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Area forecast discussion 
National Weather Service Cheyenne Wyoming
356 am MDT Sat Aug 30 2014

Short term...(today through monday)
issued at 335 am MDT Sat Aug 30 2014

Current infrared satellite loop shows mostly clear skies over the
forecast area as the next broad upper level trough is currently
pushing across the Pacific northwest early this morning. With
easterly winds over the High Plains and clear skies...have to
monitor the potential of some patchy fog early this morning.
Otherwise...a warm and pleasant day is expected for the beginning
of the Holiday weekend as high temperatures increase into the
upper 70s to upper 80s this afternoon. Western Nebraska locations
will likely see readings around 90 degrees this afternoon. The
upper level trough and associated cold front are trending a little
slower compared to 24 hours ago...with models indicating the front
slowly moving across northwest Wyoming today. Thunderstorms may be
slow to form...but expect widely scattered showers and thunderstorms
developing from west to east across the area. Most of western
Nebraska will not see any convective activity until this evening
due to a weak cap inversion and drier air aloft. This front will
eventually accelerate eastward late tonight resulting in at least
isolated showers and thunderstorms as a stronger than normal 105 knots jet
moves over the Wyoming/Colorado border.

Expect a cooler than average day on Sunday behind the cold front
as the trough axis moves across the area and 700mb temperatures
lower between 4c to 8c...resulting in surface temperatures in the
upper 60s to middle 70s across most of the forecast area. With a
strong jet over the area...believe models are downplaying the
coverage of showers and thunderstorms on Sunday. Increased pop between
25 to 40 percent across most of the region with scattered showers
and some thunder. Windy conditions are expected this
weekend...especially west of the Laramie range with gusts up to 45
miles per hour possible. Shower activity will quickly come to an end Sunday
evening as drier air and more stable conditions move over the
forecast area.

Another cool day expected on Monday with highs struggling to reach
the low to middle 70s across most of the area. There is some model
disagreement during the day with the European model (ecmwf) showing a secondary
shortwave trough quickly moving over the area. The GFS...NAM and
Gem either show this feature further to the north or much weaker
compared to the European model (ecmwf). Kept a slight chance of showers in the
forecast for now...with pop around 20 percent across the mountains
and High Plains.

Long term...(monday night through Friday night)
issued at 300 am MDT Sat Aug 30 2014

Warm...windy and dry will be the main weather story through much
of the extended forecast period. Monday night will start off with
a fast moving shortwave pushing east of the forecast area. There
may be a few evening showers depending on the timing of the
shortwave... otherwise a vast majority of the area will be dry Tuesday
and Wednesday as westerly downslope flow kicks in along with ridging
over the western Continental U.S.. with warm and dry conditions in place
gusty winds will likely produce critical fire weather conditions.

Questions begin to arise Thursday and Friday and extended models diverge.
GFS showing a much more pronounce trough across the far western
portions of the Continental U.S. With a weak shortwave bringing moisture into
southeast Wyoming for Thursday. The ec keeps westerly flow with a
weak trough digging into the northwest Continental U.S. Which would mean dry
through Thursday.


Aviation...(for the 06z tafs through 06z Saturday evening)
issued at 1050 PM MDT Friday Aug 29 2014

Isolated thunderstorms continue along the Wyoming/Colorado state
line with movement towards the southeast. Should not impact any of
our airports through the overnight hours. VFR conditions expected
through the overnight and morning hours with convection increasing
Saturday afternoon. Still too early to nail down specific timing
of just went with thunderstorms in the vicinity wording in tafs. Later
shifts can more accurately time thunderstorms...but looks like
maybe 21z through 01z or so for best coverage.


Fire weather...
issued at 236 am MDT Sat Aug 30 2014

No significant fire weather concerns this weekend and into early
next week. A strong weather disturbance and associated cold front
will move across the area late today through early Sunday. Showers
and thunderstorms will develop from west to east across southeast Wyoming
and move the western Nebraska. Gusty west to southwest winds are
expected along and west of the Laramie range this weekend with
gusts between 30 to 40 miles per hour. Minimum humidities will remain above
20 percent however into Monday with cooler than normal


Cys watches/warnings/advisories...


Short term...tjt
long term...small
fire weather...tjt

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