Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 172339
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
539 PM CST Sat Nov 17 2018

.AVIATION...
For the 00z TAFs...
IFR ceilings in MVFR visibilities expected to prevail through
much of the night.  Potential exists for occasional light
freezing drizzle through the overnight hours.  Improvement
expected late tonight or around sunrise, with VFR conditions
expected most of the day on Sunday.  Timing of category changes
will be difficult.  Amendments will be issued as necessary.
North and northeast surface winds expected next 24 hours.

Cockrell

&&

.PREV DISCUSSION... /Issued 329 PM CST Sat Nov 17 2018/

SHORT TERM...Tonight through Sunday...
Breezy north winds from this mornings cold front will continue
through the evening across the Panhandles, but will diminish by
later tonight. Winds will still remain out of the north
thereafter, they will just be lighter. Saturated layer near the
surface about 3000-5000ft thick will result in patchy freezing
drizzle across the Panhandles. Right now it looks too sparse to
pinpoint any specific area that might be more favored than others,
and therefore no winter weather highlights will be issued. It
looks like mainly elevated surfaces and bridges will be the most
prone areas to get a thin ice coating, if at all. Later tonight
the temperatures should be cold enough aloft to get some dendrite
growth and thus have shifted to a patchy freezing drizzle with
isolated flurries.

With the shallow cold layer in place tonight the conditions are
favorable for industrial enhanced snowfall from power plants. If the
power plants are running we might see some light accumulations in the
Pampa, Borger, Eastern Amarillo areas.

Clouds will begin to break up Sunday morning and sunny skies will
take over by afternoon.  Cold airmass will still be in place, but
winds will be light, so may not feel too cold, at least compared to
todays mid 20s wind chills, if in direct sunlight.  Highs are
expected to be in the lower 40s on Sunday.

Weber

LONG TERM...Monday through Saturday...
A warming and drying trend can be expected through
the extended with progressive split flow pattern aloft. Mid level
zonal flow will transition to northwest flow going into Monday as
northern stream trough digs south into the OH Valley while
southern stream ridge traverses the Great Basin through Tuesday.
Meanwhile, a southern stream shortwave trough is expected to cross
SoCal region Monday into Tuesday, approaching the Southern Plains
early Wednesday. This is all ahead of a potentially stronger
northern stream trough expected to come ashore on west coast
Wednesday into Thursday with a series of shortwaves possibly
emanating from that upper wave and crossing the Southern Plains
late week through the weekend. Model guidance is in decent
agreement with synoptic features through about Wednesday, with a
lot more spread over the weekend.

The area will start out chilly Monday morning with temperatures
in the upper 20s, but will rebound into the 50s during the day
given ample insolation and as the cooler airmass from over the
weekend shifts out of the area. Ironically, a weak front is
expected to shift winds back to the north Monday, but this will
initially act to advect a relatively warmer airmass into the area
given model 850mb temperatures upstream. Some weak cold air
advection is then expected Monday night almost more as a backdoor
front while surface ridge moves into central and eastern OK. This
will lead to another chilly morning Tuesday with almost a repeat
of Monday, except there will be a weak lee trough trying to
develop on the backside of the sfc high resulting in some minor
breezy southwest winds around 10 to 20 mph Tuesday afternoon. The
better forcing and moisture with aforementioned southern stream
shortwave at this time is progged to stay just south of the
Panhandles going into Wednesday. However, increased cloud cover
is expected Tuesday night through Wednesday morning, which will
keep low temperatures moderated especially for southern Texas
Panhandle Wednesday morning with 50s again expected in the
afternoon as clouds clear out.

A fairly potent shortwave breaks off the main west coast upper
trough and may bring some windy conditions in combination with a
developing lee surface low late Thursday into Friday. The
Panhandles are currently progged to be in the dry slot with this
system as a ~70 knot 500mb jet crosses Thursday night. The initial
sfc pressure gradient will make for breezy to windy conditions
Thursday afternoon, favoring the northeastern FA where 35 to 45
mph wind gusts are possible based on the latest data. Then a
Pacific cold should result in northwest winds early Friday and may
remain gusty depending on how much wind aloft is able to mix
down.

Guidance really starts to diverge going into the weekend with the
handling of the main western CONUS northern stream trough as the
ECMWF is stronger and much further south compared to GFS while
the Canadian is somewhere between. It will definitely be something
to keep an eye on for the next potential for winter weather,
possibly combined with some strong winds if the ECMWF solution
becomes the trend. In any case, it seems colder air will be making
a come back if not over the weekend, then early next week.

Ward

&&

.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX                25  41  29  56  28 /  10   5   0   0   0
Beaver OK                  24  41  28  55  26 /  10   5   0   0   0
Boise City OK              22  42  26  54  25 /  10   5   0   0   0
Borger TX                  25  42  29  57  28 /  10   5   0   0   0
Boys Ranch TX              26  42  28  57  27 /  10   5   0   0   0
Canyon TX                  25  42  27  57  28 /  10   5   0   0   0
Clarendon TX               27  43  30  59  29 /  10   5   0   0   0
Dalhart TX                 24  42  24  55  25 /  10   5   0   0   0
Guymon OK                  23  42  25  55  25 /  10   5   0   0   0
Hereford TX                25  43  27  56  27 /  10   5   0   0   0
Lipscomb TX                24  40  28  56  26 /  10   5   0   0   0
Pampa TX                   23  39  29  55  29 /  10   5   0   0   0
Shamrock TX                27  42  28  58  29 /  10   5   0   0   0
Wellington TX              29  44  30  59  30 /  10   5   0   0   0

&&

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

&&

$$

03/77



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