Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 220147
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
747 PM MDT SUN AUG 21 2016

.UPDATE...
Issued at 747 PM MDT Sun Aug 21 2016

Winds have eased and humidities are slowly on the rise this
evening across the high country in southeast Wyoming, so went
ahead and cancelled today`s Red Flag Warning. Critical fire
weather conditions still look likely for tomorrow, so went ahead
and upgraded the Fire Weather Watch to a Red Flag Warning. This is
in effect 10am-8pm Monday for much of southeast Wyoming and
northern portions of the Nebraska panhandle. In addition to dry
humidities and gusty west to southwest winds, may see isolated
thunderstorms that produce very little rainfall for southern
portions of FWZ 309 & 310, in addition to FWZ 311 & 312.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 223 PM MDT Sun Aug 21 2016

Forecast challenges deal mainly with critical fire weather
conditions over the next 24 hours.

Currently...1011mb low on surface analysis over southern Albany
County this afternoon looks to be assisting in enhancing winds out
across Carbon and Albany Counties this afternoon. Getting wind
gusts to 30+ MPH at numerous WYDOT sites along I-80 with close to
30MPH at Saratoga. Further off to the west, water vapor imagery
showing next low pressure system pushing into southeastern
Vancouver Province with upper level ridge axis located from
central Montana into western Wyoming and eastern Utah.

Both the GFS and ECMWF 12Z guidance showing the upper low tracking
slightly further south Monday and Monday night as compared to
yesterday. This is a good track for gusty winds here in southeast
Wyoming and confidence is growing that we should see stronger
winds tomorrow. Went ahead and extended the Fire Weather Watch
further south to include FWZs 309, 310 and 312 as well as most
fire zones that were already in the watch. Evening shift should
probably upgrade these watches once the current red Flag warnings
expire at 8PM tonight.

Timing of front pretty consistent between the GFS and ECMWF as
well. Both bring the front into the northern CWA around 06Z
Tuesday and into the southern portion of the CWA by 12Z. 850MB
winds out in the Panhandle Tuesday quite strong,GFS showing 35-
possibly 40kts behind the front. Could be looking at wind
advisories out there for late Tuesday morning and afternoon.

.LONG TERM...(Tuesday night through Sunday)
Issued at 223 PM MDT Sun Aug 21 2016

The front pushes well south and east of our forecast area by
Tuesday evening with some lingering instability being denoted in
the models across the higher terrain and mountains when we hold on
to chance PoPs for evening showers and thunderstorms. The pattern
gets fairly messy synoptically mid through late week with a
lingering upper trough lingering over Idaho, Nevada and Arizona
and several hard to time pieces of midlevel shortwave energy
ejecting east across the central Rockies through Friday. Right now
we kept most PoPs out across the western zones Wednesday into
Thursday with a trend for an increase in PoPs Friday into Saturday
along and east of the Laramie range and onto the high plains
Friday into Saturday as we see a broader plume of midlevel
moisture and deeper instability as the midlevel flow increases
from the southwest and becomes more active. We should be trending
warmer again by next weekend after a cooler post frontal pattern
midweek.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 527 PM MDT Sun Aug 21 2016

VFR prevails. Gusts of 20 to 25 knots after 15Z Monday.


&&

.FIRE WEATHER...
Issued at 747 PM MDT Sun Aug 21 2016

TODAY`S CRITICAL FIRE WEATHER CONDITIONS HAVE EASED, SO CANCELLED
THE RED FLAG WARNING THAT WAS IN EFFECT THROUGH THIS EVENING.
MORE WIDESPREAD WINDS MONDAY TO COVER MUCH OF SOUTHEAST WYOMING
AND THE NORTHERN HALF OF THE NEBRASKA PANHANDLE. UPGRADED THE FIRE
WEATHER WATCH FOR TOMORROW TO A RED FLAG WARNING. CANNOT RULE OUT
ISOLATED THUNDERSTORMS PRODUCING VERY LITTLE RAINFALL AS
WELL...MAINLY FOR THE SOUTHERN PORTIONS OF FWZ 309 & 310 IN
ADDITION TO FWZ 311 & 312. COLD FRONT THAT IS CAUSING THESE WINDS
WILL FINALLY MOVE INTO THE AREA TUESDAY MORNING WITH COLDER AIR
AND INCREASED CHANCES FOR WETTING RAINS. SHOULD SEE FIRE WEATHER
CONDITIONS EASE BEHIND THE FRONT.

&&

.CYS Watches/Warnings/Advisories...
WY...Red Flag Warning from 10 AM to 8 PM MDT Monday for WYZ301>304-
     306-308>310.

NE...Red Flag Warning from 10 AM to 8 PM MDT Monday for NEZ311-312.

&&

$$

UPDATE...RJM
SHORT TERM...GCC
LONG TERM...JG
AVIATION...RUBIN
FIRE WEATHER...RJM


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