Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 092149
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
349 PM CST Fri Dec 9 2016

.SYNOPSIS...
Issued at 350 PM CST Fri Dec 9 2016

A broad trough of low pressure aloft continued across
the lower 48 this morning. Several shortwaves were embedded within
the trough across Canada and the northern CONUS. Lows were located
over the eastern Aleutians, off the coast of southern British
Columbia, southern Manitoba and eastern Quebec, with a trough
extending south into New England. At the surface, high pressure
extended from eastern North Dakota, south into the lower Mississippi
valley. West of this axis of high pressure, a surface trough of low
pressure was located along the eastern slopes of the Rockies.
Southerly winds have increased this afternoon across western and
north central Nebraska. temperatures remained cold however with
readings ranging from the upper teens across north central Nebraska,
to the 20s across central and southwestern Nebraska. Skies were
partly to mostly cloudy with a thicker veil of clouds noted over
north central Nebraska. Some light snow/flurries were located over
northern Nebraska earlier this afternoon and this morning. As of 3
PM CST, most of this activity had dissipated.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 350 PM CST Fri Dec 9 2016

One disturbance departing with another one on its heals to be the
main focus along with potential for fog where snow melt occurred
today. Linger light snow possible across far northeastern zones
this evening with little if any accumulation expected.

Eyes then focus on the next wave which bring a chance for snow
overnight into tomorrow, mainly across northern Nebraska. May see a
few snow flakes down to the interstate but most will be well north
of the interstate. Warm push off the surface could result in the
melting and refreezing of precip near the surface. Models have the
warm air fairly dry and expect there to be nothing reaching the
ground once temps get above freezing. Will pass on to next shift for
close monitoring. Lift is marginal but the cold air should push
liquid/snow ratios on the high side (fluffy snow). Thus an inch or
so cannot be ruled out near the S Dakota border with the wave.

Other concern is far SW Neb where some afternoon snow melt with
temps close to freezing has increased the BL moisture. Should see
some stratus develop with the next wave which will limit cooling
thus only included patchy freezing fog. It could be the snow melt
was not enough and the clouds keep temps to warm resulting in no fog
or other words a low confidence fog forecast.

Clouds continue tomorrow however 850 mb temps in the wake of the
warm air advection increase. Temps look to jump 5 to 10 degrees from
today with highs in the mid 20s to near 40 which is in agreement
with MOS guidance.

.LONG TERM...(Saturday night through Friday)
Issued at 350 PM CST Fri Dec 9 2016

Mid range...Saturday night through Monday...In the mid range, the
threat for a light mix of precipitation along with temperatures are
the main forecast challenge. For Saturday night: Warmer air aloft
will have pushed into the forecast area with h85 temps in the 5 to 8C
range. At the same time an upper level jet streak will retreat east
of the area with another one appg the high plains, placing the
northern forecast area in a nice area of divergence aloft. The GFS
solution develops light precipitation over the northern 2/3rds of
the forecast area Saturday night into Sunday morning. The NAM12
solution is drier as it has a sizable mid level dry layer noted,
which extends down to the surface. Utilizing the blended fcst,
yields  very little or no QPF across the forecast area during the
period. For this reason, decided to limit any pops to slight
chances. In addition, both the NAM12 and GFS solutions have a
thermal profile Saturday night into Sunday morning which favors the
threat for freezing pcpn with the exception of the far northeastern
forecast area. With the dry layer noted in bufkit soundings and
limited QPF, will use patchy freezing drizzle vs. the mention of
freezing rain for the Saturday Night/Sunday morning period. The
trailing jet streak will push east of the forecast area Sunday
afternoon with some limited clearing noted for the afternoon hours.
Warmer air aloft will remain in place Sunday into Monday with highs
in the 20s to mid 30s Sunday followed by 30s to lower 40s for
Monday.

Monday night through Friday...An arctic front will push across
the forecast area Monday night, effectively placing western and
north central in the deep freeze through the end of the week.
Highs next week will struggle to get out of the teens with lows
around zero. The next threat for snow will arrive on Tuesday night
into Wednesday as another jet streak lifts across the central and
northern plains. Snowfall in association with this feature should
be light as low level moisture is still locked into the southern
plains and southeastern states. Beyond Friday, the latest ECMWF
solution is indicating an even stronger arctic airmass pushing
into the central and northern plains next weekend. H85 temps with
this airmass are in the mid 20s below zero C! This would equate to
highs around zero next weekend. This could even go lower, if we
can develop any snowcover across the forecast area next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1212 AM CST Fri Dec 9 2016

Light snow continues to push across north central Nebraska this
afternoon, east of the KVTN terminal. Visibilities have dropped
briefly to around 3 miles otherwise snow has been generally
flurries. Cigs have also been at or above OVC030. Expect the
clearing across the west to spread east this evening ahead of the
next system which arrives overnight. The main system moves across
the north and cold temps with snow expected. Models appear too dry
with some only lowering cigs across the south, the KLBF terminal.
Further north, and the KVTN terminal, expecting light snow with
visibilities likely to be reduced to MVFR at times.


&&

.HYDROLOGY...
Issued at 350 PM CST Fri Dec 9 2016

Arrival of first major cold outbreak of artic air has resulted in
ice formation on the area rivers (ice jamming). So far sights have
been jumping around at times reporting above flood stage. However
with the help of partners, rivers have been checked and no flooding
being reported yet. Will continue to monitor as the cold air remains
and ice jamming remains a possibility.

&&

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

$$

SYNOPSIS...Buttler
SHORT TERM...Masek
LONG TERM...Buttler
AVIATION...Masek
HYDROLOGY...Masek



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