Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 280915

Area Forecast Discussion
National Weather Service Cheyenne WY
315 AM MDT WED SEP 28 2016

.SHORT TERM...(Today through Thursday Night)
Issued at 315 AM MDT Wed Sep 28 2016

Blocking pattern in place across the CONUS this week as
downstream upper-low near the Great Lakes is taking its time
departing. The result for us is a very pleasant stretch of dry
and seasonably warm Autumn conditions. Satellite pix early this
morning reveal cloudless skies across much of the intermountain
west with a cold front evident settling south thru central
Montana. This as an upper-level ridge of high pressure amplifies
along the front range. Don`t see much change for today aside from
increasing clouds from the southwest as the next upstream
shortwave near the Great Basin begins lifting northeast. Progd H7
temperatures of 8-12C will yield afternoon highs that will climb
well into the 70s for all lower elevations, with even some low
80s across lowest elevations.

For Thursday, the aforementioned upstream shortwave will continue
lifting northeast into western and central Wyoming by Thursday
night. Preceding moisture will yield more cloud-cover west-east on
Thursday as well as increasing precipitation chances especially in
and near the Snowy, Sierra Madre, and northern Laramie Range.
Temperatures will again be seasonably warm on Thursday as thicker
cloud canopy offsets low-level warm air advection.

.LONG TERM...(Friday through Tuesday)
Issued at 315 AM MDT Wed Sep 28 2016

High pressure weakens and moves east onto the high plains Friday
as an upper level low moves slowly southeast across the Pacific
Northwest through Sunday. As the upper trough moves slowly east
across the Sierra Nevada Sunday a surface low reflection will
likely form up in the lee of the central Rockies moving east
across western Nebraska on Monday. This will bring a strong cold
front east across the forecast area Sunday into Monday with
chances of showers and a few thunderstorms Sunday afternoon into
the overnight hours over the eastern 2/3rds of the forecast area.
As the colder air moves into place late Monday night we transition
precip type to snow showers in the higher elevations west of I-25.
Operational model trends are colder late Monday into Tuesday with
700 mb temps around -5C over much of eastern Wyoming and the
western Nebraska Panhandle 18Z Tuesday...plenty cold enough to see
snow chances increase. For this morning`s forecast will wait and
see if superblend ensembles start to trend closer to latest
operational runs of the GFS and ECMWF for Tuesday...keeping main
chances for measurable snow in the mountains late Monday into
Tuesday with lesser amounts out east onto the lower elevations. If
the models continue to trend colder...this is something we are
going to have to watch closely for the next few days for early
next week for our first real shot at measurable snow for
elevations above 6000 ft.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 230 AM MDT Wed Sep 28 2016

VFR category expected at all airports in SE Wyoming and the
western Nebraska Panhandle for the next 24 hours as high pressure
remains centered over the central Rockies. Light northwest to
northerly winds this morning will become more east to
southeasterly by late today as high pressure moves east.


Issued at 315 AM MDT Wed Sep 28 2016

No critical fire conditions expected over the next week. Seasonably
warm conditions to continue in area districts with high
temperatures reaching the 70s most locations through the end of
the week. Afternoon minimum relative humidities will fall into
the 20s today and Thursday, with 30s and 40s for Friday. Will see
a slight chance of precip spread over the mountains, but coverage
will be limited. Better precipitation chances return early next
week, with snow-levels falling perhaps to around 6000 feet.


.CYS Watches/Warnings/Advisories...



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