Northern California Fire Weather and Fuels

UPDATE: 9/15/2021, 1:35pm

Area Forecast Discussion
National Weather Service Sacramento CA
134 PM PDT Wed Sep 15 2021

Chances of moisture (not a bunch) increasing with best chances on
Sunday. Cooling definitely on track with coolest day Sunday. Some
gusty winds possible early next with temperatures slowly rising.


The cooling trend has started today as a weak upper wave has
driven down the upper ridge that has been in place for a few days.
Not too much change in weather tomorrow as next precipitation
bringing system drops into Pacific Northwest coastal areas. Expect
a dry and mild day Thursday.

Friday...mid level winds will start to increase as the next system
advances further onshore in Pacific Northwest. This will case a
brief period of localized elevated fire weather concerns...but
areas that reach that criteria in the Sierra is short lived and
spotty thus we aren't going with any fire weather highlights.
Onshore flow will bring delta breeze and in general more moist air
into the area.

Saturday...a lot like Saturday but mid level wester to southwest
winds increase. This will continue to bring up relative humidity
levels. Wind criteria would be a possible issue for fire weather
but looks like relative humidity should keep us out of anything
too bad.

Saturday night chances of precipitation will start in the north
and push south through Sunday. Confidence in areas north of I-80
getting some measurable rain is increasing. Looking at NBM, GFS
and ECMWF ensemble data good to see they are all in line in
places like Redding, Blue Canyon and Sacramento. Probabilities
from NBM of 0.10 or more around the 50% mark in the higher
elevations and foothills and northern Sacramento Valley. So
system not super wet but wouldn't be surprised a few half in
reports in some areas. Hopefully this consistency continues as the
system get closer.

9/15/2021, 7:30am

Here is some weather discussion from the National Weather Service and Predictive Services at NorthOps in Redding.
Strong winds are forecast for the Dixie Fire area on Friday. Firefighters have had a week to work on taking the heat out of the active northern edge of Dixie, so hopefully she stays in the box through these forecast winds.

 329 AM PDT Wed Sep 15 2021
 Dry and warm conditions remain through the week. More typical 
 late-day breezes return today through Friday. Low pressure system
 coming in off the Pacific will bring stronger winds, cooler 
 temperatures, and even some light showers this weekend. Drier 
 conditions along with some locally gusty north to east winds will 
 be possible early next week.

Energy Release Component

Fire scientists and firefighters use a data product called the Energy Release Component (ERC) to evaluate the relative dryness and flammability of forest vegetation. ERCs are calculated using historic and current weather trends and measurements of the moisture in sticks. Earlier in the year, we were experiencing record ERC levels, which were a warning we could expect extreme fire behavior for any new fires. Following last week’s rain, the ERCs in the ‘Far Eastside’ and ‘NE California’ zones (Dixie Fire) dropped down well below average levels for this time of year, but they are climbing steadily back up toward record levels with the current warm weather. Data from