Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 071722
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1022 AM MST Wed Dec 7 2016

.UPDATE...
Issued at 554 AM MST Wed Dec 7 2016

Adjusted PoPS and snow amounts to account for current trends.
Shortwave trough is still in place over our CWA, however back end
is probably 3hr away based on WV imagery and RAP PV analysis.
Radar and satellite trends have already been quicker than earlier
guidance, and observed snow has been lower on at 6hr basis than
anticipated. Light snow is still expected through at least mid
morning, but it was necessary to speed up PoPs and lower snow
amounts. An additional 0.5 to 1.0" will still be possible, but a
dusting appears more likely for most locations for the rest of the
morning.

&&

.SHORT TERM...(This morning through Friday night)
Issued at 256 AM MST Wed Dec 7 2016

Shortwave trough is in the process of moving across Colorado
towards  western Kansas, with the main plume of deep moisture
across northeast Colorado extending eastward into our northwest
CWA. A deep dry layer is still in place along and south of the
I-70 corridor with Td depressions still 15-20F, and RAP soundings
along with VAD wind profiles show this layer is between 5-8kft
deep. This should saturate over the next few hours. Tds have
jumped at KGLD by 10F in a short period of time, and snow could
begin here soon. Light snow accumulations have already occurred
from northeast Colorado into southwest Nebraska, and snow covered
roads can be observed on area webcams.

Main forcing is tied to 850-700 mb layer where stronger
frontogenesis is shown by RAP and this should continue to
transition southeast. There is also weak instability in this
layer, likely aiding in moderate snow band formation. Higher
resolution guidance is still in line with current coverage/track
of snowfall with strongest precip signal over our CWA through 15Z
before decreasing in coverage and transiting out of CWA to the
south and east by early afternoon. I am still concerned that the
current moderate band could linger north of I-70 allowing for
amounts approaching advisory criteria (3"), but trend should be
for this to begins to shift and lighten up, and dry layer likely
will have some impact on totals. Still looks like most will see 1
to 2 inches, with isolated 3+ possible (north of I-70).

Winds have increased some where snow is occurring (a few gusts 20
mph), but visibility restrictions so far are tied to snowfall with
no reports of blowing snow yet. Strong frontal inversion is
limiting mixing, so it is unlikely we see widespread wind gusts
supportive of more than minor drifting or isolated blowing snow.
There could still be minor drifting and isolated vsby reductions,
so I kept patchy blowing snow in grids mainly where gusts 19kt or
higher are forecast.

Regarding temperatures and wind chills tonight: as skies clear in
the evening temperatures will rapidly decrease with most overnight
lows tonight dropping near zero, and western locations possibly
below zero. Tds decrease to below zero as far east as Hoxie, and
with good radiational conditions negative temperatures could be
possible for locations further east than indicated by some of the
bias corrected blends. BL winds do remain high, but with strong
inversion in place it is hard to say what surface winds will
ultimately be. Conservatively 5kt would still support wind chills
around 15 below in our west, and ultimately we may need a wind
chill advisory. This was considered during this update cycle, but
the decision was made to hold off with main focus on near term
snow concerns. This will be considered by day shift.

Thursday-Friday night: Zonal pattern begins to establish itself
allowing for a gradual warming trend through the end of the week
with dry conditions persisting. Thursday/Thursday night should
still be below normal with arctic air mass still entrenched over
the region. Overnight lows Thursday night should be in the single
digits (slightly warmer) and wind chills should remain above
advisory criteria. Highs should warm above freezing Friday in our
west, though arctic high pressure to the east could limit warming
and highs may struggle to reach freezing.

.LONG TERM...(Saturday through Tuesday)
Issued at 254 AM MST Wed Dec 7 2016

Shortwave approaches on Saturday bringing a return flow to the
region, allowing high temperatures to rise into the upper 40s
and lower 50s. Will carry a slight chance of rain for extreme
western portions of Yuma and Kit Carson counties beginning around
noon and extending through the evening. Some of this precipitation
may change over to light snow during the overnight hours with no
accumulation expected at this time.

System lifts off to the northwest Sunday, leaving cooler
temperatures in its wake with highs predominately in the mid to
upper 30s and lows in the mid teens. Winds should stay below 15
mph across the region for the day and night.

Next chance for precipitation comes Tuesday as a trough approaches
from the Pacific Northwest. A slight chance of snow should be
primarily confined to areas north of I-70. Temperatures Monday and
Tuesday should be close to climatic normals.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1020 AM MST Wed Dec 7 2016

MVFR conditions will persist into mid afternoon at both KGLD and
KMCK due to the combination of visibility restrictions in light
snow and blowing snow and lowered ceilings. However, as the upper
system begins to pull away expect VFR to prevail from mid to late
this afternoon, with clearing skies tonight.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

UPDATE...DR
SHORT TERM...DR
LONG TERM...SME
AVIATION...024


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