Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 160531
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1131 PM MDT Wed Mar 15 2017

.UPDATE...
Issued at 809 PM MDT Wed Mar 15 2017

Subsidence associated with a weak upper level PV anomaly passing
to the north along with deeply mixed boundary layer will allow
westerly winds to increase to near 25 mph with gusts to 40 mph by
late Thursday even into the SW Nebraska Panhandle. Latest short
range models are consistent in bringing in critical RH values
around 15 percent in this same area with the HRRR time-lagged
ensembles giving a 90 percent probability of critical fire weather
conditions. One caveat is the potential for more cloud cover
associated with the shortwave which would reduce the amount of
insolation and prevent RH from reaching critical thresholds. In
light of all this, decided to go with a Fire Weather Watch for
zone 313 to allow the later shifts to monitor trends in the cloud
cover.

&&

.SHORT TERM...(Tonight through Friday Night)
Issued at 243 PM MDT Wed Mar 15 2017

High clouds continuing to stream across much of the CWA but
clearing from the west with the upper ridge moving slowly east
into the Rocky mtn area. The ridge will move across the area while
weakening overnight leaving a generally zonal flow over the CWA
Thursday through Friday. Another warm day across the CWA Thursday
with plenty of sun and dry downslope flow. Max temps will be in
the 70s east of the mtns...nearing 80 across the southern Neb
Panhandle.

A cool front will sink south across the plains Thursday night as
a shortwave moves across the northern Rockys into the northern
plains. Dry air will preclude pcpn for the most part though a few
light showers not out of the question Thursday evening over
northern parts of the CWA closer to the shortwave. Friday will be
dry and cooler especially over the plains where max temps should
be about 15 degrees cooler from Thursday.

.LONG TERM...(Saturday through Wednesday)
Issued at 243 PM MDT  Wed Mar 15 2017

A warm and dry weekend is ahead with upper-level ridging remaining
in place and H7 temperatures in the +6C to +8C range. Larger scale
subsidence will yield little or no chance for precipitation. Highs
will likely be in the 70s along/east of I25, and possibly even low
80s in the southern NE Panhandle or Platte River Valley. Mid-level
flow remains westerly through early next week, but a cold front is
expected to push temperatures back into the mid/upper 50s for much
of the area. May see a period of showers in the mountains and over
our northern zones with the fropa, but overall the weather pattern
will remain quiet.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1128 PM MDT Wed Mar 15 2017

VFR. Winds gusting 37 to 45 knots from 15Z to 01Z at Wyoming TAF
sites. Winds gusting 32 to 35 knots from 15Z to 02Z at Nebraska
TAF sites.

&&

.FIRE WEATHER...
Issued at 809 PM MDT Wed Mar 15 2017

A period of enhanced fire weather conditions are possible late
Thursday morning into the afternoon for parts of the SW Nebraska
Panhandle. Winds will be increasing ahead of a shortwave passing
to the north with afternoon RH values between 15 and 20 percent.
Decided it would be prudent to issue a Fire Weather Watch where
fuels are driest and where dewpoints are progged to be the lowest
Thursday afternoon in zone 313.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...Fire Weather Watch from 11 AM MDT Thursday through Thursday
     evening for NEZ313.

&&

$$

UPDATE...DEL
SHORT TERM...RE
LONG TERM...CLH
AVIATION...RUBIN
FIRE WEATHER...DEL



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