Soberanes Fire VIIRS data

We have a new official fire outline this morning from Cal Fire:

The lighter red is the 8/3 fire area, and the darker portions indicate the fire advance up to midnight last night.

Taking a closer look:

Some fairly large expansions of the southern border.

There is one place where the fire appears on both sides of a firebreak:

This could be an error, it could be back burning, or it could be wildfire compormising the fire break.

Looking at the overnight (the pass was at 3 AM PDT) high-resolution VIIRS data, with the new fire boundary superimposed:

The western new fire activity is strong, widespread, and appears to be within the official fire boundaries for the most part. The southeastern activity is west of where the official Google Earth fire polygon says it is.

Looking closer at the Cachagua area:

I can’t sort out the back burns from the real fires in this map.

Here is the best I can do.

I can't tell what's what in this circled area — I can’t tell what’s what in this circled area

At eight, we have MODIS data from both of last night’s passes:

Looking closer:

Although newer, the coarser resolution of the MODIS data, coupled with, IMHO, a greater propensity for error than the VIIRS high-res data, makes it less useful than what I showed above. Of the people blogging about this fire, I appear to be the only one using the VIIRS high-res data sets. Do they know something that I don’t?

The orange lines are the dozer fire breaks that were in as of 7/30, plus one that I added by hand. The pink lines are the ones that were planned as of that date.

How to read the MODIS/VIIRS heat indications: The size of the square represents the nominal margin of error. The fire could be anywhere in the square, not just at the center. Dark red squares were detected less than six hours before the data set was created. Light red squares were detected less than twelve hours before the data set was created. Orange squares were detected less than 24 hours before the data set was created. Yellow squares were detected less than six days before the data set was created. When the squares overlay other objects, the color of the square changes somewhat, but the color of the dot in the middle does not. So look at the dot if you’re uncertain what color the square should be. Since the fire is now over six days old, some of the early detections have dropped off the map. MODIS makes mistakes, sometimes missing outbreaks, and sometime misplacing them outside the nominal margin of error. It is also a snapshot of the activity at the time the satellite is overhead, and will definitely miss flare ups between passes. MODIS can’t tell the difference between wildfires and intentional back burns.

This mornings operations map shows that new fire lines have been completed to the east of the main Cachagua fire lines, although there has been no new Google Earth fire line data issued.