Standing closed canopy timber is producing active fire behavior and spotting, adjacent fuels become less continuous with scattered timber, brush, grass, and exposed granite hillsides.

Red fir fuel type with montane shrub and brush understory interspersed with pockets of nonburnable fuels in granitite rock outcrops. Fir trees are large diameter and over 100 ft tall and suffer from insect and disease mortality, leading to significant snag component and 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 dad and down with standing snags, increasing spotting potential. 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 below 10%. Active burning in recent days illustrates a fuel complex that is generally available across all types and size classes.

Active Fire Behavior was observed with isolated torching, flanking and creeping.

Fire has continued to spread to the north and northeast via surface spread in heavy fuels and short to medium range spotting (between ¼ to ½ of a mile). The red fir fuel type has a significant dead and down component and is highly conducive to both ember production as well as ember reception, leading to frequent spotting. Wind alignments from the south and west increase spotting to the north and northeast, with a noteworthy large spot fire established east of Tanner meadow on the SW facing slope. The heavy fuel loading presents resistance to control issues for ground resources, reducing line production rates, though numerous granite outcroppings and bare areas provide some opportunities for using natural barriers. To the north, fire growth is expected to slow as it encounters the footprint of the 2017 Empire Fire. Threats to values at risk and potential fire behavior are greatest as the fire moves downslope to the west and southwest, where heavier mixed conifer fuels increase potential for fire behavior that would challenge ground resources. The fire remains wholly within the wilderness area of Yosemite National Park and is expected to stay that way through the forecast period.

Construct direct handline where topography and fire behavior permit. Strengthen secondary and contingency lines. Employ rotary-wing aviation assets to check fire spread, moderate flame lengths to thresholds suitable for direct attack. Continue to identify and construct helispots and sling sites to support operational mission.

12 hours:  Persistent flanking to the west and east is expected to continue. Uphill runs remain possible where wind and slope align but will remain short in duration. The northern perimeter will be impacted by sheltering as it hits control lines and movement subsides. Minimal growth is expected. 

24 hours: The highest potential for light precipitation occurs tomorrow. This will come with much cooler temperatures, increased cloud cover, and elevated humidity resulting in decreased fire behavior. Expect surface spread rate to be slow combined with decreased spotting distance. As the low pressure exits to the east in the evening, it will create moderate to strong N/NE winds, especially overnight. While these will occur during a period of reduced fire potential, they will nonetheless exacerbate spotting in the red fir and lodgepole, especially toward the Alder Creek drainage where continuous fuels exist with high loading in an area with no recent fire history. While major fire spread is not expected, this could present a challenge for the western flank of the incident. Minimal growth is expected. 

48 hours: The combination of increased relative humidity, lower temperatures, and light wind speeds will continue to suppress fire behavior. Activity is expected to remain minimal even as the probability of precipitation departs the area. Minimal growth is expected. 

72 hours: A warming and drying trend will return to the fire area, bringing incremental increases in potential fire behavior. Expect surface spread to remain minimal for 1-2 days following the cool and humid weather. Minimal fire growth is expected to continue. 

Anticipated after 72 hours: The warming and drying trend will persist, bringing incremental increases in potential fire behavior. Daytime temperatures in the mid-60s will combine with RH values in the mid-20s, which has been a critical factor driving ground fire spread; however; light winds will allow fire behavior and anticipated growth to remain low.

OBSERVED: An area of low pressure moving into central California brought increasing southwest winds to the region along with an increase in cloud cover. Wind gusts this afternoon are expected to reach 20–25 mph, with temperatures in the upper 50s to lower 60s and afternoon humidity falling to the mid-30s to mid-40s. 

12-Hour Overnight: Winds will diminish this evening after sunset, becoming southeast at 4–7 mph. Expect the inversion to develop after 2200. Humidity recovery will generally be good, reaching the 50s. Temperatures will fall into the 40s and 50s. 

24–72 Hour Forecast: Low pressure will track across the region Monday, bringing a 20% chance of afternoon showers and a 10% chance of thunderstorms. Rainfall amounts are expected to remain light, with totals ranging from a trace to a few hundredths of an inch. The greatest threat for more widespread rain will occur east of the fire, closer to the Sierra Crest. Snow levels will generally remain above 9,000 feet, with light accumulations possible above 9,500 feet. Monday will be the coolest day, with temperatures 5–8 degrees below normal, keeping highs in the upper 40s to mid-50s. This will also boost relative humidity, with minimums in the 40–50% range. The system responsible for this cooler, unsettled weather will move east, allowing high pressure to build back into the region starting Tuesday. Expect warming temperatures, drier conditions, and lighter winds. Typical diurnal winds will return, with daily inversions lifting by mid- to late morning. 

Extended (Beyond 72 Hours): Dry conditions will persist into next weekend with above-normal temperatures, generally sunny skies, and typical diurnal winds.