Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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
FXUS65 KCYS 281812

Area Forecast Discussion
National Weather Service Cheyenne WY
1212 PM MDT Fri Oct 28 2016

Issued at 1040 AM MDT Fri Oct 28 2016

A dense area of cloud cover has developed across parts of the area
this morning, likely in response to ongoing mountain wave activity
as an upper-level disturbance moves across the area. The area from
the southern Laramie Range northeastward into Torrington, and most
points to the southeast of that line are impacted the most w/temps
still in the middle/upper 50s at Cheyenne. The main challenge with
the morning update will be how this impacts high temperatures. Our
confidence in 75+ degrees today is quite low unless clouds finally
scour out within the next couple of hours which seems unlikely. So
have lowered highs 5-10 degrees over those areas. This may have an
impact on winds too, but did not make too many changes there as an
increasing pressure gradient may be enough for gusty wind into the
afternoon hours despite limited mixing. Also adjusted cloud trends
through the day. Updates have been sent.


.SHORT TERM...(Today through Sunday)
Issued at 252 AM MDT Fri Oct 28 2016

Current IR satellite loop shows cloudy skies over most of the
forecast area as high cirrus moves eastward into the High Plains.
This has kept temperatures very mild this morning for late October
with temperatures still in the 50`s and 60`s at 3 AM. To put this
into perspective...our average highs for today are in the 50`s to
low 60`s. Windy conditions have been observed across the wind
prone areas of southeast Wyoming...with occasional gusts between
40 to 50 MPH near the Arlington exchange earlier this morning.
Although the winds will not be quite as strong this
afternoon...these winds will begin to impact the high valleys and
high plains of southeast Wyoming by late this morning where gusts
up to 40 to 45 MPH are possible.

Expect more cloud cover today and tonight across the area with the
Water Vapor loop showing a constant stream of upper level moisture
from the central Pacific. There is a potent upper level trough off
the California coastline which will move eastward into the Great
Basin and eventually Wyoming/Montana late tonight. By
will weaken and become a more progressive shortwave disturbance as
it moves into the strong ridge of high pressure currently along
the Rockys. Models continue to indicate that this feature will
pass to the north of the forecast area...with even the current
Canadian model trending towards the 00Z GFS and ECMWF from
yesterday. Kept a chance of rain in the forecast in those areas
with POP between 30 to 45 percent from Rawlins northeast towards
Douglas/Lusk and Chadron Nebraska. However...will continue to
monitor the track of this system in the event it tracks further
south. Little if any precipitation is expected along I-80 from
Laramie to Sidney. High temperatures will be a few degrees cooler
compared to yesterday mainly due to the persistent cloud cover.

The other forecast concern will be winds across the wind prone
areas of southeast Wyoming Friday night as a weak cold front moves
towards the area. As of right appears the northern Snow
Range foothills between Rawlins and Laramie will be the most
likely location to see strong winds with models showing the best
low-mid level subsidence and 700mb winds near 50 knots. Will just
mention this in the Hazardous Outlook since models have trended
lower on the llvl gradients and wind speeds. However...gusts
between 50 to 55 mph are still possible along the higher
elevations of I-80.

Saturday and Sunday will be noticeably cooler...especially
further north...with high temperatures in the 60`s to low 70`s. A
few locations from Converse county eastward to the northern
Panhandle of Nebraska may struggle to reach 60 on Saturday as the
bulk of the cooler air clips the northern zones...but will likely
not make it too far south of the Platte River valley. Any
lingering shower activity will likely end by Saturday afternoon as
dry northwest flow develops over the area.

.LONG TERM...(Sunday night through Thursday)
Issued at 214 AM MDT Fri Oct 28 2016

Sunday night/Monday...Fast moving shortwave sweeps into the western
Dakotas Sunday night with its associated cold front quickly moving
across our forecast area. Low and mid level moisture fairly limited
with the shortwave, thus only expecting scattered showers over
Carbon county, mainly over and near the Snowy and Sierra Madre
Ranges. Quite windy in the wake of the cold frontal passage, and our
wind prone locales may be near high wind criteria Sunday night.

For Monday...Low and mid level gradients suggest a windy day with
some wind prone locations perhaps near high wind criteria. Cooler in
the wake of the cold front. Dry with limited low and mid level
moisture. The evening should be quite tolerable for outdoor
activities and trick or treaters.

Tuesday...November will come in quite tame with southwest flow aloft
and a dry day. Relatively mild temperatures with 700 mb temperatures
near 2 Celsius.

Wednesday...Ridging aloft will keep us dry. Continued relatively
mild with plenty of sunshine and 700 mb temperatures near 2 Celsius.

Thursday...Flow aloft becomes southwest and strengthens. Perhaps a
few afternoon showers over our Snowy and Sierra Madre Ranges as
moisture creeps up from Colorado. Continued mild with 700 mb
temperatures near 6 Celsius.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1142 AM MDT Fri Oct 28 2016

Mostly vfr conditions through the taf period. Winds will increase
at the southeast WY sites through the afternoon with gusts to
20-30 kts. Widespread mid to high level clouds will pass over the
region through Saturday morning. Mvfr cigs will be possible at CDR
after 12-15Z.


Issued at 200 AM MDT Fri Oct 28 2016

No Fire Weather concerns are expected through the weekend and into
early next week. A cold front will move across the area tonight
resulting in cooler temperatures and higher humidities. It will
be windy across most of southeast Wyoming...with the strongest
winds likely occurring Sunday and Sunday night ahead of the next
cold front early Monday morning.




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