Precip to date figures

[dave54]

From the North Ops Intelligence unit:

(North Ops or NOPS is the joint FS/BLM/CDF/NPS/local fire agency fire and emergency services coordination center for northern California. Redding)

PSA is the weather predictive area. Based on climate zones rather than watershed basins, like the CDEC site. These figures are for total precip, including snow water content. I am not sure the Eastside/Susanville value is right. It looks fishy. Typo? Bad data?


Precipitation Totals for 2006-2007 Wet Season
(Jul 2006-March 2007)

North Coast PSA
Eureka: Jul 2006 thru March 2007 = 34.18 Normal = 33.79
Percent Normal = 99%

Mid Coast/Mendocino PSA
Ukiah: Jul 2006 thru March 2007 = 29.74 Normal = 45.36
Percent of Normal = 66%

Bay Area PSA
San Francisco: Jul 2006 thru March 2007 =10.58 Normal =18.37
Percent Normal =58%

Northwestern Mtns PSA
Orleans: Jul 2006 thru March 2007 = 34.85 Normal = 47.12
Percent Normal = 74%

Sac Valley/Foothills PSA
Shasta Dam: Jul 2006 thru March 2007 = 33.60 Normal = 55.41
Percent Normal = 61%

Northeastern CA PSA
Alturas: Jul 2006 thru March 2007 = 4.40 Normal = 9.21
Percent Normal = 48%

Northern Sierra PSA
Blue Canyon: Jul 2006 thru March 2007 = 39.93 Normal = 60.37
PercentNormal =66%

Eastside PSA
Susanville: Jul 2006 thru March 2007 = 2.25 Normal = 12.24
Percent Normal = 18%

[gdurkee]

That Susanville number may not be a typo. Here's the state meteorologist's latest:

April water supply summary, the D-word, and Long Term Climate
forecasting.

(Note; users may have to cut and paste the 2 longer links given in
today's newsletter. The mailman plain text format cannot handle lengthy hyperlinks, so clicking will only work with those that are shorter, and clearly linkable. Also, the format carriage returns long sentences in a paragraph. Apologies.)

April 1 statewide conditions can be summarized as the following:

Snowpack 40% of average (has fallen to 32% of normal, or 8", on average statewide, as of April 18)

Precipitation 65% of average
Runoff 60% of average
Reservoir Storage 110% of average

Please see Bulletin 120 April, 2007 for graphs, charts, and table
information:

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

A dry, and sunny March lead to a loss of 20 percentage points in
snowpack water content, rather than the usual gain in the month. River year-to-date runoff at this time last year was 155% of average.

Questions and concerns about drought abound, with the below normal snowpack and Southern California currently seeing one of its driest water years on record. Many locations there have received between 18-25% of normal precipitation since July 1, 2006. Water supply, agriculture, and natural ecosystems each have their own definition of drought. From some perspectives, drought may be an appropriate term for Southern California, given it's current conditions. However, from a state water storage perspective, the word drought is, at this time, premature. Reservoir storage is above normal for this time of year,
thanks to carryover supplies. Groundwater levels are also benefiting from previous wet years.

One depiction of drought conditions on a nationwide basis is provided by the U. S. Drought Monitor. The Drought Monitor is a collaborative product of climate scientists and local specialists that relies primarily on measures of precipitation and soil moisture. Other elements such as water storage are included subjectively to create a general picture of drought conditions. To see the Drought Monitor map which is updated weekly, go to:

http://drought.unl.edu/dm/monitor.html

See Jan Null's Golden Gate Weather Services for additional information and links:

http://ggweather.com/

California water supply is, in general, a highly engineered system
designed to deal with dry years by capitalizing on multiple sources, and utilizing carryover capabilities in the state's reservoirs. Coming off several wet to above normal years, we have a buffer for this year, at least. Successive dry seasons would cause greater stress. The Department of Water Resources manages a drought preparedness page at:

http://watersupplyconditions.water.ca.gov/

and provides a lengthy historical write-up about dry periods in
California, and long-term past California climatic conditions at:

http://watersupplyconditions.water.ca.g ... ground.cfm

Interestingly, long-range forecast models are having a tougher time with La Nina/ El Nino forcing patterns. Those computer models are providing monthly to seasonal climate averages, and it has been tough going the past several cycles. Perhaps the models are not well parameterizing (mathematically representing) additional, lesser understood forcing or feedback processes that have an impact on larger time scale predictions.

The El Nino Southern Oscillation update of April 16 states there is a
neutral pattern currently in place, but a La Nina pattern could develop over the Pacific in coming months:

http://www.cpc.ncep.noaa.gov/products/a ... na/enso_ev
olution-status-fcsts-web.pdf

The Climate Prediction Center outlook for the early summer
(May-June-July) shows above average temperatures for all of eastern California, from the valleys over the Sierra, and throughout the desert Southwest. That same period shows a slightly increased chance for drier than normal conditions for the southern half of California.

http://www.cpc.ncep.noaa.gov/products/p ... lead02/off_
index.html

[dave54]

I suspected the figure for Susanville was off because north of there (Alturas), and south (Reno) are much higher. West of Susanville is higher because of the rain shadow effect, and appears right. Susanville was not that dry this winter. I am not sure which rain sensors the figure was derived from.