Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 200553

Area Forecast Discussion
National Weather Service Cheyenne WY
1152 PM MDT Mon Jun 19 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 228 PM MDT Mon Jun 19 2017

Previous forecast remains on track so minimal changes were made
with this package. Strong and warm upper ridging remains the
dominant weather feature through Wednesday. Some very weak
shortwave energy may track to sneak over the top of the ridge late
Tuesday into early Tuesday evening. There will be just enough
moisture in place for a few isolated showers and thunderstorms
mainly over the higher terrain late Tuesday but coverage should be
isolated as there will be quite a bit of warm, dry air aloft. A
weak frontal system will pass through the area from the north late
on Wednesday. This front will affect mainly areas east of the
Laramie Range and be little more than a wind shift to the north
and northeast. Model forecast soundings indicate enough moistening
and instability for widely scattered convection with weak upslope
flow just behind the front.

.LONG TERM...(Wednesday night through Monday)
Issued at 228 PM MDT Mon Jun 19 2017

A few thunderstorms are possible Wednesday night, but the bulk of
these storms should dissipate after sunset. More thunderstorms are
possible again on Thursday as a much stronger shortwave starts
diving in from Canada. The GFS/GEM show this feature drawing in
some decent moisture into areas east of the Laramie Range on
Thursday afternoon. This could set the stage for some strong to
severe storms for these areas Thursday afternoon through Thursday
evening ahead of a strong cold front. However, there is some
question on the timing of the cold front. The NAM/ECMWF are
showing this front moving through a bit quicker on Thursday which
may limit the convection potential. All the models show the
strong cold front exiting the area by Friday morning. Behind this
front, unseasonably cool air will be in store for the area this
weekend with highs only climbing into the 60s on Saturday with a
slow warmup to the low to mid 70s on Sunday.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday evening)
Issued at 1152 PM MDT Mon Jun 19 2017

VFR. Light and variable winds overnight. Westerly winds gusting to
25 kt Tuesday, mainly southeast WY.


Issued at 228 PM MDT Mon Jun 19 2017

Warm and predominantly dry weather will continue
through mid week.  Afternoon RH values will drop to around 15
percent Tuesday and Wednesday afternoons west of the Laramie Range.
Winds will be generally light but may be a bit more breezy on
Wednesday as sfc troughing develops over western NE. Fuels remain
green however so not expecting much in the way of fire weather
concerns.  A strong cold front is still expected to affect the area
by late Friday into Saturday with cooler temperatures and a better
chance for showers and thunderstorms along the front.




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