Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

FXUS65 KCYS 131747

Area Forecast Discussion
National Weather Service Cheyenne WY
1147 AM MDT Tue Mar 13 2018

.SHORT TERM...(Today and tonight)
Issued at 308 AM MDT Tue Mar 13 2018

Latest water vapor loop was showing a fairly strong potential
vorticity anomaly diving southeast across the upper midwest. As
this feature continues to push southeast, it will enable the
upper level ridge to build over region during the next couple of
days. As a result, we should see nearly full sun today and mostly
clear tonight except for the west where the cirrus will be a bit
more prevalent.

.LONG TERM...(Wednesday through Monday)
Issued at 308 AM MDT Tue Mar 13 2018

Wednesday could be a bit breezy mainly around Rawlins and the
Muddy Gap region, but temperatures will be on mild side with
afternoon highs in the 60s and perhaps low 70s in the North Platte
Valley. The only thing that may put a damper on the day will be
the veil of high clouds.

As we head into Wednesday night and Thursday, the models are in
better agreement in pivoting a shortwave from the base of the
upper level closed low currently over the Pacific northwest. This
shortwave and associated jet energy is expected to induce a
surface low over northern Colorado. Another concern is that the
models are also showing some jet energy moving through western
Wyoming. This in combination with the jet energy moving through
southern Colorado, could result in a coupled jet scenario over the
Laramie Range. It may also result, in a surface low over the
northern Laramie Range. What this means, is that we may start to
see snow as early as Thursday afternoon across the higher
elevations in areas along and west of the Laramie Range and
continue into Thursday evening, before the shortwave tracks east
across the rest of the forecast area Thursday night. WPC is
advertising this scenario as well, but they are also concerned
that this shortwave may dig a little further south. If this
occurs, we may be looking at a quicker changeover to snowfall. For
now, we have backed off on highs on Thursday due to the
increasing cloud cover in the afternoon especially in Wyoming. At
this point, we are advertising the highest snow amounts across the
Laramie Range (4-8 inches), (4-6 inches Snowy and Sierra Madres),
with 2 to 4 inches possible along and north of a Douglas to
Alliance line by Friday morning. Elsewhere, we are looking at
mostly at rain/snow mix but this changeover could happen sooner if
this system dives a little further south.

The snow should come to end on Friday morning over the Nebraska
panhandle. Due to the proximity of the surface low, areas along
the I-80 corridor in southeast Wyoming may experience a windy day
as well. The next shortwave in line to affect the region will be
on Sunday, but there is still quite a bit of uncertainty on the
track of this feature.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1147 AM MDT Tue Mar 13 2018

Fairly quiet weather regime for the next 24 hours with light to
moderate winds and VFR category expected to prevail.


Issued at 308 AM MDT Tue Mar 13 2018

A strong upper level ridge will build into the area today and
Wednesday and bring mainly dry conditions to the area. However, it
will be a bit windy across the west on Wednesday afternoon with
humidity values ranging from 25 to 30 percent which may cause some
elevated fire weather conditions. The next disturbance is expected
to move into the area Thursday-Thursday night and bring mostly
snow to the higher elevations of Wyoming Thursday afternoon with
rain changing over to snow Thursday evening and Thursday night
across the rest of the state. Meanwhile, the Nebraska Panhandle
may see mostly snow in the north on Thursday night with a
rain/snow mix further south. This will be followed a windy day on
Friday and another disturbance moving into the region Sunday and
Sunday night.




FIRE WEATHER...REC is the U.S. government's official web portal to all federal, state and local government web resources and services.