Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 292123
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
423 PM CDT Sat Apr 29 2017

.SYNOPSIS...
Issued at 423 PM CDT Sat Apr 29 2017

A vigorous upper level low was located over northwestern
New Mexico with a deep trough of low pressure extending into western
Mexico. Down, and upstream of the low and trough at tandem of high
pressures were noted. One around 750 miles off the coast of central
California and a second off the carolina coast. East of the trough,
a broad shield of precipitation extended from southeastern Colorado
eat into the Ozarks. Some of the precipitation was falling as snow
across western Kansas and southeastern colorado. Across western and
north central Nebraska, high pressure had nosed into northeastern
Wyoming and this had ushered in some dry air into western and north
central Nebraska today. Though skies were mostly cloudy the higher
ceilings had allowed partial sun which allowed temps to reach the
middle 40s to lower 50s.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 423 PM CDT Sat Apr 29 2017

Tonight through Monday...In the short term, wintry
weather in association with an approaching upper level low is the
main forecasting concern. Over the next 12 to 36 hours, a strong
cold core low will track across the southern plains into Kansas then
Iowa Sunday night. The models have come to a general consensus on
the track and general timing of the system, but one question
remains: How will the abundant convection in the Ozarks and southern
plains influence the track of the low and the area of strongest
deformation precipitation. Already this morning, the models have
trended slightly farther east with the main area of deformation
precipitation late tonight into Sunday. The upper level low will
track from the OK panhandle into northeastern Kansas tonight into
Sunday. A strong area of deformation will set up from the
southeastern into the far eastern portion of the forecast area
overnight tonight into Sunday evening. Right now based on the timing
of the system, the greatest threat for accumulating snow will be
late tonight through mid morning Sunday with the area of main
concern across Frontier into the southeastern half of Custer county.
In these areas, with it being nighttime or early morning, snow will
have a better potential to accumulate. As it stands, anywhere from 5
to 7 inches is possible in these areas. Further west from Hayes up
to Lincoln, Logan and Blaine counties, lighter amounts will be
possible, additionally temps will be slightly warmer west of the
heaviest band which would favor less dynamic cooling and more of a
rain/snow mix. With accums of 1 to 3 inches in these areas, hoisted
a winter weather advisory and winds will be fairly strong Sunday
morning. Now as we trend into late morning Sunday into early evening
Sunday, additional accumulating snow will be severely hampered by
expected highs in the middle 30s and the high April sun angle. Look
at western Kansas and eastern Colorado this afternoon where snow
continues with visbys of under a mile and no accumulations-that with
temps in the lower to middle 30s. The threat for snow will shift to
the northeast into the northeastern forecast area Sunday evening
into Sunday night. Once again with the sun going down, it will be
more favorable for accumulating snow. Based on the timing of the
best lift being late evening, decided to hold onto the winter storm
watch in the northeast and will advise the evening crew of my
reasoning for standing pat. This is just in case the low decides to
trend further east as well as the greatest impacts hitting this area
third forecast period. The system will push northeast of the area
late Sunday night into Monday morning. Immediately behind this
feature, much warmer air will spill into western and north central
Nebraska. Highs Monday will range form the lower 50s in the east to
around 60 in the west and southwest.

.LONG TERM...(Sunday night through Saturday)
Issued at 423 PM CDT Sat Apr 29 2017

Monday night through Saturday...The longwave trough of
low pressure across the CONUS will shift east and weaken through
midweek. The next threat for precipitation will be Tuesday night
into Wednesday morning as a shortwave trough drops south from the
northern Rockies onto the central plains. After this feature clears
the central CONUS Wednesday, ridging aloft will build into the
central CONUS toward the end of next week. After seasonal highs in
the 60s Tuesday and Wednesday, highs will climb into the upper
60s/70s late next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1228 PM CDT Sat Apr 29 2017

Some uncertainty exists in the overall evolution of the upcoming
storm system poised to impact the Sandhills region beginning
tonight. Current thinking is that convection well southeast of
the region will pull the upper low eastward moreso than what is
suggested by the model runs today, thus not too confident that
the KLBF terminal will fall under the heart of the eventual
frontogenetic band. But KBBW and KONL should eventually do so.
Another concern is that it will take the brunt of the system to
cool the column enough for a complete changeover to snow,
especially if the brunt of the precipitation occurs after sunrise
on Sunday /which is currently forecast/. Where the fgen band
develops, it will be dicey, especially given northerly wind gusts
in excess of 30kts forecast. Visibility will be an issue. Continue
to monitor and understand that short term updates will be
required across southwest Nebraska and eventually north central
Nebraska. For the central Sandhills and northwest Nebraska,
including KVTN, there will be a sharp cutoff with the
precipitation to the west, thus outside of the gusty winds and
possibly marginal mvfr ceilings, flight conditions should not be
impacted much.


&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 1 AM Sunday to 7 AM CDT Monday for
NEZ038.

Winter Storm Watch from 1 AM CDT Sunday through Monday morning
for NEZ009-010-027>029.

Winter Weather Advisory from 1 AM Sunday to 1 AM CDT Monday for
NEZ037-059-070.

Winter Storm Warning from 1 AM Sunday to 1 AM CDT Monday for
NEZ071.

Winter Weather Advisory from 1 AM Sunday to 7 AM CDT Monday for
NEZ026.

&&

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...Jacobs


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