through Thursday night.

A shortwave trof west of Vancouver is expected to top the western
ridge, moving more slowly than the Alberta wave, and should reach
the Texas and Oklahoma Panhandles on Thursday.  As the western
CONUS ridge amplifies, meridional flow sets up over the Panhandles.

The models suggest a third shortwave trof comes ashore late
Friday, possibly passing the forecast area Saturday, Sunday or
Monday.  Significant differences exist in the models Friday
onward, leading us to have considerable lack of certainty for
Friday and beyond.

Cold front arrives late tonight and Wednesday morning, with breezy
north winds.  Late Wednesday night, large-scale ascent may wring
out a few flurries in northwest sections.  Have introduced slight
chance of light snow in northwest Thursday morning, as the
shortwave trof axis passes.  Have increased cloud cover and
lowered max temperatures on Thursday.  Modest recovery gets
underway on Friday as mid-level flow trends toward zonal and lee
trof develops.

Saturday night slight chance pops have been trimmed to include
only far northwestern sections, owing to uncertainty and downward
trend of pop guidance.  Sunday pops have been removed.  03


Southwest and west winds tonight will shift to the north late
tonight and Wednesday morning as a cold front arrives.  Elevated
fire weather conditions are expected across nearly all of the
forecast area Wednesday as the dry north winds increase.  Cooler
conditions on Thursday lead to relative humidities remaining well
above necessary thresholds for elevated or critical fire weather
conditions.  Moderate southwest winds resume on Friday, with
relative humidities remaining above necessary thresholds for
elevated or critical fire weather conditions.  Elevated to
critical fire weather conditions are expected on Saturday as
strong dry southwest winds develop, with a cold front bringing a
wind shift in the afternoon and evening.  No elevated or critical
fire weather conditions are expected Sunday and Monday as
relative humidities remaining above necessary thresholds.  Light
winds are expected on Tuesday.  03


.AMA Watches/Warnings/Advisories...


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