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Area forecast discussion 
National Weather Service Cheyenne Wyoming
1013 am MST Wednesday Dec 17 2014

Short term...(today and through Friday night)
issued at 350 am MST Wednesday Dec 17 2014

Split flow pattern will be in place across the region today. There
is a weak shortwave moving to the north of the County Warning Area and a more
potent and moisture laden shortwave over northern New Mexico. This
puts US in the middle between the systems. The models continue to
indicate that the best moisture associated with the southern wave
will be south into Colorado. Thus...only have slight chance to
chance probability of precipitation over the Sierra Madre and snowy ranges through the
day. The only noticeable impact over much of the County Warning Area will be an
increase in middle and high level clouds. The eastern zones will be
dealing with stratus through the morning as winds to the east of
the surface trough are southerly out there. Another cool day is in
store and dropped highs a few degrees over the Panhandle where
snow cover is still present. Winds will once again be rather weak
with minimal low level gradients and flow aloft.

There will not be much change in the pattern through the remainder
of the short term. The cag-cpr gradient...which stays below 25
meters through Thursday night...will increase to 35-40 meters by
Friday morning and afternoon. Thus...will begin to see winds become breezy
over much of southeast Wyoming by Friday and locally windy in the wind
prone spots. Temperatures will remain constant through
Friday...generally at seasonal norms for middle Dec. Slight chance probability of precipitation
will be confined to the mountains west of the Laramie range.

Long term...(saturday through wednesday)
issued at 350 am MST Wednesday Dec 17 2014

The main highlights for the weekend and early next week will be the
return to breezy to locally windy conditions across southeast
Wyoming along with a good shot of mountain snow late Sunday through
Monday. Weak non-descript west/northwest flow will be in place on
Saturday. Weak shortwave energy will be embedded within the
flow...but aside from light snow shower chances for the snowy/Sierra
madres expect little if any sensible weather impact. Saturday will
be the last relatively wind-free day across southeast Wyoming before
the wind machine gets cranking sun-Tue.

00z models have trended faster with the timing of the nose of the
anticyclonic pushing it in during the day on Sunday. So
will see a steady increase in wind speeds...first across the wind
prone areas Saturday night before spilling into lower elevations
Sunday and Monday. 700 mb wind forecasts continue to reach 50-60 knots
during this period which should be enough to necessitate a wind
highlight at least for the wind prone areas with time. Areas away
from the typically windy areas are more tricky and typically tied to
magnitude of planetary boundary layer which can be affected by a number of things
including cloud cover. At the very least will see widespread breezy
conditions even spreading over into the western Nebraska Panhandle Monday-
Tuesday. The good news with the return of the wind will be that
temperatures will warm around 5f area wide with deeper low level mixing.
High temperatures on Monday will return to near 40 west of the Laramie
range and middle 40s east.

Models clip the area with a series of shortwave troughs Sunday and
Monday. Moisture advected by these will combine with favorable
orographic flow to produce a good chance for accumulating mountain
snows especially late Sunday through Monday. Amounts would add up in
a hurry in this pattern and if trends continue would probably need
some sort of a winter highlight there in time. Areas outside of the
mountains may see some precipitation as well especially Sunday night
and Monday...though do not see significant accumulations with this

Dry conditions will return Tuesday-Wednesday with early indications of a
fairly strong cold frontal passage for just beyond this
time period...for Christmas.


Aviation...(for the 18z tafs through 18z Thursday morning)
issued at 1013 am MST Wednesday Dec 17 2014

VFR expected over southeast Wyoming terminals through the period. IFR to MVFR
ceilings/visibilities likely to hold across the Nebraska Panhandle for most of
the period due to snow cover and weak upslope flow.


Fire weather...
issued at 328 am MST Wednesday Dec 17 2014

No fire weather concerns through Friday. Cold temperatures
will keep snow cover on the ground across much of the region.
Afternoon humidity values will generally be above 45 percent and
winds will be weak through Thursday. By Friday...west winds will
become breezy for areas along and west of the Laramie range.


Cys watches/warnings/advisories...


Short term...zf
long term...cah
fire weather...zf

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