Golden Gate Weather Services

A recent CPC blog post said:  "We recommend that you track the verification skill scores over time (not just for one forecast), as they give you a feel for whether you should trust them or not.  Any individual forecast could hit the mark or be way off".  Consequently, below are the CPC seasonal forecasts for winter for the past 20 years. It is left to the reader to assess how "skillful" these outlooks are.

For the full breakdown see  http://ggweather.com/cpc/verify/cpc_winter.htm

Jan Null, CCM
Golden Gate Weather Services
http://ggweather.com 

Is the date and time of a full moon called the "offical full moon" or the definition of "pi" called the "offical value of pi"? So, why do so many call the Vernal (Spring) Equinox, which occurs today at 3:45 pm pdt (2245 utc/gmt), the "official" beginning of Spring. It is simply an astronomical event that defines when the plane of earth's equator passes the center of the sun causing the earth's axis to be perpendicular to its orbit around the sun. It is not a weather event and no one or no agency issues a proclamation making it "official" anyway.

And meteorologically, Spring is defined as the months of March, April and May.

Jan Null, CCM
Golden Gate Weather Services
http://ggweather.com 

Too little, too late?

CPC has upgraded their El Nino Watch to an El Nino Advisory <http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html>, but with only a 50-60% chance it will persist through summer.  The upgrade is despite the ONI dipping from +0.7 to +0.6. <http://ggweather.com/enso/oni.htm> and during a time of year when the influences of El Nino are waning.

An excellent analysis of these potential impacts can be found at http://www.climate.gov/news-features/blogs/enso/march-2015-enso-discussion-el-ni%C3%B1o-here.

Jan Null, CCM
Golden Gate Weather Services
http://ggweather.com 

In general the Golden State saw a dry and warm February.  Average maxima at Eureka was "only" 3.4 degrees above, while the remaining key cities ranged from 5.4 (San Diego) to 8.4 (Redding) above normal. See http://ggweather.com/calif/feb2015.htm 

February 2015 rainfall generally ranged from more in the north to less in the south.  Eureka was 90% of normal while San Diego totaled only 8% of normal with most locales in the middle between about 33% to 66%. See http://ggweather.com/calif/feb2015.htm

Correspondingly, season to date rainfall numbers slipped; but on the weight of our very wet December they are still better than some of the previous years.  SF Bay Area season to date numbers are mostly between 90% and 110% of normal, while statewide key cities percent of nomal values range from 75% to 99% of normal. See  http://forecast.weather.gov/product.php?site=NWS&product=RR4&issuedby=MTR 

In the key Sierra Nevada basins the 8-Station Northern Sierra Precipitation Index is at 90% of normal while the 5-Station San Joaquin Index is only at 49% of normal.  See http://cdec.water.ca.gov/cgi-progs/products/PLOT_ESI.pdf and http://cdec.water.ca.gov/cgi-progs/products/PLOT_FSI.pdf 

Jan Null, CCM
Golden Gate Weather Services
http://ggweather.com 

What a difference a week makes! If the AT&T Pebble Beach Pro-Am Golf Tournament had been played last week it would have been what many think of as "typical Crosby weather".  In fact, it has only rained on 58% of the years during the tournament.  See http://ggweather.com/pebble.htm for a year-by-year breakdown of rain during this event.  

This year it will picture postcard weather with temperatures in the low to mid-70s.

Below are a number of links relating to Atmospheric Rivers (ARs). These relatively narrow (~240 miles) slow moving bands of subtropical moisture account for between 30% and 50% of the rainfall occuring along the West Coast. Many of Washington, Oregon and California's historic flooding events have been related to ARs. They are also colloquially known as the "Pineapple Express" because some of their moisture originates from the vicinity of the Hawaiian Islands.

http://www.esrl.noaa.gov/psd/atmrivers/

http://www.esrl.noaa.gov/psd/atmrivers/questions/ 

http://tenaya.ucsd.edu/~dettinge/Dettinger_Ingram_sciam13.pdf  

http://pubs.usgs.gov/of/2010/1312/of2010-1312_text.pdf 

Jan Null, CCM
Golden Gate Weather Services
http://ggweather.com 

To illustrate the roller-coaster ride of both rainfall and reservoir storage in California, see the following three graphics from the 1st day of the month for December 2014, January and February 2015.  

For example, the 8-Station Index for Northern Sierra Nevada Precipitation went from 86% of normal on December 1, to 127% on January 1 and back to 86% on Feb 1st. Most other metrics statewide saw similar swings.

Jan Null, CCM
Golden Gate Weather Services
http://ggweather.com