Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 200833

Area Forecast Discussion
National Weather Service North Platte NE
333 AM CDT Thu Apr 20 2017

Issued at 330 AM CDT Thu Apr 20 2017

H5 analysis from earlier this evening had a decent shortwave
trough across the Dakotas into northern Nebraska. Ridging was
present across the northern Rockies from western Wyoming into
southern Alberta. West of the ridge, a closed low and trough of
low pressure was located from just off the coast of British
Columbia, south to off the coast of northern California. East of
the shortwave across the Dakotas and northern Nebraska, low
amplitude zonal flow extended across the Mississippi valley east
to the Atlantic coast. At the surface, low pressure was located
over eastern Iowa with a cold front extending to the southwest
into south central Kansas and the northern Texas panhandle. High
pressure was located over eastern North Dakota with a shroud of
low clouds extending from North Dakota into northeastern Nebraska.
Some of these low clouds have pushed as far west to a line from
Cody to Sargent. West of this line, a more westerly component to
the winds was noted and has limited the further west ward
progression of this low cloudiness overnight. Readings as of 3 AM
CDT were generally in the 40s.


.SHORT TERM...(Today and tonight)
Issued at 330 AM CDT Thu Apr 20 2017

Over the next 24 hours,
temperatures today, followed by the threat for rain late tonight are
the main forecast concerns. For today: northwesterly winds are
expected to persist through the afternoon hours with a weak ridge
aloft building east onto the high plains. Highs today will be in the
60s with coolest readings over the far northeast, where low clouds
may linger into the afternoon hours. Clouds will begin to increase
from southwest to northeast as an upper level wave lifts into the
central Rockies tonight. At the same time, a reinforcing shot of
high pressure will build southeast into the upper Mississippi
valley. This will force a back door cold front into the area tonight
with low level easterly winds developing. As the wave aloft
approaches the central Rockies this evening, light precipitation
will spread from southwestern into south central Nebraska once the
boundary layer and low levels can saturate. For the most part, the
inherited forecast had this handled well. The main change was to
delay the onset of precipitation slightly based on the latest NAM12
and WARW solutions. Based on the latest model solutions, the onset
of pcpn was delayed 3 to 6 hours. With increasing cloudiness, lows
will will be mild tonight with readings in the 40s.

.LONG TERM...(Friday through Wednesday)
Issued at 330 AM CDT Thu Apr 20 2017

Operational models and the GFS ensemble mean have been fairly
consistent with the track of the system Friday. Friday morning
expect a closed low at H700mb to be centered across southeast
Wyoming. An associated surface low will be across eastern Colorado.
Deep lift will be on the increase across western and southwest
Nebraska Friday morning and expect rain to develop. Dry air aloft
will keep areas farther east across central and eastern Nebraska
precipitation free. Low level upslope easterly flow to the north of
the Colorado surface low will ensure a cloudy and cool day for most
of the area, with perhaps a few breaks in the clouds across eastern
portions of north central Nebraska, where the drier air will be
located. Expect the upper level low to develop toward central Kansas
by Friday afternoon, with the surface low developing from eastern
Colorado toward Oklahoma. This track will keep rain chances confined
to mainly southwest Nebraska Friday afternoon into Friday evening.
Late Friday night into Saturday drier air aloft will spread over the
entire area with clearing skies.

Upper level ridging will build across the area Saturday into Sunday.
This will ensure mainly sunny skies and warmer temperatures. H850mb
temperatures support low to mid 60s for highs Saturday. Sunday will
be warmer as H850mb temperatures rise several degrees and expect
highs in the low to mid 70s. South winds will be on the increase
Sunday as a leeward trough develops along the front range of the
Rockies. A tight surface pressure gradient will support gusts up to
30 mph by mid to late afternoon across central and western Nebraska.

The next system is forecast to move across the northern plains
Monday. Most of the precipitation with this system will remain well
north in the Dakotas. A cold front behind the system will cool highs
back from around 70 Monday to lower 60s by Wednesday.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1154 PM CDT Wed Apr 19 2017

Western Nebraska will continue to see decreasing clouds over
night with northwest winds continuing around 10kts. Some MVFR cigs
over south central South Dakota may move into the KVTN taf site
but current trend has low stratus just to the east and have left
taf VFR with this in mind. Northwest winds will increase late
morning on Thursday and continue through the afternoon under
mostly sunny skies.




SHORT TERM...Buttler
LONG TERM...Taylor
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