Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 202305

Area Forecast Discussion
National Weather Service Goodland KS
405 PM MST Tue Feb 20 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 245 PM MST Tue Feb 20 2018

Main issues will be low temperatures tonight and wind chill
temperatures through Wednesday morning. Temperatures struggled to
climb very much with the coldest highs in the northwest half where
the snowfield is located. Surface ridge moves in during the night so
will have a lengthy period of little to no winds and low dewpoints.

A caveat is the model output showing a batch of mid and high level
moisture. Based on satellite trends, this is looking overdone. So am
going to take the coldest guidance and drop of a few degrees with
the northwest half having subzero readings. The winds will not be
very strong but the combination of the wind speeds and temperatures
I have in there is yield wind chill temperatures near to or colder
than advisory criteria. So will be hoisting a wind chill advisory
over the northwest half from mid evening tonight to mid morning

Look to a decent amount of sun. Surface will begin moving off to
the east which will bring in recycled cold air. However, it will
be blowing off of dry ground. The guidance blend was pretty cold,
and went with.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 245 PM MST Tue Feb 20 2018

Southwest upper level flow will persist through Saturday when a
stronger short wave trough will move through, then dry westerly
flow behind the trough. Currently the upper level short wave
trough looks to move through quick enough Friday night and
Saturday to produce only a couple inches of snow. However theta-e
lapse rates will be near or below 0 in the snowfall. If this
continues to be the case by the time Friday night/Saturday arrive,
snowfall amounts will need be to increased, despite the snow
moving through fairly quickly.

Aside from the first part of the weekend, the other timeframe of
interest will be Wednesday night.  Currently the forecast is dry for
this night.  However latest data suggests the potential for freezing
drizzle.  There are two factors that greatly limit confidence of
freezing drizzle occurring.

The first is the small amount of lift that occurs during the night.
The freezing drizzle event in late December had more lift than
Wednesday night, which is what lowers confidence of this occurring.
However with a saturated environment above the surface, not much
lift is needed to create drizzle.  So have moderate confidence there
will be enough lift to form freezing drizzle.  Currently the best
lift/saturation is east of Highway 83.

The second factor limiting confidence is the saturated layer is very
close to the -10C line, so almost cold enough to support snow
instead of drizzle.  If the saturated layer deepens further, or
cools more, the odds of snow forming instead of drizzle go up.
Confidence of precipitation type for Wednesday night, should any
occur, is low.

Temperatures will warm during the period, with the warmest day on
Tuesday as the jet stream slides slightly further north.  However,
looking out past the forecast period, more cold air looks likely for
the latter half of next week as an upper level short wave trough
deepens over the Rockies early in the week.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 405 PM MST Tue Feb 20 2018

For KGLD and KMCK, vfr conditions expected through the period.
Both terminals will see variable winds 5kts or less early this
evening through mid morning Wednesday then an increasing southeast
wind approaching 11kts through the rest of the period. Clouds
increase across both terminals tonight then again during the day


KS...Wind Chill Advisory from 8 PM MST /9 PM CST/ this evening to 9
     AM MST /10 AM CST/ Wednesday for KSZ001-002-013-014-027.

CO...Wind Chill Advisory from 8 PM this evening to 9 AM MST Wednesday
     for COZ090>092.

NE...Wind Chill Advisory from 8 PM MST /9 PM CST/ this evening to 9
     AM MST /10 AM CST/ Wednesday for NEZ079>081.



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