Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Cheyenne Wyoming
1141 am MDT Monday Mar 30 2015

issued at 1018 am MDT Monday Mar 30 2015

Looking at area observations this morning...we are getting wind
gusts here at Cheyenne...Pine Bluffs and wydot sites at Bear Creek
and gun barrel at or slightly above 25 miles per hour. With continued think we will continue seeing these gusts through the
afternoon. Went ahead with a red flag warning for fire weather
zone 310 today. More widespread winds expected went
with a Fire Weather Watch for areas east of the Laramie range.


Short term...(today through wednesday)
issued at 402 am MDT Monday Mar 30 2015

A couple of quite mild/warm days will occur over the County Warning Area today
through Tuesday as an upper ridge approaches today then shifts
east across the region on Tuesday. A weak surface high will move into
northern Wyoming today creating a weak downslope flow over the plains with
mostly clear skies allowing temperatures to rise well into the 60s to
lower 70s across lower elevations. Similar pattern for Tuesday
though a bit stronger Lee trough should exist over the High
Plains. Maximum temperatures should be about 4-7 degrees warmer over the
plains as a thermal ridge moves across with 700mb temperatures warming to
about 5-8c Tuesday afternoon. Middle level moisture should begin to
step up a bit Tuesday afternoon as the upper ridge axis moves east
of the County Warning Area and west-southwest upper flow sets up. May see a few high-based
showers mainly around the mountains later Tuesday afternoon into
Tuesday night as weak impulses move by. Pacific front will then
pass across early Wednesday as a decent shortwave swings across the
northern rockies into the northern plains by late Wednesday afternoon with
cooler and somewhat breezy conditions for Wednesday.

Long term...(wednesday night through sunday)
issued at 402 am MDT Monday Mar 30 2015

The main forecast concern will be the return of accumulating
snowfall generally south of the North Platte River Valley Thursday
and Thursday night. A broad upper-level trough comprised of two
shortwaves will be in place across the western U.S. And northern plains
Wednesday nt. The cold front associated with the shortwave over the
northern plains will already be well south by Wednesday night. There will
be little if any moisture available Wednesday nt with perhaps just a
few very light showers close to the Wyoming/Colorado Stateline. This initial
front will effectively prime the llvls in time for the second
shortwave that will approach on Thursday and move overhead Thursday
nt. Both the GFS/European model (ecmwf) are consistent in breaking out some light
precipitation across northern Colorado and areas south of i80 Thursday morning.
As the trough approaches as Thursday progresses...moist isentropic
lift atop the low level upslope flow will be the culprit for precipitation
becoming more widespread. 700 mb temperatures are even colder than earlier have cooled highs into the 30s for locations above around
5500 feet on Thursday. Suspect this will be a reasonable cut-off
elevation for the accumulating snow potential as well. Moist
isentropic lift persists Thursday night before the trough departs
Friday morning. Areas of light to moderate accumulations will be
possible above 5500 feet mainly Thursday afternoon and Thursday
night. Although the trough axis departs on Friday...the trailing middle-
level cold pool and associated daytime destabilization will be
enough to continue shower chances Friday. Temperatures will still be
relatively cool on Friday with highs only reaching the 40s at most

Temperatures will warm back towards normal on Saturday and Sunday
with a broad low-amplitude ridge yielding dry conditions.


Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1138 am MDT Monday Mar 30 2015

VFR conditions through the taf period. West to northwest winds
will gust to 20-30 kts at many of the sites through 00z. Winds
will come down after sunset and remain weak through the remainder
of the night. Cloud cover will be limited to scattered high clouds
over the northern Nebraska Panhandle.


Fire weather...
issued at 402 am MDT Monday Mar 30 2015

Warming temperatures this morning has allowed stronger winds to
mix down from higher elevations. Already seeing wind gusts in
excess of 25 miles per hour at several locations and expect these gusty winds
to continue into the afternoon hours. More widespread winds are
expected for Tuesday as afternoon temperatures climb 8 to 10
degrees warmer over todays highs. Wind gusts in excess of 30 miles per hour
appear likely Tuesday. A cool front will pass across early
Wednesday bringing cooler temperatures Wednesday and especially Thursday with
at least scattered rain and snow showers Thursday and Thursday


Cys watches/warnings/advisories...
Wyoming...Fire Weather Watch from Tuesday morning through Tuesday evening
for wyz301-310.

Red flag warning until 8 PM MDT this evening for wyz310.

NE...Fire Weather Watch from Tuesday morning through Tuesday evening
for nez311>313.



long term...cah

National Weather Service Glossary of Abbreviations