An unusually strong (for October, in any case) Gulf of Alaska storm system is currently moving ashore in Northern California. The associated 500 mb trough is remarkably well-defined for such an early-season storm, and a powerful 130 kt jet is currently rounding the base of the trough off of the NorCal coast this evening. Strong upper-level diffluence, a very moist airmass (PW values approaching 1.5 inches), and an abundance of cold air behind the cold front will lead to a pretty solid soaking across much of the state over the next 24 hours, especially from the Monterey area northward.
Water vapor imagery of the incoming Gulf of Alaska storm stystem (NOAA)
Several inches of rain could fall in the favored locations in the mountains and along the coast, while even some low elevation inland areas could see upwards of an inch before all is said and done. Though surface pressure gradients are fairly steep at the moment and 800 mb winds will approach 50 kts near the time of cold frontal passage, I would expect these stronger winds to stay mostly above the surface (except possibly in some stronger convective elements embedded in the frontal precip band). Lapse rates near and behind the cold front are quite steep for early fall in California, and there is indeed already a large post-frontal cumulus field visible on satellite imagery. Isolated to scattered thunderstorms are possible across much of the state by late tomorrow as this unstable airmass slowly moves through the region. Even Southern California will get in on some of the action–it won’t be anything too spectacular, in all likelihood, but it certainly won’t be too bad for the first week in October. After the present storm, though, I expect conditions to clear out and warm up nicely once again by the weekend.
On a related note, the recent and anticipated rainfall in NorCal will probably bring an end to fire season north of about the Monterey Bay Area this week. SoCal is certainly going to get wet, but since we still have the peak of Santa Ana season to get through, it is still too early to call for more than a temporary reduction in fire risk. Enjoy the rain!
© 2011 WEATHER WEST
Here is a link on wunderground for the Euro model. You can see a huge explosion of moisture and it takes the low more West.
http://www.wunderground.com/wundermap/?zoom=4&rad=0&wxsn=0&svr=0&cams=0&sat=0&riv=0&mm=1&mm.mdl=GFS&mm.type=SURPRE&mm.hour=0&mm.opa=100&mm.clk=0&hur=0&fire=0&tor=0&ndfd=0&pix=0&dir=0&ads=0&tfk=0&fodors=0&ski=0&ls=0&rad2=0
It is looking like a strong Santa Ana, High wind warnings/Watches and Red Flag Warnings posted. Winds with guts 60 to 90 MPH depending where you are and a cold one. I remember a similar pattern in Dec. of 1977. Winds in the East County of SD reached 100 MPH, a lot of crop damage, barns blown down, power lines and trees down, we chased small fire for 72 hours. Had some rain the day before. Man did it blow. I also remember a cold wind from the north in the early 80′s, brought wind, not as strong, but the cold air mixing in caused Thunderstorms with Snow down low and hail in the lower elevations. Fun Times. Going to miss this one, have to fly to Nashville.
Be Safe.
Up to 17 mph wind gust in Redlands, Ca as of 915pm 11/30/11 — Hi today 76 – Low 47 —-
This ridge is brutal. Nobody along the entire West Coast is gonna get anything for a while.
Amen! That ridge just looks awful. Hopefully, this sucker doesn’t stick around for long!
I have been reading on a couple of weather blogs that the ridge may retrograde westward by mid-December, which would allow more storminess into the west coast. This, of course, is not etched in stone yet, but it is definitely a possibility. It seems that when we have a strong cold Santa Ana event, it doesn’t take too long to get some rainfall in the area, such as in a week or two. I haven’t officially kept track of that, but it has happened more than once if I recall correctly. Has anyone else noticed that trend by any chance?
I see Mammoth Mountain has a sustained wind of 133 MPH with gusts to 140 MPH.
Mountains of Northern LA mountains have winds in the 30 to 55 MPH range. Cold front moving south. interesting next few days wind rise.
The Santa Ana winds haven’t come up here in Orange as of yet, but it was breezy out of the southwest or southeast earlier in the evening. There were even some low clouds earlier, but they have cleared out now, but it is still hazy. I have been moving some of my plants into a more protected area so they don’t suffer wind damage, as wind gusts up to 60 mph are expected here.
Humidity was up to 78% round 745pm in Redlands, Ca — down to 27% right now as of 11:15pm — At 11:05pm we had a gust to 25 mph
My humidity up here did more or less that same thing. Now, it’s 27F 65RH, gusts to 60mph easy (wind prone near a ridge top) and it’s snowing sideways, but i still see the stars perfectly! Welcome to Dec. socal!!
23F when i left @ 6am, enough snow & wind to create blizzard conditions. From the valley it’s cool seeing a storm creep over the mountains from the high desert rather than being slammed in fog and not seeing the storm coming at all. We don’t see these storms very often, and i actually haven’t at all since living here, and it’s quite impressive! Semi’s on their side all over the 210 in rancho to fontana. One fell right off an overpass…Trees down everywhere… how’s your neck of the woods??
Strongest wind gust in Whittier 12 MPH. No rain and a few clouds. Very boring weather so far here.
Jumped right over you man! I hear pasadena got hit hard, and the LAX area also.
The wind came up from the north a little bit around 2 a.m. last night and it smelled like a Santa Ana. However, it was just breezy for a little while and then it died down again. This morning it has been about as calm as it could be here in Orange with only a slight breeze. I was just watching the Channel 9 (KCAL) news a few minutes ago, and couldn’t believe the tree damage in Pasadena and Sierra Madre from the winds. Schools are actually closed in Pasadena today because of the wind. I don’t recall if I can remember any time that schools in my area have been closed due to strong winds.
I think what is happening is that this isn’t quite a true Santa Ana wind, but a more northerly to slightly northwesterly wind that tends to affect L.A. and vicinity much more than inland Orange County. If the wind trajectory switches around more to the northeast, then my area will be under the gun for strong winds.
Sure enough the wind direction veered to the NE this afternoon, and the wind came up here in Orange around 2 p.m. and has been blowing since. It has been a light to moderate run-of-the-mill cool Santa Ana here so far, but it may strengthen some overnight into the early morning hours before decreasing Friday afternoon.
Only up to 25 mph wind gust in Redlands, Ca for November 30/ Dec-1 — nothing like other areas got
Today in Redlands, Ca — 12/3/11 we had a wind gust to 31 mph ===