Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 261111

Area Forecast Discussion
National Weather Service Cheyenne WY
511 AM MDT Mon Jun 26 2017

.SHORT TERM...(Today and tonight)
Issued at 249 AM MDT Mon Jun 26 2017

Quiet weather continues today as a stable airmass remains in
place underneath ridging aloft. Temps will be a bit warmer than
yesterday and winds should be generally light. A shortwave trough
will move onshore northern CA today and this shortwave will serve
to beat down the persistent upper ridge on Tuesday. At the
surface, a deepening lee trough will take shape over our panhandle
counties on Tuesday in response to height falls aloft. CAPE
values of 1000 to 1500 J/KG along with deep layer shear of around
40kt expected over our panhandle counties early Tuesday afternoon
and expect some convective initiation by mid afternoon as
increasingly diffluent upper flow spreads across the area. Models
are quick to shunt the best instability quickly eastward into
north central NE by late afternoon but if things fire early
enough, one or two severe storms are possible in the panhandle.

To the west of the surface trough on Tuesday, breezy to windy
conditions will develop in a deeply mixed boundary layer.  Raised
temperatures especially in the lee of the Laramie Range where
downsloping will be maximized.

Pacific cold front will pass across the area Tuesday evening and
breezy to windy conditions may last into the evening hours
immediately behind the front as the surface gradients remain tight.

Wednesday will be slightly cooler with continued westerly flow. Weak
shortwave energy may affect our northern counties on Wednesday
afternoon and with steep lapse rates in place, widely scattered
afternoon convection is likely.

.LONG TERM...(Tuesday through Sunday)
Issued at 249 AM MDT Mon Jun 26 2017

Slightly cooler pattern continues into Thursday with a gradual
warming trend expected going into the weekend as weak ridging
aloft builds in from the west behind Thursday`s passing shortwave.
We keep some small PoPs going for afternoon/evening thunderstorms
east of the Laramie Range Thursday with a few showers and
thunderstorms over the mountains going into the weekend...but
overall a mostly dry pattern expected Friday through Sunday.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 511 AM MDT Mon Jun 26 2017

We are getting some radiation fog around Alliance this morning.
Expect any IFR visibility issues to diminish as we get past
sunrise and mixing increases through mid morning. Otherwise,
mostly a wind forecast in the aviation department for the next 24
hours with a bit more wind from the southeast toward late in the
day over the Nebraska Panhandle. With some scattered Cu at 050-070
this afternoon, expecting VFR category into tonight.


Issued at 249 AM MDT Mon Jun 26 2017

Dry conditions continue today with light winds. Tuesday will be
windy west of the Laramie Range with afternoon RH values falling
to around 15 percent so elevated conditions would be possible
except that fuels remain relatively green. Unsettled pattern
continues into mid week with chances for afternoon convection and
breezy conditions in the afternoon.




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