Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 240255

Area Forecast Discussion
National Weather Service Cheyenne WY
855 PM MDT Sun Sep 23 2018

Issued at 848 PM MDT Sun Sep 23 2018

8 pm Update. Made some adjustments to POPs using latest hi-res
model guidance. HRRR and NAM Nest show showers developing between
06-08z moving over southeastern Wyoming. Most areas could see a
sprinkle or two overnight but wetting rain does not look highly
favorable. The best shot looks to be the mountain peaks in far
southern Wyoming near the Colorado border.

Other updates include the addition of smoke and haze as the Ryan
Fire continues to burn. Should see the rain reduce that some
through the day tomorrow. Along the same lines, winds were
increased slightly with the latest guidance. This pushed some area
toward more critical Fire Weather COnditions and the Red Flag
Warning was expanded as a buffer.


.SHORT TERM...(This evening through tuesday night)
Issued at 200 PM MDT Sun Sep 23 2018

Fire weather will continue to be the main concern Monday, then
a break expected Tuesday. Currently pretty quiet across the CWA
weatherwise with some cumulus spreading across the area in
southwesterly upper flow. A upper shortwave will move across the
area overnight into early Monday setting off widely scattered
showers and maybe a few tstms. It will also push a cool front
across the CWA later tonight and bring about 10-15 degrees of
cooling Monday, especially east of the mtns. Still breezy out west
Monday afternoon. A better coverage of showers/tstms expected
Monday afternoon and evening over the plains as another shortwave
nears the area. A second push of colder air moves into the area in
the wake of the second shortwave Monday night with dry and mild
conditions Tuesday along with light winds. Chilly night Tuesday
night under mainly clear skies and light winds as a surface high
settles down the northern and central Plains with many areas
falling into the 30s.

.LONG TERM...(Wednesday through Sunday)
Issued at 200 PM MDT Sun Sep 23 2018

The latest medium range models are in good agreement depicting a
northwest flow aloft Wednesday and Thursday, transitioning to west
to southwest next weekend. Little to speak of in terms of sensible
weather, aside from a cold frontal passage Wednesday night. Cooler
than normal temperatures Wednesday and Thursday will moderate to
above normal Friday through Sunday. Breezy conditions will occur
each afternoon west of the Laramie Range, which will maintain the
elevated fire danger.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 531 PM MDT Sun Sep 23 2018

Forecast for today and tonight VFR to MVFR at times with some rain
showers and smoke/haze from ongoing wildfires. Gusty southwest
winds will continue though the early evening as an area of low
pressure strengthens over southeastern Wyoming. Ceilings will
begin to drop as a stalled coldfront slowly moves its way south.
Scattered showers and isolated thunderstorms will develop
overnight and early tomorrow. VCSH was introduced to many TAF
sites, but lack of agreement on short term guidance precludes the
inclusion of thunder at this time. Northwest to northeasterly
winds behind the front will change early tomorrow morning and
continue through the day.


Issued at 848 PM MDT Sun Sep 23 2018

Yet another day with critical fire weather conditions expected
Monday but mainly over Albany and Carbon counties. A cold front
will pass across the area overnight with widely scattered showers
and a few evening storms possible across the area. A second surge
of cooler air will arrive Monday night and should bring a respite
to the critical fire conditions for Tuesday. Elevated concerns
then look to return over western districts beginning on Wednesday.

Added Zones 302 and 309 to the Red Flag Warning replacing the
previous Fire Weather Watch. While condiitons are Marginal, strong
winds and marginal humidity may allow extreme Fire Behavior.


WY...Red Flag Warning from noon to 8 PM MDT Monday for WYZ302>309.



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