Golden Gate Weather Services

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

Groundhog Day has its roots in an ancient Celtic celebration called Imbolog. This date is the midpoint between the winter solstice and the spring equinox. In an agrarian society that was very dependent on the weather, this was a time to celebrate having made it halfway through winter. The superstition arose that if the weather was fair on Imbolog, the second half of the winter would be cold and stormy, but if the weather was cold and overcast or stormy, the second half of the winter would be mild.

In Christian times, February 2nd was celebrated as Candlemas, but the earlier Imbolog superstition continued. In Scotland they said, ``If Candlemas be bright and clear, there'll be two winters in the year'' and in England, they said, ``If Candlemas be sunny and warm, ye may mend your mittens and look for a storm.''

The Romans learned of this tradition from the Celts, and eventually brought them to the area that would become Germany. Eventually German immigrants brought these beliefs to Pennsylvania. Their tradition of predicting the weather became centered on the woodchuck, or groundhog, and if he could see his shadow, there would be six more weeks of winter.

A newspaper in Punxsutawney, PA helped keep the tradition alive and in 1887 declared Phil as America’s official forecasting groundhog. As the story became embellished each year the other newspapers picked it up and the rest as they say is history. Regionally there have been a number of other furry rodent contenders such as General Beauregard Lee of Atlanta, Sir Walter Wally in Raleigh, NC and Jimmy of Sun Prairie, WI.  And in 1993 the motion picture "Groundhog Day" popularized the event even further.

NOAA's National Climatic Data Center's look at this tradition and some of the associated climatology is at http://www.ncdc.noaa.gov/customer-support/education-resources/groundhog-day  

Today it has been reported that Punxsutawney Phil did see his shadow this morning (despite a Winter Storm Warning still being in effect) and forecasted six more weeks of winter for 2015.


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

Across much of Northern and Central California there has been little if any rain this month and monthly totals will wind up at or near long term records.  Below are the 15 lowest January totals for each station's period of record.

Looking at San Francisco, note that three of the five driest years are in the top five.  This has brought the average for the past ten years down to 3.03, dramatically lower than the 30-year normal of 4.55 inches.  

In San Francisco, January 19th begins the second half of the July 1 to June 30 rainfall season.  A few other cities in Northern California reached their halfway point in the past few days and most of the state will exceed it in the next week.

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

Happy New Year and Best Wishes for a healthy, happy and properous 2015.

December 2014 was a wet and warm month across the Golden State. Precipitation ranged from "only" 120% of normal at Eureka to 294% at Los Angeles and 297% at San Jose.  December maxima were well above normal, ranging from 1.6 degrees above normal at Redding to 5.9 above normal at Sacramento; with the exception of Los Angeles whose maxima were 0.2 below normal.

December California Key City Climatology
http://ggweather.com/calif/dec2014.htm 

December Max Anomaly Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dTxdep.gif 

December Mean Anomaly Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dTvdep.gif 

December Min Anomaly Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dTndep.gif 

December Precipitation Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dP.gif 

December Precipitation % of Normal Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dPpct.gif 

July - December Precipitation Table
http://www.cnrfc.noaa.gov/awipsProducts/RNOWRKCLI.php 

July - December % of Normal Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc6mPpct.gif 

Northern Sierra Nevada 8-Station Index
http://cdec.water.ca.gov/cgi-progs/products/PLOT_ESI.pdf 

Southern Sierra Nevada 5-Station Index
http://cdec.water.ca.gov/cgi-progs/products/PLOT_FSI.pdf 

California Snow Water Content
http://cdec.water.ca.gov/cgi-progs/products/PLOT_SWC.pdf 

Jan Null, CCM
http://ggweather.com 

With the recent rains I have been re-asked the eternal question: "Should I Walk or Run in the Rain?" This is a classic question that meteorologists get asked and upon which we have probably spent way too much time. So, does a person make impact with more droplets as they run faster even though they are exposed for a shorter period of time? Or do more drops hit the front of a running person than on their head and shoulders when they run instead of walk?

There have even been a number of studies to "scientifically'' calculate whether it's better to run or walk to shelter. One of the simpler studies had people wear a piece of cardboard over their heads and in front of them as they walked or ran through the rain and then the number of drops that marked the cardboard were counted. A more detailed effort from the National Climatic Data Center in Asheville, North Carolina had their experimental subjects wear identical moisture absorbing clothing as they walked 100 yards at 3 mph and then ran the same course at 9 mph. Their clothing was then weighed to find out how much water was absorbed. They found that speed helps ... the person who ran the course absorbed 40 percent less water than the walker!

And of course someone, again with way too much time on their hands, has put up a website to calculate how wet you would get based upon your size, speed and the rate of rainfall. See http://www.dctech.com/physics/notes/0006.php and http://www.dctech.com/physics/notes/0005.php.

Stay dry!

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