Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 250558
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1158 PM MDT Thu Sep 24 2020

.UPDATE...
Issued at 824 PM MDT Thu Sep 24 2020

Red Flag Warning was allowed to expire at 8 PM this evening as winds
were decreasing and humidities increasing above 15 percent. Large
smoke plume from Mullen wildfire to the west remains elevated with
visibilities above 6SM over southeast WY. Critical fire weather
conditions will resume by midday Friday over much of southeast WY,
along with areas of smoke and haze.

&&

.SHORT TERM...(This evening through Friday)
Issued at 246 PM MDT Thu Sep 24 2020

Summary: Mullen Wildfire is quite active today via visible and
3.9 micron channels this afternoon. Well above normal temperatures
are ongoing and will continue tomorrow with a slight cool down
Saturday. Critical Fire weather conditions with Red Flag Warnings
are in place. Critical Fire weather conditions will continue
Friday.

Weather Details: Shortwave H5 ridge axis from NE to SW across the
Dakotas to the desert SW of the US is suppressing and compressing
lower atmospheric layers across the region. This feature, coupled
with a faster H7-H5 speed belt is resulting is dry, warm, and
windy conditions. Critical fire weather conditions are ongoing and
this is expected to continue Friday and perhaps into Saturday as
well. Trough coming onshore in the Pacific NW will flatten out but
tight height gradients combined with deep mixing will bring
elevated winds to surface Friday. Locally very critical fire
weather conditions could occur tomorrow with winds gusting upwards
of 30-40 mph and humidity down to near 10 percent. A dry frontal
surge will move through Friday morning before backing to the
west/southwest by the afternoon. Saturday will be slightly cooler
but another near critical to critical fire weather day possible
as winds remain elevated through the overnight Friday and
Saturday. May need to watch for High Wind Warnings in the known
gap areas of Bordeaux and Arlington Saturday.

.LONG TERM...(Friday night through Thursday)
Issued at 246 PM MDT Thu Sep 24 2020

Decent cold front will sweep across the CWA Sunday as a shortwave
dives southeast over the northern and central plains. A few
showers possible with this system but little rain from them. It
will be much cooler Sunday with gusty nwly winds. After that a
generally nwly flow aloft will result in mild and dry weather
across the CWA for the early and mid part of next week with
temperatures fairly close to seasonal averages.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1149 PM MDT Thu Sep 24 2020

Currently VFR conditions for area terminals tonight, but KLAR
could drop down to MVFR levels with residual smoke from the Mullen
Fire plume earlier in the afternoon. A weak cold front is
approaching northern portions of the CWA and will pass through NE
Panhandle terminals over the next few hours turning winds more
northerly. Otherwise, winds will pickup in the afternoon for SE
WY terminals.

&&

.FIRE WEATHER...
Issued at 246 PM MDT Thu Sep 24 2020

Critical to near critical fire weather conditions ongoing this afternoon
across much of Southeast Wyoming. Critical combination of elevated winds
in the 25-30 mph range and humidity in the teens, is occurring
across Carbon, Albany, Converse, and the terrain areas. This will be
the case again tomorrow with Red Flag Warnings in place once again but
a bit more focuses south and excluding Converse and Niobrara. Expect
active fire behavior overnight with poor recoveries and once again
tomorrow for the active wildfires currently ongoing. Winds will r
remain elevated into Saturday and will need to monitor for Fire
Weather Watch.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning from noon to 8 PM MDT Friday for WYZ303>310.

NE...None.
&&

$$

UPDATE...MAJ
SHORT TERM...JSA
LONG TERM...RE
AVIATION...MB
FIRE WEATHER...JSA


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