Strong early-season storm for California

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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

217 thoughts on “Strong early-season storm for California”

  1. Looks like the low has turned more Southeasterly now, looks like it will make landfall closer to SD(further North) than predicted. Might end up, picking more rainfall up. Noticed a few scattered showers in the SD area. I am also picking up a good breeze from the E-SE at the house. Looks like the SD NWS office is mentioning the closer track as well as a lower snow level tonight for the SB mountains. Guess we will know in the morning.

  2. That we do. Yellow band on the radar just left a fairly heavy shower across the south end of the bay and Otay Mesa. Tijuana seems to be getting a good rain as well. This will be last post for another month.

  3. It was an interesting day yesterday. Was at Fullerton most of the day and not a single drop for rain. We came back to Whittier for a bit and it was raining with no real clouds around it rained for about 2 min just about a trace of rain. After that I was at Cal State Long Beach and sure enough it wasn’t raining. On the way home back to Whittier the only place it was raining was Whittier. Even that it was only around 0.12 for the early morning.

  5. We are well over an inch of rain and it is still raining, picking up strong east winds now the low must be to the west. Fire units are responding to power lines downs as well as trees in the area.

      • Ken, your area in general received much more rainfall than up here in Orange County. Many areas in San Diego County received anywhere between 1/2 and 1 inch, while most of O.C. got between .10 and .25, with the exception of far southern areas, in which .33 to .5 fell. I will report my total later on tonight when I am sure the storm is over.

  6. As of 953pm on 11/12/2011 — Redlands, Ca has only received 0.04 — what a flop of a storm —- recently got a new rain guage – bout a week ago — only got 0.01 — dont think its very accurate as my Davis/Vantage pro rain guage—- Looks like above that some areas south of Redlands got nice amounts of rain

  7. San Diego did get quite a bit of rainfall 1.21 at the house. had a strong east wind follow the rain. I am sure Tom picked up some good rain. Next weekends storm looks more like a normal cold storm. Redlands and Dan you should get a better rainfall.

    • Only .19″ fell here in Orange from the storm, as most of the activity was well south of the area. I had another brief shower last night, so I didn’t want to check the gauge until the event was completely over. Hopefully next weekend’s storm doesn’t sideswipe us offshore in “outside slider” fashion and comes in closer to the coast to bring higher totals to a larger area than this last one did.

    • The latest model runs of the GFS and Euro are showing the possibility of that happening. It shows that the storm will completely miss Southern California and make landfall in Baja California. It is taking a very similar path as the previous storm. I hope the models are wrong…becuase if they are right than that is just unprecedented. I never seen two storms in a row take a “outside slider” track. Especailly, in a short period of time. Time will tell what will happen though…I am trying to be optimistic as I can.

  10. It seems to me that this Baja “outside slider” storm track has been a recent phenomenon that started sometime this last decade. It could also be that I have been analyzing the patterns more closely in recent years than I did back in the 80s and 90s, and it may have happened back then from time to time and I just didn’t notice it.

  13. I don’t like the trend of tonight’s 0Z GFS run trending toward the EURO in keeping this weekend’s storm more offshore and potentially keeping the area drier in yet another “outside slider” storm track.

    What’s up with this pattern, anyway? It seems that we used to always be missed by the “inside slider” track until the 2000s, and now we are occasionally missed by BOTH patterns. The good thing is that the area is getting fewer Santa Ana events that often result from an inside track, but it would be nice to get more widespread rains when a storm moves through, instead of sliding by offshore.

  14. Current GFS shows us getting zip, nada for the whole weekend, and the low veering hundreds of miles offshore.

    If you like to grab at straws, which i do LOL, this does open the door for a whopper around thanksgiving =)

  15. Well, just for every ones info, we ran through some weather earlier this week, probably the one your t6alking about. Didn’t amount to a whole lot. Scattered rain squalls and some wind 15 to 20. Were in fair weather today could hit some heavy stuff further west.

    sent viar marsat wqmm/ch148usb/111930znov11/ser287354274956247C

  16. It has been somewhat foggy and drizzly here in Orange tonight. Earlier I thought that the fog was going to get really dense, but then it began to drizzle and the fog actually lifted somewhat, probably in response to the deepening marine layer.

  18. sounds decent, first moderate snow storm for the resorts, sounds like 5″ to 11″ snow possible above 6k, and another on thanksgiving, and the models have been fairly consistent with one again next sunday or so, we’ll see, fairly active start to the season compared to previous years….

  20. Looks like you are getting pounded down there! You can’t get all the storms though, and the Thanksgiving storm now looks like a dud for socal on the latest GFS.

    The GFS had also been clinging to an odd pattern that included a bunch of warm air pumping into Vermont in the long term, which just doesn’t make sense this time of year! Sure enough, it’s reverted to a more normal pattern of snow starting to fall after thanksgiving. Unfortunately the latest GFS isn’t too wet for CA in the long term,…but we all know how often that is wrong.

  21. It has been raining moderately to somewhat heavily here in Orange for the last hour or so and earlier in the day it was intermittent off and on. I would guess that at least a half inch has fallen here so far with a little more to come this evening.

    One of the weather blogs I read regularly has been consistently saying that we would be going into a drier pattern after Thanksgiving at least into early December as a ridge builds along the west coast and a trough develops in the east, bringing colder air there. Hopefully the Thanksgiving storm isn’t a dud down here, and the GFS has plenty of time to change its tune and revert back to strengthening the storm before then.

  23. 5″ of snow on the ground and lots of rain/sleet mixed into that @ 6200′. Makes for a nasty morning clearing the berm…

    now when will this madness ever end?

    “…THIS MEANS THAT SOUTHERN CALIFORNIA MAY ONCE AGAIN
    SEE MORE WET WEATHER FOR THE HOLIDAY OR THE BRUNT OF IT MAY GO TO OUR SOUTH.”

  28. The highest total i see is Crestline which didn’t see any snow, 1.78″ rain. But that is light, we get that from drizzle storms :D . It’s not a rain storm unless it’s over 5″. We haven’t had a Really rainy season in awhile, i hadn’t moved up here yet, but several years ago Crestline recorded 133″ for a season.

  31. .57″ fell here in Orange from Sunday’s storm. It appears this area got shorted a bit in terms of amounts this time as many places in L.A. and San Diego counties, and even portions of Riverside County received between 3/4″ to 1″.

  32. It does look like the Thanksgiving storm may be a dud… and the GFS, at least, doesn’t show much for CA in the long term . We all know how useless the long term is though… it’s all over the place for Vermont too. Meanwhile, the cold weather is definitely here now, we were down to 15 last night. Not record breaking by any means but the coldest it’s been this year. We are expecting snow Wednesday.

    • It does sound like a torch this weekend with highs in the upper 70s to low 80s, possibly even some mid 80s in spots. I hate to say that we are due for some more Santa Ana wind events, and this weekend or next week that just may happen. Fortunately, we have been in a relatively active pattern and the ground is fairly wet from recent rains, so I don’t feel that fires would be a problem unless we got into an extremely long dry spell, which I hope doesn’t occur.

  36. Hope everyone is having a happy Thanksgiving!

    Has anyone recorded any rainfall anywhere today? I am visiting my relatives out in Hemet, and there hasn’t been any rain anywhere I have been between Orange and Hemet, just cloudy skies and cool temperatures.

  37. Happy Thanksgiving, No Rain here in my area SD Foothills. Just clouds. Looks like it might even get hot on Sunday & Monday highs near 90 with a moderate East winds.

  38. According to tonight’s San Diego NWS forecast discussion, a 590 DM upper level high is forecast to build over our area from the west along with a surface high over Utah. That is an awfully strong upper high for this time of year, as highs of that strength are usually seen in the summer months. With the high this strong, it could possibly reach 90 in some areas. I wonder of Hurricane Kenneth has anything to do with the strength of this high.

  39. No rain in Redlands, Ca for thanksgiving 2011 hi of 58 low of 43 —- I sure hope it doesnt get up to 90 — thats too hot for late november — its not good for putting up xmas lights/decorations

    • If it does get to 90 degrees thats nothing. I remember we got a death ridge from hell in January 2007(or 2008?) that brought us temperatures well in the 80′s and 90′s. I was thinking about going to the beach during that time ahaha.Now, that is unusual!

  40. This is getting comical, even NWS has given up LOL

    MODEL SOLUTIONS VARY GREATLY TOWARDS THE END OF NEXT WEEK. ANOTHER PESKY CUT-OFF LOW MAY FORM OFF THE SOUTHERN CALIFORNIA COAST AND EVENTUALLY MAKE ITS WAY
    TOWARDS US…THOUGH AT THIS POINT IT IS IMPOSSIBLE TO TELL IF THIS WILL BRING ANY RAIN OR NOT.

  41. The models have been all over the place and differ from run to run and model to model. I think a pattern change is coming to the whole US, probably something unusual that the models have trouble dealing with. As someone else made mention of I wouldn’t be surprised if Kenneth threw things off, the models have a lot of trouble with unusual storms like that.

  42. Toasty day. Very nice So. Cal Day. High 86, Low 51, East winds to 14 MPH with 10% RH.(Granite Hills) Looks like changes to cool to cold end of the week with a chance of showers and T-Storms.

    • I was down at our condo in La Jolla today and it was near 80 there, one of the warmest days that I have seen there in a while (when I am down there, that is). Later on in the afternoon I did a little metal detecting around Mission Beach, and things began to cool down into the lower and mid 70s as an onshore breeze came up out of the northwest. The beaches weren’t really too crowded, but there were many people enjoying the nice weather outdoors, walking and bicycling. It was pretty clear as well, as the mountains to the east were clearly visible. I am back in Orange tonight and it is milder than in recent nights as the temperature is near 60.

  43. Hey folks! Sorry for the dearth of posts lately–the combination of a busy schedule and a relatively quiet (for most of the state, anyway) start to winter have contributed to that. In any case…do expect a full update once things start to get more active once again. The retrogressive “inside slider” system for later this week looks to be potentially interesting for SoCal–possible very strong winds and/or convective precipitation. This won’t be a hot offshore wind, that’s for sure…if anything, it will be pretty chilly out there. Certainly something to keep an eye on…and potentially a portent of things to come if the high amplitude blocking pattern the models keep suggesting will set up in the far E. Pac. actually does come to fruition…

  44. Was 82 in Redlands, Ca at my station — 11/27/11 — The 82 ties the record for warmest 27th —- thought it was gonna get hotter —- Hope we start getting colder – more interesting weather

  45. SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
    NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
    300 AM PST MON NOV 28 2011

    THIS IS A COMPROMISE FORECAST. AND HAVE TO SAY THAT IF THE WIND
    FORECAST DOES PAN OUT AS THE CURRENT MDLS FORECAST IT IS GOING TO BE
    A DOOZIE. ON THURSDAY THE LAS TO DAG GRADIENT PEAKS AT 12 MB AND
    MOST IMPORTANTLY THERE IS GOING TO BE 9 TO 12 DEGREES CELSIUS OF
    COOLING COMBINING WITH A 70 TO 80 850 MB LOW LEVEL JET. THIS COULD
    RESULT IN A 5 TO 10 YEAR SANTA ANA WIND EVENT WITH 80 MPH GUSTS
    POSSIBLE OVER A WIDE AREA. ALL THAT SAID THE MDLS OFTEN OVER DO
    THESE WIND EVENTS AS THEY OVER-DO THE COLD AIR ADVECTION AND THE
    UPPER SUPPORT. STAY TUNED FOR MORE UPDATES AS THIS SYSTEM DEVELOPS

  47. Oh man this event is going to suck so bad for my area. Sounds like the usual in this type of event never any wind for my area and likely get no moisture.

  48. It is looking increasingly likely for a cold strong Santa Ana event from Wednesday night into Friday morning as an upper low drops into the Great Basin, although the exact strength of the event isn’t known as of yet. Most of the models have trended more inland with the track of the storm, so moisture is limited. This is a pretty typical pattern for this time of the year, although this one may turn out to be stronger than average. The PNA is positive right now, keeping the ridge near the west coast with CA in a dry pattern. I have been reading on another blog that the PNA may turn negative toward mid-December and the MJO may be in a favorable phase to have the Pacific ridge retrograde and allow a stormier pattern to take hold later in the month. I certainly hope that happens, but it is still too early to say for sure.

  49. Ive been reading post on here and listening to weather reports from tv — I really dont think my area will get the predicted hi winds — up to 80 mph for the mtns — 60-70mph for the valleys — maybe the usual windy areas but not Redlands — we wont even get 25-30mph wind gust —- Was warmer today in Redlands — 84 — bit too warm for me

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