Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KCYS 271711
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1108 AM MDT SAT AUG 27 2016

.UPDATE...
Issued at 1108 AM MDT Sat Aug 27 2016

Fog has dissipated across the North Platte River Valley and
vicinity, so let the Dense Fog Advisory end at 10am. Still expect
dry and breezy conditions to develop for many locations along and
west of the Laramie Range, in addition to western Converse County,
so will maintain the Red Flag Warning as is. Models are showing a
bit more convection developing along the southern Laramie Range
and vicinity within the sfc convergence zone this afternoon, so
bumped up PoPs just slightly for these locations.

&&

.SHORT TERM...(Today through Monday)
Issued at 338 AM MDT Sat Aug 27 2016

A dry and warm period ahead this weekend and into early next
week. Satellite imagery depicts northern stream shortwave trough
rotating into the western Dakotas early this morning. Clouds have
been and will continue to slowly decrease thru sunrise. Fog has
been slowly forming across Cheyenne, Morrill, Box Butte, Sioux
and now into Niobrara Counties already. Latest HRRR suggests this
fog will continue for these areas and even expand south into
Scotts Bluff and Goshen Counties too. This fog is anticipated to
lift by around 14-15z. Attention then shifts to increasing fire
weather danger for this afternoon/evening. Northwest flow at
sunrise will back to westerly by day`s end. Minimum relative
humidities will easily reach the critical 15% threshold by
afternoon. The GFS is the strongest with progd flow at the top of
the deep mixed layer of 15-25 knots. The NAM is lighter with 5-15
knots at that same level. Favor the higher GFS at this point...so
will continue the Red Flag Warnings for the inherited areas of
southeast Wyoming. Much of the same ahead for Sunday, although
winds within the mixed layer look lighter compared to Saturday.
Winds turn easterly for Monday, which will suppress fire weather
concerns. Temperatures return to the 70s West and 80s East today,
and 80s everywhere on Sunday-Monday, with even some low 90s in
lower elevations of the northern Nebraska Panhandle.

.LONG TERM...(Monday Night through Friday)
Issued at 338 AM MDT Sat Aug 27 2016

Monday night/Tuesday...Quiet Monday night, with isolated
thunderstorms near the mountains Tuesday with a slight influx of
moisture.

Wednesday...Ridging aloft will limit areal thunderstorm coverage,
though still expect isolated to scattered thunderstorms over and
near the Snowy and Sierra Madre Ranges.

Thursday...Coverage of thunderstorms increases slightly as low and
mid level moisture increases. Still though, thunderstorms will be
confined over and near the mountains with weak steering winds aloft.

Friday...As the mid level southwest flow strengthens, will see an
increase in low and mid level moisture and a corresponding increase
in thunderstorms coverage over and near the Snowy, Sierra Madre and
southern Laramie Ranges. Should also see an increase in wind speeds
due to stronger winds aloft.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday morning)
Issued at 1108 AM MDT Sat Aug 27 2016

VFR expected to prevail across all terminals through Sunday morning.
There is some possibility for patchy fog once again later tonight
into Sunday morning around the North Platte River Valley.

&&

.FIRE WEATHER...
Issued at 338 AM MDT Sat Aug 27 2016

A critical fire weather day ahead across east-central Wyoming and
in areas west of the Laramie Range. Minimum humidities will easily
fall to 15% and below by afternoon, with wind gusts in the 15-25
mph range (locally higher in places). Red Flag Warnings have been
hoisted for these areas. Conditions will improve by mid-evening.
Although temperatures are warmer and humidities less on Sunday,
winds look less as well. Winds turn east for Monday which will
suppress fire weather concerns.

&&

.CYS Watches/Warnings/Advisories...
WY...Red Flag Warning until 8 PM MDT this evening for WYZ301>304-306-
     308.

NE...None.
&&

$$

UPDATE...RJM
SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...RE
FIRE WEATHER...CAH



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.