Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 102346 CCA
AFDLBF

Area Forecast Discussion...CORRECTED
National Weather Service North Platte NE
546 PM CST Sat Dec 10 2016

.SYNOPSIS...
Issued at 348 PM CST Sat Dec 10 2016

he H5 pattern this morning remains largely unchanged
over the past 24 hours. Broad west to east flow continues across the
lower 48. Further north in Canada, closed lows were noted just east
of Labrador, north central Canada and off the west coast of British
Columbia. The jet ran across the northern third of the CONUS with a
broad shroud of high level clouds extending from northern
California into the central and northern Plains. Light snow which had
been falling across northern Nebraska overnight had since moved east
of the forecast area as of midday. At the surface, a lee side trough
of low pressure was present from north central Wyoming into
southeastern Colorado. A warm front was located along the
Nebraska/South Dakota border. South of the front, winds were
southerly and temperatures were in the mid 20s to around 30. North
of the front, temperatures were in the teens.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 348 PM CST Sat Dec 10 2016

Tonight and Sunday.  Precipitation chances headline the short term
with a lesser emphasis on the arrival of a cold front on Sunday. The
arrival of upper level divergence coupled with weak upglide centered
near the 285K surface with provide for at least a slight chance of
snow and/or freezing drizzle across the western Sandhills and
northern Nebraka this evening and overnight.  Condensation pressure
deficits are not overly supportive of accumulating snow and moisture
is largely confined below the DGZ.  Thus will re-introduce patchy
freezing drizzle into the forecast.  Downglide takes over behind a a
northern plains front with the precipitation chances quickly waning
after 06z.  If precipitation occurs, whether snow or freezing
drizzle, little to no accumulations are anticipated.  Otherwise the
front arrives largely after 09z Sunday with a glancing blow.
Temperatures will be similar or slightly warmer in most places
compared to today as downsloping westerly flow develops in the
afternoon and warm air advection in the lower troposphere spreads
east off the high plains.  The latest blend of guidance suggests
highs Sunday in the middle 20s across north central Nebraska with
upper 30s possible over the higher terrain of far southwest
Nebraska.

.LONG TERM...(Sunday night through Saturday)
Issued at 348 PM CST Sat Dec 10 2016

Mid range...Sunday night through Tuesday...In the mid range, the
arrival of another arctic cold front, then light snow chances are the
main forecast challenges. For Sunday night into Monday: An upper
level disturbance will track into the upper midwest. This will be
followed by a back door cold front and high pressure building into
northern and eastern Nebraska. Lows behind the front for Sunday
night will be seasonal with readings in the lower to middle teens.
By Monday, low pressure will track to the east southeast from
northern Wyoming into northern Nebraska, then western Iowa. A cold
front trailing the low toward the west, will track south entering
the northern forecast area by late morning, pushing through the
forecast area by mid afternoon Monday. South of the front, H85 temps
will reach 1 to 3C and with good mixing ahead of the front, highs
may reach the mid 40s in the southern forecast area. Further north
with the earlier expected timing of the front, highs will struggle
to reach the freezing mark. Cold arctic air will settle into the
forecast area Monday night as a 1030 MB surface high builds into
central and eastern Nebraska. With clear skies expected, overnight
lows will bottom out in the single digits with lows around zero in
far northern Nebraska. High pressure will push east into the mid
Mississippi valley for Tuesday. A secondary high will drop southeast
from Montana into South Dakota. A secondary arctic front, will be
oriented between the highs and will push into far northeastern
Nebraska by 00z Weds. Further southwest, cold arctic air will remain
entrenched across western and north central Nebraska. With an
approaching jet streak aloft, abundant mid and high level clouds
will stream into the are from the west and will limit the warm up
for Tuesday. Highs will range from the middle teens in the north to
the middle 20s in the south.

Long term...Tuesday night through Saturday...With the upper level
jet streak draped across the central CONUS, mid and upper level
moisture will continue to stream into the forecast area from the
Pacific. At the same time, with the arctic front stalled off to
the south of the forecast area, the mid level frontal boundary
will stall across western and north central Nebraska. Light snow
will develop INVOF of the elevated front Tuesday night into
Wednesday. Precipitation chances will be highest in the west,
decreasing the further you head east, as drier air in the lower
levels is more prevalent. Any accumulations will be fairly light
as the bulk of moisture is Pacific in origin. The mid level front
will remain entrenched across the Central Plains through the end
of the week with a threat for light snow continuing. By Friday
into Friday night, another reinforcing shot of very cold arctic
air will push into western and north central Nebraska. MEX
guidance highs for Valentine and North Platte are 1 above and 10
degrees respectively for next Saturday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 545 PM CST Sat Dec 10 2016

The SREF and ECMWF models were the basis for the forecast. These
two models were similar with MVFR/local IFR cigs tonight. The
models improve flight conditions to VFR all areas Sunday
morning...15z onward. The MVFR cigs...if they develop as
progged...are associated with a push of weak arctic high
pressure. Daytime mixing with this airmass could lift these
ceilings to VFR. The SREF actually show the low cigs exiting
eastward with the progression of the front late tonight and Sunday
morning.

Isolated patches of light snow or freezing drizzle are possible
tonight ahead of the arctic front. Confidence with this element
is low given the short range model reflectivity product appear
quiet with minimal radar returns progged..

BKN-OVC100 cigs Sunday morning are expected to become scattered in
the afternoon.

&&

.HYDROLOGY...
Issued at 348 PM CST Sat Dec 10 2016

Minor flooding remains possible along the North Platte river at
North Platte due to ice Jamming. The river level this morning was
6.40 feet. This stage is expected to fluctuate over the next
several days as temperatures remain at or below freezing.

&&

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

$$

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



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