@fyre, admittedly I don’t have time for the full-length explanation, but here is a graphic you can use for your research of the topic at hand. Readers digest version. even if you remove the active 40mph wind component as other have said there is/are other factors, fuel, length of days, slope, fuel moisture, 1"-1000 etc. etc.
Reference this graphic… probably as of today, we are “breaking records” in the ERC arena. this is just a snapshot of one psa. good luck in your educational endeavor.
I believe it.
Got buddies at Thompson in camp at Chico. All on OES but not assigned. I imagine with this weather there staged informally for IA in the area with all the local resources still commited to Thompson
You’ve gotta differentiate live vs dead fuel moisture, though. With your chart, after 10 days of heat wave, yes, the 100 hr (dead) fuels are going to be at record dryness, but at higher elevations, the brush still has quite a bit of moisture in it. So yes, things can be explosive with wind and terrain in the lower elevations without having massive potential yet up in the mixed conifer forest.
Here is me trying to light brush from 5,000’ on Highway 20 in the Sierra with a blowtorch this Monday:
It’s the calm before the storm right now in the state for the next few hours….
Forgive me if I speak out of turn but it has always seemed to me that when highs are at the extreme end of the scale, large fires do not happen much. I always attributed that to the stability necessary to generate these temps but I am not a met. Maybe it is just because yay-hoos stay inside and do not cause ignitions when it is real hot out. It seems when the weather moderates back into the 80s with instability and breezes, that is when the large fire growth occurs. Feel free to tell me I am wrong.
Fuel,Weather,Topography, and yay-hoos!
I agree . In my experience it is usually on the back end of the heat wave.
Agreed Birken. Saw it many times over the years. When we ‘thought’ everything was so called ‘ripe’ and hardly anything happened of any consequence anyway. Most LG will run crazy as usual, but in the wildland? Time will tell…
Well, what if more/less everyone is equally right & equally wrong at the same time here? Heck yeah, there are plenty of critical fire weather days and zero fires. Plenty of history for big fires & small ones happening in stable and un-stable environment(s). Equating stable or un-stable Wx with large, small, good OR bad Fires seem’s to be a view that most if not all of us grow up with - until you learn how the fire environment works - especially that Wx leg of the triangle. Meanwhile the general citizenry & news anchors see it in that binary good/bad way because it’s simple and i think most just want to know if they need an umbrella or sunscreen. Plenty examples of certain fuels characteristics combining to over-ride LFM to the point where an otherwise un-available “green fuel” burns just fine and in some cases it burns like it’s dead. Also plenty of fires happening at elevations AND in places that make us scratch our collective heads and wonder what does it signify about the bigger Fire picture… My 2 cents after reading the discussion in this thread, not that you needed it… Questions/discussion is good. #studentsoffire #studentsofclimate
(X) = IGNITIONS the ultimate variable - and not just do we get an ignition, but where and when add so much to this equation. So its HAWT, WINDY, RECORD ERCs and we get an IGNITION in 3 foot tall cured grass and on the wrong side of the road it goes nuclear, on the other side its backing into the wind. We have all seen these. This vehicle fire into the veg is going the opposite direction we are here for a week.
Very simply put it goes way back to Contry’s fire environment if you are able to generate enough heat to break through the the inversion then all bets are off. We are there in the lower elevations not so much in the upper elevations
The temps in Vacaville still high 105) but the RH is now rising (26%) and the winds are subsiding. Hopefully we are on the down side now.
At the risk of sounding like an old…
This should (still) be required reading for all wildland padawan’s & the public…
I will actually enjoy reading this… thank you.
Anyone know if there is an electronic link or copy of the original Firefighter Handbook. I think that’s what it was called, from USFS??
Some might not be aware and may be curious about fire behavior history worth remembering…
All of “us” in the biz - retired or in the arena - use the term “student of fire” and it is upon the shoulders of giants in fire behavior research & understanding that all of us stand. Frank Albini, Dick Rothermel, Donald Haines & Clive Countryman (among others) are on the Fire Environment / Fire Behavior mount rushmore… \m/
USFS Fireman’s Handbook - circa 1966. One of the first things I was given when I started in 1971, guess I’m dating myself. I love the old pen and ink drawings
From NWCG
***** High Risk for Heat & Dryness across Mid Coast to Mendocino, Diablo-Santa Cruz Mtns & Sac Vly/Foothills PSAs Today-Sat & for Sun for Sac Vly/Foothills PSA *****
***** High Risk for Heat & Dryness NW Mtns Sat-Sun and for Wind/RH Diablo-Santa Cruz Mtns PSA Sun *****
- Breezy westerlies this morning w/mdt-poor RHs east bay area, Sac River Delta area, & Mt Diablo to Santa Cruz Mtns will increase this afternoon-evening & expand into the Mid Coast to Mendo PSA w/gusts 20-35mph along w/low RHs 15-30%.
- Westerly flow coming in from the coast each afternoon to evening will gradually strengthen w/each day thru the weekend & then persist early next week. Expect enhanced evening winds for bay area to S & W Sac Valley each evening today thru early next week.
Increasing onshore flow this weekend into early next week will enhance marine influence for coastal areas, first in the bay area, then expanding to other coastal & near coastal areas, bringing cooler temperatures and higher RH.
Ridge center shifting E of N Ops Sat afternoon results in southerly flow aloft next week. This will open the door for potential T-storms, though atmosphere likely to be too dry initially. Current potential looks to be very slight (10%) across mtns NW-N-E of the Sac Valley Sun-early next week increasing later next week in mtn areas NW-N-E of the Sac Valley.
- Potential for increased winds w/low RH Thu-Sat of next week will need to be monitored for potential High Risk.
The persistent high pressure ridge will continue to drift slowly eastward today allowing inland temperatures to cool slightly while marine layer onshore influences begin to return to the coast and coastal interior areas.
- Near coast and coastal interior areas will begin to see much better moderation in temperatures as cool and more moist marine air pushes a little further eastward each night. Max temps will range in the upper 70s to mid 80s while min RH values generally range from 35-45%. Overnight periods will relatively cool with excellent recoveries through the remainder of the week.
- Generally light winds today across most areas but breezy W winds of 15-25 mph do develop out of the Bay Area/Delta, Coastal Gaps and Shasta Vly late this afternoon/evening. Westerlies pick up Tue afternoon favoring the Delta again but also higher gusts of near 30 mph across the NE, Sierra Crest and Far NE.
Gusty N-NW winds expected on Wed down the Shasta Valley Wed afternoon/evening with gusts of 20-30 mph.
Afternoon mtn cumulus may begin to start showing up today and each afternoon/evening through Thurs along with very isolated showers and tstorms across the northern mtns and Sierra.
- Southerly flow brings better chances for more widespread tstorms on Fri including the NW mtns, with coverage shifting slightly eastward on Sat. Any cells will likely be moving from S to N at moderate speeds and may trend on the dry side.
- Potential outflow boundaries and stronger W-SW winds across the NE and Far Eastside on Sat-Sun will combine with persistent hot temperatures and very low RH.
