Wildfire in Wyoming, August 13, 2020

Area Forecast Discussion
National Weather Service Riverton WY
1120 AM MDT Thu Aug 13 2020

.SHORT TERM...Today through Saturday night

The main concern of the day looks to be critical fire weather. A
weak cold front will be dropping toward Wyoming today. At the same
time, a shortwave will be tracking across Montana. This will tighten
the pressure gradient across the area. With 700 millibar winds
expected to be in the 30 to 40 knot range across much of the area,
and the area in the right front quadrant of a jet streak that will
enhance downward forcing, it will be breezy to windy across much of
the area. This, combined with humidity that will fall into the
single digits, will bring critical fire weather to most of the area
this afternoon. As for convection, there may be just enough lift for
some northern border running storms but otherwise expect nothing.
Temperatures will continue to average above normal. There will be a
bit of a change tomorrow though.

The aforementioned cold front will sag southward across the state
tonight, settling near the Continental Divide on Friday. This will
bring cooler temperatures and less wind to the northern portion of
the area. As a result, fire weather concerns should ease tomorrow,
probably below critical. However, southern Wyoming will continue to
see gusty winds and low humidity and the Red Flag Warnings will
probably have to be extended there for another day. We will let the
day shift make the final call there. But even here, winds will not
be as strong as today. On Saturday, the front should begin to wash
out as ridging builds into the area from the south. The result will
be a warm and dry days on Friday and Saturday. With the ridging
building, it will decrease the pressure gradient further and
possibly the first day in a while with no fire weather highlights.

.LONG TERM...Sunday through Thursday

On Sunday and Monday, a strong upper ridge will be in place across
the Rockies. The center of the subtropical ridge looks to be along
the border of Utah and Nevada. Due to this ridge, the wind fields
will relax which in turn will give the forecast area a break in the
continuous elevated to critical fire weather conditions. Otherwise
dry and very warm to hot temperatures. High temperatures both days
will be about 10 degrees above average west, and about 5 above east.

A combination of the ridge flattening with time, and weak
disturbances moving around the center of the subtropical high should
result in diurnal convection Tuesday thru Thursday. Temperatures
will remain above to well above average. Overall wind fields have
trended weaker for middle of next week on tonight's model runs which
would keep fire weather concerns to a minimum.

&&

.AVIATION...18Z Issuance

Expect dry, VFR conditions to prevail at all terminals through the
next 30 hours. Winds will gust to 25-35 knots during the afternoon
for most locations through about 02Z Friday. More warm and dry
weather expected Friday, but winds will be quite a bit lower.

&&

.FIRE WEATHER...

Any thunderstorm today will be limited to the northern border of
Wyoming. However, a combination of low humidity and a gusty wind
will bring likely critical fire weather to all areas that have
critical fuels today. Mixing and smoke dispersal will be generally
good to excellent in the afternoon. A weak cold front will drop
southward and settled near the continental divide on Friday. Fire
weather concerns should ease in most areas but critical fire weather
may persist into Friday across the south.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM MDT this evening for WYZ275>283-
285>289-300-414>416.

&&

SHORT TERM...Hattings
LONG TERM...Murrell
AVIATION...Hulme
FIRE WEATHER...Hattings

Hazardous Weather Outlook
National Weather Service Riverton WY
156 AM MDT Thu Aug 13 2020

WYZ001>020-022>030-141230-
Yellowstone National Park-Absaroka Mountains-Cody Foothills-
North Big Horn Basin-Southwest Big Horn Basin-
Southeast Big Horn Basin-Owl Creek and Bridger Mountains-
Bighorn Mountains West-Bighorn Mountains Southeast-
Northeast Johnson County-Southeast Johnson County-
Teton and Gros Ventre Mountains-Jackson Hole-
Wind River Mountains West-Wind River Mountains East-
Upper Wind River Basin-Wind River Basin-Lander Foothills-
Green Mountains and Rattlesnake Range-
Natrona County Lower Elevations-Casper Mountain-Star Valley-
Salt River and Wyoming Ranges-Upper Green River Basin Foothills-
Upper Green River Basin-South Lincoln County-
Rock Springs and Green River-Flaming Gorge-East Sweetwater County-
156 AM MDT Thu Aug 13 2020

...Red Flag Warning in effect through 8 pm this evening...

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Today and Tonight.

Critical fire weather conditions most across the area. Please see
Red Flag Warning for details.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...Critical fire weather conditions possible in southern
Wyoming.

Saturday...Elevated fire weather possible in southern Wyoming.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions.