Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 262010

Area Forecast Discussion
National Weather Service Cheyenne WY
210 PM MDT Thu Apr 26 2018

.SHORT TERM...(This evening through Saturday night)
Issued at 200 PM MDT Thu Apr 26 2018

Tonight...As already seen in satellite imagery, expect low and mid
clouds to dissipate by late this afternoon or early this evening
with clear skies overnight. Cooler in the wake of the cold front,
with  most low temperatures near freezing at lower elevations.

Friday...Considerably warmer with ridging aloft, minimal cloud cover
and warming airmass. Expect maximum temperatures in the 70s with 700
mb temperatures near 5 Celsius.

Friday night...Mostly clear skies prevail under ridging aloft with
low temperatures not quite as cold as tonight under the moderating

Saturday...Ridge axis aloft moves off to our east, with warm
temperatures continuing under 700 mb temperatures near 7 Celsius.
With increasing low and mid level moisture and instability, we may
see isolated afternoon thunderstorms over and near the Snowy and
Sierra Madre Ranges, dry elsewhere.

Saturday night...Enough low and mid level moisture for isolated
showers to continue into the evening hours west of a Douglas to
Laramie line, dry elsewhere. Even more mild overnight with decent
mixing, scattered to broken cloud cover and a moderating airmass.
Most minimum temperatures will remain in the 40s at lower

.LONG TERM...(Sunday through Thursday)
Issued at 200 PM MDT Thu Apr 26 2018

The long term period will be unsettled with several opportunities
for measurable precipitation. Western CONUS upper trough will
slowly track east across the Rockies and Northern Plains through
the middle of next week. There will be a couple of upper lows
pinwheeling through the mean trough. The first will impact MT, WY,
and the Dakotas Monday afternoon through Tuesday morning.
Preceding this low will be a weak shortwave late Sunday which may
spark isolated convection over the high plains. The stretch of
warm temperatures will continue Sunday with highs in the 60s and
70s. A period of widespread precipitation commences Monday and
lingers through Tuesday. Instability both days will be be marginal
for afternoon thunder. High temperatures cool 5-10 degrees Monday
and Tuesday. Will need to keep a close eye on the second upper
low as tracks east-northeast from southern CA Wednesday morning
toward the NM-CO border Thursday morning. More widespread
precipitation is forecast Tuesday night through Wednesday night.
The ECMWF has been trending colder the past couple runs for
Wednesday and Thursday with highs in the 30s and 40s and snow
levels dropping to 6000 feet. The GFS is not as cool with highs
in the 40s and 50s Wednesday and Thursday and snow levels lowering
to 7000 feet. For now, favored a model blend until the models
and ensembles come into better agreement. Regardless of the
differences, higher elevations can expect some measurable snow.


.AVIATION...(For the 18Z TAFS through 18Z Friday morning)
Issued at 1130 AM MDT Thu Apr 26 2018

VFR CIGS /5000-10000 ft AGL/ and gusty north winds 20-30 kt will
prevail through 22Z along and east of the Laramie Range. Skies
will become clear with light and variable winds after 01Z.


Issued at 200 PM MDT Thu Apr 26 2018

Relatively low humidities will continue into the afternoon hours
Friday through Sunday west of Interstate 25. Fortunately, winds
will be relatively light Friday and Saturday. Will need to monitor
the potential for high fire danger in zone 306 and Saratoga Sunday
as southwest winds become quite gusty and afternoon humidities
lower to 15 to 20 percent.




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