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 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KCYS 241759
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1145 AM MDT SAT SEP 24 2016

.SHORT TERM...(Today through Sunday night)
Issued at 255 AM MDT Sat Sep 24 2016

The main concern today will be how long the precipitation will
linger across the northern portions of the forecast area today.

Today:
Latest radar loop was showing the precipitation continuing to lift
north to northern Wyoming. This precip. caused quite the show
overnight especially between Rawlins and the I-80 Summit. In fact,
the I-80 summit received nearly 4 inches of snow with Laramie
receiving 2 inches. This precip was beginning to dissipate in
response to a dry slot to the northeast of this precip. Not
completely sure if this trend will continue, since there appears
to be more radar returns developing across southern Wyoming as the
dry slot continues to fill in across Colorado. Latest water vapor
loop was showing some signs of cyclogenesis taking place across
northwest Wyoming. However, the bulk of the jet energy was lifting
north into the northern plains. The mid level flow was trying to
back to southeast and forming a weak trowal over northwest
wyoming. On the back side of this upper level low in northwest
Wyoming there is significant potential vorticity anomaly and jet
energy diving south. This potential vorticity anomaly should help
kick this upper level low east during the course of the day.
However, I am not seeing any signs of the moisture kicking out of
the picture yet. As a result, we may see the development of more
scattered showers this afternoon across southeast Wyoming. We did
lower temperatures a bit compared to the previous forecast since
the ground temperatures will be a bit cooler from the precip.
overnight.

Tonight:
A chilly night is in store for much of Wyoming as the surface high
settles over the area. In fact, Laramie and Rawlins may drop below
freezing with rest of the area ranging from 35 to 40. Day shift
may want to look at the potential for frost headlines in portions
east of the Laramie Range.

Sunday-Sunday night:
Cool temperatures will remain in tact on Sunday as the surface high
slowly drifts east into the Nebraska Panhandle. Could be a bit
breezy in the panhandle on Sunday afternoon. Otherwise, the
sunshine will be prevalent with afternoon highs ranging from 55 to
65. Overnight lows will once again be quite chilly with lows
mainly in the 30s.

.LONG TERM...(Monday through Friday)
Issued at 255 AM MDT Sat Sep 24 2016

Monday...Decent warming trend on tap as the ridge aloft strengthens
and the airmass moderates. Based on thicknesses and 700 mb
temperatures near 8 Celsius, expect high temperatures from the mid
60s to lower 70s.

Tuesday...Another dry and mild early Autumn day with the ridge aloft
overhead. Sticking close to guidance maximum temperatures based on
progged 700 mb temperatures.

Wednesday...Will likely see some increase in middle and high
cloudiness ahead of the next approaching slow moving shortwave over
the Great Basin states. Continued mild per thicknesses and 700 mb
temperatures.

Thursday...A little bit cooler as cloud cover increases with a weak
shortwave approaching from western Wyoming and western Colorado.
Perhaps enough moisture for isolated mountain showers in the
afternoon.

Friday...Weak southwest flow aloft continues and with limited low
and mid level moisture, no precipitation expected. Continued mild
based on the expected 700 mb temperatures.

&&

.AVIATION...(For the 18Z TAFS through Sunday morning)
Issued at 1130 AM MDT Sat Sep 24 2016

MVFR conditions will likely continue at KRWL this afternoon and into
this evening with low CIGS and scattered rain showers. VFR
conditions will prevail at KLAR and KCYS...but periods of MVFR CIGS
are expected as rain showers push further east and dissipate near
the Laramie Range. VFR will continue across the western Nebraska
terminals with West winds shifting into the northwest with gusts up
to 30 to 35 knots this afternoon.

&&

.FIRE WEATHER...
Issued at 255 AM MDT Sat Sep 24 2016

Drier air is expected to filter into the Nebraska Panhandle today
as the upper level trof lifts into the Northern Plains. This area
will receive strong west-northwest winds this afternoon at speeds
of 15 to 25 mph with some gusts to 35 mph. Relative humidites will
also be quite low in the panhandle this afternoon with values
possibly dropping to 20 to 25 percent. Meanwhile, southeast
Wyoming may see the redevelopment of more scattered showers this
afternoon. The threat for critical fire weather conditions will be
quite low from Sunday through the middle of next week due to light
winds.

&&

.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&

$$

SHORT TERM...REC
LONG TERM...RUBIN
AVIATION...TJT
FIRE WEATHER...REC



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