Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 061956
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
156 PM CST Tue Dec 6 2016

.SYNOPSIS...
Issued at 316 AM CST Tue Dec 6 2016

At 08z...A center of surface low pressure extended across northwest
Minnesota with a fairly tight pressure gradient across North Dakota
and northeastern South Dakota. Much of this area is currently being
impacted by blizzard and winter storm conditions. Further south
across western Nebraska, skies clearing from west to east.
temperatures range from 15 at Valentine (a clear sky) to 24 at North
Platte and Broken Bow (a mostly cloudy sky).

&&

.SHORT TERM...(Today and tonight)
Issued at 316 AM CST Tue Dec 6 2016

Today...A deep upper level low and associated winter storm will move
across northern Minnesota today. Strong Arctic high pressure behind
this system will extend from Alberta Canada southeast into Montana,
northeast Wyoming, and the western Dakotas. Colder h85 temperatures
from -8C to -13c will reside across western Nebraska today. Skies
will be mostly sunny, except for increasing clouds into the western
sandhills by mid afternoon.

An upstream upper level trough currently moving through the Pacific
Northwest will drop southeast across Idaho and northern Utah. Ahead
of this trough, isentropic upglide will begin to develop from
northern Colorado into Southern Wyoming.

Tonight...Across the Southeastern Panhandle and southwest
Nebraska,the above mentioned isentropic upglide will be most
favorable in the 285K, 290K, and 295k surfaces, where up to 150
millibars of lift occurs 03z-09z. Through 12z Wednesday, model
differences remain, with the NAM a bit further north and slightly
heavier QPFS than the GFS. The NAM forecast QPFs from a tenth of an
inch or greater south of a line from Oshkosh through Hayes Center.
The GFS is somewhat less with a tenth of an inch only across
southwest Chase County.

A frontogenetic band will develop from the southern Panhandle and
northeast Colorado into far southwest Nebraska and Northwest Kansas
overnight. The models are not indicating a strong well-defined
band, but rather a more broad and diffuse band across this region.
Model consensus is for 1-2 inches of snowfall overnight south of an
Oshkosh through Hayes Center line. The higher amounts around 2
inches are most likely to fall across southwest Deuel, western
Perkins and Chase County. With forecast amounts below advisory
levels and winds northeast up to only 10 kts, no winter weather
advisory is anticipated.

.LONG TERM...(Wednesday through Monday)
Issued at 316 AM CST Tue Dec 6 2016

Temperatures and the possibility of accumulating snow across
southwest Nebraska are the primary forecast concerns in the
extended. First up is the snow.  The medium range forecast models
are fixed on a solution that largely keeps the area of synoptic lift
associated with a moderately strong mid level jet largely south and
west of the forecast area through the day on Wednesday.  So any
additional snowfall across southwest Nebraska will be associated
with a increasing frontolytic deformation band and/or decaying
upglide. Additional accumulations past 12z Wednesday will be on the
order of an inch or less, with the highest amounts along the
southern and western portions of Chase and possibly Hayes Counties.
At this point the LSR should be pretty high, possibly on the order
of 20:1 as an additional shot of Arctic air dives south. The latest
guidance shows h925 temperatures of minus 10 to minus 14C with this
secondary Arctic push, which would support teens for highs through
Thursday. Overnight Wednesday into Thursday guidance indicates
single digit to below zero lows. Minus 10 Fahrenheit or colder is
possible over northern portions of Garden and southern portions of
Sheridan County.  A modest warm up is expected to begin on Friday as
the upper pattern transitions to zonal and heights rise from the
west. The cold air will slosh east and temperatures will warm back
above Freezing along and west of highway 61...but across our far
northeastern zones...highs in the lower 20s still are likely.  Will
have to watch the progression of a wave for late weekend, which may
bring our next real next shot at qpf.  Timing and strength
differences between the GFS and Euro camps keep confidence low at
this point.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 150 PM CST Tue Dec 6 2016

A weather system will cross the area tonight into Wednesday. MVFR
ceilings and light snow are likely along and south of interstate
80 late tonight into the first half of Wednesday. Conditions will
improve quickly Wednesday afternoon.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SYNOPSIS...Roberg
SHORT TERM...Roberg
LONG TERM...Jacobs
AVIATION...Taylor



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