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Area forecast discussion 
National Weather Service Cheyenne Wyoming
913 PM MST sun Jan 25 2015

Update...
issued at 906 PM MST sun Jan 25 2015

No significant adjustments necessary to the forecast this
evening...with winds slowly falling as expected. The only change
was to bump up cloud cover across western and northern zones to reflect
latest satellite pictures which shows a broad area of cirrus drifting
southeast towards the County warning forecast area from western/central Wyoming. Although
dissipation was occurring on the downstream side of the cloud
canopy...felt it was enough to at least add a partly cloudy
mention to mainly Carbon and Converse counties.

&&

Short term...(this evening through Tuesday night)
issued at 358 PM MST sun Jan 25 2015

Light rain showers occurred this morning in the vicinity of the
Pine Ridge and from Lusk to Scottsbluff within warm air advection regime and a
band of higher low level moisture. Associated low-midlvl stratus that
plagued much of the area this morning has lifted and is quickly
shifting east into central Nebraska this afternoon with mainly
some middle-hi level cirrus associated with a weak shortwave moving
overhead in northwest flow. The warm air advection pattern is also maintaining
breezy winds over much of the County Warning Area this afternoon while the
850/700mb cag-cpr pressure gradient hovers around 50/35 dam
respectively.

Breezy conditions will continue through the short-term period in the
wind prone areas under subsident flow and with a persistent low level
gradient in place. Gusts will average 35 to 45 miles per hour with higher
speeds at times especially during climatologically favorable times
such as early morning hours. Dry conditions will occur as well
within this setup...along with very warm temperatures. 700 mb temperatures will
generally range 4-6 c for Monday and Tuesday and models continue
to show minimal cloud cover overhead both days.
Therefore...continued the trend toward slightly higher than MOS
guidance in some areas...especially near the Laramie range...with
warm temperatures aloft and downslope winds likely to add a few more
degrees. Many records are in jeopardy both Monday and Tuesday with
highs expected to be well in the 60s across the plains...and 40s-50s
out west. The other issue will be enhanced drying to the Lee of the
Laramie range due to breezy downslope winds. Rhs could drop into the
middle teens on Tuesday with gusty winds of 25-35 miles per hour in this
area...enhancing fire weather concerns. Looking mainly at fwz 310
for enhanced concerns.

Models continue to agree on the next shortwave trough moving up from
the southwest and over The Rockies late Tuesday into Wednesday.
Leeside troughing will strengthen the low level gradient ahead of the
wave Tuesday night...so could be dealing with a marginal high wind
event in the wind prone areas early Wednesday morning. NAM shows 800-
750mb winds of 50 to 60 kts from 06-12z Wednesday mainly along
the Laramie range...so highest winds could be focused near
Bordeaux/foothills. Will have to keep an eye on how models trend
with this setup the next few days. In addition...moist upslope
flow will increase along the western slopes in addition to weak
jet diffluence...so snow will likely develop in the snowy and
Sierra madres late Tuesday night as well.

Long term...(wednesday through sunday)
issued at 358 PM MST sun Jan 25 2015

Shortwave will pass across the area Wednesday bringing cooler temperatures to
the County Warning Area with scattered rain and snow showers mainly over western parts
of the County Warning Area. Precipitation will end Wednesday night with a short upper ridge
passing by on Thursday...though temperatures will be more seasonal. GFS
has now come into much better agreement with the ec in handling
the shortwave energy moving into the SW Continental U.S. Late Thursday and
Friday...closing off an upper low over the far SW and now keeping
the bulk of its associated precipitation south of the County Warning Area. Ec just glances
the southern County Warning Area with some precipitation Friday into Friday night while the GFS
keeps it well south...quite a change from yesterdays depiction.
Will continue favoring the ec given its better consistency. Other
change is to reduce the amount of cooling late in the week as
models now shift the bulk of the colder air farther east towards
the large upper cyclone over southeast Canada and the northeastern US.
Dry weather should prevail over the weekend with northwesterly flow aloft.

&&

Aviation...(for the 00z tafs through 00z Monday evening)
issued at 358 PM MST sun Jan 25 2015

VFR expected through Monday as a drier northwesterly upper wind flow sets
up over the area ahead of upper ridging to the west.



&&

Fire weather...
issued at 358 PM MST sun Jan 25 2015

No major fire weather concerns. Warm temperatures and locally breezy
conditions are likely through Monday afternoon. Locally enhanced
drying to the Lee of the Laramie range could drop humidities into
the middle teens on Tuesday...with breezy conditions in place. The
main focus for these conditions will be for eastern fwz 309/western
fwz 310.

&&

Cys watches/warnings/advisories...
Wyoming...none.
NE...none.
&&

$$

Update...cah
short term...rjm
long term...re
aviation...re
fire weather...rjm

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