Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 281212

Area Forecast Discussion
National Weather Service North Platte NE
612 AM CST Mon Nov 28 2016

.SHORT TERM...(Today and tonight)
Issued at 349 AM CST Mon Nov 28 2016

The primary sensible weather concerns in the short term period
were strong winds developing mid morning persisting through the
afternoon and then light accumulating snow across the extreme
northeast NEB Panhandle and northwestern Sandhills after midnight.
The latter will combine with moderate winds that won`t lessen
overnight as much as will be seen across the southeastern half of
the local forecast area. A winter weather advisory was issued
this package for western Cherry and Sheridan counties because of
the combination of snowfall and strong winds. The greatest
snowfall accumulations, 1 to 4 inches, are expected along and
north of Highway 20 from Kilgore to Hay Springs. Snow and snowfall
amounts, sky cover, and winds were the main forecast challenges
today and tonight.

The large scale pattern features a broad 500 hPa trough currently
present over the Western CONUS and Great Plains with a ridge
extending from the central and eastern Gulf coast to the Lower
Great Lakes. Water vapor imagery shows a mid-level disturbance
currently entering the Upper Mississippi Valley with a mid-level
closed low over the Middle Missouri Valley. In addition, strong
cyclogenesis has occurred with a surface low now present over
eastern SD at about 978 mb presently. The aforementioned
disturbance aloft will continue to rotate around and move into
western/central ND by this evening. The 500 hPa closed low will
feature little movement today-tonight over the Northern Plains.
Overnight, it`s anticipated that moisture will wrap around the
circulation as the short wave trough pushes through western and
central SD late tonight. Light snow is expected to develop in the
far northwest quad of the local forecast area (the extreme
northeast NEB Panhandle, Pine Ridge, and extreme northwestern
Sandhills) after midnight. The aforementioned surface low will
see little movement today-tonight as well and fill in to about
985 mb by early tomorrow morning. The low pressure system will
prompt strong winds today across western and north central NEB
today with very good potential for upper levels winds to mix down
to the surface via momentum transfer. Gusts are expected to peak
to 28-35 kts this afternoon based on BUFKIT soundings, strongest
across the eastern NEB Panhandle and the western and central
Sandhills. Winds will lessen some overnight, however, strong
breezes will persist. Cold air has not quite worked it`s way into
western and north central NEB, thus today will see highs near to
slightly above normal.

.LONG TERM...(Tuesday through Sunday)
Issued at 349 AM CST Mon Nov 28 2016

Tuesday through Wednesday Night: In the mid range, snowfall
chances and snow accumulations are the main forecast concern.
Upper level low pressure and an associated surface low will
meander and drift slowly south across eastern South Dakota and
western Minnesota on Tuesday into Wednesday night. Temperatures on
Tuesday will be cold as a cold front will continue to push south
of the area into Kansas. Highs will generally be in the 30s and
will struggle to reach the freezing mark over northern Nebraska.
In addition to much colder temperatures, there will be an
increased threat for snow Tuesday, especially over northern
Nebraska. This is in response to a mid level disturbance, rotating
around the western and southwestern periphery of the low over
eastern South Dakota. Favorable lift in association with this
feature, will increase over far northern Nebraska Tuesday into
Tuesday night. This lift will lead to an increased threat for
light snow during the Tuesday into Tuesday night time frame.
Snowfall will be light however, as the upper level low will be
well occluded, vertically stacked, with a very limited moisture
fetch originating east of the low. At the moment, the greatest
threat for accumulating snow will be over the far northwestern
forecast area, where it will be locally enhanced over the Pine
Ridge given the northwesterly winds. In these areas, based on the
latest blend of model QPF, and incorporating a 13:1 snow to water
ratio, yields snow accumulations from Tuesday morning into
Wednesday morning of 1 to 4 inches along and north of highway 20
in Cherry and Sheridan counties. In addition to snow, a decent
surface pressure gradient will reside from western South Dakota
into western Nebraska. Gusty northerly winds will combine with the
snow, producing an increased blowing snow threat, especially on
Tuesday in the northwestern CWA. After conversing with UNR, it was
decided to issue a winter weather advisory for Sheridan and
western Cherry county-focusing on areas along and north of highway
20 where local enhancement along the Pine Ridge will be the
strongest. The threat for snow will continue into Wednesday
morning as one final vort max on the western side of the low
impacts northern Nebraska before the main system pushes east
Wednesday night.

Thursday through Sunday: The upper level low will push into the
Great Lakes and southern Canada on Thursday into Thursday night.
At the same time, a second low will deepen across the
intermountain west as it dives south into the southwestern CONUS
by the weekend. Further east across the central and northern
plains, a fairly cold airmass will remain in place. H85 temps will
remain stagnant in the -2C to -6C range into Friday, with a slight
warmup noted for Saturday into Sunday. Looking at the mid range
model solutions, they do diverge somewhat with their handling of
the southern system late in the week into the weekend. The EC soln
is much more aggressive with the ejection of this system, forcing
it across the southern plains into the Ozarks by the weekend. The
GFS soln has this feature remaining stationary across the swrn
CONUS into Baja Mexico and actually develops west northwest flow
across the northern plains next weekend. This second scenario
would favor warmer temperatures compared to the EC solution. For
now, have favored a model blend with temps into the weekend with a
gradual warmup back into the 40s to possibly the lower 50s for
Saturday into Sunday.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 600 AM CST Mon Nov 28 2016

Latest satellite imagery shows high clouds streaming eastward across
western and north central NEB. VFR flight categories are currently
observed. High clouds will persist overhead much of the day,
however, southwest NEB into portions of the central and
southeastern NEB Sandhills will see decreasing sky cover this
afternoon. Low-end VFR ceilings (less than 7 kft) are expected to
develop and advance southward into the northern-third of the
forecast area early this evening. These ceilings will deteriorate
further this evening becoming MVFR, and this is anticipated to
impact the KVTN terminal. Strong winds will develop today with
gusts to 30 to 35 kts, strongest across the eastern NEB Panhandle
and the western and central Sandhills. Winds will diminish some
tonight, lessening the most across the southeastern half of the
forecast area including KLBF. Tonight, a storm system in the
Northern Plains will bring increased chances for snow after
midnight. The focus for snow will be greatest across the
northeastern NEB Panhandle and northwestern NEB Sandhills (where a
winter weather advisory is in effect). Confidence is low in regard
to snow impacting KVTN at this time and this will need to be
further monitored.


Winter Weather Advisory from 3 AM CST /2 AM MST/ Tuesday to 6 AM
CST /5 AM MST/ Wednesday for NEZ004-094.



LONG TERM...Buttler
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