Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 251742

Area Forecast Discussion
National Weather Service Cheyenne WY
1142 AM MDT Sat Mar 25 2017

.SHORT TERM...(Today through Monday)
Issued at 431 AM MDT Sat Mar 25 2017

Pretty nice late March day is in store across the region.  A
shortwave ridge is currently overhead, but will quickly move
eastward through the afternoon.  Highs today will moderate some
compared to yesterday, mostly in the 60s to the east of the Laramie
Range.  A progressive shortwave trough will be located over eastern
Utah by this evening, and then will dive southeastward into
southeast Colorado by early Sunday.  With weak upper level
divergence, there will be a chance of rain/snow showers over
southeast WY this evening/tonight that will spread into the Nebraska
Panhandle by Sunday morning.  Not a whole lot of cold air behind the
front with wet bulb zero heights of 7000-7500 ft.  While snow
accumulations over the mtns will be 2-4 inches, not expecting much
(less than an inch) over lower elevations of southeast WY.  Highs
will be 10-15 degrees cooler on Sunday behind the front and with
widespread cloud cover.  Temps warm to back above normal by Monday
with shortwave ridging aloft.

.LONG TERM...(Monday night through Friday)
Issued at 431 AM MDT Sat Mar 25 2017

A robust upper trough will dig into the SW US Monday night.
The GFS rapidly closes off the upper system over northern Arizona
while the EC closes the system off later and further east over
New Mexico. In the low levels, both models show an elongated
trough of low pressure developing and extending northward into
southern Wyoming from the main system over the SW US. This serves
to focus enough lift and moisture for high chances for precip
across much of the area from late Monday night through Tuesday
night. Temperatures will once again be tricky with this system as
there is just not a lot of cold air available to work with. At
this time, the best chance for accumulating snow will be in the
mountains and near the I-80 summit. Elsewhere, some snow/mix is
possible during the evening and overnight hours both nights
especially in SE Wyoming but think warm surface temperatures will
preclude much accumulation. Another limiting factor in significant
snow is that the main upper system and best dynamics are tracking
pretty far to the south which will probably serve to limit
precipitation rates and associated cooling. Will need to watch
model trends as the track and strength of the system is still up
in the air.

After a break in the clouds and precip on Thursday, yet another
upper trough approaches the area on Friday. A lot of model spread
with this system so maintained a chance of rain/snow similar to
the previous system.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1135 AM MDT Sat Mar 25 2017

Wyoming TAFS...VFR prevails, except for MVFR at Rawlins from 03Z
to 15Z. MVFR at Laramie from 06Z to 15Z. MVFR at Cheyenne from
09Z to 15Z.

Nebraska TAFS...VFR prevails, except for IFR at Chadron, Alliance
and Sidney after 12Z, and MVFR at Scottsbluff after 11Z.


Issued at 431 AM MDT Sat Mar 25 2017

No fire weather concerns through the weekend.  Minimum humidity
values will mostly be above 25 percent this afternoon.  Cooler
temperatures along with a chance of rain and snow showers are
expected on Sunday.




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