Scientific Forecaster Discussion

Return to Local Conditions & Forecast
Area forecast discussion 
National Weather Service Cheyenne Wyoming
1129 PM MDT Wednesday Apr 23 2014

issued at 614 PM MDT Wednesday Apr 23 2014

Increased pop this evening with light rain showers near the
Colorado border as an upper level disturbance pushes across the
central Rocky Mountains. Rain was reported in Sidney in the last
half hour...otherwise it has been dry in Cheyenne and Kimball so
far. This activity will move out of the area in the next few hours
as the disturbance quickly moves east into Kansas and Nebraska.

Also updated forecast to allow the Wind Advisory to expire this
evening. Breezy conditions are expected over western Nebraska
tomorrow with gusts around 30 miles per hour in the afternoon...with windy
conditions further west across southeast Wyoming.


Short term...(this evening through Friday night)
issued at 412 PM MDT Wednesday Apr 23 2014

Forecast challenges in the short term deal with fire weather
concerns. Please see fire discussion below.

Currently...cold front that moved through the area overnight and
this morning continues to move into central Nebraska this
afternoon. Still seeing some pretty strong west to northwest winds
behind the front with reports in the Panhandle still showing wind
gusts in excess of 42mph at the Scottsbluff and Agate RAWS sites.
Sidney has just recently begun to get really close to advisory
criteria out will keep the Wind Advisory going this
afternoon. It may be possible to cancel early as latest infrared imagery
showing dense middle and high level clouds beginning to develop over
the south Laramie range...spreading east.

Winds will ease some tonight...though would expect our wind prone
areas to continue to experience elevated winds. GFS 700mb winds
remain strong tonight...keeping 40+mph winds going over Albany
County. 850mb wins stay up all night as well out over the
Panhandle with 20 to 25kts forecast on the GFS. This should keep
overnight humidities from recovering very we will start
off Thursday pretty warm and dry.

Looking at model soundings Thursday...looks like we should mix
well during the afternoon...reaching possibly 600mbs where winds
are forecast at 35kts on the usually weaker NAM. This should be
easily enough winds to create fire weather conditions in the
Panhandle Thursday afternoon. GFS 700mb temperatures quite warm as
well...warming from -4c this afternoon...up to +2c tomorrow we should be considerably warmer over todays highs.

Warmer temperatures for Friday as upper level ridge builds over
the County warning forecast area. GFS forecasting 700mb temperatures of +4c over southern
Wyoming. So afternoon highs should be in the middle 70s across the
Panhandle with upper 60s across southeast Wyoming.

Long term...(saturday through wednesday)

Issued at 412 PM MDT Wednesday Apr 23 2014

Models remain fairly consistent with the synoptic pattern in the
long term. A strong upper level low will move across the Great Basin
and Desert Southwest on Saturday...and looks to become a stacked
system on Sunday over the Central Plains. Ahead of the
low...increasingly diffluent flow will move overhead along with
strong positive vorticity advection. The leeside trough will deepen on Saturday
morning...with a surface low prognosticated to develop over northeast
Colorado through the day. Low level moisture advection occurring within
the northern and eastern periphery of the developing surface low will
bring increasing chances for showers and thunderstorms in the
afternoon for this area...which includes northern portions of the
Panhandle and east central Wyoming. With the energetic flow moving
overhead...will also see activity increase through the day over
the mountains. Areas east of the southern Laramie range may lack
overall moisture and surface forcing to support thunderstorms until the surface
low wraps up later in the afternoon/evening. Models show the surface
low slow to move to the east-southeast on Sunday as the upper low
moves into the Central expect continued chances for
showers and thunderstorms for the Nebraska zones which may still be in
the warm sector at this time. Further west...will begin to see
more of steady rain with snow in the higher elevations of the
snowy and Sierra madres through the day. As cold air advection increases behind
the slow moving system through the evening...will likely see a
changeover to snow in the lower elevations of southeast Wyoming as
well. May not see snow in the Panhandle until Monday morning.
Timing of this changeover will be very tricky though as the origin of
the cold air looks to be highly modified airmass from the Pacific
and Continental may not be all that cold in general.
Regardless...strong surface and midlevel forcing will keep quantitative precipitation forecast on the
higher end...with models producing a quarter to half inch of quantitative precipitation forecast
for a good portion of the County Warning Area through late Sunday night. The
system will trek toward the Midwest on Monday...with wraparound
moisture and energetic northwest flow maintaining chances for rain
and high elevation snow. Northwest winds will be blustery through
this time as the surface pressure gradient remains fairly tight as the
system departs. Tuesday will see continued gusty northwest
winds...but less moisture will be available for rain and snow.
Daytime temperatures will fall from the 60s and 70s on the
40s and 50s through the remainder of the forecast period.


Aviation...(for the 06z tafs through 06z Thursday evening)
issued at 1126 PM MDT Wednesday Apr 23 2014

VFR prevails.

Wyoming tafs...winds gusting near 30 knots overnight...then 35 to
40 knots during the daylight hours on Thursday.

Nebraska tafs...winds gusting 25 to 30 knots during the daylight
hours on Thursday.


Fire weather...
issued at 412 PM MDT Wednesday Apr 23 2014

Critical fire weather conditions in the Nebraska Panhandle
Thursday as downsloping winds continue to dry out the lower layers
of the atmosphere. Looking at minimum afternoon humidities of 10
to 13 percent with winds gusting to 30 miles per hour...especially for fire
zones 312 and 313. Will be issuing a Fire Weather Watch for
Thursday afternoon for these zones. Low pressure causing these
winds over eastern Montana will move east into the Dakotas
Thursday night into Friday with the associated cold front moving
east. Next chance for wetting rains and mountain snows will be
Saturday night into Sunday as a strong Pacific low pressure system
moves into Utah and tracks across northern Colorado. Everyone
should see accumulating rains and mountain snows Sunday into
Monday as this slow moving low moves northeast into southern


Cys watches/warnings/advisories...
NE...Fire Weather Watch from Thursday afternoon through Thursday
evening for nez312-313.



short term...claycomb
long term...rjm
fire weather...claycomb