From Daniel Swain of Weather West:
“During the Wednesday/Thursday cold frontal passage, it is more likely than not that hourly rainfall rates will exceed thresholds capable of triggering significant debris flows over portions of the LNU Complex, CZU Complex, SCU Complex, and Dolan Fire burn scars from 2020. The highest risks to people may be in/near the LNU/CZU scars due to proximity to populated areas, but the highest meteorological risk may actually be in Monterey County.
This is because the front and associated AR is expected to stall somewhere along the Monterey/SLO County coast on Wednesday before lifting slightly back *northward* by Wednesday night as a mesoscale frontal wave develops. It’s still not 100% clear exactly where this stall will occur, but I would expect a swath of widespread 5-10 inch rainfall where this occurs (and locally 15 inches or more in orographically favored parts of the stall zone). Some flooding could occur even outside of wildfire risk zones around the location of this stall. Right now, Monterey County looks like the most likely bullseye for this–but it could happen as far north as Santa Cruz County. Even absent a stall, rain rates across the Santa Cruz Mountain burn scar will be concerning–but if the AR does find its way back north for a second pass, local concerns will be further exacerbated.”
Interactive #GIS map showing risk of #DebisFlow for wildland fires. For the legend and to get the most benefit from the map, please click “Map tips” in upper left corner. To search on address click Menu > Search. #CAwx
Open #GISsurfer map: bit.ly/39Y5BRA
2/_ The map opens at the #CZULightningComplex. You can pan the map to other 2020 fires and see the same type of data. Be patient! The map might be slow to refresh. It depends in part on how much other work the GIS server is doing.
3/_ The map can display the risk of debris flow for fires back to 2018. Here is one way to make a map to see the risk of debris flow for a fire prior to 2020:
A. Click the basemap button and look under the “Overlays” heading
B. Click “Turn off all overlays”
C. Pan the map to the approximate area.
D. Click the basemap button, look under the “Overlays” heading and turn on layers in the following order:
ESRI roads and labels
(year) Basin combined hazard
All streams rivers lakes
Segment combined hazard
CAVEAT: I HAVE NOT TRIED THIS MYSELF AND CANNOT HELP YOU NAVIGATE IT, BUT THIS NAVIGATING IS FOR FIRES BEFORE 2020 AS I UNDERSTAND IT.