Predictive services has added high risk days for lightning.
A trifecta of weather concerns. The excessive heat and dry conditions that have been occurring, the ridge is breaking down this weekend leading to strong and gusty onshore winds, and the shortwave responsible for breaking down the ridge will lead to elevated thunderstorms with a mix of wet and dry storms.
For areas north of Lake County… Onshore winds are increasing this afternoon, through Friday. More sunshine, plus a trough moving into the Pacific NW are tightening gradients, leading to gusty winds. Drier conditions and these winds, aided by upper level support from the trough… will cause growth on already burning fires and lightning holdovers. Mid level moisture is sufficient for pyrocu development on the most intense fires, but thunderstorm coverage with wetting rains will be suppressed due to lowering moisture values. This means the chance of dry lightning strikes outside of storm cores is increased today and tomorrow.
Continued drying through the weekend, as the ridge rebuilds in the wake of the Pacific NW trough. As we are headed for the 8th - 11th time frame, there exists concern over a dry trough interacting with the remnants of Hurricane Frank and producing some very gusty onshore winds. This is a pretty rare scenario, so it will be monitored and forecasted as we get closer.
To summarize… increasing onshore winds, drier conditions, more sunshine and lightning holdovers should keep resources busy through the weekend. Warmer weather will build in this weekend, with the potential for a major ridge breakdown the 8th-11th. The same conditions exist in Oregon and Washington, which are experiencing significant growth on existing and new starts. A very challenging period for resources, ie airtankers could be ahead as the conditions drive and expand fires.
GOES-18 fire temperature showing many large fires burning across the NW
Markleeville checked in with 1.8 inches of rain in 2 hours today. Yikes.
Video shows debris flows near Markleeville. A flash flood emergency has been issued for parts of Alpine County. Read more >> https://t.co/GWtrdnMjQx pic.twitter.com/uZ7OEO6zCl
— kcranews (@kcranews) August 4, 2022
Since I moved from Twain Harte to Sonora. I have not put a new rain gauge out, but under all the drip line of my trees it is wet. Standing water everywhere on asphalt and concrete. My buddy in construction said the rain stopped all the dirt work and paving they were doing today. It rained better this morning than most of our storms last winter. So much for the 20% chance of rain. Rain gauge going up after it stops raining.
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1056 AM CDT Fri Aug 05 2022
Valid 051700Z - 061200Z
An isolated dry thunderstorm risk area is introduced to portions of
northern CA into southern OR. Latest MRMS rainfall estimates suggest
ongoing convection is a mix of wet/dry thunderstorms with pockets of
wetting rainfall. Thunderstorm chances will persist into the
afternoon as a weak mid-level disturbance moves into the northern
Great Basin. Forecast soundings show inverted-V soundings with cloud
bases near 2.5-3 km and PWAT values near 0.8 to 1.0 inch. These
thermodynamic conditions are supportive of a mix of wet/dry
thunderstorms over a region with receptive fuels and a history of
recent fire starts. See the previous discussion below for additional
forecast concerns.
Grass Valley has wet pavement in some places, but other places little rain fell. Not enough to stop work anywhere. The sun will burn it all off whenever it comes out, I’m sure.
Haines of 6 today and strong S winds in the Siskiyou area and really for everywhere north of Mt. Shasta.
Could be an interesting day with existing fires and any potential new starts.
Looking at next week it looks like increased chances for some more lightning in SOPS and NOPS. This would follow a distinct warm up with valley temps pushing 110.
North Ops weather: Monday 6:30am
*** Hot, dry and unstable today with isolated thunderstorms possible Tue afternoon & evening and increasing in coverage Wed-Thu including drier high based nocturnal storm potential Wed night ***
Ridging strengthening overhead will bring hot, dry and unstable conditions through the first half of the week. S to SE flow aloft developing Tue and strengthening Wed & Thu as small upper level disturbances moves up the coast will bring increasing thunderstorm chances to the area.
Isolated thunderstorms with limited moisture will begin developing along the Nrn Sierra Mtns Tue afternoon and potentially extend into NE CA, the Far Eastside & portions of the NW Mtns Tue evening.
Mixed wet & dry thunderstorm coverage will increase across N & E areas Wed with increasing
chances of drier thunderstorm activity of continuing through the overnight hours Wed Night through Thu morning.
