Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 172108

Area Forecast Discussion
National Weather Service North Platte NE
308 PM CST Sat Feb 17 2018

.SHORT TERM...(This evening through Sunday)
Issued at 306 PM CST Sat Feb 17 2018

One more day of dry and quiet weather is in store for north central
Nebraska. High pressure currently over the central US will slowly
drift south and east of the region by Sunday morning. For the
overnight Saturday period, expect an increase in clouds as the next
disturbance moves into the region from the west. Overnight low
temperatures will be in the upper 20s to low 30s. Locations across
the south will bottom out in the mid 20s, as overnight clouds will
take a little longer to reach the I-80 corridor.

For Sunday, most of the day remains dry, but cloudy as the next
system continues to move into the area. Gusty southeast winds are
also possible early Sunday. Sustained winds will rise up into the 20
to 24 mph range with gusts up to 35 mph. Winds diminish by early
afternoon. Precipitation will then begin to move into the extreme
northwestern portion of Sheridan county by late afternoon (3pm to
6pm CST). Little snow accumulation is expected before 6pm as the
majority of the precipitation will fall after the 6pm CST timeframe.
High temperatures will have a dramatic range across the forecast
area on Sunday. Low 40s should be expected near the South Dakota
border. Across the southern portion of north central Nebraska, highs
in the upper 50s to low 60s could be observed.

.LONG TERM...(Sunday night through Saturday)
Issued at 306 PM CST Sat Feb 17 2018

Arctic high pressure, currently over Alaska, has strengthened to
around 1044 mb. This high will move south into nrn Neb late Sunday
afternoon. The models are stronger with the upper level dynamics and
shifted the better forcing about 50 miles south into nrn Neb since
yesterday. H850mb temperatures are now progged to fall to around -
20C which would produce single digit highs across Nrn Neb Tuesday
and lows well below zero Tuesday and Wednesday morning. The result
will be wind chill readings of -15F to -30F with snow falling Monday
into Tuesday morning.

The midlevel frontogenesis in the GFS, SREF and ECM are now strong
and model soundings across nrn Neb suggest the arctic airmass could
be shallow supporting a more robust snow growth zone between 850mb
and 500mb. The GFS suggest the potential for inch an hour
accumulations Monday night and the plume derived median QPF across
Sheridan county has increased to about 0.4-0.5 inches of liquid;
about a tenth higher than yesterday.

The NAM has moistened up some since yesterday but still shoves dry
air into nrn Neb which limits snow accumulations. The SREF has
joined the envelop of wet models. Thus, confidence for heavy snow
has increased.

The forecast uses a blend of models for 6 to 9 inches of snow across
Sheridan County and wrn Cherry County. This is slightly higher than
the WPC forecast. The Winter Storm Watch runs Sunday evening through
Tuesday morning as the models are slower with the departing
snowfall. Note the Gridded MOS, which is a statistical product
derived from the GFS, produces 11 inches of snow in Valentine. If
this is correct, then later model runs of the deterministic models
will catch up to the guidance which would necessitate the Winter
Storm Watch farther east into ncntl Neb.

The arctic high will move slowly across the nrn Plains and ridge
through the cntl Plains. Thus, the cold weather will last through
Wednesday with modest warming Thursday and Friday. A broad longwave
trof will be forming late this week and this unsettled pattern may
send another disturbance through wrn/ncntl Neb next Saturday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1205 PM CST Sat Feb 17 2018

One last quiet aviation day before active weather arrives Sunday
night. Dry weather will persist at both TAF sites through Sunday
morning with scattered ceilings being prevalent. Once again there is
a chance for some low level wind shear tonight as the low level jet
increases over Nebraska. Both terminals could experience some low
level wind shear during the overnight hours before ending shortly
after sunrise.


Winter Storm Watch from Sunday evening through Tuesday morning
for NEZ004-094.



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