November 2007

Overview

For the most part, November’s precipitation was below average (northeast counties being a notable exception). Temperatures were also below normal, but this is to be expected: Oregon’s driest Novembers are often colder than average.

Table 1 is a summary of monthly averages and totals at selected stations throughout the state. Table 2 lists daily temperatures and precipitation for most of the locations listed in Table 1. In Table 3, monthly precipitation totals throughout the state are listed. Figure 1 is a map showing the percentage of normal precipitation statewide for the Water Year.

Basin Summary

Here is a summary of water indicators at the end of the month, by river basin:

*SWSI are as of November 1, 2007
n.a. Not available
(1) Percent of normal November precipitation, from NOAA Cooperative sites
(2) Percent of normal seasonal precipitation (since Oct. 1), from NOAA Cooperative sites
(3) Percent of normal seasonal precipitation, from Natural Resources Conservation Service (NRCS) SNOTEL sites
(4) Percent of normal snow water equivalent, from NRCS SNOTEL sites
(5) Percent of normal November stream flow, from U.S. Geological Survey (USGS)
(6) Percent of normal seasonal stream flow (since Oct. 1), from USGS
(7) Surface Water Supply Index, from NRCS (-4 = very dry, 0 = normal, +4 = very wet)

Forecasts

The Climate Prediction Center’s (CPC) forecasts for December-February appear below. Temperature probabilities show equal chances of above-, near-, and below-normal for Oregon, while precipitation probabilities show above-normal probabilities.

Oregon Climate Service predicts below-normal temperatures and above-normal precipitation for the next three months.

ENSO Update

Australian Bureau of Meteorology, December 5, 2007

A La Niña event is well established in the Pacific. The main features of the event are colder than average surface temperatures along much of the equator, cold sub-surface temperatures in the eastern tropical Pacific, stronger than average Trade Winds and reduced cloudiness. The Southern Oscillation Index (SOI) has also risen to more typical La Niña values after being neutral for most of the year. November's SOI was +10 and monthly rainfall totals were above normal across much of Australia's eastern half.

Computer models continue to indicate the persistence of cold Pacific temperatures, consistent with a La Niña, until about April or May 2008.

CPC ENSO Forecast (December 7, 2006)

La Niña reached moderate strength during November 2007, with below-average sea surface temperatures (SSTs) extending from 160E to the South American coast. All of the Niño region indices remained cooler than 1.0°C, with the most substantial cooling occurring in the Niño-4 region located in the central equatorial Pacific Ocean (150W-160E and 5N-5S). The upper-ocean heat content (average temperatures in the upper 300 m of the ocean) in the central and east-central equatorial Pacific remained below average, with temperatures ranging from 2°C to 5°C below average at thermocline depth. Consistent with these oceanic conditions, low-level easterly winds and upper-level westerly winds strengthened across the central equatorial Pacific, convection remained suppressed throughout the central and eastern equatorial Pacific, and an area of enhanced convection covered the far western Pacific. Collectively, these oceanic and atmospheric conditions reflect La Niña.

The recent SST forecasts (dynamical and statistical models) for the Niño 3.4 region indicate a continuation of La Niña into Northern Hemisphere spring 2008. Over half of the models indicate a moderate-to-strong La Niña through February, followed by a gradual weakening thereafter. Current atmospheric and oceanic conditions and recent trends are consistent with the model forecasts.

CoCoRaHS Comes to Oregon

The Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS) is a non-profit, community-based network of volunteers working together to measure and map precipitation (rain, hail, snow). CoCoRaHS originated with the Colorado Climate Center at Colorado State University in 1998. This is a community project and everyone interested is encouraged to help. Volunteers take measurements of precipitation from as many locations as possible. The precipitation reports are then recorded on the CoCoRaHS website (www.cocorahs.org). The National Oceanic and Atmospheric Administration (NOAA) is a major sponsor of CoCoRaHS.

The Oregon Climate Service has decided to participate with and contribute to the CoCoRaHS network. Participation requires volunteers from around the state of Oregon to take daily measurements and record them online with the network. To participate go to the CoCoRaHS website and sign up to become a volunteer with them. When you sign up with CoCoRaHS we will be able to keep track of every Oregon observer.

The following is from the CoCoRaHS web site.

What is CoCoRaHS??

CoCoRaHS is an acronym for the Community Collaborative Rain, Hail and Snow Network. CoCoRaHS is a unique, non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation (rain, hail and snow). By using low-cost measurement tools, stressing training and education, and utilizing an interactive Web-site, our aim is to provide the highest quality data for natural resource, education and research applications. We currently operate in many states across the country. If we are not in your state please drop us a line and let us know that you have an interest in participating. This helps us know where a desire exists for the network and where to focus our future expansion efforts.

Where did the CoCoRaHS Network originate??

The network originated with the Colorado Climate Center at Colorado State University in 1998 thanks in part to the Fort Collins flood a year prior. In the years since, CoCoRaHS has expanded rapidly with over 6,500+ observers in twenty-six states. Folks in many parts of the country have shown interest in having their state join the CoCoRaHS Network in the not too distant future. (for further information on the origins of CoCoRaHS, check out “http://radarmet.atmos.colostate.edu/~rob/hail/origins.html). Click here for a look at the order of states admission to the network.
Who can participate??

This is a community project. Everyone can help, young, old, and in-between. The only requirements are an enthusiasm for watching and reporting weather conditions and a desire to learn more about how weather can effect and impact our lives.

What will our volunteer observers be doing??

Each time a rain, hail or snow storm crosses your area, volunteers take measurements of precipitation from as many locations as possible (see equipment). These precipitation reports are then recorded on our Web site www.cocorahs.org. The data are then displayed and organized for many of our end users to analyze and apply to daily situations ranging from water resource analysis and severe storm warnings to neighbors comparing how much rain fell in their backyards.

Who uses CoCoRaHS??

CoCoRaHS is used by a wide variety of organizations and individuals. The National Weather Service, other meteorologists, hydrologists, emergency managers, city utilities (water supply, water conservation, storm water), insurance adjusters, USDA, engineers, mosquito control, ranchers and farmers, outdoor & recreation interests, teachers, students, and neighbors in the community are just some examples of those who visit our Web site and use our data.

What do we hope to accomplish??
CoCoRaHS has several goals (as stated in our mission statement). 1) provide accurate high-quality precipitation data for our many end users on a timely basis; 2) increasing the density of precipitation data available throughout the country by encouraging volunteer weather observing; 3) encouraging citizens to have fun participating in meteorological science and heightening their awareness about weather; 4) providing enrichment activities in water and weather resources for teachers, educators and the community at large to name a few.

Who is sponsoring this network??

The National Oceanic and Atmospheric Administration (NOAA) is a major sponsor of CoCoRaHS. Other organizations have contributed either financially, and/or with supplies and equipment. Our list of sponsors continues to grow. Click here to visit our sponsor’s page. Many other organizations and individuals have pitched in time and resources to help keep the network up and running. We are grateful to all of you, as CoCoRaHS would not be possible without your help.

What benefits are there in volunteering??

One of the neat things about participating in this network is coming away with the feeling that you have made an important contribution that helps others. By providing your daily observation, you help to fill in a piece of the weather puzzle that affects many across your area in one way or another. You also will have the chance to make some new friends as you do something important and learn some new things along the way. In some areas, activities are organized for network participants including training sessions, field trips, special speakers, picnics, pot-luck dinners, and photography contests just to name a few.
How can I sign up??

Go to www.cocorahs.org. Click on the Oregon map for specific info.