Timber (Litter and Understory) Brush (2 feet) Heavy Logging Slash

Red fir fuel type with montane shrub and brush understory interspersed with pockets of non-burnable fuels in granite rock outcrops. Fir trees are large diameter, over 100 ft. tall, and suffer from insect and disease mortality, leading to a significant snag component with large amounts of heavy dead and down coarse woody debris. Most active fire behavior has come from the dense, closed canopy red fir stands, where torching and isolated crown fire pockets have also contributed to spotting. Fuels in 2017 fire footprints have less closed canopy but contain significant dead and down with standing snags, increasing spotting potential. Surface spread rates are lower in the Empire Fire (2017) Footprint, but spotting continues to drive spread. Montane shrubs and brush in the understory are generally available to burn but are not at critical fuel moisture levels. Heavy dead and down fuels are dry, with fuel moisture in 1,000 hr. fuel around 12%.

Moderate, Spotting, Uphill Runs, Single Tree Torching

Active fire behavior was observed through the operational period and well into the late evening. The fire established below Horizon Ridge continued to spread upslope. The fire continues eastward spread toward Ostrander Lake. On the western edge of the fire backing withh rollout rollout and and falling snags challenge control lines. Fire is backing toward Alder Creek. Jackpots of dead and down fuel within the old burn scar continue to consume and contribute to spotting. With continued dry and warm weather, daily incremental increases of fire behavior are anticipated.

Strengthen primary and contingency lines. Employ rotary-wing aviation assets to check fire spread, moderate flame lengths to thresholds suitable for direct attack. Implement tactical firing operations in Branch 10, as necessary to support direct line. Crews may conduct firing operations as appropriate to bring fire to containment line from Division M/Q break to the east and south toward Division T. In Branch 5 Continue with patrol and mop up in Division A. In Division Z
crews will be constructing direct line to Division T/Z break and patrolling completed primary lines from the A/Z break north towards the ZIT break. In Division Twill be scouting and/or constructing direct/indirect fire lines along the eastern portion of the fire to the T/Q break.

12 hours: A low inversion overnight continues to support smoldering. Heavy Interior fuels will continue to consume overnight. With lack of pronounced overnight winds fire spread will be minimal beyond what occurred during the main burning period.

24 hours: Increased mixing heights may give the fire increased ventilation and potential for larger column formation. Fire spread will generally be terrain driven. Continued spread eastward toward Ostrander Lake and east from H-17 are possible on the eastern flank. Fire will continue to back down toward Alder Creek on the western flank. With Increased receptiveness of fine fuels, spot fires may be more frequent and are a primary driver or fire spread. Heavy dead and down will allow continuous burning to continue. Indirect control lines may be challenged if reached by fire spread.

48 hours: Continued spread eastward toward Ostrander Lake and east from H-17 are possible on the eastern flank. Fire will continue to back down toward Alder Creek on the western flank. With increased receptiveness of fine fuels, spot fires may be more frequent and are a primary driver of fire spread. Heavy dead and down will allow continuous burning to continue. Indirect control lines may be challenged if reached by fire spread.

72 hours: Continued spread eastward toward Ostrander Lake and east from H-17 are possible on the eastern flank. Fire will continue to back down toward Alder Creek on the western flank. With increased receptiveness of fine fuels, spot fires may be more frequent and are a primary driver of fire spread. Heavy dead and down will allow continuous burning to continue. Indirect control lines may be challenged if reached by fire spread.

Anticipated after 72 hours: Fire continues threatening critical values in Yosemite National Park. Numerous culturally significant sites are present throughout the fire area and are at risk to lire impacts. Infrastructure and structures in Wawona. West Yosemite and Badger Pass Ski Resort. Wawona Rd (Highway 41)

There has been an increase in overhead resources listed on the 209 as previous reporting did not include incident management personnel. Temporary Flight Restriction expanded slightly north as of 0730.

Observed: Mostly clear skies, well above normal maximum temperatures in the 70s and dry conditions with Min RHs 20-30% are generally being observed across the fire area today. Winds are being mainly terrain driven, from the west-southwest at 4-8 mph with occasional gusts 10-18 mph.

12-Hour Overnight: Mostly clear skies will prevail. Drainage winds, mostly from the north and then east, at 2-4 mph are expected overnight with localized ousts 4-8 mph. Relative humidity recoveries east, at 2-4 mph are expected overnight with localized gusts 4-8 mph. Relative humidity recoveries are likely to be slightly higher, in the 40-60% range. Low temperatures will be variable, in the upper 40s to near 60 degrees. Smoky conditions are expected in valleys in the vicinity of the fire.

24-72 Hour Forecast: 24~72 Hour Forecast Winds will be more westerly Monday afternoon, turning northwest later in the day with 5-10 mph winds with guts 10-15 mph Monday afternoon. Mostly clear skies will continue Monday but low pressure brushing by is likely to lead to some mid-level cumulus build-ups to the northeast and east of Yosemite National Park over the Sierra Crest Clear skies are expected Tuesday and Wednesday. Very warm and dry conditions will continue with highs in the 70s and RHs are likely to be about the same with minimums 20-30%. RH maximums are likely lo be in the 40-60% range Tuesday morning. Slight warming and drying is expected Tuesday-Wednesday. Mixing heights in lhe afternoons will be greater, peaking on or about Monday. Winds will be mostly westerly in the afternoons 5-10 mph with gusts 10-20mph.
 

Extended (After 72 Hours): No significant changes are until Friday into the weekend when southwest winds, mixing, and humidity are likely to increase ahead of a weather change.