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Area forecast discussion 
National Weather Service Cheyenne Wyoming
1042 PM MST Wednesday Jan 28 2015

issued at 817 PM MST Wednesday Jan 28 2015

Rain showers have mostly changed over to snow showers for
portions of southeast Wyoming near and west of the Laramie range.
Some light accumulations showing up on wydot webcams near The
Summit between Cheyenne and Laramie. Based on current radar and
latest model data...could see an inch or so of snow near The
Summit before the end of this evening. With temperatures near or
slightly above freezing...slippery roads are likely to develop
along this stretch of Road this evening. Snow should end by
midnight or shortly thereafter. A few inches of snow possible into
the Snowy Range through the overnight with snow ending toward
sunrise Thursday. Updated forecast will be out momentarily.

Update issued at 505 PM MST Wednesday Jan 28 2015

A few light rain showers...and snow showers over higher
elevations will continue this evening mainly near and west of the
Laramie range. Could see localized light snow accumulations on
the order of a few tenths of an inch in the mountains...otherwise
mainly looking at nuisance showers.

Wind Advisory for the Nebraska Panhandle has been allowed to
expire as winds have dropped below critical thresholds. Winds
will continue to drop off over the next few hours.


Short term...(late this afternoon through Friday night)
issued at 215 PM MST Wednesday Jan 28 2015

Early afternoon water vapor imagery showed the upper level trough
crossing the High Plains...with its associated surface cold front
through the NE Panhandle. Gusty northwest winds up to 50 miles per hour
prevailed behind the front due to a tight low level pressure
gradient. The gusty winds will continue through late afternoon.
Regional radars indicated areas of light rain with light snow
above 8000 feet. Douglas received a tenth of an inch during the
past few hours. Temperatures remained steady or slowly fell behind
the front...ranging from the 30s west of the Laramie
the 40s and 50s east.

12z numerical models are in good agreement...depicting a progressive
large scale flow across the lower 48. Upper trough tracks east across
the Great Plains and Midwest through Thursday. Lingering Post-
frontal precipitation will end tonight. Could see an additional
few inches of snow for higher elevations out west. Drier
northwesterly flow downstream of intermountain west upper ridge
will become the dominant feature. Winds decrease tonight with the
relaxing low level pressure gradient...with lighter winds Thursday
through Friday as the ridge axis mov3es overhead. Late in the
period...a upper low pressure system will track across northern
Baja California/Southern California toward Arizona and produce a large precipitation
shield over The Four Corners region. The northern edge of the
moisture will spread north into far south central and southeast Wyoming
Friday afternoon and night. Only light quantitative precipitation forecast is forecast from the
snowy/Sierra madres east into far southeast Wyoming plains.
Temperatures will remain above seasonal normals with highs in the
40s east and 30s west...and lows mainly in the 20s.

Long term...(saturday through wednesday)
issued at 125 PM MST Wednesday Jan 28 2015

Medium range models continue to show a broad-scale circulation along
the US-Mexico border early in the period. Not much has changed from
our earlier thinking with this system being too far south to have an
impact on our County Warning Area. GFS/ECMWF/NAM all show split flow over southeast
Wyoming and the western NE Panhandle. The best 700 mb-300 mb moisture remains to
the south of the Wyoming-Colorado state line...and the northern stream midlevel
energy stays out of reach over the western Dakotas. The models paint
very little/if any quantitative precipitation forecast...even over the mountains. Went ahead and cut
probability of precipitation for most areas except the southern zones. A cooling trend will
likely persist through the weekend with the main cold front arriving
on Sunday...forcing 700 mb temperatures to between -8 and -10 degree c east of the
Laramie range. The GFS suggests strengthening low level gradients by late
Sun night or early Monday as a surface low over northern Wyoming contributes
to pressure falls over the plains. 700 mb-800 mb winds are prognosticated above 50
kts during that would not be surprised to see a high wind
episode for the wind prone. Models are in decent agreement with the
northern stream taking over the flow pattern on Tue/Wed. A few weak
disturbances and periodic shots of middle level moisture should support
low end precipitation chances through middle week...but no major storms appear
likely at this time.


Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1037 PM MST Wednesday Jan 28 2015

VFR for areas along and east of Interstate 25 including across the
Nebraska Panhandle through the taf period. IFR to MVFR tonight
through the Laramie valley and into Carbon County due to low
clouds. Snow will reduce visibilities and cause mountains to be
obscured into the snowy and Sierra Madre ranges tonight. Ceilings
will improve and clouds will disperse into Thursday morning as
drier air moves into the region.


Fire weather...
issued at 125 PM MST Wednesday Jan 28 2015

No fire weather concerns through the upcoming weekend. Gusty
northwest winds...cooler temperatures...higher humidities and
some precipitation will spread across the district this afternoon
in the wake of the morning cold frontal passage. Winds will
frequently gust to 50 miles per hour this afternoon...then diminish tonight
with the relaxing pressure gradient. Snow will end from north to
south along and west of the Laramie range tonight...with another
one to three inches possible for elevations above 8000 feet. Drier
conditions and lighter winds will return Thursday and Friday...with
minimum humidities between 35 and 40 percent. A low pressure system
will move across the central and southern rockies this weekend. While
the bulk of the precipitation will fall south of Wyoming...there is
a chance for light precipitation over portions of southeast Wyoming
and western Nebraska.


Cys watches/warnings/advisories...



short term...mj
long term...clh
fire weather...mj

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