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Area forecast discussion
National Weather Service North Platte NE
1046 PM CST Wed Nov 20 2019

Synopsis...
issued at 320 PM CST Wed Nov 20 2019

500 mb analysis from this morning had a highly amplified
pattern across the Continental U.S.. ridging extended north from the arklatex
into eastern South Dakota and western Minnesota. East of this
feature, low pressure was located off the coast of New Jersey with a
trough extending south into the northern portions of the Bahamas.
West of the ridge, low pressure was closed off just off the coast of
Southern California. Downstream of this feature, shortwaves were
noted over Baja California, northern Mexico, and the Texas
Panhandle. Current WV imagery has the northern Mexico shortwave,
now over eastern New Mexico to the northern Texas Panhandle. At the
surface, low pressure was located over east central South Dakota
with a secondary are of low pressure over sern Colorado. A cold
front extended from east central South Dakota into south central
Nebraska and sern Colorado. East of the front, gusty southerly winds
and warm air has pushed into eastern Nebraska with readings in the
60s. Behind the front, temperatures have remained steady from their
highs earlier in the day. As of 2 PM CST, under mostly cloudy skies,
temperatures ranged from 38 at Gordon, to 55 at Imperial. All
locations in western and north central Nebraska had northerly winds.
Wind gusts up to 38 miles per hour were reported at Gordon over the past hour.
Elsewhere, winds were gusting in the 20 to 30 miles per hour range.

&&

Short term...(this evening through Friday night)
issued at 320 PM CST Wed Nov 20 2019

The main forecast challenge in the near term is precipitation
chances and the threat for snow tonight into early Thursday
morning. For tonight, lift will increase quickly early this
evening across SW Nebraska as the shortwave, currently over the
srn High Plains, lifts northeast into Kansas. This lift will
transition northeast overnight with precipitation lingering in the
northeastern forecast area. As for precipitation types, temps
will be warm enough to support all rain around 00z this evening,
with a quick transition over to snow from west to east through 08z
tonight. This morning's model solutions trended toward
development of a band of precipitation from southwestern Nebraska
into the sandhills this evening. Quantitative precipitation forecast in this band ranged from
around 20 to 40 hdts with the NAM 12 soln being the heaviest.
Decided to utilize the lighter wpc/and a blend of the warw/nmm qpf
forecast for precipitation amounts tonight. With temps becoming
cool enough to support snow by mid evening in portions of SW and
the central Nebraska sandhills, and quantitative precipitation forecast during this time frame in
the 20-30 hdts of an inch, snowfall amounts of 1 to 2 inches were
forecast from SW Nebraska into the central sandhills. Within the
expected band, we may even see snowfall amounts approach 2+ inches
locally along a line from Grant, to west of Paxton to south of
Thedford. Since this will be impacting the I-80 corridor and
northerly wind gusts up to 35 miles per hour are expected this evening,
decided to hoist a short duration Winter Weather Advisory. This
will run from 6p-4a CT tonight. Further north, there will be a
brief freezing rain/sleet threat over the northwest sandhills. Confidence
in this materializing is fairly low at this juncture. Given the
lack of forecast confidence and very limited freezing qpf, will
not extend the advisory into the northwest sandhills. By Thursday
morning, a northern stream trough will traverse the Dakotas
shifting precipitation quickly east of the area. Cold air will
remain entrenched across the forecast area on Thursday. Even with
some limited clearing Thursday afternoon, temps will struggle to
get out of the 30s. On Thursday, the 500 mb low will track into the
intermountain west, emerging onto the plains Thursday night into
Friday. Attm, precipitation is expected to remain off to the south
of the forecast area as a surface high and drier air builds into
central and northern Nebraska. We may see a small threat for light
snow across far southern portions of the forecast area Friday
evening.

Long term...(saturday through wednesday)
issued at 320 PM CST Wed Nov 20 2019

Benign weather will develop this weekend thanks to low amplitude
flow across the western Continental U.S.. this will lead to highs in the 50s
for Saturday and Sunday. Some significant model differences begin
to come to light early next week as the mid range models lift a
major winter event across the Central Plains or a fairly benign
open wave. The latest GFS lifts a closed low across the Central
Plains Tuesday, while the ec lifts an open wave across the area.
The forecast blend, continues to advertise low pops and will
continue to incorporate this into the current forecast. This
system will bear watching, as travel impacts could be very high
with the system arriving just ahead of the Thanksgiving Holiday.

&&

Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1046 PM CST Wed Nov 20 2019

Light snow will continue across portions of southwest Nebraska
tonight. Brief reductions in visibility is anticipated as well as
slippery runways. Snow will end by 08z to 10z Thursday with gusty
winds developing for the first part of Thursday. Winds diminish by
the afternoon with gradual clearing skies and a return to VFR
conditions.

&&

Lbf watches/warnings/advisories...
Winter Weather Advisory until 4 am CST /3 am MST/ Thursday for
nez024-025-036-037-057>059.

&&

$$

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