Area Forecast Discussion
Issued by NWS North Platte, NE

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844
FXUS63 KLBF 182323 AAA
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
523 PM CST Sat Feb 18 2017

.SYNOPSIS...
Issued at 318 PM CST Sat Feb 18 2017

The H5 pattern this morning was highlighted by a high
amplitude trough of low pressure which extended from western
Washington state south to off the coast of Baja California.
Downstream of this feature. A ridge extended from western Texas
north into the high plains of eastern Montana. Further east, a
closed low was located over the Arklatex with a weak downstream
ridge noted over the Carolinas into the upper Ohio valley. Across
central Canada, a closed low and shortwave trough was located from
northern Manitoba south to the arrowhead of Minnesota. At the
surface, high pressure had built into eastern Nebraska this
afternoon. West of the high, southerly winds had developed across
central and western Nebraska. This has pushed temperatures into the
60s across the forecast area. Skies were clear this morning, but
have since become partly to mostly cloudy as a veil of high clouds
moves into the area from the southwest.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 318 PM CST Sat Feb 18 2017

A storm system will lift northeast from the desert southwest Sunday.
Flow aloft and at the surface will become southerly ahead of the
system tonight into Sunday. Moisture will increase both aloft and at
the surface, with dew points rising into the 40s by Sunday afternoon
across southwest and central Nebraska. There may be some patchy fog
late tonight into Sunday morning as the moisture begins to increase.
With the increase in moisture aloft, expect mid and high level
cloudiness to continue increasing tonight and right through Sunday.
This, along with the increase in low level moisture, will have some
impact on lows tonight, with most areas expected to remain above
freezing. For Sunday, opted to not go with the warmest guidance, as
think cloud cover in spots will limit heating some. Highs most areas
expected to reach the mid to upper 60s, but kept out of the lower
70s due to the clouds.

.LONG TERM...(Sunday night through Saturday)
Issued at 318 PM CST Sat Feb 18 2017

Sunday night through Wednesday: In the mid range, the
threat for thunderstorms Sunday night, then temperatures are the
main forecast concerns. Beginning Sunday evening, an upper level low
will lift to the east northeast from the four corners into western
Kansas. As this feature emerges onto the high plains of eastern
Colorado Sunday evening, elevated instability will increase across
southwestern Nebraska. This instability will track northeast into
central and eastern portions of the forecast area overnight. Even
with meager instability at the surface, LI`s calculated at the 850
MB level are running -2 to -4c Sunday evening. That being said, will
continue to leave in a mention of thunderstorms Sunday evening. As
for the threat of severe storms, deep layer shear is fairly strong
Sunday night, however it is highly unidirectional, and elevated CAPE
(where the strongest instability is) is near zero. With this in
mind, the severe threat Sunday night is expected to be minimal. By
Monday, the upper level trough will lift east across Kansas and
Nebraska. Shower chances will continue through the morning hours,
ending by early afternoon as the trough axis slides east of the
forecast area. Westerly winds and mild air will continue behind the
exiting trough. This will allow highs to reach the 60s Monday
afternoon. By Tuesday, a trough of low pressure aloft will approach
the Pacific northwest. This will initiate some downstream ridging
across the high plains. H85 temps Tuesday afternoon will reach the
teens across western and north central Nebraska. Current forecast of
lower 70s appears on track given the expected H85 temps and the
expected lack of high cloudiness. The trough of low pressure aloft,
will lift into the western CONUS Wednesday. Surface low pressure
will develop over northeastern Colorado with a warm front extending
northeast into western Nebraska. Highs Wednesday will range from the
upper 50s in the northwest to upper 60s in the central, south and
east.

Wednesday night through Saturday: Beginning Wednesday night a strong
upper level trough of low pressure will track east, impacting the
plains Wednesday night into Friday. As was the case yesterday, the
track and strength of this feature are still uncertain. The 12z
Canadian and 12z GFS this morning lift an open wave across the
central plains, which would limit the snow and precipitation
potential. The 12z ECMWF however, closes off a low over northern
Kansas into southeastern Nebraska Thursday night into Friday, which
would bring plenty of snow to the region. Forecast details with this
system will continue to be ironed out over the next few days. One
forecast aspect with this system which remains constant is the
threat for strong winds Thursday into Friday and they were continued
with this forecast package.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 523 PM CST Sat Feb 18 2017

VFR is expected all areas overnight through Sunday.

Sfc low pressure will slowly deepen across the Cntl/Nrn high
plains overnight and Sunday. BKN-OVC150-200 skies are expected to
continue during this time which represent remnent moisture from
the West Coast storm system moving inland through the Srn Rockies.

&&

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

$$

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



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