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Area forecast discussion 
National Weather Service Cheyenne Wyoming
929 PM MDT Thursday Apr 17 2014

issued at 921 PM MDT Thursday Apr 17 2014

Inherited grids in decent shape. Flat Ridge aloft moves overhead
by dawn and with decent low level mixing...winds...will see a
relatively mild overnight period. In response to a developing
surface Lee trough...will see a low level jet develop as seen
on the 850 mb height and isotach plot with a 30 to 40 knot jetlet
producing locally gusty south winds across western Nebraska from
late this evening until around 3 am...especially at Chadron and
Alliance where the low level jet often makes an appearance at
night during the springtime. Minor adjustments made to temperatures
..dewpoints and winds overnight based on trends.


Short term...(this evening through saturday)
issued at 230 PM MDT Thursday Apr 17 2014

Middle/upper level trough continues to move east into the Central
Plains with upper ridge along the West Coast maintaining a
northwesterly flow across our region this afternoon. Closer to the
surface a broad high pressure ridge to our east is producing a
moderate southeast to southwesterly flow across much of southeast Wyoming
and western Nebraska this afternoon with the usually windier spots
such as Arlington and Rawlins getting periodic gusts 30 to 40 miles per hour.
Models continue to hint at a nocturnal low level jet setting up
across our eastern zones with 15 to 25 miles per hour winds projected late
tonight into tomorrow morning.

There might be just enough moisture around on Friday to get a few
showers/isolated thunderstorms over the western areas in the
mountains during the we continued to carry some small
probability of precipitation tomorrow afternoon for that. Otherwise we continue to watch
the next system coming in from the west on Saturday when the European model (ecmwf)
and GFS both advertise a weakening upper low (currently approaching
southern california) to move across northern Colorado. At the same
time...a weakening frontal boundary will stall across our eastern
zones. We continued the trends of the previous forecast package
bringing probability of precipitation up across the southwestern half of the forecast area
Saturday with lower probability of precipitation over much of the Panhandle where model
soundings indicate a more stable easterly boundary layer flow
continuing well into Saturday afternoon. There may be some isolated
thunderstorms Saturday and we maintained slight chance thunder
wording along with chance for mostly showers on Saturday.

Long term...(saturday night through thursday)
issued at 230 PM MDT Thursday Apr 17 2014

A few showers still possible near the Colorado border Sat evening
on the northern periphery of an upper system passing into the
Southern Plains. A secondary impulse on Sunday may interact with a
bit of instability to set off widely scattered showers and a few
weak storms again near the Colorado border into Sunday evening.
Similar pattern for Monday with some instability moving up the
High Plains aiding in a bit of convection Sunday afternoon. Mild
and mainly dry weather for Tuesday ahead of the next significant
upper trough that will move onshore along the West Coast by the end
of the day. This system should acquire a negative tilt Wednesday as it
moves into the northern rockies and northern plains. Dry slotting
ahead of this system should inhibit precipitation over most of the County Warning Area Wednesday
but rather breezy conditions likely. Cooler Thursday as an
associated Pacific front passes across late Wednesday with widely
scattered showers over mainly the mountains and northern parts of the
County Warning Area.


Aviation...(for the 06z tafs through 06z Friday evening)
issued at 921 PM MDT Thursday Apr 17 2014

Overnight...VFR flight categories expected at all airports into
the next 24 hours. Main issue will be gusty winds tonight in the
Panhandle where the models are suggesting a 30 knots low level jet
will set up which suggests we advertise winds 15g30kt possible at
a few of the airports in the east not sheltered by terrain.
VFR continues on Friday with gusty south and southwest winds...
especially across Wyoming taf sites.


Fire weather...
issued at 230 PM MDT Thursday Apr 17 2014

Main fire weather concerns will be on Friday as temperatures will
be at their warmest for the period into early next week. Winds
will be strongest over western districts but rhs will be the lowest
over the plains. Do not expect red flag conditions as fuels not
ready out west and over eastern areas winds will be somewhat
lighter. Still elevated fire conditions for a time Friday afternoon.
Cool front will pass across late Friday with milder conditions and
widely scattered showers and a few tstrms over the weekend.


Cys watches/warnings/advisories...


short term...garmon/tjt