Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 300900
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
300 AM MDT Tue May 30 2017

.SHORT TERM...(Today through Thursday)
Issued at 245 AM MDT Tue May 30 2017

More seasonable weather seen for the CWA through Thursday with warm
temperatures and a little convection in the afternoons and evenings.
An upper ridge over the western CONUS will move slowly eastward over
the next few days and pass across the area by Thursday. Warming
mid-level temps will allow max temperatures to be well in the 70s
over lower elevations today with upper 70s and 80s common east of
the mtns both Wednesday and Thursday. A surface boundary will hold
up against the mtns today and should help to set off some showers
and a few storms around the mtns this afternoon into early this
evening. Similar setup for Wednesday then the boundary slips backs
east Thursday. Some decent instability progged to reach the Panhandle
Weds afternoon but warming mid level temps with the approach of the
upper ridge may cap convection for the most part.

.LONG TERM...(Thursday night through Monday)
Issued at 300 AM MDT Tue May 30 2017

00Z medium range models and ensembles are in general agreement with
the central CONUS upper ridge breaking down as a shortwave trough
tracks southeast through the northern Plains early in the period.
A upper ridge quickly builds over the Intermountain West late
Saturday and slides east across the Rockies and high plains
through Monday. West to southwest flow aloft will prevail through
late Friday, becoming northwest with the passage of the trough to
the north Saturday.

South to southwest low level flow will draw moisture into Wyoming
ahead of a Pacific front Thursday night and Friday. Precip water
values increase to 0.50-0.75". Evening convection west of the
Laramie Range decreases through the night, with an increase along
and east of the mountains Friday as the front moves east through
the CWA. Convection ends early Friday evening after the frontal
passage. High temperatures will trend cooler from west to east
Friday, but remain above seasonal normals.

Saturday and Saturday night will be dry and slightly cooler than
normal with northwesterly flow aloft. A weak shortwave will slide
northeast of the CWA Saturday.

A change to unsettled weather returns Sunday with the resurgence
of low-level moisture, especially over the plains where precip
water values approach an inch. Widely scattered convection
develops Sunday afternoon over the mountains and shifts east onto
the plains Sunday night. Monday will be a carbon copy of Sunday
with widely scattered afternoon and evening convection. Little
day-to-day temperature change is forecast Sunday and Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 300 AM MDT Tue May 30 2017

VFR. Light and variable surface winds will become northwesterly
12-20 kt after mid-morning Tuesday. Afternoon convection will be
more isolated than recent days, and mainly be confined to the
mountains. Included VCTS at Laramie from 21Z to 00Z.

&&

.FIRE WEATHER...
Issued at 245 AM MDT Tue May 30 2017

Fire weather concerns look to remain nil for the rest of the week
with greenup well established and weather conditions remaining
non-critical. There will be some late day showers and storms
mainly around the mtns today and Weds then again by the weekend.
Warmer temperatures over the next couple days before cooling a bit
over the weekend.

&&

.HYDROLOGY...
Issued at 300 AM MDT Tue May 30 2017

Warmer temperatures through the end of the week will result in
increased snow melt and runoff of the mountain snowpack above 9000
feet. Winds will not be a factor, however isolated to widely
scattered late day convection will accentuate the snow melt. The
North Platte River at Saratoga is forecast to climb above the
action stage of 7.5 feet late Thursday.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&

$$

SHORT TERM...RE
LONG TERM...MAJ
AVIATION...MAJ
FIRE WEATHER...RE
HYDROLOGY...MAJ


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