Ridiculously Resilient Ridge continues to shatter records, but pattern shift may be approaching

Filed in Uncategorized by on January 25, 2014 344 Comments

Current weather summary

Exceptionally warm, dry, and stable weather conditions have prevailed over California since early December. Precipitation totals over the past 40-60 days have been near zero across most of the state of California, with only very light precipitation observed in the north. Various observing sites have now surpassed their previous all-time records for the greatest number of consecutive dry days during the “rainy” season, and these new records will almost certainly be extended at least a few more days as bone dry conditions continue. Nearly all of California has been experiencing record high temperatures on a daily basis over the past several weeks, including the establishment of new all-time January record high temperatures in a few places (most notably Sacramento, at 79 degrees).

Cracked, dry soil in San Luis Reservoir, January 2014. Photo courtesy of Jason Liske.

Cracked, dry soil in San Luis Reservoir, January 2014. Photo courtesy of Jason Liske.

In addition to this impressive stretch of record-breaking January warmth, the observed atmospheric flow pattern over California has been downright bizarre over the past couple of weeks. Weak disturbances have been propagating westward or northwestward over the state around the south side of the highly persistent ridge, bringing periodic mid and high-level cloudiness and occasional offshore winds. This flow pattern is completely reversed from its normal orientation (weather systems in winter typically move eastward over California). Just to give some indication of how strange this pattern really is: the moisture source for the observed cloudiness across parts of California over the past few days is the subtropical East Pacific Ocean southwest of Baja California (rather than the Gulf of Alaska).

 

The increasing impacts of California’s extraordinary dry spell

California Governor Jerry Brown formally declared a Drought Emergency on January 17, and a slew of voluntary or mandatory water restrictions have been rapidly enacted across Northern California since the start of the calendar year. Certain communities dependent on local water sources are facing extreme shortages as supplies are already running dry. While most major urban areas in California have a larger “storage buffer” in the form of shared water supplies in the larger reservoirs around the state, even these water levels are plummeting as runoff approaches zero in most places.

Extreme low water levels at Lake Oroville, January 2014. Photo courtesy of Weather West member "TheNothing."

Extreme low water levels on the north side of Folsom Lake, January 2014. Photo courtesy of Jeff Houser.

The secondary effects of the drought have also becoming more apparent in January. Extreme fire weather conditions and associated Red Flag Warnings have been issued multiple times for large parts of the state that have not experienced these conditions during mid-winter in living memory. Localized dust storms are starting to occur in the San Joaquin Valley, where powder-dry topsoil from hundreds of thousands of acres of farmland that has gone un-planted and un-irrigated as a result of the drought is being lofted by unusually strong southeasterly winds. Air quality as a result of this stagnant weather pattern has been extremely poor throughout the state, but conditions in the Central Valley have been especially bad, where levels of fine particulate matter (PM-2.5) have reached dangerous levels even for healthy adults. The Sierra snowpack is nearly nonexistent–only 5-7% of normal in the north–and the winter sports industry has come to a virtual standstill except at those venues capable of generating “artificial snow.” In short: it does not feel very much like winter here in California.

 

Signs of weakness in the “RRR”, or just more false hope?

On quite a few occasions over the past four months, our best atmospheric models have suggested that a pattern change might be in the works: that the “Ridiculously Resilient Ridge” might finally be breaking down or at least moving into a position that would allow some storms to reach California. So far, however, the models have been wrong in every instance: the RRR has remained stronger and more persistent than projected by the models. At the time of this writing, however, there are more convincing signs that there may be at least a temporary weakening and/or shift in the persistent ridging over the East Pacific that would finally allow for some precipitation to reach California for the first time in nearly two months.

gfs_model_forecast

GFS model depiction of late-week precipitation event. (NOAA/NCEP)

California will likely experience 3-5 more days of dry weather and record-breaking high temperatures before a Pacific storm system takes advantage of a weakness in the mean ridge and approaches the state from the northwest. It’s not clear at this point how much precipitation this system will bring to California–since while it appears to contain a fairly large amount of atmospheric moisture, the system will have to overcome an exceptionally dry existing airmass. That said, it does appear that there’s a chance that NorCal could see a soaking/moderate rain event later this week. While this event probably won’t have a major impact on the extreme drought conditions in California, it may be enough to settle the dust, clear the air, and reduce wildfire risk temporarily.

 

Few prospects for significant drought relief in the medium to long term

In the longer term, the evolution of the large-scale pattern is even less clear. The models have already backed off their more aggressive solutions from a couple of days ago (i.e. strong zonal flow and significant storminess in California) and are now (once again) depicting a familiar pattern of high-amplitude blocking over the far eastern Pacific. There is one big difference between the projected pattern and what we’ve observed recently, though: the blocking ridge may set up somewhat further to the west as we enter February, which would put California in the region of anomalous northerly flow on the downstream side. In practical terms, this means that we can almost certainly bid our record warmth goodbye and might possibly need to prepare for very cold conditions. Some recent runs of the GFS and ECMWF have depicted exceptionally cold (yet mostly dry) conditions developing over the West during the first half of February, which would constitute a drastic change in the weather but not help much with the extreme drought conditions. It is worth noting that persistent, high amplitude blocking in this region has historically been associated with most of California’s major Arctic outbreaks, including the notable February 1976 and December 1990 events. However, it’s still far too early to discuss the details of this possible pattern evolution, and it’s entirely possible that our not-so-good friend the RRR could set up shop once again in a position favorable for unusually warm conditions in California. Regardless: what is becoming increasingly clear is that drought-busting rains are not headed our way for the next two weeks, at least.

ridiculously_resilient_ridge_2014

ridiculously_resilient_ridge_2013

 

 

 

 

 

The RRR during calendar year 2013 (left) and Water Year 2013-2014 (right)

In the even longer term, current seasonal projections suggest that California will continue to experience below-normal precipitation for the rest of the rainy season. While it would only take an atmospheric river or two to really jump-start river runoff and reservoir inflows, the prevailing pattern of weak zonal flow and amplified East Pacific ridging does not favor this kind of critically-needed precipitation event. I’ve previously discussed the possible role of a region of very high sea surface temperature anomalies in the North Pacific in reinforcing the RRR, and unfortunately the seasonal climate models suggest that the warm pool will persist right into the summer. In the really, really long term, the dynamical ocean models are currently projecting an increasing chance of El Nino conditions developing across the tropical East Pacific over the summer, though even if this projection comes to fruition it will unfortunately occur too late to affect rainfall potential for this water year.

 

A note on the severity of the current California drought

sierra_8_station_drought

Water year 2013-2014 is now the record driest to date in California. (CA DWR)

Calendar year 2013 was the driest on record in California’s 119 year formal record, and likely the driest since at least the Gold Rush era (the current event is without precedent in San Francisco’s precipitation records, for example, which go back to 1859). Observed precipitation for the current (2013-2014) water year–which began in October 2013–is tracking below all previous water years, including both years in the 1976-1977 drought and the extremely dry winter of 1923-1924. While we don’t know for sure what the rest of winter holds in store–and it is certainly still possible that February and March bring much-needed rainfall–current precipitation deficits are so large that it would require very heavy, sustained precipitation for the rest of winter to bring us up toward average values. In fact, an informal analysis suggests that we would have to receive more precipitation between now and the end of the rainy season than has ever been observed in California during the February-April period in order to erase the deficit. Therefore, even a repeat of the (highly alliterative) drought-busting late-season events in California’s meteorological history–the infamous “Fabulous February”, “Miracle March“, and “Awesome April” wet spells of years past–would probably not be enough to end the drought.

precipitation_anomaly

Water Year 2013-2014 precipitation deficits over the West. (WRCC/DRI)

For now, I’ll be keeping an eye on the medium range forecast models for any signs of significant drought relief. In the meantime, I strongly encourage everyone in California to be mindful of their water usage in the midst of these increasingly severe drought conditions and to take active conservation steps in advance of what promises to be a challenging summer and fall ahead. Stay tuned.

© 2014 WEATHER WEST

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  • redlands

    Redlands, Ca Weather Update — We received a measly 0.03 of rain – for Jan-31-2014 —- to end the month with 0.04 of rain — making this January 2014 – the 2nd driest January — The driest being January 2003 with only 0.03. Also January 2014 ended up being the 2nd warmest maximum average – The warmest January maximum average was January 2003. Records back to January 1982. — We were very lucky to get the 0.03 of rain — I noticed that 0.03 didn’t do anything to moisten the soil — still looks bone dry — like nothing happened — only way u can tell it rained a bit is the few drops on my car — along with the water stains. So for the month of December 2013 and January 2014 – at my station in Redlands, Ca — we have only received 0.30 of rain. 62 days and only 0.30 of rain — Not good !!!!!

    • Dan the Weatherman

      .01″ fell here in Orange last night with about 5-10 minutes of rain, which is also the monthly total for January. A very poor month for rainfall, indeed. The last measurable rain here was way back on December 19.

    • craig matthews

      I hope that the cut off low later this weekend gives you more rain down there. Up here where I live we received .44 near big sur as a storm total, and monthly total for January. Normally we get around 15 inches for January.

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  • craig matthews

    There is a very strong push of westerlies occurring along the equator west of the dateline that seams to be increasing in strength. Starting to see a change in the flow pattern over the western north pacific as well. Its going to get interesting over the next 2 weeks. Got to be a change for the better for the west coast because I don’t see how it can get any worst then this here in California.

    • Loyal Brooks

      I’m writing this on Game Day, so few will see this. I think you are right – that supposed invincible ridge shows signs of weakening all over the place. It seems like it would like to fully reassert it self, but it has too many lows embedded in the westerly flow to completely fend off all of them. .

  • craig matthews

    Here’s some good info about El Nino and California rainfall. The webpage is called El Nino/La Nina and California rainfall by Jan Null, address http://www.ggweather/enso/calenso

    • craig matthews

      Sorry that’s ggweather.com/enso/calenso.htm

      • Loyal Brooks

        Great maps with insight. Thanks for sharing!

      • Xerophobe

        Jan Null’s site is excellent. Thanks

  • http://www.weatherwest.com/ Weather West

    Immediate coastal parts of CA may see some showers tomorrow from the low that’ll be skirting the coast. Unfortunately, totals will probably be 0.25 inches or under, though that may actually be more than the Bay Area received with the last system.

    Could be quite cold (and dry) later this week, esp. if ECMWF pan out.

    Next weekend could bring a return to rain chances once again, and the GFS (but not ECMWF) hints at some possible signficant precip in NorCal. After day 10, though, it looks like a ridge may try to build back in again. The blog update will take place either later tonight or on Sunday…

    • Xerophobe

      Started raining here in Monterey about 7:45 this morning (Sunday). Still coming down steady, not hard.

      • craig matthews

        I’m just south of you about 30 miles. Looking out my window I’m seeing a lot of convective cells that appear to have some rotation between pt sur and Monterey. Probably wont make landfall but you never know.

        • Xerophobe

          I just looked at 4km infrared and you could get hit with some activity rotating your way. I was down your way a month ago.

  • Ricky Wogisch

    Have not seen any green for months!

    • http://www.weatherwest.com/ Weather West

      Keep in mind that these are entirely automated on weekends, and the models have uniformly been overly optimistic lately. But I’ll agree that there is a promising trend. More tomorrow!

    • Dan the Weatherman

      I know that this is entirely computer-generated, but i would like to see that green down into Socal as well!

  • Dreamer

    Here’s an educational video to show to Californians who will start whining when the rain finally does arrive- http://www.youtube.com/watch?v=8LAVVGJtrRM

    • http://www.weatherwest.com/ Weather West

      We could use a PSA along these lines…

      • Loyal Brooks

        For a reality check….

  • snow755

    The 06z has a ch of rain starting next weekend and it keeps going off and on ever day of the week the other storm comes in the following weekend on two. The following Monday of that week

  • rainscout

    Dreamer..that was a good one..LOL..and it is amazing that so many people just don’t get it on so many levels when it comes to where the their water actually comes from???!!!

    • Dreamer

      I’d like to see how Californians would react to a “real” storm that drops inches of rain in a couple of hours accompanied by thunder and lightning. 911 calls? Mass panic?

      • kurt frohling

        Which Californians are you talking about? It’s a big state.

        • Dreamer

          LA and San Diego area mostly. Bay Area to a smaller extent. I know the mountains have actual weather but only a small minority of Californians live there. I’ve lived in the Midwest, Gulf Coast, and Southern California. Southern Californians are the biggest WIMPS on the planet.

      • Loyal Brooks

        911 calls because of a passing heavy shower? What?

      • TheNothing

        I’ve been trying to get through to a 911 dispatcher for the last two hours but the line has been busy, looks like I’m not the only one panicking out here in California.

    • Loyal Brooks

      What do you mean? Water comes from the faucet, just like everywhere else. Whatever are you talking about?

      Most of the country gets its water from wells or water from local rivers of the watershed. CA is so different. CA has “virtual watersheds,” where cities farms rely on a distant river drainages. Usually, they are water-dependable. Everyone is in trouble when these usually wet areas fai – as in this year….

  • Coldspot

    Wow, will it really come true? Sounds like significant precip to hit our area starting Saturday per NOAA Medford and continuing for some time. This sounds like cold and wet which will build our snowpack and help with our summer irrigation. A fantastic February? Keeping the fingers crossed.

    • tomocean

      It is looking more and more hopeful. That first storm we got last week seems to have dislodged the pattern, at least for the time being.

    • Loyal Brooks

      The Medford NWS forecast office covers NE CA, and they often explain their thinking behind their forecasts. They are definitely not rookies. Sometimes they go into the MJO, the situ W of the dateline, areas in the Pacific with zonal flow. While they didn’t do that here, look what is up right now at 3pm my time for the extended. This is hands down the most positive forecast (suggestion) I have seen them make in a very, very long time. http://www.wrh.noaa.gov/total_forecast/getprod.php?prod=XXXAFDMFR&wfo=MFR

  • Doug

    Wow, actual rain here in the Livermore / Pleasanton area. A nearby reporting station has us at 0.08″ in the last hour. Not even a dent in the amount we need, but it makes me happy to see real rain.

  • John b

    I know it’s fantasy land, but that 995 mb low northwest of Hawaii at 384hrs. On the 12z run of the GFS looks very interesting

    • Guest

      Where can I see that?

  • Dogwood

    Nice cold windy rain here in San Jose this morning. Notice the regional sat shows a fairly organized band from Santa Rosa southward, with a big yellow and orange gob just off SLO & SB counties ready to for landfall. I was in Cambria for a project first week of Jan and it was amazing. However, they are surely one of those tragic water cases this year. Little market had a pic of the east village under 4 feet of water from ’94. Ironic.

  • Utrex
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  • Utrex

    This is on day 9 from the gfs in North Sacramento.

    http://www.twisterdata.com/data/tmp/scratch/models/processing/GFS_3_2014020212_F192_38.5000N_121.5000W_HODO.png

    When the red line on a hodo graph pushes back and then forward in the beginning, this signifies formation of supercells.

    But in this case, there is very high precipitation amounts, and as you can see, the clockwise turning goes all the way to 37 vertical wind kts… That’s a signal for very explosive super cellular development…! Midwest stuff! We might even see record-breaking tornadoes!!!

    • http://www.weatherwest.com/ Weather West

      Favorable vertical wind profiles are only one of many necessary ingredients for strong deep convection. I’d be willing to bet that surface stability parameters would actually suggest a rather stable environment in this case. Vertical wind shear can be quite high near and ahead of cold fronts around here, but when that’s not associated with instability it means very little.

  • http://www.weatherwest.com/ Weather West

    Update in the works…will be out by late afternoon.

  • craig matthews

    Just had lightning north of big sur here and a brief hailstorm. It appears as though there is some rotation to the black cloud I am seeing offshore. Wish I had a camera. I’ve witnessed a few waterspouts just offshore of me in the last 40 years. Might get one offshore today. Picked up .68 at my house and I see snow on the hills. Lot of cold unstable air with this tiny low. Hope socal gets this low too. Its a fun one

    • http://www.weatherwest.com/ Weather West

      A waterspout could definitely occur with that cell.

    • Dan the Weatherman

      Is that your most substantial rainfall for the season so far?

      • craig matthews

        Yes this is the most substantial storm this season so far, with the storm total now at .87.

  • Dan the Weatherman

    We may have our biggest rain of the season here in Orange County if everything comes together just right as NWS is forecasting.25″ to .45″ for the area. In a normal year, this would be a piddly storm for February standards, but in this year it is a much bigger deal. Hopefully this is paving the way for more substantial rainfall as we head later into the month. I knew the utter dryness of January couldn’t go on for much longer.

  • http://www.weatherwest.com/ Weather West

    New post is up.

  • redlands

    Will have to check it out — Is the rain still coming

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