California Applications Program / California Climate Change Center
From the California Department of Water Resources

Weather and Climate Newsletter
Last update: May 1, 2008
May 1, 2008
Water Supply
Today's May 1 snow survey measurement at Phillips along Highway 50 was just 11% of normal for this time of year. May is the final measurement of the season, ending what has been a dry year, and very dry spring. Phillips is in a sunny open spot, so it came in lower than most other medium to high elevation locations. Nonetheless, there are many factors negatively impacting statewide water supply. The sum total meteorological and hydrologic conditions of the past 2 years paint a dry picture. A set of factors, tidbits, and data is included in today's newsletter that relate to the low runoff projections DWR is making for this year.

Current Conditions May 1 '08, and comparisons to 1976-77

Drought?
Factors in a large scale drought determination include precipitation, deficiencies in water supply, below-normal streamflow, depleted soil moisture, low groundwater, lake and reservoir levels. These ingredients have not yet combined to create an all out drought designation. Some runoff related comparisons:

GOOD NEWS?
In comparison to the most recent drought period (late '80's, early '90's), the hydrologic conditions of this 2 year period (2006-2008) are projected to end 15-20% wetter, on average. The Sacramento River had readings in the 9 MAF range for that time period, 1987-1992. Last year (2007) ended at 10.25MAF, this year is estimated to end at 11.3MAF (2 yr average about 20% higher). The San Joaquin had an average near 2.75MAF in the late 80's, early 90's. Last year was 2.5MAF, but this year was 3.8MAF (2 year average about 15% higher).

*8 Station Index

8 locations for which DWR tracks total precip (rainfall and snow). These stations represent the "top" of the State Water Project. The 8 Station Northern Sierra Index stations are: Mt. Shasta City, Shasta Dam, Mineral, Brush Creek, Quincy, Sierraville, Pacific House, and Blue Canyon. (Other California towns' and cities' weather data is maintained and available through the National Weather Service - DWR records, charts, and archives the 8 Station Precipitation Index, referred to as the "8 Station.")

**Next Runoff Forecast

Following the snow surveys results of the next week, the most updated (May 1) runoff estimates and hydrologic classification indices for this year will be made available the week of May 5. Official water year types are based on May 1 forecasts. Hydrologic classification year types: Wet, Above Normal, Below Normal, Dry, and Critical.

Other regions

Sacramento, Stockton, Modesto and Redding have all had their driest March/April (2month) on record.
Los Angeles (and much of Southern California) has had significantly higher rainfall totals than last year. LA now has over 10" of rain for the season, with 2007 ending with only about 2" (25% or so - driest ever). Not a typical La Nina year.

Here is the official DWR press release, which includes the impacts of pumping restrictions on state water supply:
http://www.water.ca.gov/news/

April 9, 2008

The April 1 Water Supply Index and Bulletin 120 Runoff Forecasts are complete. The forecast includes the observed conditions through the end of March:

http://cdec.water.ca.gov/cgi-progs/iodir/WSI
http://cdec.water.ca.gov/cgi-progs/iodir?s=b120
http://cdec.water.ca.gov/snow/bulletin120/b120apr08.pdf

For the Sierra basins, the projected median APRIL-JULY runoff forecasts range from 91% (Kaweah River) to 68% (Cosumnes River). The statewide forecast is down, on average, about six percent since the March 25 forecast update. The statewide April through July snowmelt runoff forecast is about 80% of average.

The MEDIAN WATER YEAR Sacramento 4 River (Sacramento R at Bend, Feather R at Oroville, Yuba R at Smartville, and American R at Folsom) runoff forecast is now 11.9 Million Acre Feet (MAF); 64% of the 1956-2005 average. The median Water Year San Joaquin 4 River (Stanislaus R below Goodwin, Tuolumne R below La Grange, Merced R below Merced Falls, and San Joaquin R inflow to Millerton) runoff forecast is 4.2 MAF; 71% of the 1956-2005 average. The statewide Water Year runoff forecast is about 65%.

WATER YEAR TYPE Forecast: The Sacramento Valley Water Year Type Index forecast is "Dry". The San Joaquin Valley Water Year Type Index forecast is "Dry". The final designation will be made in May. Last year those indices were "Dry", and "Critical", respectively. While the last newsletter indicated the forecast for the San Joaquin was for "Below Normal", March figures had yet to be tallied. It was a very poor month for rain and snow. You've heard of a Miracle March? This was a Malicious March. March, 2008 has been re-ranked as the sixth driest March of 89 years of record for the 8 Station Index, with a precipitation total of 1.6" (23% of average). The MARCH Sacramento River Region unimpaired runoff was 50% of average. The March, 2008 San Joaquin River Region was 60% of average.

In addition to being dry, March temperatures remained cold enough early in the month to retain the majority of the snowpack. Those factors, and dry antecedent conditions resulted in OCTOBER thru MARCH cumulative runoff of only 55% of average, statewide. (The Sacramento River Region observed unimpaired runoff was 52% of average through March, 2008. On March 31, 2007, it was about 58% of average).

"Unimpaired Runoff" or "Full Natural Flow" represents the natural water production of a river basin, unaltered by upstream diversions, storage, or by export or import of water to or from other watersheds. Gauged flows at the given measurement points are increased or decreased to account for these upstream operations.

NOAA's California Water Supply Outlook is also available:

http://www.cnrfc.noaa.gov/products/water_supply/2008/ws042008.pdf

As of April 1, reservoir storage was 85% of average for the date, still well below average. Since we are passing the time of year for highest flood control concerns, reservoirs will be able to retain a great deal of the incoming snowmelt. However, the ground is very dry. Perhaps less of the snowmelt will make it off the mountainside than in other years.

Snowpack water content (as of April 8) from automated sensors is at 91% of average statewide. The snow water content sensors are indicating the pack is consolidating and melting. Warm weather will enhance snow melt and start to increase the flow of creeks and streams.

Forecasts are for a dominant High pressure system over the western US and eastern Pacific throughout the weekend. Both daytime highs and overnight lows will be above normal statewide. One computer model holds on to a developing storm pattern early next week, but this is the same model that's been saying "look out, storm in 5-7 days" for about 5 weeks in a row, now. Hard to decide which to believe, but others are coming into consensus about some sort of trof or cutoff low developing over the Eastern Pacific. Either way, enjoy several days of very warm, sunny conditions until then. The period Friday through Monday could see readings in the 80's for many valley, coastal and even foothill locations! (For weather buffs, the high will be of the 582-584 decameter variety.)

Upcoming presentations or conferences of note:

April 10, Delta Emergency Response Planning Workshop, 4-6pm, Courtland, CA.
A collaborative effort is underway by the Department of Water Resources, the Governor's Office of Emergency Services, the U.S. Army Corps of Engineers, the Delta Protection Commission, the five Delta county emergency services offices, and other stakeholders to develop a comprehensive Delta emergency response and operation plan.

State Climatologist Dr. Michael Anderson heads to downtown Los Angeles this Friday, April 11 for the Alluvial Fan Task Force to talk about climate change and alluvial fans. Next week is a trip to Hood River, Oregon to discuss snow with snow experts from the western U.S. In May, the climate tour heads for Honolulu, HI for the American Society of Civil Engineers Water and Environment Congress 2008 to talk about describing/modeling climate with dynamic (time varying) probability distributions.

April 16, Elissa Lynn, American Meteorological Society speaker, UC Davis, 6pm. "Media-Rology"

May 6-9 ACWA Association of California Water Agencies Spring Conference, Portola & Marriott Hotels, Monterey, CA. Elissa Lynn, "Climate Change" breakfast opening keynote, May 7. Additional info: http://acwa.com//events/SC08/INDEX.asp

June 20, 2008 California Extreme Precipitation Symposium Theme: "Estimating and Forecasting Extreme Floods" University of California, Davis 8:00 to 4:30 $50 (early registration) Online registration is open and to get more information: http://www.arwi.us/precip

Be back in May with another newsletter. Have a nice spring!

April 2, 2008

A closed low is working its way toward the central coast today. While it is making fairly good progress, totals have been very modest. Expect highest totals in the half inch to one inch range for the coastal mountains from Monterey Co. to San Diego Co., with lower amounts in typically drier areas. Burn areas are perhaps less at risk due to additional vegetative growth since last fall, and less than intense rainfall rates. Thunderstorms are not as likely as earlier forecast over those regions. Doubt much rain or snow will make it to the Sacramento Valley or Northern Sierra. Look for a dry and warm trend to begin Thursday across most of the state.

The next chance for rain comes late Friday, but only for the very far northernmost locales. This is a Gulf of Alaska low, which is fairly minor. There is good model agreement that this will track into Oregon, trailing only light precip to the CA-OR border, and northwest coast.

Beyond that time frame, there may be quite a 'PIG' forming over the Eastern Pacific. (Pigs being low pressure systems that dominate a weather map). I'd put the chances at pretty small for this to come into fruition. Nonetheless, both the GFS (Global Forecast System) and the ECMWF (European model) are producing a large low pressure center off the coast of Oregon by Tuesday morning. 500mb heights could be as low as 526-528 decameters, which would make for a windy and cold system. Each computer update is different, however, so don't batten down the hatches just yet. Seems storms are having a hard time hanging onto their organization recently.

Last week's snow survey was very interesting. More interesting is the public perception that this winter has put all right in terms of water supply. At the gas station last night, the attendant told me we don't need any more snow or rain because it was such a good season. Oh, contraire! Last year was quite dry, and we are not looking to make up for that deficit. Had March been as productive as January and February, we may have come closer.

Incoming survey results indicate regional Sierra snowpack percentages of normal that range from 94% to 119%. The statewide April 1 average is right at 100% for those courses that are completed. Specifically, Phillips at Highway 50 measured 98% of long-term average, with 27.8" of water content. That was better than last year's 10". But without a wet fall, and a then very dry March, runoff projections are below average. The soil moisture deficit (dry antecedent condition) means snowmelt will first be absorbed before running off. The DWR estimate for the water year runoff (ending Sept. 30, 2008) is 70% of normal for the statewide average. April-July runoff estimates are higher than the water year estimates, but down from a week ago, now standing at 87%. The Bulletin 120 April 1 water supply report will be available next week. Indications from the California-Nevada River Forecast Center (part of the National Oceanic and Atmospheric Administration) are that runoff may be even lower than the 70% of normal state figure for the water year. It is a difficult thing to model soil moisture deficits over the mountainous regions of the Sierra. Bottom line, don't assume the near normal April 1 snowpack readings mean our reservoirs will fill back up. That's a simple statement, but important. And if April stays as dry as March, dry conditions could worsen.

For a nice photo of DWR snow master Frank Gehrke and story about this month's readings in light of Delta pumping curtailments, go to: http://www.sacbee.com/101/story/815025.html

This month's video interview can be found here: http://www.water.ca.gov/news/ See 3/26 Snow Survey Video

Water year type projections did climb 2 rating levels for the San Joaquin River System thanks to cold, snowy storms over the southern Sierra in January and February. Here are classifications by year for both the San Joaquin and Sacramento systems:

2007-2008 forecast 2006-2007 2005-2006
Sacramento DRY DRY WET
San Joaquin BELOW NORMAL CRITICAL WET

March, 2008 is in the record books as one of the driest. According to the California Climate Tracker (Western Region Climate Center), March, 2008 was the 5th driest March in 114 years for the Golden State, with a statewide average of 0.53". The driest March on record according to the Tracker was 1923 when only 0.25" fell on average.
http://www.wrcc.dri.edu/monitor/cal-mon/index.html

For the 8 Station Index over the Northern Sierra/ Shasta area, it was a tough month. There was only 1.5" of precip recorded, making it the 5th driest on record. Last year (a dry year overall), March had 1.7" of precip. Hard to believe, but this March was actually worse than last March for the precip that enters at the top of the State Water Project. March, 2007 has moved to 7th driest in ranking. Seasonally, the 8 Station is at 79% of average to date, a drop from about 90% of normal one month ago. Sacramento stands at 82% of average.

Sacramento rainfall salvaged itself from being the driest March ever by getting 0.12" over the 2 day period March 28, 29. This puts March at 6th driest. Red Bluff had it's 2nd driest March, with 0.07"; Modesto 4th driest, with 0.01". Bakersfield had only a trace of precip, in comparison to it's normal of 1.41", so March, 2008 ties for 2nd driest. In Fresno at the Yosemite Airport, an over 2" deficit yielded the 5th driest March on record.

One correction to recent news reports about Delta drainage area. It is often quoted as collecting runoff from about 60% of the state. But Chief Hydrologist Maury Roos puts that figure at 37.5%.

A few upcoming meetings of note:
The Water Education Foundation's Executive Briefing will be held this week, April 3 and 4 at the Radisson Hotel in Sacramento. A great line up of speakers is slated for this year's theme "Adapting to the New Realities." For more information please go to: http://www.watereducation.org/08%20EB%20Invite.pdf

The California Energy Commission holds a meeting and webcast on Monday, April 7 from 2:30 - 5:00pm on research findings on climate and energy: http://www.energy.ca.gov/pier/notices/2008-04-07_climate_change_meeting/2008-04-07_notice.html

This year's Western Snow Conference will be held April 15-17 in Hood River, Oregon: http://www.westernsnowconference.org/2008.html

The third town hall meeting in conjunction with the "California's Water" PBS Series will be held in Sacramento at the Crest Theater on Thursday, April 17. Huell Howser will host, with a collection of speakers on key water issues facing the state and Sacramento region. Please see: http://aquanet.water.ca.gov/more/2008/040108acwa.pdf

Look for another newsletter next week, followed by only monthly issuances between May and September.

March 20, 2008
Ecosystem decline, water supply unreliability, poor Delta water quality, flood risks, and State Water Project pumping cutbacks have combined to create a crisis in the Delta. The area has had 162 levee failures in the last 100 years. There is a 64% chance of a catastrophic failure due to an earthquake or storm in the next 50 years. Water deliveries are likely to be reduced by up to 30% this year as a result of a court order protecting Delta smelt.

Accordingly, DWR has announced the start of the public process to study the environmental impacts of a Delta conservation plan including alternative water conveyance, new statewide water conservation efforts, and emergency response preparedness.

  • A public workshop on the environmental review process is scheduled for Monday, March 24 at 1:30pm in the Resources Building Auditorium at 1416 9th Street in Sacramento. At least four alternatives are being proposed, including no new Delta conveyance facility, dual conveyance as suggested by the Blue Ribbon Task Force's Delta Vision process, an isolated facility, a Delta improvements solution, as well as alternatives that may result from these analyses.
  • Water conservation efforts are being discussed on Friday, March 21 as part of the California Water Plan Advisory Committee at the Doubletree Hotel, 2001 Point West Way in Sacramento.
  • A public workshop on Delta Emergency Response will be held on April 10, 2008 from 4-6pm in Courtland, CA at the Courtland Auditorium, at 146 Primasing Avenue. In an effort to improve emergency flood response in case of a catastrophe, DWR is placing a quarter of a million tons of rock in strategic locations around the Delta. This rock is designed for large-scale water quality protection, and would be barged to necessary locations in the days following a major event. Additional scoping meetings on Delta Emergency Response will also be held over the coming months:
    http://www.water.ca.gov/news/newsreleases/2008/031708delta2.pdf
  • Last week the State Water Project was forced to make additional reductions in pumping due to increased salvage of adult smelt. Water transfers have already been impacted as a result of Judge Oliver Wanger's ruling. DWR will be drawing from San Luis Reservoir at least a month earlier than it normally would in order to meet demands.
For more on these critical Delta issues, please see the following link:
http://baydeltaoffice.water.ca.gov/sdb/bdcp/index_bdcp.cfm

The winter season seems to be coming to a halt here. While storms can and do occur of significance in March, they are less likely as the season wears on. If it were to stop precipitating (I'll explain why I didn't say 'stop raining' in a moment), we would be left with a well-below normal season. More specifically, the 8-Station Index that is used to track north-state mid to high elevation precipitation (whether it falls as rain or snow) would end at 65% of normal. We should be at about 39" of precip by now, but we have recorded about 33" since October 1, 2007. It's been a dry March with only 17% of a normal March having fallen so far. And only weak systems are forecast in the next 10 days by numerical weather prediction models. Look for a nice weekend, and then a cold front passage on Tuesday/ Wednesday, March 25/26.

While numbers sound discouraging about precip that occurred in the vicinity of Mt. Shasta to the Feather River basin, there were a number of very cold, very southerly storms this winter. So, contrary to the fairly low precip recorded, our snow pack, which is measured up and down the crest of the Sierra is still doing pretty good. According to snow sensor data, as of March 20, statewide average snowpack water equivalence stands at 100% of the April 1 average. Many snow sensors in the lower elevations are recording snow water equivalent depths well over their April 1 averages.

For graphical depictions of the northern, central, and southern Sierra snowpack data over this season, please go to:
http://cdec.water.ca.gov/cgi-progs/snow/PLOT_SWC

For detailed current snow pillow data:
http://cdec.water.ca.gov/cgi-progs/iodir?s=page6

It stayed fairly cold in early March, which helped retain some of that snowpack. Of course, runoff will get going in earnest soon due to higher sun elevation and longer days. The current Unimpaired Runoff rates in all major Sierra basins are well below their March averages, thanks to low snow levels during the winter storms. The projected median April-July runoff now ranges from 105%(Kaweah River) to 87%(Shasta Lake). Statewide, the March 18 forecast update is lower for all basins than the March 1, 2008 Bulletin 120 forecast:
http://cdec.water.ca.gov/cgi-progs/iodir?s=b120up

The next snow survey is set for Wednesday, March 26th.

A new daily statewide reservoir storage percentage estimate is available on CDEC (California Data Exchange Center):
http://cdec.water.ca.gov/cgi-progs/reports/RES
Scroll to the bottom of the report.

Today's summary:
Total Storage 14,221,990 acre feet
Total Average Storage 17,362,608 acre feet
Total Statewide % Average for this date 82.35%

Thanks to our snow surveys and CDEC sections for this very nice data addition. It will provide mid-month estimates of storage, supplementing the more thorough 1st of the month reports available at:
http://cdec.water.ca.gov/cgi-progs/reservoirs/STORAGE

Please check the State Meteorologist website for monthly weather and hydrology summaries going back to May, 2006. These are very helpful reference materials, as they summarize rainfall, snowpack, reservoir storage and weather conditions. These are not the same as the newsletters, but are easily accessed and archived. February's is now posted:
http://www.weather.water.ca.gov/summaries/

Look for the next issuance of this newsletter in about two weeks. It becomes a monthly product in the summer.

March 5, 2008

Will it or won't it?
Western Snowpack
Drought Conditions Improving
Spring Things

As to the will it or won't it question...
It won't rain all weekend, other than the Eureka area. The valley will stay spring like and beautiful, with great driving and skiing conditions for the Sierra. There are 3 frontal systems efforting their way to the coast; some are not yet discernable on satellite. But their efforts will not amount to much in the way of ridge busting. The previously forecasted storm of interest was set for Monday. But now it looks more meager, with the only excited model, the GFS, now tracking the system further to north, in alignment with other guidance. It has a juicy tap, but the precipitable water band is fairly thin. It has a good jet into Monday night, though. So a few showers are likely. These would be rain showers even in the higher terrain, with a snow level as high as 9,000' initially, dropping to 6,000' by Tuesday morning. Sacramento probably won't see more than a few drops of rain overnight Monday. Beyond the first half of Tuesday, the ridge just powers up again. This is a big swing from what was shown a few days ago. So, we're off storm watch for now. Oh, the Feather/ Shasta areas are forecast to get only about a quarter inch of precip on Monday.

Sacramento's precip stands at 96% percent of normal for this time of year; 14.60" vs. the normal of 15.25" for this date. February was cooler than normal for the Capitol City, with the mean downtown temperature 2.0 degrees cooler than average. That was driven by cooler overnight lows, primarily.

From the State Climatologist, the January monthly climate summary is now complete. Please go to:

http://www.climate.water.ca.gov/climate_data/

Snowpack latest.
The western U.S. has had a very good snow season this year. Colorado, Arizona and northern New Mexico are seeing surprisingly high values for a La Nina year.

The National Water and Climate Center in Portland, OR creates and transmits the weekly Western US Basin snowpack and cumulative precipitation report every Monday. For detailed information on specific basins across the west, please go to their website:

ftp://ftp.wcc.nrcs.usda.gov/data/snow/update/ws.txt

Or for a nice graphical color depiction of the Snotel data by the Western Region Climate Center that shows virtually all SNOTEL sites at or above normal for this time of year, go to:

http://www.wrcc.dri.edu/snotelanom/basinswe.html

Our own snowpack stands thus:
Northern 117%
Central 103%
Southern 122%
Statewide Avg. 112% (101% of April 1 average)

For great footage of the last survey, please see the DWR public affairs page. Our video guys do great work:

http://www.water.ca.gov/news/
Click on Snow survey video.

February's Bulletin 120 is completed and on-line. The statewide conditions graphic on page 16 is most instructive. It depicts all 4 critical variables; snowpack, precipitation, runoff, and reservoir storage for the past 12 years:

http://cdec.water.ca.gov/snow/bulletin120/

Bulletin 120 is a publication issued four times a year, in the second week of February, March, April, and May by the California Department of Water Resources. It contains forecasts of the volume of seasonal runoff from the state's major watersheds, and other summaries.

And of course, for all water supply and hydrologic information, you'll want to go to the California Data Exchange Center website:

http://cdec.water.ca.gov/

The American Association of State Climatologists provides information and links to all states within their organization. Readers of this newsletter would find information of interest:

http://www.stateclimate.org

Thanks to Jan Curtis with the Natural Resources Conservation Service for that link, as well as this one on drought:

http://www.drought.gov

California has been improving as far as drought conditions. The areal extent of dry, moderate and severe conditions has been shrinking over the past several weeks, and currently no sections of California are labeled extreme or exceptional!

The U.S. Drought Portal was officially launched on November 1, 2007. It was created to provide comprehensive information on emerging and ongoing droughts, and to enhance the nation's drought preparedness. The Drought Portal is part of the National Integrated Drought Information System (NIDIS).

Spring signals.
Daylight saving time begins this weekend. Yes, you lose an hour of sleep. Set the clocks forward one hour overnight Saturday into Sunday morning. The official time change is 2:00am. Statistically, there are more accidents on a Monday morning following this time change than any other day; blamed on driver's sleep reduction. Be careful!

The Vernal Equinox occurs locally at 10:48pm Wednesday night, the 19th of March.

DWR hydrologists and NWS personnel will be helping judge this year's Sacramento Regional Science and Engineering Fair. The event will be held on Saturday, March 29 at Rosemont High School. For participation, volunteer and sponsorship information, go to:

http://www.srsefair.org/

Be back next week-

February 29, 2008

La Nina vs. Madden-Julian Oscillation
State Climatologist news
Leap Day!

This year has been an atypical La Nina for California. More frequently than not, La Nina brings Southern California a very dry winter, and Northern California a good first half, but drier second half of winter. That has not happened. Let's hope it keeps not happening.

First off, La Nina is the cooling of equatorial sea surface temperatures (SST's) over the Pacific Ocean. It is the counterpart to the more 'famous', or perhaps 'infamous' El Nino. La Nina conditions have been in place since last year, and are expected to continue through spring of 2008, possibly longer. This La Nina is the strongest in 8 years, and in the top 1/3rd of La Ninas. Forecasts are for it to continue at least at moderate strength through April, May and June. Indications are that it has peaked and that the below average SST's are waning in the far eastern Pacific.

For the most recent La Nina forecasts, conditions and Q&A's, go to: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml

The impacts to CA listed above, as well as usual predictions of very dry weather for the southwestern U.S. as a whole have not entirely come to pass. In fact a wet and cold La Nina has never happened before in Tucson, AZ, but is now. And southern California seasonal precipitation values are running in the range of 100-160 percent of normal! So it's been clear since the storm door opened in early January that something else must be in play. Or clear at least, that this La Nina is unique.

The culprit, or assistant(?), may be what is known as the Madden/Julian Oscillation (MJO). Briefly, MJO refers to periods of enhanced convection (storm activity) over the tropics. These fluctuations may occur every 30-60 days. For our part of the world, the MJO can promote an extension of the jet stream all the way across the Pacific to the west coast of the United States, leading to rain. This pattern can occur even during strong La Nina conditions, which primarily set up a blocking ridge over the west coast. Most La Nina high pressure domes are difficult to penetrate, moreso in the second half of winter. That is why La Nina's typically bring reduced rainfall in January, February and March. But this year, we've had a couple of rounds of storms that may have been set up by this MJO. The positive numbers in snowpack for January and February are quite likely linked to MJO variability.

There are no experts here at the Department of Water Resources on the MJO, but there are some very smart folks at NOAA who research it extensively. For additional details, please go to:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

The position of State Climatologist is now 100% official! Our Dr. Michael Anderson of the Department of Water Resources was instrumental in getting the State Climatologist post re-instituted in California. While there has been a acting climatology presence since the 1980's, it wasn't until July of 2007 that the California State Climate Office was officially recognized by the American Association of State Climatologists (AASC). The National Climatic Data Center (NCDC) has recognized Dr. Anderson's role for over 2 years.

Dr. Anderson received his Ph.D. in Civil and Environmental Engineering from the University of California, Davis in December, 1998. His M.S. in Civil and Environmental Engineering was from the University of California, Davis in December, 1993. He received a B.S. in Civil Engineering from Colorado State University in Fort Collins, Colorado, in May 1991.

Just yesterday, Dr. Anderson's promotion was finalized within the Department of Water Resources. He will now be able to devote 100% of his time to this vital position. Many other state's climatologist posts are within the academic environment, not government. His office will collect, analyze and evaluate climate data for California.

The link to the CA State Climatologist's website is:

http://www.climate.water.ca.gov/

There you can find data, information, and summaries of interest.

Today is Leap Day! February 29th doesn't come around every year, as most of us know. It is designed as a calendar adjustment to correct for the fact that the actual time it takes to get around the sun is not an even number. If the path took exactly 365 days, or some other easily divisible number, we wouldn't have leap days. The actual length of a year is 365.2422 days. If a year is divisible by 4, it's a leap year, unless it is also divisible by 100, then it is not a leap year. But it gets even weirder. If a year is divisible by 400, it IS a leap year. The modern Gregorian Calendar just can't mimic the actual astronomy taking place. 2008 is a leap year, so enjoy your extra day! If you feel like you're getting back 'in sync,' that may be the reason.

Back next week.

February 28, 2008

Snow Survey measurements, water supply, and historical perspective

Today's measurements were taken at Phillips Station, along highway 50 as part of the manual snow course measurements that are taken statewide at 260 Sierra sites near the first of each month in winter and spring. Readings at that site (elevation 6,800') showed 86.1" snow depth. The more important figure is the water equivalence of that snow, which came out to 33.7". That is 136% of normal for this time of year at Phillips. While all the readings are not finished, we have numerous automated snow sensor measurements that provide a rough estimate of the total snowpack. They show the following:

North 31" 122% of normal
Central 29" 110% of normal
South 28" 130% of normal
Statewide average 29" 118% of normal

The physical course measurements are the more accurate, and will likely come in slightly above those estimates, just like they did last month.

For comparison, course measurements of the past (statewide average)

One month ago One year ago Last season's April 1, 2007 reading
21" / 131% 17"/ 68% 12.4"/ 40%*
*Lowest since 1988, which had been 30% on April 1.

Historic min and max April 1 snowpack water content readings (approx. 60 year record)

1977 25%
1969, 1983 225%

Our current reservoir storage is running about 50% of capacity on average for the major reservoirs statewide. There is certainly plenty of space available for the coming snowmelt. In fact, we'd like to see a few more of these cold storms come through, but the next 9 days look dry. It would have taken a very impressive year to make up for last year's poor snowpack. It's estimated we'd have needed an 85% of normal runoff season to get our reservoirs back to normal. However, current projections are that we will have about a 77% of normal runoff year, doing a general statewide average. That's going to keep us from slipping further toward drought conditions, but will not fill things back up.

Current reservoir status for a few headliners:

Folsom 37% capacity 66% of normal for this date
Oroville 41% capacity 57% of normal for this date
Shasta 57% capacity 77% of normal for this date

Reservoir comparisons to some historically very dry years (the count your blessings figures)
Statewide Percent of Normal to Date Reservoir Storage (compared to today)

200877%
vs.
197663%
197735%
199252%

So we are doing better than some of our driest years.

It's been an interesting year. The first half of the year was not impressive, with only 55% of normal runoff flowing down the rivers as of February 1. (In part due to the dry previous year). We also had lower than normal precipitation until January. And then, in January and even February, we had a lot of very cold storms. These have been really good snow producers, but we've not seen the runoff increases yet. The snow has yet to melt. And they also did not produce as much rainfall as you might expect, given the impressive snow totals. (This sometimes happens in La Nina; more tomorrow). But that dry initial third of the water year (which begins Oct. 1) won't be offset by a close-to-average spring snowpack, which is probably where we will end up. Since we are at 102% of April 1 average for snow water content already, were it to stop snowing, we'd at least end up with a decent, fairly average 1-year. On it's own merit, '07-'08 is doing fine. But classification projections for the Sacramento and San Joaquin River systems are still both "DRY." (On a scale that includes wet, above normal, below normal, dry and critical).

The Department of Water Resources issued a press release today that combines today's snow measurements with a curtailment announcement for Delta pumping. Please read this important information:

http://www.water.ca.gov/news/newsreleases/2008/022808.snowsurvey.pdf.pdf
or
http://www.water.ca.gov/news/
and link from there.

Look for another newsletter on Friday, with an explanation of just why La Nina is not doing what it normally does in California. And why we want it to keep not doing it!

Special thanks to Steve Nemeth of DWR Snow Surveys; Maury Roos, DWR Chief Hydrologist; and Ted Thomas, DWR Public Affairs.

February 22, 2008

Updated Storm Forecast
Delta Winds very high, especially west

A few headline changes on our storm. First, the bulk of it strikes Saturday night. While conditions deteriorate during the afternoon/ evening on Saturday, it's mainly the overnight hours and early Sunday morning that bring the heaviest rains and strongest winds. This is good because fewer people will be on the road. Highest surf and seas (at least for the coast from Mendocino to Monterey) will occur early Sunday.

Other change of note is that it may be a little less intense than forecast yesterday, with the low undergoing its most rapid intensification while still out to sea. It tracks a bit further south into central CA, sparing the far north coast some of the very high winds that had been predicted. So the upper coast will have southeast winds, not as damaging, with the low passing to their south.

Big winner in terms of snow will be the southern Sierra. As has happened many times this winter, the track has been more favorable for that region than the central Sierra (Yuba through Merced). Case in point, snow water equivalents look like this:

North 114% 28"
Central 98% 25"
South 113% 23"

While the inches are not highest in the south, the percentages are more robust. Southern Sierra snow totals will range from 4-5.5', elsewhere 3-4'. Snow levels in the Sierra will rise to around 6,000' during the day Saturday, then fall to 3,500' or 4,000' early Sunday. Sierra winds will not be extreme, as the center of the low impacts the coast as it is weakening, so the strongest winds will be at the coast, and on the east side of the coastal range. Sierra gusts go to 65mph.

The Grapevine could pick up a bit of snow Sunday afternoon, as southern CA will have a later onset of stormy conditions. Burn areas in southern CA are at risk during each storm, but excessive rainfall in a short period of time is not expected in those locations this go-round. They had a soaking of rain already this morning.

Contrary to the Sac Bee story, I wouldn't say the winds in the Sac area will get to 70mph. I'd commit to my original 40mph steady, with gusts to 50 around town, maybe a bit more. Many places will fare worse than Sacramento. The duration of the wind is the problem, and those speeds are nothing to sneeze at. (In fact, sneeze is exactly what most of us are doing this winter.) There is a 24 hr. period of time that trees or power lines being downed is a possibility somewhere in the northern 2/3rds of the state.

The length of time that we will be vulnerable to very high (although not extreme) winds is the characteristic of note this weekend. Much of California (including the coasts, Redding to Marysville area, and Delta, especially west) will have 12-18 hours of steady 35-45+ mph winds, with bigger gusts possibly to 60mph. That puts stress on Delta levees, especially those vulnerable to a south wind, which will be the direction of the strongest and longest lasting winds from 4pm Sat- 7am Sun there. Coastal surf will be high, picking up to combined sea and swell heights of 20-25' on Sunday morning. For more on the latest watches, warnings and advisories (which are numerous for this weekend and will be changing over time), please go to:

http://www.wrh.noaa.gov/cnrfc/warnings.php

With the southeasterly flow more predominant due to the position of the low, the east side of the coastal range will get the best orographically enhanced precip. Rainfall amounts there could be quite heavy, so creeks and streams (eg. Cottonwood to Cache Creek) may see good inflow/ rises. Mainstem rivers remain low, and reservoir flood control space is more than enough for what is coming in.

Agencies will monitor this system in coming days. It will not be as windy as the early January storm. Nor will rainfall amounts be as heavy. Duration of these high wind conditions will range from 12-16 hours, perhaps not 18-24. But a storm is heading our way, no doubt. Check out the satellite:

http://www.cnrfc.noaa.gov/satellite/epac_enhanced_ir.php

After this quiets throughout the day Sunday, we are done for a while.

February 20, 2008

From the California Department of Water Resources

The storm track has reopened over the west coast. We are looking at rain nearly each day through this weekend. Sierra snow could exceed 3 feet by Monday morning!

The next system is a 996mb low for Thursday night/ Friday. The strongest jet approach is 145 knots at 10pm Thursday night off Sonoma Co. That indicates a pretty good shot of moisture for central and southern CA; both coasts and mountains. The snow level with this will vary from 3,500' to 5,000' during the event, with the Feather River average snow level at 4,500'. It starts snowing up and down the Sierra at about 4pm Thursday, and won't basically stop till Friday night. Winds will be strong for this system, and it is reinforced with a shortwave entering the flow pattern on Friday. Onshore winds at 850mb will range from 30-40 knots out of the south/ southeast (35-46mph), and 700mb winds will be west to southwest at 40-50 knots for the northern half of the state.

Saturday and Sunday bring another, juicier low across California. This will be very windy and wet. The long distance fetch that is conveying these lows into California is a jet that has stretched all the way back to Asia in one long, rare zonal jet stream. The weekend system is the crescendo of the increasing waves we've seen, starting yesterday. And after Sunday's climax, its back to the dry....

Anyway, getting back to our weekend storm.... Warm air advection gets things started Saturday. The low deepens to 976mb at the surface, ushering big winds for Saturday night at 10pm as follows: Coast and Shasta 700mb SW winds to 60-80 knots (70-90mph), with 850mb winds to 40-60knots (46-57mph) out of the south. This makes for high swells, good orographics, and very poor driving conditions. This may not pack exactly the same wallop as the early January storm, but it will be a good snow producer, and may lead to locally heavy downpours. The snow level will be about 4,000' over the Northern Sierra. The strong winds die down Saturday night, but on Sunday morning the North Coast will again see gusty winds up to 70mph just off shore. The storm persists through Sunday.

10-day quantitative precip forecast for the Northern Sierra 8 Station index (Mt. Shasta City, Shasta Dam, Mineral, Brush Creek, Quincy, Sierraville, Pacific House, and Blue Canyon) is 2.69", with the Feather River Basin expected to pick up 3.9", possibly more.

NOAA'S Hydrometeorological Testbed Project finds these 2 systems worth investigation, especially the weekend one. The potential is there for "Atmospheric Rivers" or moisture/energy transport surges that can lead to flooding. Intensive Operational periods 7 and 8 will take place over the American River Basin over the next 5 days, but the extent of observation will assist prediction over a much broader portion of the state.

Current hydrologic numbers: The 8 Station stands at 55% of a normal water year, with 27.5" out of a normal 50". Last year at this time, we were at 22.9", or 71% of average. The Northern Sierra Snowpack water content is at 111% of normal, 26"; the Central at 95% of normal, 24"; the Southern at 108% of normal, 21". This gives a statewide average snowpack water content of 24", or 103% of normal. January and current systems have had very agreeable snow levels. The next Snow Survey will take place Thursday, February 28th.

There will be a total lunar eclipse tonight! Hopefully today's drying skies will give as a good view. Actually, the 7-7:52pm outlook for the Sacramento area should be decent. High clouds area a possibility, but should be increasing the hours after the eclipse. Cross your fingers, and try to give this one a look. After 3 years of a lunar eclipse each year, we now won't get another till December 20/21, 2010! Tonight's sunset in Sac is at 5:49pm, with the moon rising at about the same time; 5:41pm toward the northeast. A lovely full moon it should be, too. The eclipse will be visible to all moon-facing Earthlings at the same time. The total eclipse lasts 52 minutes, starting at 7:00pm locally, but the minutes prior and following offer that great crescent shape of the Earth's shadow over an orangish-red moon.

On Saturday, February 23rd, American River College will be hosting "Squeezed Dry, California's Water Future," as the first Community Lecture and Concert Series. Panelists will be Elissa Lynn, DWR; Martha Lennihan, Water Attorney; Dennis O'Connor, CA State Senate Natural Resources and Water Committee; and Rita Schmidt Sudman, Water Education Foundation. The public is welcome and the talks run from 2-4pm, with questions from the audience. A variety of topics will be covered for general audiences in the Main Theater on College Oak between Madison and Winding Way. For more information, call (916) 484-8646.