Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 241814

Area Forecast Discussion
National Weather Service Cheyenne WY
1214 PM MDT Mon Oct 24 2016

.SHORT TERM...(Today through Wednesday)
Issued at 346 AM MDT Mon Oct 24 2016

A shortwave disturbance moving into Wyoming from NV/UT today
will bring gusty winds to areas along and west of the Laramie
Range this afternoon. The track of the wave should keep the
deepest moisture to our west and northwest, so brought PoPs down
a bit for this afternoon over Carbon County. A second wave right
on the heels of the first will track in more from the west this
evening, bringing higher Pacific moisture into the high country
and thus a better chance for rain and high elevation snow showers
this evening through the overnight hours. Relatively warm
temperatures through the column should keep any snowfall up above
10kft through Tuesday morning. Southerly sfc flow ahead of the
wave across Nebraska will advect llvl moisture into this area
tonight, with fog/stratus a possibility mainly from Alliance down
to Sidney.

A strong zonal jet moving into the intermountain west on
Tuesday will maintain chances for orographic showers through the
day along with continual stream of mid and high clouds. Another
upper level trough digging over the Pacific will enhance the
downstream ridge over the Rockies, bringing a return of mild and
dry conditions to our forecast area for Wednesday.

.LONG TERM...(Wednesday night through Sunday night)
Issued at 346 AM MDT Mon Oct 24 2016

Medium range models in reasonable agreement late this week...but
then model solutions start to diverge next weekend as some Pacific
energy moves onshore. Models generally show dry conditions
continuing through the last full week of October with mild
temperatures. Models continue to show 700mb temperatures
increasing between 7c to 10c for pretty confident
that most of the forecast area will see high temperatures in the
70`s to near 80 across the high plains...warmest below 4500 feet
in elevation. Locations west of I-25 such as Saratoga...Laramie...and
Rawlins will remain a little bit cooler and generally in the mid
to upper 60`s Thursday afternoon.

For Friday...00z models are a little different compared to 24
hours ago. All models show a back door cold front moving across
the high plains Friday morning. The GFS and Canadian are the most
aggressive showing 850-700 mb temperatures lowering substantially
through the day with highs struggling to reach the mid 50`s to mid
60`s across the plains. The ECMWF is not as aggressive with the
front...with temperatures lowering a few degrees at best. A
progressive upper level trough axis will quickly move across the
area for can not rule out some rain showers across
southeast Wyoming and possibly the east central plains from
Douglas to Chadron Nebraska. For now...kept POP between 10 to 20
percent and lowered temperatures a few degrees Friday and
Saturday. Ensembles are all over the place this weekend in regards
to the overall pattern...with some members showing zonal flow and
others showing an amplified ridge axis moving eastward into
Wyoming. A few members are even showing the Pacific energy moving
eastward...impacting most of the forecast area by Sunday. For
now...kept the forecast dry this weekend but started lowering
temperatures across the western and far northern zones across
southeast Wyoming as it appears a strong cold front will approach
the area this weekend.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1211 PM MDT Mon Oct 24 2016

No real major concerns with this taf issuance. VFR conditions will
prevail during the next 24hrs. There may be a few showers around
KRWL tonight, in response to a shortwave moving through the area.
However, ceilings should only drop to around 4-5kft.


Issued at 346 AM MDT Mon Oct 24 2016

Fire weather concerns will remain minimal through midweek as
a steady stream of Pacific moisture moves into the district.
Gusty southwest winds will occur along and west of the Laramie
Range this afternoon but humidity values will range 20 to 30
percent or higher. Rain with a few high elevation snow showers
will occur this evening through late Tuesday over the high
country. A shower or two may trek east across the Wyoming plains
as well. Breezy and dry conditions look to return to the plains
on Thursday.




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