Weather

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Area forecast discussion 
National Weather Service Cheyenne Wyoming 
139 PM MDT Friday Aug 29 2008 


Short term...tonight through Sunday. 
The Holiday weekend will start with a great day for a variety of 
outdoor activities...featuring dry and breezy conditions with 
temperatures expected to be around 10 degrees above normal across 
the area. 


The main concern present Saturday will be the need to monitor both 
the western zones and Nebraska Panhandle zones for critical fire 
weather conditions. Have held off on issuing a Fire Weather Watch 
as forecasts continue to call for conditions not quite reaching 
red flag criteria. However...the western zones will need to be 
monitored for strong winds than currently expected...and the 
Nebraska Panhandle will need to be monitored for the possibility 
that relative humidities may drop more than currently anticipated. 


The breezy conditions in the Panhandle will actually develop this 
evening as the surface pressure gradient tightens ahead the jet 
streak currently moving on-shore over Washington state in 
southwest flow aloft. This is the first jet feature of a series 
that will affect the northwest United States over the next few 
days...and models agree on formation of a surface low over 
southeast Montana and eastern Wyoming Saturday. The next jet 
streak moving into the Gulf of Alaska this afternoon will become 
more northerly and act to amplify the upper trough as it moves 
onto the Pacific northwest coast. This jet streak will round the 
base of the trough Sunday...and will create a second surface low 
over eastern Nevada and western Utah. The combination of the 
exiting initial jet streak into southern Canada and the approach 
of the second will create a favorable area for lift and 
precipitation production across western Wyoming and into the 
western portion of the forecast area. The best chances for showers 
and thunderstorms will be across Carbon...Albany and Converse 
counties Sunday afternoon. The increased cloud cover and 
precipitation will create cooler and near normal conditions across 
those areas...while areas east of the Laramie range will likely 
continue to see temperatures reach values 5 to 10 degrees above 
normal Sunday. 


Long term...Sunday night through Friday... 
western Continental U.S. Upper trough will slowly move toward the region Sunday 
night and Monday while cutting off an upper low over northern Utah. 
System will then lift into the northern plains Monday night and 
Tuesday pushing a cold front across the County Warning Area Monday night. Expect 
scattered showers and tstrms to spread over the western parts of the 
County Warning Area Sunday night but may be delayed into the eastern plains until 
later Monday when surface front drops across and surface flow turns 
upslope. Fairly good chances for rain over most areas Monday night 
as upper trough axis passes across with clearing expected Tuesday as 
upper trough passes to the east of the area. Broad cyclonic flow 
will keep temperatures a little below seasonal averages for the 
rest of the week with mainly dry weather. Another upper system 
could drop southeast across the region Friday bringing next chance for 
rain and cooler air. 




&& 


Aviation... 
VFR conditions are expected to continue this evening across the 
area. Areas of MVFR...and locally IFR...ceilings are expected to 
develop overnight by around 09z over the Nebraska Panhandle with 
patchy fog also possible for the brief period prior to sunrise. 
Expect that low clouds and fog will have lifted by around 15z 
Saturday morning. 


&& 


Fire weather... 
breezy south winds will develop east of the Laramie range this 
evening...and will continue across Nebraska zones 200 and 202 in the 
Nebraska Panhandle Saturday. Although winds will be gusting to 
around 30 miles per hour in the Nebraska Panhandle...Saturday afternoon 
minimum relative humidities should remain above critical values in 
the 20 to 25 percent range. Across Wyoming zones 291 to 
294...minimum relative humidities will fall into the lower teens 
Saturday afternoon but the forecast continues to be for wind 
speeds only reaching the 15 to 20 miles per hour range. In summary...although 
red flag conditions are not expected to be met through 
Saturday...anyone with outdoor interests this Holiday weekend should 
use caution due to the relatively dry and breezy conditions. 




&& 


Cys watches/warnings/advisories... 
Wyoming...none. 
NE...none. 


&& 


$$ 


Short term/aviation...CArpenter 
long term...re