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Area forecast discussion 
National Weather Service Cheyenne Wyoming
617 PM MDT Wednesday Apr 16 2014

issued at 614 PM MDT Wednesday Apr 16 2014

Inherited gridded forecasts from our day shift forecast team in
good shape. Cheyenne WSR-88D reflectivity showing isolated
showers moving eastward across central Platte and central Goshen have painted some probability of precipitation here through the early
evening...though these likely will dissipate in the next few
hours with the loss of daytime heating.


Short term...(rest of today through Thursday night)
issued at 3 PM MDT Wednesday Apr 16 2014

Scattered rain and periodic light snow showers continue to traverse
southeast Wyoming and western Nebraska in the deep northwesterly
flow. On this forecast release we will continue with chance probability of precipitation
through the afternoon several areas tapering them back to slight
chance to none overnight with the loss of instability. Looking
aloft...the shortwave that moved through this morning has now pushed
well east of our area with no dynamic forcing tonight to support
additional probability of precipitation. Winds today across the Nebraska Panhandle gusted
close periodically to Wind Advisory criteria...but we didnt quite
get there on the speeds...and we think winds will diminish tonight
as pressure gradient relaxes as the low level ridge to the northwest
builds eastward.

Still expecting an uneventful Thursday in the weather department as
temperatures warm to the middle 50s to lower 60s east of the
mountains with 30s out west above 7500 feet. We may get some isolated
showers again on Thursday as a jetmax rolls over the top of the
southwestern upper ridge...and that may provide enough forcing to
squeek out a few showers...particularly in the north and
northeastern counties. Otherwise...previous forecast package we
inherited was not adjusted significantly for the next 24 hours.

Long term...(friday through wednesday)
issued at 314 PM MDT Wednesday Apr 16 2014

Models are in good agreement going into the weekend...showing a
pair of upper level troughs pushing across the western United
States on Friday and Saturday. All models show the northern branch
of the jet lifting further northward allowing the storm system
moving across the Pacific northwest to ejecting northeast into
Canada. The southern trough is still trending further
north...moving across The Four Corners region on Saturday and into
the Central Plains by Sunday. Scattered showers and isolated
thunder still looks possible this weekend with rain showers
becoming more numerous Friday night. Continued to increase
pop...and adjusted isolated coverage further to the northeast to
cover most of the High Plains into western Nebraska since the
trough is trending further north with marginal low level instability.
Even though a brief cool down is expected on Saturday...above
normal temperatures are expected with highs generally in the 50s
and 60s across southeast Wyoming and middle 60s to middle 70s across
western Nebraska. Isolated coverage of showers and thunder is also
possible on Sunday as the trough moves kept pop
around 15 percent near the Colorado border.

For early next expected...the GFS has backed off on the
strong upper level ridge over the Rocky Mountains. All models show
a flattened low amplitude ridge across the area and are now
hinting at the possibility for daytime convection each afternoon.
Increased pop over the area as showers and thunderstorms ahead of the
potent storm system pushing onshore on Tuesday can not be ruled
out. Either way...confident that temperatures will be well above
normal on Monday and Tuesday with highs pushing 80 degrees across
portions of western Nebraska.

For Wednesday...models show the deep upper level low moving across
the western United States. The exact position and movement of this
storm is still uncertain...but will need to watch it closely for
potential impacts during the middle of next week. At this
time...the GFS and European model (ecmwf) show the storm north of the forecast
area. Some of the ensemble do show it digging southward and
ejecting northeast into the Central Plains. For now...started to
increase pop from west to east...lowered temperatures back to near
normal...and increased winds over the area.


Aviation...(for the 00z tafs through 00z Thursday afternoon)
issued at 535 PM MDT Wednesday Apr 16 2014

Wyoming tafs...isolated showers across Platte and Goshen counties
will dissipate by early this evening. VFR prevails at Rawlins.
IFR will develop at Laramie and Cheyenne after 06z in fog and/or
low clouds with ceilings and visibilities improving to VFR after
13z. Some mountains obscured late tonight through early morning

Nebraska tafs...isolated showers near Scottsbluff through early
this evening. VFR this evening...then IFR in low clouds and fog
developing after 05z...with ceilings and visibilities improving
to VFR after middle morning Thursday.


Fire weather...
issued at 230 PM MDT Wednesday Apr 16 2014

Minimal fire weather concerns as the area remains cool with high
humidities at during the day. Drier conditions expected into
Friday...but humidities will remain above critical levels with
excellent overnight recoveries through the weekend.


Cys watches/warnings/advisories...


short term...garmon
long term...tjt
fire weather...tjt