Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Cheyenne Wyoming
515 PM MST Thursday Nov 26 2015

issued at 508 PM MST Thursday Nov 26 2015

Automated sensors and radar trends shows snow diminishing across
the region early this evening. Expect this trend to continue through
the rest of the went ahead and allowed the winter
weather advisories to expire at 5 PM. Even so...roads will remain
snow-covered and slick overnight. The next question mark will be
the need for a potential Wind Chill Advisory across parts of
Wyoming tonight. Will take a closer look at that here shortly.
Otherwise...overnight lows will plummet into the single digits
across the Panhandle and in areas closest to the Wyoming/NE
Stateline...along with single digits below zero for areas along
and west of I-25.


Short term...(tonight through saturday)

Scattered snow showers continue across much of southeast Wyoming and the
western NE Panhandle this afternoon. No changes from this am...with
the more persistent snow band over central/eastern Laramie Colorado. This
is likely the result of northeast low-level upslope beneath upper-
level divergence associated with the h25 jet energy now focused over
the Central High plains. The light/fluffy nature of the snow is not
causing too many problems with visibilities. Impacts from the winter
storm are starting to wind down...with the majority
National Weather Service Cheyenne wyof wydot webcams
hinting at slick roads but no issues with snow/blowing snow. Decided
to let the Winter Weather Advisory ride through 5 PM since there are
still some areas of accumulating snow.

Wind chills are the main concern for tonight...mainly along the I-80
corridor from The Summit westward into Rawlins. Low temperatures are
going to heavily depend on cloud cover. There is plenty of low-level
moisture around which could promote continued stratus...but both visible
and water vapor satellite suggests subsidence spreading into western
Colorado along with some clearing. This could help clear things out
enough to allow temperatures to plummet. With winds at or above 10
would almost certainly yield wind chills -20 to -25 f. Will let the
evening shift re-evaluate and assess the need for an advisory.

An unsettled pattern will continue through Saturday. GFS/NAM/ecm are
in good agreement with several pieces of shortwave energy continuing
to rotate around the parent low over the southwest US. One such wave
is lifting across central Colorado at this time...and is prognosticated to lift to our NE
tomorrow. Subsidence and drying behind this wave should yield precipitation
decreasing in coverage through the day on Friday. Next chance for accumulate
snowfall will be late Friday night/Sat am as positive vorticity advection increases ahead of the
next disturbance and a warm front lifts north. Potential exists for
an inch or two of snow...but looks sub-advisory right now.

Long term...(saturday night through thursday)
issued at 330 PM MST Thursday Nov 26 2015

Confidence in the extended forecast period is relatively low. The
evolution of the current cut off upper low which is over the
western Continental U.S. Is the main source of forecast uncertainty. Models
are generally in good agreement showing a slow eastward
progression of the upper low into the plains by early next
week...however models tend to handle these situations poorly. The
other question is to what extend will pieces of shortwave energy
rotate across southeast Wyoming and the western Nebraska
Panhandle. Chances for precipitation will be largely determined by
timing and strength of shortwave energy. Therefore not completely
ruling out chances for precipitation into the later portions of
the forecast period but at this time the forecast is mainly dry
Wednesday and Thursday. One thing is certain...daytime
temperatures will be below normal for early portions of next week.
Warming is expected by late in the week but that too is dependent
on eastward progression of the upper level low.


Aviation...(for the 00z tafs through 00z Friday evening)
issued at 515 PM MST Thursday Nov 26 2015

With snow coming to an end across the region...have generally
trended taf categories up through the overnight period. The exception
will be at kcys...where things may head up for a time this
evening...but should see low ceilings and/or fog roll back in 06-18z.
For western Nebraska Panhandle sites...conditions will trend back
towards VFR after the 03-06z timeframe.


Fire weather...
issued at 300 am MST Thursday Nov 26 2015

No fire weather concerns anticipated in the near term due to snow
through the end of the week...and very cold temperatures through the


Cys watches/warnings/advisories...


short term...clh
long term...small
fire weather...clh

National Weather Service Glossary of Abbreviations