Unusually dry and windy conditions to continue across California

Posted on by

Much of the fall has been very dry across large portions of California, and what precipitation did fall came relatively early in the season and was generally not sufficient to generate meaningful runoff. The past week has seen one of the most powerful Santa Ana/offshore flow wind events in recent memory, with reports of widespread damage and wind gusts well in excess of 100 mph on some mountain peaks. Unfortunately, the prevailing pattern is not showing many signs of change in the near future.

GFS 00Z Analysis 500 mb heights, 12Z 12/3

A large, powerful and persistent blocking ridge has set up in the Eastern Pacific, creating high amplitude meridional flow upstream and downstream of the block (poleward in the Central Pacific, equatorward over the Great Basin and Intermountain West). Occasional disturbances riding down the backside of the block have generated strong pressure gradients and powerful offshore winds over California and other Southwestern states in recent days, and will most likely continue to do so for the next 1-2 weeks as the blocking ridge holds strong.

Prospects for a pattern change in the immediate future are pretty slim. These sorts of blocks can be difficult to break down, usually requiring an easterly extension of the East Asian jet to displace the Central Pacific ridge. Two other options are for the block to retrogress and the equatorward flow on the east side to shift westward, or for the block to slowly weaken with time. The former option brings the possibility of Arctic intrusions along the West Coast, and the latter brings the possibility of very slow-moving cutoff systems forming southwest of California. One caveat is that the MJO does appear to be fairly active in the Western Pacific, and the GFS is indicating that the signal may begin to propagate eastward over the next 1-2 weeks. If this does indeed occur, there is some hope for the block to break down and for more zonal flow to take over along the West Coast. We’ll just have to see about that…

Despite early fall rains in Northern California, very dry offshore flow with continuing strong winds in the higher elevations is beginning to lead to fire weather concerns. Though December Red Flag Warnings are not particularly rare in Southern California, they certainly are in the northern half of the state. The possibly very strong wind event for later next week could result in critical fire weather conditions from the Sierras to the Bay Area, which would be extremely unusual, to say the least.

We have now entered the critical period for Northern California rainfall. Each day that passes without precipitation adds to the deficit that must be made up later in the season if we are to avoid a significantly below average water year. Since the first half of December appears unlikely to produce that sort of pattern, we may have to hope for wetter conditions in the new year.

© 2011 WEATHER WEST

130 thoughts on “Unusually dry and windy conditions to continue across California”

  1. Tonight: Scattered showers and thunderstorms. Some storms could be severe, with large hail, hail, and gusty winds. Mostly cloudy, with a low around 43. South southeast wind around 5 mph becoming calm. Chance of precipitation is 30%.

    • *scratches head*
      is this a joke?
      Sorry to pessimistic, but I highly doubt its going to happen. There is barely enough dynamics for the development of general thunderstorms. Most of the dynamics are down south near the center of the low.

  4. This storm, was full of wind for our area, not much rain, just started a light spitting out there about an hour ago, has barely got the ground wet. looks like it will get even more dry as we go into the end of the month. Weird pattern.

    • Coastal Socal has actually been wetter this month than the Pacific Northwest and northern CA so far, as the storm systems have either tracked offshore or over the desert areas and back into Socal, bypassing the areas to the north.

    • Ken, we had a shower across the south bay early this morning. Was up to Lemon Grove around 2 and looked like they just had one, probably the one you were referring.

      Driving home just now I noticed the top of Mt San Miguel was socked in like a late afternoon island effect.

  6. Redlands, Ca got a whopping 0.02 of rain on Dec-18 — It doesnt look good — looks like we will only get 0.29 for December — last December over 10 inches

      • Last December we had a freak storm pattern that delivered about 9 inches of rain here in Orange in about a week, which only happens every once in a great while. Despite having more rain down here than up north this month, it still has been drier than average across the entire west coast. I am ready for a pattern change that would allow larger storm systems, as opposed to these dinky cutoff lows, to bring significant rain and snow across the entire state and to help build up the Sierra snow pack.

    • I don’t see anything coming for the next week or so, but I have been reading about a possible pattern change in early January that could bring rain to CA, but I’m not sure how far south it will come.

  8. As Daniel pointed out, blocking highs – where they set up and how that in turn, determines where the jets twist and turn and bring the rain have a lot of influence on the patterns we get.

  9. A mere sprinkle from this pesky low that past by, Looks like a pretty strong Santa Ana wind event for Thursday. Batten down the hatches. Possible pattern change under way, maybe the folks up north will get some much needed rain. Daniel do you see anything in your crystal ball. Looking dry here in the southern part of the state for a couple weeks.

  10. The pattern has been unbelievably persistent – dry in much of the West, cutoff lows through the Southwest, blizzards in the lower plains, rain in the center of the country, and storms from the south zipping into New England with warm air and rain alternating with wet snow. Right now it’s raining in Vermont and 35 degrees… yuck! There is freezing rain in places too.

    It kind of looks like a pattern change may bring snow and a storm track from the west into Vermont but it isn’t looking great for socal right now.

  11. Inyo, my folks In Ohio always say, when we have clear fair weather in winter, they get snow, and when they have fair weather, we get rain. Have you noticed that in Vermont as well, your not that far from Ohio.

  12. Tom, I’ve actually noticed something a bit different. The Midwest does tend to be opposite to California, but Vermont is often closer to so-cal with its storms… meaning, we often seem to get good storms with the same patterns. Not always… but often. Of course, the parallel doesn’t always work as cold dry weather here might be linked to a Santa Ana out there.

  14. I have noticed on some of the Zone Forecasts issued by the San Diego NWS as of late that the wind advisories and high wind warnings issued for a particular time period don’t match up to the forecast wind speeds for that same period for that zone. Tonight’s forecast is a prime example and an excerpt follows below to show this discrepancy:

    ORANGE COUNTY COASTAL AREAS-
    133 PM PST THU DEC 22 2011

    …HIGH WIND WARNING IN EFFECT UNTIL 1 PM PST FRIDAY…
    …WIND ADVISORY IN EFFECT FROM 1 PM FRIDAY TO NOON PST
    SATURDAY…

    .TONIGHT…CLEAR. LOWS 37 TO 47. AREAS OF WINDS NORTHEAST 20 TO
    30 MPH. GUSTS TO 45 MPH…BECOMING 40 MPH OVERNIGHT.
    .FRIDAY…SUNNY. HIGHS 65 TO 70. AREAS OF WINDS NORTH 15 TO
    25 MPH. GUSTS TO 35 MPH…BECOMING 30 MPH IN THE AFTERNOON.
    .FRIDAY NIGHT…MOSTLY CLEAR. LOWS 39 TO 49. AREAS OF WINDS
    NORTHEAST 15 MPH. GUSTS TO 25 MPH IN THE EVENING.
    .SATURDAY…MOSTLY SUNNY. HIGHS 65 TO 70 NEAR THE COAST TO 69 TO
    74 INLAND. LIGHT WINDS.
    .SATURDAY NIGHT…MOSTLY CLEAR. LOWS 41 TO 51. AREAS OF WINDS
    NORTHEAST 15 MPH.

    The 40 mph wind gusts forecast for tonight are Wind Advisory criteria, not High Wind Warning criteria. The winds forecast for Friday night don’t even fall into the Wind Advisory category and almost no wind is forecast for Saturday. The Forecast Discussion, on the other hand, does indicate that the strong winds will continue to blow in the High Wind Warning and Wind Advisory criteria for that same period, but why is that not reflected in the Zone Forecast in terms of the forecast wind speeds?

  16. That’s another side also. I haven’t been home that much this winter, but my wife says, even when Ive been out, we just haven’t had the gales we usually do this year. This last one, I got the usual panic High Wind Alert email from Channel 10 but all we got was just a few fresh breezes. I know the folks lout in Alpine or Laguna probably benefit from those warnings, but none of the high winds this year have made it to the beach.

    • It doesn’t look like rain down here for at least a week or two, but Norcal may begin to get some rain later next week. It appears a zonal flow is setting up in the Pacific NW and extreme Norcal, which just leaves us dry, but at least that will stop the strong Santa Ana wind pattern that we have been in for the last few weeks. We were doing well rainfall-wise in October and November, but it has turned drier this month, and Norcal has been even drier this fall as a whole and they are really in need of some rain. I am ready for larger winter storms that bring rain and snow to much of the state.
      I think one of the problems this year is that the AO (Arctic Oscillation) is positive and there hasn’t been the high-latitude blocking to buckle the flow pattern as we have had the last couple of years and the solar activity has been higher this year as well.

  24. Is that the next time we will have a chance of rain — bit after the new years
    Was nice today but i prefer colder rainy/snowy weather for christmas 75 in redlands for xmas

  25. Was looking at my rain-records back since Aug-1981 — for July – to the end of Dec – Redlands Ca should be sitting at 3.75 — presently we stand at 2.37 — so we are 1.38 behind —-

    • Murphy’s Law says that it won’t rain again for the rest of the winter now that you have a new rain gauge (Just kidding!)

      Seriously, though, from what I have been hearing and reading, I think the pattern may start to change about the second week of January as the jet stream begins to buckle again. Right now we have zonal flow across the Pacific NW and that typically results in dry boring weather for Socal and it is really mild for a large part of the country right now. Even the Pacific NW and the eastern U.S. have not had much snow lately, although that is now changing in the NW. There appears to be no high latitude blocking this year like there was the last couple of years. Also, the Arctic Oscillation (AO), the Pacific North American (PNA) index, and the North Atlantic Oscillation (NAO) are all positive, keeping the Arctic air bottled up far to the north, and the result is that the majority of the U.S. is milder than normal for this time of year.

      • It really has been extraordinarily mild throughout the country. I saw Minneapolis was 52 degrees yesterday and some parts of North Dakota haven’t got any snow yet this season. Virtually nobody got a white Christmas this year east of the Rockies. People all around the country are complaining about the boring weather! It’s great for everybody’s heating bills, though.

        • Vermont has been really mild and yesterday in CT we had a downpour with very strong winds. VT got some rain too but it switched to snow and when I get home tomorrow there should be a few inches. Subzero temps may also finally be on the way, though we may have another thaw on new years day.

      • Sounds good. I bought myself a Kestrel wireless to carry around for Christmas. The ships have Coastal Weatherpaks and a couple other brand lines, but i wanted a personal handheld or portable one of my own. I’m anxious to try that out next run.

        • This one set me back $180. It’s a “3500″ has a barometer/altimeter, pressure trend, temp., rel humidity, dewpoint, wind, time, and some other stuff.
          I got this one because it gives crosswind as well as true.

          Can’t beat a straight up tin can for a rain guage, except when the cat knocks the dang thing over.

  30. Red,

    KESTREL, they make all kinds. They also make a wall mounted wireless that my relief in the cabin last trip, that’s how how I found out about them..

    ttp://www.kestrelmeters.com/collections/all-kestrel-meters/crosswind

  32. Area forecast discussion
    National Weather Service San Francisco Bay area
    936 am PST Friday Dec 30 2011

    Extended…through the next 7 days expect very little change in
    the overall pattern. Long wave ridge well established along the
    West Coast centered just off California. Shortwaves will ride over the top
    of this ridge impacting mostly extreme northern California and the pacnw
    where very heavy rain has and will occur periodically as warm moist
    atmospheric rivers slam into Southeast Alaska and northwest Washington. See very little to
    perturb this general pattern through the next week or two. If one
    looks at the overall hemispheric pattern the dominate pattern
    appears to be driven by wave number 2 which is a very stable
    pattern. There appears to be little to amplify the pattern and
    most likely any amplification and potential retrogression of the
    pattern will be a stochastic process and models will have
    difficulty forecasting this. Drier than normal conditions are
    typical of a combined La Nina and negative phase of the pdo which
    we have been in now for several years. Last year was very much an
    anomaly as the strength of the La Nina allowed the long wave
    trough to be slightly west of where it is this year and put California in
    a semi-permanent trough. With a weaker La Nina and negative pdo
    below normal precipitation is typical. We Sam this for a majority of
    the years in the 50s and 60s extending into the early 70s.
    Although the mjo appears to be active right now and has shown
    signs of activity over the past two months in reality it appears
    to be more related to periodic Kelvin waves the excite the
    persistent La Nina pattern and the mjo quickly dies out near 120
    to 130e and then cycles back into the far western Pacific. Only in
    October did we see a strong mjo in the Indian Ocean that helped
    retrograde the trough back off the West Coast which gave US some
    early rains and even these were mostly south.

    So we may be in for more years with below normal rainfall than
    above normal. It is not to say we can not get a strong upper
    trough to amplify the ridge enough to either undercut or
    retrograde it for a period of a few days to maybe a week. Some of
    the long range GFS ensemble members have been hinting at this but
    again this will most likely be a random process where the normal
    teleconnections that we use for forecasting major changes may not
    be to helpful.

    Given this will be my last afd it is with some sadness that I
    leave with such a Boring weather year. Having worked most of my
    40 year meteorological career in California I have experienced the feast
    or famine cycles of California Winters. It has been a challenging and
    rewarding career with the National Weather Service and a privilege to lead this office
    for the past decade. I will miss the day to day forecasting but
    will always be watching the weather. I know this office will
    continue to provide high quality products and services long after
    I am gone. Wishing everyone a Happy and healthy New Year as I move
    on into the next act.

    • Wow, a lot to chew on here. Everything does seem to be pointing to a below average winter precipitation-wise. I was doubting we would get two wet La Ninas in a row.

      By the way, this is probably the most touching AFD I’ve ever read.

  33. Ah, that’s the old La Nina we know and loathe so well in So Cal.

    Cant say it wasn’t predicted. I personally don’t expect much for the rest of the winter, mebbe a shower or two towards spring, but Ive been feeling as well, its going 2 B one of those long dry cool ones.

    Best of everything to you Nicholas, having made a couple career changes myself, I know its hard to leave old digs for new ones sometimes.

    Tom

    • Most of the country has been absent of cold air and snowfall this season, not just the Sierras. Because of that I think there is more going on in this pattern than just La Nina and the -PDO, even though that combo is known to bring below normal precip to CA, especially Socal. I don’t think the rest of the winter will be bone dry, unless we are having a really oddball year such as 2006-07, or 1971-72. We will probably have some wet spells separated by dry spells, but I am not sure how long the rainy season will last this year. Whether it will just quit in March or go on into April or early May remains to be seen. This season up to this point in some ways, except for the storminess in Socal and the 4-Corners region, reminds me of the 1998-1999, 1999-2000, and 2001-2002 seasons in which the flow was predominantly zonal and was very mild across the U.S. as a whole. I hope this mild pattern doesn’t continue, as it doesn’t give the jet a chance to amplify like we need it to do for good storms in CA.

  34. The San Francisco Bay Area has been in a rather long dry spell that began on November 25, as a whopping total of .13″ has fallen in downtown San Francisco during this time. It is more unusual for them to be in a long dry spell this time of year as Daniel pointed out in his last blog, than it is for us in Socal, but it does happen every so often. I have been reading a couple of blogs and weather forums lately and it is looking like a possible pattern change may occur either the end of next week or the following week. However, tonight’s SFO Forecast Discussion seems to say otherwise:

    IN THE LONGER RANGE…THE ECMWF AND GFS INDICATE THAT THE SOUTHERN END OF A SYSTEM MAY CLIP THE NORTH BAY WITH SOME LIGHT RAIN AROUND WEDNESDAY NIGHT OR THURSDAY OF NEXT WEEK AND THEN A MOSTLY DRY INSIDE SLIDER SYSTEM WILL DROP INTO THE WESTERN U.S. LATE IN THE WEEK. NEITHER OF THESE SYSTEMS ARE ANTICIPATED TO PRODUCE RAINFALL OF ANY SIGNIFICANCE ACROSS OUR FORECAST AREA. THEREAFTER BOTH MODELS RE-BUILD THE RIDGE FOR CONTINUED DRY WEATHER AS WE MOVE INTO THE SECOND WEEK OF JANUARY.

    That just sounds like the same old patterns repeating themselves, as opposed to a true pattern change. This dry spell has to stop at some point, that is, it can’t possibly continue all winter long, especially in Norcal. Other years that have had the combination of La Nina and a -PDO have had off and on winter rains as far south as Socal, even though some ultra-dry years (6 inches or less total in Los Angeles) have also occurred during that time frame, but they were ENSO neutral or very weak El Nino.

  35. Was a toasty 85 in Redlands, Ca today — last day of 2011 — Dec-31-2011 — This is a record for the 31st at my station — previous record was 79 degrees — I wonder what areas got today — Its nice weather — but would rather have 85 in the middle of July — i want some cold snowy rainy weather now when its suppose to be blustery

  36. Hasn’t been that many years since we had that Rex block ridge thingy ring the entire arctic and sat, and sat, and sat, and sat, for how many weeks? The whole month of January and into February, 2005 something like 7 weeks wasn’t it?

  37. Happy New Year, everyone!

    Let’s hope the new year ushers in a new weather pattern that will bring beneficial rain and snow to CA, as the Sierras are in dire need of some snow after being dry for 5 weeks straight.

  40. I was trying to say X?n Nián Kuài Lè
    (Happy New Year in Mandarin, but Word Press doesnt like Chinese characters. so I had look up the pinyin equivalent.

    • Thats Xin Nian, not X?n Nian. Anyway, back to weather.

      It may not be rain, but all this dense fog of late has certainly had the same effect keeping the grass green down here. Yesterday was the worst, but this mornings wasn’t too shabby either. I cant remember when its been quite this foggy, late 70′s early 80′s I think.

  41. Happy New Year to you all, I wish we had some exciting weather to break in the New Year, but as Tom and you all have stated, looks like a year of wishful thinking. I am afraid if this weather trend continues, we will be in the Wildland Firefighting mode, Thinking back, I have been on the following fires, Viejas fire in Alpine on Jan. 3, 2001, 10,000 plus acres and in Feb. 2002 The gavilian fire in Fallbrook serveral thousand acres with numerous home burned. Also Jan. 1995 the Rocoso Fire in Lakeside 4,000 plus acres. If I remember right those years started with some rain in the fall and turned dry with offshore flow following. Looks like a similar trend. Hoping for some rain.

    • I don’t think it was January, 1995, unless the early part of the month was dry in San Diego. 1994-95 was an El Nino year and precip was well-above average. We moved to our current location here in Orange during mid-January of that year and it was quite wet at the time.

Leave a Reply