Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 181734

Area Forecast Discussion
National Weather Service Cheyenne WY
1030 AM MST Wed Jan 18 2017

.SHORT TERM...(Today through Friday)
Issued at 202 AM MST Wed Jan 18 2017

Winds are the primary forecast challenge today and Thursday. Not a
typical high wind event for this area.

Currently...1035MB surface high continues over western Wyoming
this morning. Fairly strong surface gradient over Carbon and
northern Albany Counties this morning. 1AM temperatures still
pretty cold out west with 5 degrees at Rawlins, 6 at Laramie and 3
at Saratoga. East of the Laramie Range, we are seeing 26 at
Cheyenne, 23 at Torrington and 22 at Douglas. So we continue to
have a fairly tight pressure gradient from the temperature
differences. 700mb winds really light, generally less than 15kts
this morning. But Bordeaux is really close to sustained warning
level winds. Craig to Casper 850mb gradients continue to be
forecast to rise through the day today. Will let the High Wind
Warning ride since Bordeaux is so close this morning.

Other forecast challenge this morning is fog out by Laramie.
Laramie did go down earlier in fog, but has since come back up.
Can`t see the fog on WYDOT webcams or the 11-3.9u satellite
imagery, so it must be really localized. Thinking with the
increased pressure gradient that this fog should dissipate and
will hold off on any Advisories out there this morning.

WRKHGT product from NAM increases the 850mb Craig to Casper height
gradient up to 52mtrs at 21Z this afternoon and up to 56mtrs by
06Z tonight. Current 850mb gradient of 35mtrs is causing near
warning winds at Bordeaux, so I feel confident that Bordeaux will
hit later this morning as the gradient continues increasing.
Timing on warning looks good, running through tonight. Dayshift
may need to extend it roughly 6 hours longer into Thursday as that
is when the lower level gradients are forecast to ease.

Attention turns to Thursday night/Friday when the next Pacific low
pressure system begins to move into northern Colorado. Looks like
most of the energy stays south over Colorado from this system. Did
continue fairly high PoPs for the Snowy and Sierra Madre Ranges
though. Not expecting a lot of snow out there as both the GFS and
ECMWF showing maybe .2 inches liquid. Something to keep an eye on
though as we get closer to the event.

.LONG TERM...(Friday night through Tuesday)
Issued at 202 AM MST Wed Jan 18 2017

Fairly quiet over the weekend across the CWA as the next upper
system tracks far south of the CWA...across the southern Rockys
and the southern plains through Sunday. Seasonably cool across the
CWA both days with just some higher mtn snow showers possible.
Short upper ridge moves across Sunday night then conditions turn
more wintry Monday as the next upper trough approaches the area
from the west...closing off an upper low over northern Colorado
Monday night then moving it across the Kansas/southern Nebraska
area Tuesday. EC a bit farther north with the track but either way
it should bring snow to the CWA by late Monday...continuing for
much of Tuesday before tapering off. Could be some decent snowfall
amounts so will have to watch how this develops. Otherwise turning
colder late Monday through Tuesday with northerly winds in
response to lee cyclogenesis initiating over far se Colorado late
Monday...moving east across Kansas Monday night through Tuesday.


.AVIATION...(For the 18Z TAFS through Thursday morning)

Other than some patchy fog in the Laramie valley possibly producing
brief periods of MVFR/IFR visibilities for KLAR tonight...expect VFR
to prevail for all terminals today with winds generally below 15


Issued at 202 AM MST Wed Jan 18 2017

Wind prone areas of southeast Wyoming will see wind gusts in
excess of 40 MPH today through Thursday. Afternoon humidities
though should stay above critical levels with driest conditions
around the low 20 percent range immediately east of the Laramie
Range. Existing snowpack and expected snow on and off through the
week will keep fire weather concerns at a minimum threshold.
Widespread snow event still on track for Monday and Tuesday next


WY...High Wind Warning until 6 PM MST this evening for WYZ106.



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