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Area forecast discussion 
National Weather Service Cheyenne Wyoming
337 PM MST Sat Feb 28 2015

Short term...(this evening through Monday night)
issued at 340 PM MST Sat Feb 28 2015

A few snow flurries will linger along the eastern fringes of the
southern Laramie range through this afternoon. The main chances
for accumulating snow will occur this evening and into the
overnight as subtle shortwave features move into southeast Wyoming
from Colorado...and elevated warm advection develops. The best
chances for snow accumulations outside of the mountains will be
along and near the Colorado border but even there any
accumulations will be minimal and generally less than one inch.
Kept slight chances going into east central Wyoming and the
northern Nebraska Panhandle...but it is looking less likely that
any snow will occur in those areas tonight or tomorrow with the
best upper level forcing well to the south.

Will have to keep an eye on how the upper levels evolve early next
week. Models showing a cut off low ejecting northeastward out of
California as a kicker drops south off the Pacific northwest
coast. European model (ecmwf) initially keeps much of the energy over southcentral
Wyoming Monday into Monday night and then quickly pushes things
eastward. The GFS brings the main energy over far southeast
Wyoming and produces higher amounts of precipitation there. Not
confident in either solution and somewhat surprised how much
precipitation the models are producing given the placement of the
upper level jet.

Depending on the next round of model runs...may need winter weather
headlines for southcentral Wyoming Monday through Monday night.
Light snow could start falling in that area late Sunday night but
at this time it appears a majority of the snow will fall after 12z
Monday through Monday night across this area.

Long term...(tuesday through saturday)
issued at 315 PM MST Sat Feb 28 2015

Main forecast concern in the medium range will be the continuing
winter weather event on Tuesday. Models are in pretty good
agreement with this storm system...showing a secondary shortwave
aloft digging southward...which will be associated with the
Arctic airmass moving into Wyoming early Tuesday morning. High
temperatures on Tuesday will likely be similar to the low
temperatures Monday night...and generally in the teens to low 20s.
Temperatures will lower into the single digits and low teens
through the afternoon as the 1035mb Arctic high at the surface
moves into the area. Kept a 60 percent to 80 percent chance of snow for
most of southeast Wyoming into Tuesday evening for an additional 1
to 3 inches of snow accumulation. Low temperatures Tuesday night
will be tricky and will greatly depend on the extent of surface
snow cover...depth...and if skies clear out or not. Considering how
progressive the system is as indicated by models...believe most of
the forecast area and especially north of i80...will have clearing
skies overnight. Low temperatures may approach -15 to -20 in the
more sheltered valleys across southeast Wyoming with the center of
the Arctic high just east of the Laramie range.
Elsewhere...temperatures between -5 to -10 appear likely at this
time if broken to overcast conditions continue through most of the

Wednesday through the end of the week...some flurries are possible
as the storm system exits the region to our south. Wednesday will
be the coldest day of the week with highs struggling to reach the
low to middle teens. Kept highs a few degrees above MOS...but gambling
that the westerly winds and March sunshine will result in
temperatures a few degrees higher than guidance.
Otherwise...temperatures may be stuck in the single digits through
the afternoon. Either way...a warming trend is expected for the
remainder of the week as the strong eastern Pacific Ridge expands
eastward a bit into the central and southern Rocky Mountains. Due
to potential snow cover...did keep temperatures lower than MOS
through the week...with temperatures above guidance by next
weekend as most of the snow should melt by that time. Expect highs
to return to the 40s to around 50 by Friday and Saturday


Aviation...(for the 00z tafs through Sunday evening)
issued at 231 PM MST Sat Feb 28 2015

MVFR ceilings will continue for portions of southeast Wyoming and
western Nebraska late this afternoon and into this evening due to
low level upslope flow. Isolate snow flurries will generally stay near
kcys into this evening...until light snow develops from south to
north along the i80 corridor by 04z late this evening. IFR
conditions and light snow are expected near klar...kcys...and
possibly ksny after 03z. The northward extent of this snow should
remain south of a line from krwl to kaia. This snow should
diminish in intensity by Sunday morning with a return to MVFR or
higher conditions by the afternoon.


Fire weather...

Issued at 240 am MST Sat Feb 28 2015

C0lder than normal temperatures...ample surface moisture from
snowfall...and high relative humidities will preclude fire weather
concerns through next week.


Cys watches/warnings/advisories...




Short term...small
long term...tjt
fire weather...maj

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