Area Forecast Discussion
Issued by NWS Cheyenne, WY

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505
FXUS65 KCYS 082114
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
214 PM MST Fri Dec 8 2017

.SHORT TERM...(This evening through Saturday)
Issued at 147 PM MST Fri Dec 8 2017

High Wind Warnings remain in effect until 5 PM this evening. Winds
this afternoon have ranged from 35-45 MPH in the warned area, with
a peak gust to 66 MPH near Curt Gowdy. The 120-130 knot H25 jet is
translating eastward at this time, extending from the eastern Daks
into eastern Neb per WV satellite imagery. Subsidence is likely to
continue to weaken into the late afternoon as the CWA becomes more
removed from the RFQ of the jet. In addition, flow aloft continues
to weaken but still remains above 50 knots per the CYS VAD. Mixing
will also gradually become more limited with time, so anticipate a
weakening trend in winds from here on out although there may still
be a chance for a 50 knot gust through the afternoon.

Strong northwest flow aloft should remain in place over the CWA on
Saturday, so gusty winds are likely once again for areas along and
east of the Laramie Range during the afternoon. Headlines will not
be necessary with H7-H8 flow expected to be under 40 knots.

.LONG TERM...(Saturday night through Friday)
Issued at 147 PM MST Fri Dec 8 2017

A very quiet pattern next week. At this time, the most notable mid
or upper-level feature appears to be a vigorous shortwave tracking
rapidly southeast across the Northern Plains Sunday night into Mon
afternoon. The GFS shows robust H7-H75 flow (60+ knots) along, and
northeast of a Lusk-Sidney line at 15z Monday. This, combined with
strong subsidence and low-level mixing could support a wide-spread
high wind episode on Monday.

Otherwise, a highly amplified blocking pattern will persist across
the US with ridging to the west and troughing to the east. This is
likely to keep the CWA in dry northwest flow with little/no chance
for precipitation in the foreseeable future. Temperatures are also
likely to be well above normal through next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1025 AM MST Fri Dec 8 2017

Latest surface analysis was showing a very tight pressure gradient
between northern Colorado and the Nebraska panhandle. This
gradient is expected to gradually weaken this afternoon. However,
wind gusts will range from 35 to 45 kts over KCYS with 30 to 40 kt
gusts possible over the southern Nebraska Panhandle. These wind
speeds will diminish this evening as the upper level ridge
continues to build over the region.


&&

.FIRE WEATHER...
Issued at 245 AM MST Fri Dec 8 2017

High pressure over the west coast blocking any Pacific storm
systems from moving into the area. Expect mostly sunny skies and
breezy north to northwest winds each day. Slowly warming
temperatures with afternoon humidity falling into the upper teens
and low 20 percent range. Dry day Sunday for areas east of the
Laramie Range could lead to elevated to locally critical fire
weather conditions as afternoon humidity falls to the low to mid
teens.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 5 PM MST this afternoon for WYZ116>119.

NE...None.
&&

$$

SHORT TERM...CLH
LONG TERM...CLH
AVIATION...REC
FIRE WEATHER...GCC



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