September 17th

Mammoth was in the dark last night with Edison shutting the power off throughout many areas of the Eastern Sierra. With a significant amount of power lines above ground, in forested and brushy areas, the power company can no longer afford to take risks during critical fire weather periods.  The planned power outage may become the new norm. So many of the residents and business owners of the eastern sierra need to plan according by having there own power sources, lighting and battery back up systems.


Here is some information from the National Weather Service that helps to determine when these future power outages will occur.  It is unlikely that these power outages will happen impromptu, so when a storm is coming, and critical fire weather is announced by the NWS, look for statements from Edison, so you will not be caught by surprise!



A.    Red Flag Event. Red flag events are defined by critical weather and fire danger conditions that could lead to extensive wildfire occurrences and/or control problems on existing wildfires or prescribed burns.
B.     Fire Weather Watch. A fire weather watch is issued to advise user agencies of the possible development of red flag conditions in the near future, generally the next 24 to 72 hours. Under certain conditions a watch can be issued for the first 12 hours.
C. Red Flag Warning. A red flag warning is issued to advise user agencies of occurring or imminent red flag conditions, generally within the next 12 to 24 hours.
2.   RED FLAG CRITERIA. Red flag events normally require the combination of critical fuel conditions and critical weather conditions. Several combinations of fuels and weather conditions may combine to produce red flag conditions. Fuel conditions are considered critical when fuel characteristics are favorable for large fire growth, as determined by the land management agencies. NWS forecasters determine when weather conditions are critical.
A. Primary Red Flag Criteria: 
1)   Relative humidity of 15% or less combined with sustained surface winds, or frequent gusts, of 25 mph or greater. Both conditions must occur simultaneously for at least 3 hours in a 12 hour period.
2)   Widely scattered (or more) dry thunderstorms, 15% or more coverage, constituting a Lightning Activity Level (LAL) 6. A thunderstorm is considered “dry” if it produces less than 0.10 inch rainfall.
B. Contributing Red Flag Factors: 
1)   First significant lightning occurrence after a hot and dry period.   This includes “wet” or “dry” thunderstorms, widely scattered (15%) coverage or more. After a hot and dry period, the first occurrence of thunderstorms can readily start wildfires. The RH does not need to meet the criteria listed above.
2) Significant cold frontal passage, expected to cause strong sustained and gusty winds, and an abrupt wind shift. Of heightened concern are dry cold fronts that have the above characteristics, but little or no rainfall, and expected when there are on-going wildfires or prescribed burns. The RH does not need to meet the criteria listed above.
3)   Any combination of weather and fuels conditions that would create a critical fire control situation or extensive wildfire outbreak. These may include: long term drought, much higher than normal maximum temperatures coupled with very low humidity, low fuel moisture, poor nighttime RH recovery, high Energy Release Component (ERC) or Burning Index (BI), a Haines Index of 5 or 6, etc.




From Monday the 16th,

A strong cold front is making its way through the eastern sierra today Monday with gusty winds and cooler temperatures.  Precipitation will occur north Mono County today and tonight and so Mammoth is unlikely to receive any measurable precipitation from the front. Much cooler temperatures will prevail today with frosts and freezes possible for Sierra valleys. Another weather system is possible Wednesday into Thursday with more clouds, wind and a showers possible.  This system seem cooler yet. High temperatures this week will  be near 60 the next few days with the coolest day in the 50s on Thursday. The last weekend of Summer is coming up this weekend. Expect seasonal temperatures with highs in the upper 60s Saturday and Sunday.   Fall begins at 12:50AM next Monday.


Of note, the GFS model this Morning shows a light to moderate off shore flow, with the thermal trof at the surface all the way to the coast by the middle of next week. No doubt that the CA Central Valley will be getting hot with the heat pushing into the Bay Area Tuesday and Wednesday next week. High 90s to low 100s in Mt View?  103 TO 107 INLAND?