Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 130515 AAB
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1115 PM CST Fri Jan 12 2018

.SYNOPSIS...
Issued at 317 PM CST Fri Jan 12 2018

H5 analysis from earlier this morning has a closed low
over northern Hudson Bay with a deep trough of low pressure
extending south into the Gulf of Mexico. West of this feature:
Northwesterly flow aloft extended from the Ozarks to the Pacific
Northwest. Within this flow, disturbances were noted across the
central Rockies and high plains. One of these disturbances is
pushing southeast across Nebraska this afternoon and has led to
light snow across the central and eastern Sandhills. So far, snow
accumulations have stayed an inch or less, and the back edge of this
activity is now east of highway 83. Further west, a ridge of high
pressure extended up the west coast of the CONUS into the Yukon and
eastern Alaska. At the surface: High pressure was anchored across
eastern Montana into North Dakota. The axis of high pressure
extended south into eastern Nebraska. West of this axis, winds had
shifted over to the east with the arctic airmass affecting the
entire forecast area this afternoon. Readings as of 3 PM CST ranged
from 1 above at O`Neill and Ainsworth, to 16 at Ogallala.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 317 PM CST Fri Jan 12 2018

The latest short term guidance has the central of a strong 1046mb
Arctic high over the central/eastern Dakota`s early Saturday.  As
such, weak southeasterly flow will recycle Arctic air across the cwa
overnight.  Saving us from bitterly cold temperatures will be a fair
amount of cloud cover as northwest flow aloft and weak thermal
advection from the west targets the forecast area.  The latest
guidance shows single digit lows with even a some sub zero readings
for north central Nebraska overnight.  The thermal advection/warm
front will work east across the forecast area on Saturday.  There`s
uncertainty in the forecast as to how quickly the front will advance
and throw in some cloud cover, the temperature forecast will be
tricky.  The latest guidance has temperatures ranging from the lower
teens over our far east to near freezing over far southwest Nebraska
and possibly the Pine Ridge.  Most locations, especially along and
east of highway 83 should see temperatures below average.  The
various short term solutions generate light precipitation associated
with the warm front and enhanced upper jet lift late Saturday
morning or afternoon.  Will introduce some flurries into the
forecast, extending from northwest Nebraska southeast through Custer
and Lincoln Counties, but will watch in the event we need to mention
light snow accumulations.

The Arctic high pressure to the northeast of the forecast area
tonight will allow for mainly light winds, but enough of a gradient
remains for at least a 5kt wind at times.  As such, apparent
temperatures may fall to minus 15 or so periodically across northern
Nebraska.  Those wind chills will improve with the warming
temperatures tomorrow morning.

.LONG TERM...(Saturday night through Friday)
Issued at 317 PM CST Fri Jan 12 2018

Saturday Night through Monday...Precipitation chances Saturday night
and Sunday night are the main forecasting challenges. For Saturday
night: A weak disturbance will track from the Black Hills into
northeastern Nebraska. This feature will force a warm front across
the forecast area overnight with an increased threat for light
precipitation. Was initially concerned about the threat for a wintry
mix of precipitation immediately west of the warm front, and the
latest GFS had a hint of light freezing precipitation. This notion
of wintry precipitation was void in the NAM12 solution and the
latest bufkit soundings indicated all snow Saturday night. With that
in mind, will keep ptype as an all snow mention. Any accums will be
light at an inch or less with the heaviest pcpn in the east. On
Sunday, westerly winds and warmer air will push into the forecast
area with highs reaching the 40s. The warmup will be short lived
however as a strong arctic front pushes into the forecast area
Sunday night. Light snow will accompany passage of the front. Cross
sections indicate favorable lift in association with the front which
coincides with the dendritic zone. This should lead to efficient
snow production Sunday night. Will leave snow accums on the order of
an inch, but will need to push this upward if mid level forcing and
lift in the dendritic zone increases with subsequent model runs.
Bitterly cold air will push into the forecast area on Monday with
highs ranging from around 5 in the northeast to around 20 in the far
southwest.

Monday night through Friday: Overnight lows Monday night of zero to
10 below zero are expected Monday night. This will lead to wind
chills of -10 to -25 with the coldest wind chills in the far
northeast. Will continue to hit this in the HWO as a wind chill
advisory may be needed for Tuesday morning. Temperatures will begin
to moderate beginning mid week next week as a Pacific airmass pushes
into the Rockies and Central Plains. After highs in the 20s Tuesday,
readings will rebound back into the 40s to lower 40s for Wednesday,
Thursday and Friday. Dry conditions are expected.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1115 PM CST Fri Jan 12 2018

VFR/MVFR cigs are expected overnight. An area of MVFR/local IFR
cigs/vsby in snow are expected Saturday. This feature is
associated with an upper level disturbance currently across MT.
The snow and low CIGS are expected to move east and southeast
through Wrn and Ncntl Neb Saturday and Saturday evening.


&&

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

$$

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



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