Here’s the growth of the fire yesterday, using two sets of Google Earth polygons, one from last night and one from the night before.
It’s hard to tell what is the result of wildfire, and what is the result of back burns, sinee it now looks like some pack burns are within the perimeter.
In the southwest, the fire has extended up to the fire breaks on the west (backburn?), and continues to extend southward to the east in that area.
In the southeast, the fire continued southward and also northeastward, although a great deal of that last may be back burns.
Here’s the result of last night’s first (10PM) MODIS pass:
And here’s what it looked like after the second (2AM) pass:
Zooming in on the southeast:
The fire is actively moving south, and looks like the southern part is making a move towards the east, and Cachagua and Tassahara Roads. The fire activity north of there is hard to sort out. The new hotspots inside the official fire perimeter are wildfire, but the ones outside could, at least in part, be back burns.
[VIIRS data sets added 1000]
OK, I’ve now gotten VIIRS high-resolution data from last night, and it’s clearer what’s going on:
Let’s look at the western part of the southern edge of the fire:
This data set doesn’t show the fire hard up against the southern set of fire breaks. It does show a lot of activity from the eastern part of the southwestern part of the lobe, with progress to the southeast, and progression into the already-burned area to the west, which might be back burns. The fact that the fire has burned through once doesn’t mean that it can’t go back through again and burn fuel that it missed the first time.
Looking over near Cachagua:
The two isolated hot spots in the southeast that we saw on the MODIS map are not present. Since VIIRS has been so much more reliable in the past than MODIS, I tend to believe it here. If VIIRS is right, that is good news; the fire isn’t making a run to the east down there.
The location of the VIIRS hotspots near the dam make them look like most of them are back burns, although the westerly ones are probably wild fire.
The fire is now moving onto the area burned 8 years ago in the Basin Fire. It remains to be seen how much that will slow it down.
All of the official briefing maps for today cause my copy of Adobe Acrobat to crash, so I can’t tell you much about what they say. Oh, I can open them in my browser. One good thing is that they are saying that the winds should be favorable today for “burning operations”. I’m assuming that means back burns.
FWIW, here’s the Cachagua portion of today’s ops map:
If we back up, we can see how far to the south the newly-completed dozer lines (marked in red by me) go:
And here are yesterday’s MODIS pictures:
Notes:
The orange lines are the dozer fire breaks that were in as of 7/30, plus on 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.
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