Monday, October 22, 2007
I'll start tonight with MODIS satellite thermal imagery for the county, with a few annotations of my own. The black, orange, and red areas in the image at right shows progressively more recent “hot spots” detected by the MODIS satellite. It's easy to see the two major fires in the county on this image – the Witch Fire to the north, and the Harris Fire to the south. I added purple lines to show the approximate course and branching activity of the fires. Both fires started at the extreme northeast end of their extent (the upper right) and moved WSW (slightly down from leftwards). Both seem to be marching inexorably to the sea. Both are expanding in the north south dimension, slowly north, southerly in wind-driven bursts.
In both the image above, and the more detailed image of the Harris Fire at right, I've marked the area where we live in green, the paths of the fires in purple, and the area where my niece lives in yellow. At right you can see, vividly, why we've been somewhat anxious all day: the Harris Fire is just a few miles from our home, moving rapidly – but, thankfully, not toward us. We're very aware that this could change in short order, so we'll be watching closely all night tonight to make sure it doesn't surprise us. So far the winds have not changed direction, though they have slowed down.
At right is a panorama made by stitching together the views from the east-facing and south-facing cameras on Lyons Peak. You can see here the two areas that concern us the most. Roughly in the middle of the photo is an area burning intensely, moving northward up Barrett Canyon (toward Barrett Lake). This is moving very slowly northward against the wind. If it broke out to the north, it could come at us from our east, driven by whatever wind remains tomorrow. To the right of the photo, you can see the fragmented burning areas along Honey Springs Road, State 94, and Otay Lakes Road. These have been mainly moving WNW, toward the southern reaches of the town of Jamul, and Proctor Valley. If the winds shifted, these could threaten us; at the moment they mostly present a threat to the eastern edges of Chula Vista (especially Eastlake).
Earlier this evening, we started packing our vehicles. We knocked off after about three hours of work, because (a) we were tired, and (b) things looked a bit less immediately threatening (and they remain that way). So we're going to keep a sharp eye out tonight – we'll get up every couple of hours to check the Lyons Peak cameras, and check for new satellite imagery.
Now we're starting to get concerned – the fire has advanced incrementally toward us on the latest MODIS pass (which I was finally able to get), but this doesn't tell the whole story. On the Lyons Peak cameras, we can see a branch of the fire advancing southeast of us, moving almost due north up the Barrett Creek Canyon toward the lake (the L shaped lake in the upper right quadrant of the map). Worse, the fire has spread northwest of its largest extent on the map, and is now threatening the Jamul Highlands part of the town of Jamul (the purple-tinted area). We have heard from two different people that that area is now being evacuated, and from one person we also heard that the Steele Canyon High School, which is an evacuation center, is itself being evacuated. Not good.
It remains true that from everything I can see on the Lyons Peak cameras, we are not under immediate threat (we live in that green shaded area). Nonetheless, we're going to start packing some things, just in case we do have to evacuate – so that we're not in a huge hurry when (and if) it happens.
As several of you have noticed, some of the web sites listed under the “Wildfire Information” link at right are not working. This is because of the high number of visitors at the moment. People hungry for information have driven my blog's traffic, and my Lyons Peak cameras traffic, to more than 30 times their normal level (but still holding up just fine). I can only imagine what those information web sites must be experiencing, and I'm not surprised they're having capacity troubles. With a quarter million people evacuated already just in San Diego County, it's easy to imagine they are getting many millions of hits. Just for example, I've been unable to get MODIS thermal imaging data since 6 AM because of traffic problems&helllip;
The extreme wildfire danger that southern California is experiencing right now is caused by a weather pattern that occurs every year in this season, usually a few times each year and lasting a few days each time. The main characteristic is the wind, which gives the weather pattern its name: the Santa Ana winds.
I captured these graphs from my weather station this morning. At top right, you see the raw wind data (gusts and average). The time and date on the graph are GMT, which is currently 7 hours later than local time. Around 9 AM local time yesterday, the winds kicked into high gear – and they've been there ever since, over 24 hours now. My weather station doesn't show the 60 to 70 MPH gusts we've been experiencing, because it can't respond quickly enough to catch these short but very intense gusts. Next down is the “wind run” graph; this shows how far the wind blows each day. You can see that the steady high wind results in a much higher wind run than normal – and this is what makes the winds so dangerous in a fire.
Finally, the bottom graph shows the barometric pressure over the last week – and you can see that for the past 24 hours, the pressure has been rising very rapidly. The center of the high pressure area is to our east, and the Santa Ana winds are caused by the air moving from this high pressure area to the relatively low pressure area off the coast. This is the direct cause of the winds, and this is the pattern that we see a few times each year, this time of year…
North of us the Witch Fire is burning out of control, on several fronts, and causing far more trouble than the Harris Fire that is closer to us. At right is the latest MODIS thermal imaging data, which looks pretty grim – but the news from TV and radio is even more grim: huge swaths of San Diego County are under evacuation orders, and apparently many homes have already been lost.
I got word from my company this morning to stay away from our Solana Beach office, as it was in an area that might be evacuated – and, worse, that at least one of our employees has lost his home, and several others have been evacuated. We have friends in many of the affected areas, and have heard from one (in Ramona) who has already been evacuated. We also heard that an area just north of Ramona, where we know someone with a beautiful horse farm and many animals, burned over during the night. Grim news from all over the county…
We had an anxious night – the fire was far enough away that we didn't need to stay awake all night, but close enough that we needed to keep an eye on it. So we set the alarm to get us up every few hours, and we kept an eye mainly on the Lyons Peak cameras. The view from Lyons Peak (looking south) at dawn is at right. The areas that look like flames are actually smoke that's lit up by the fire below it; the actual flames have been mostly out of sight from Lyons. Toward the right, the smaller orange areas may actually be flames on the northeast flank of Otay Mountain, but I can't tell for sure…
Just a short while later, I captured the photo at right, showing the same area. If I'm reading the smoke plumes correctly, it looks like the south flank of Mother Grundy/White Peak and an unnamed hill just north of Honey Springs Road (all out of sight from Lyons Peak) are burning and the smoke from those fires is blowing WSW over Otay mountain, completely obscuring it. It also looks like there is some burning on the NE flank of Otay Mountain, but I can't be 100% sure of this…
The MODIS satellite thermal imaging was updated during the night as the satellite made a pass. The orange areas are yesterday's hotspots, the red are the hotspots on the most recent pass. All of these are consistent with what I wrote just above, based on reading the smoke…
As always, you can click on any of these images for a larger view.
This morning the situation in the Ramona area (the Witch Fire, to the north of us) looks much worse than the Harris Fire to our south. We cannot see anything but smoke, but there's lots of that – and within the past few minutes we just started to smell smoke for the first time. The cameras are still not showing anything burning upwind of us, so I'm not sure where the smell is coming from – but most likely it is some branch of the Witch fire…
I'll start tonight with MODIS satellite thermal imagery for the county, with a few annotations of my own. The black, orange, and red areas in the image at right shows progressively more recent “hot spots” detected by the MODIS satellite. It's easy to see the two major fires in the county on this image – the Witch Fire to the north, and the Harris Fire to the south. I added purple lines to show the approximate course and branching activity of the fires. Both fires started at the extreme northeast end of their extent (the upper right) and moved WSW (slightly down from leftwards). Both seem to be marching inexorably to the sea. Both are expanding in the north south dimension, slowly north, southerly in wind-driven bursts.
In both the image above, and the more detailed image of the Harris Fire at right, I've marked the area where we live in green, the paths of the fires in purple, and the area where my niece lives in yellow. At right you can see, vividly, why we've been somewhat anxious all day: the Harris Fire is just a few miles from our home, moving rapidly – but, thankfully, not toward us. We're very aware that this could change in short order, so we'll be watching closely all night tonight to make sure it doesn't surprise us. So far the winds have not changed direction, though they have slowed down.
At right is a panorama made by stitching together the views from the east-facing and south-facing cameras on Lyons Peak. You can see here the two areas that concern us the most. Roughly in the middle of the photo is an area burning intensely, moving northward up Barrett Canyon (toward Barrett Lake). This is moving very slowly northward against the wind. If it broke out to the north, it could come at us from our east, driven by whatever wind remains tomorrow. To the right of the photo, you can see the fragmented burning areas along Honey Springs Road, State 94, and Otay Lakes Road. These have been mainly moving WNW, toward the southern reaches of the town of Jamul, and Proctor Valley. If the winds shifted, these could threaten us; at the moment they mostly present a threat to the eastern edges of Chula Vista (especially Eastlake).
