Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 202045

Area Forecast Discussion
National Weather Service Cheyenne WY
245 PM MDT Fri Apr 20 2018

.SHORT TERM...(This evening through Saturday)
Issued at 233 PM MDT Fri Apr 20 2018

Snow amounts continue to be the forecast challenge in the short
term. Currently, band of heavier precip ahead of low pressure has
moved off into Nebraska this afternoon. Did get some pretty good
rainfall amounts over the Panhandle this afternoon. Sidney got
some much needed rainfall with .3 inches observed. Alliance
received .21 inches. Looks like precip has pretty much ended
across the Panhandle. Upper low over western Colorado this
afternoon with precip breaking out across northwest Colorado into
the mountains of southern Carbon County. Here along and east of
the Laramie Range, a dry slot continues, but am seeing cooling
cloud tops over central Colorado, working their way north.

Made no changes to the ongoing headlines and forecast for tonight
into Saturday. Area is forecast to fill in with rain and mountain
snow this evening as upper low tracks into eastern Colorado.
Similar snow amounts from the overnight forecast.

Precip ends from northwest to southeast Saturday late morning.
Still need to watch the southern Panhandle as heavier precip band
from wrap around moisture just south of Cheyenne County through
the day.

.LONG TERM...(Saturday night through Friday)
Issued at 233 PM MDT Fri Apr 20 2018

The remainder of the weekend will be quiet w/ dry zonal flow aloft
and a lack of any notable mid-level disturbances. The GFS/ECM both
suggest a fast-moving short wave tracking across the Intermountain
West on Monday/Tuesday, likely bringing our next chance for rain &
snow to the area. Trending warmer and drier afterwards.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1136 AM MDT Fri Apr 20 2018

Main focus on aviation impacts will remain on the lowering MVFR
to IFR ceilings through the late afternoon and overnight along
with -RA and -SN coverage increasing over the TAF sites during
this period. -SN has already been observed at KSNY that briefly
brought visibilities down to 1/2-1 SM. Mountain TAF sites will
initially have -RASN mix this afternoon and then convert over to
all SN overnight. For KCYS, a -RA to -RASN and then brief -SN is
the expected precip type evolution early evening into Saturday
morning. For western NE sites, -RA is expected this afternoon with
a transition to -RASN overnight. Brief change over to all -SN
will be possible for NE sites but any accumulations are expected
to be low. MVFR to IFR ceilings and visibilities are likely during
this period. Patchy LIFR visibilities could occur in heavier snow
showers. Conditions will improve late morning Saturday as
precipitation ends from west to east and ceilings increase to MVFR
and VFR.


Issued at 233 PM MDT Fri Apr 20 2018

No fire weather concerns. A cool/unsettled weekend ahead with good
chances for measurable rain/snow across all of southeast Wyoming &
the western Nebraska Panhandle.


WY...Winter Storm Warning until 9 AM MDT Saturday for WYZ114.

     Winter Weather Advisory until 9 AM MDT Saturday for WYZ112.

     Winter Weather Advisory until noon MDT Saturday for WYZ116.



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