On April 15, the NWS in San Diego made a change to the criteria used to issue Red Flag Warnings.

 

The change involves the removal of the long duration, low relative humidity criterion: relative humidity equal or below 10% for at least 10 hours. This change impacts all coastal, valley and mountain zones within the NWS San Diego’s area of responsibility.

The main criteria will remain in force: relative humidity at or below 15% and winds sustained at 25 mph or gusts to 35 mph for at least six hours in duration.

Why the change? Steven Vanderburg, forecaster and fire weather specialist, conducted a study that analyzed all the major wildfires in our region in the last decade. He found that in nearly all cases, the fires spread rapidly only if there was some strong wind component in addition to very low relative humidity. He also found several cases where fires that did start in very dry conditions did not spread rapidly because strong or gusty winds were not present.

 

Local fire fighting agencies agreed that to remove this dry-without-wind criterion would be an improvement. Over the past year the final approvals were made to make this change to the criteria.

Forward by Paul, W6SJL

Volunteers are being sought for communications duties for the San Diego 100 Mile Endurance Run June 12-13.

The SD 100 mile course starts and finishes at the Al Bahr Campground which is off of Sunrise Highway within the Camp Laguna Recreational Area.  The course covers four main areas: The first 16.5 miles are located in the Recreational Area; from there, runners transition to the Pacific Crest Trail (PCT) for ten miles before descending the Noble Canyon Trail towards Pine Valley. From Pine Valley, runners climb back up to the PCT and run north for another 11 miles (on the PCT again) to Sunrise Aid Station. Runners then descend to the west and enter a 30 mile section in the Cuyamacas. After completing the Cuyamaca section, the course returns to the PCT, Camp Laguna Mountain Recreational area, and the finish line at Al Bahr.

150 runners have registered for the race, all of whom have qualified by completing (within the last year) at least one sanctioned 50 mile race within a 13 hour time limit. Runners will be monitored at 15 aid stations as well as the start/finish. (note: this means we need at least 30 volunteers to staff the aid station communications spots - preferably more so we can work in shifts). Last year's winner completed the grueling test in just 18hrs 15min 45sec (that's an average of 5½ minute miles - phew!) while 57 runners dropped out along the way and 77 others completed the course within the 31 hour time limit. Ham radio operators assistance consists of but is not limited to the following duties: keeping track of each runner (noting their times through the various aid stations), helping expedite the shuffling of supplies between aid stations, and providing health & welfare type traffic (additionally, hams have been known to provide late night entertainment around the campfire!)

Ham operators should plan on providing their own transportation, shelter, food, water, and of course radio equipment. Suggested radio equipment would ideally consist of a two meter radio (mobile preferred), power (sufficient for long-term operation), antenna (preferably some type of base antenna with mast).  Shelter could be RV, trailer, tent or car camping. Be aware that temperatures can vary widely this time of year so be prepared for warm days and very cool nights. This is a really fun event and you won't want to miss out on being a part of it.

Race information can be found at http://sandiego100.com  Any interested party should contact Ellen N6UWW at amsat.org or Wild Bill WB6BFG at amsat.org and provide the following information (length of shift available, location preference, shelter, radio equipment capabilities). All efforts will be made to ensure that the early birds will get the worm as far as shift & location preferences. (note: we will be on the road 4/28-5/3 working the Mexican 1000 off road race so be patient for a reply - all of which will be handled in the order received) 
 

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