Golden Gate Weather Services

In recent week there have been numerous articles highlighting the strong Sea Surface Temperature Anomalies (SSTA) that have developed in the Gulf of Alaska and northeast Pacific Ocean; and equating them to the "Blob" that was a dominant feature in 2014 to 2016 period.  However, it is important not to look at these particular SSTA areas in isolation without looking at SSTA patterns in other parts of the eastern Pacific.  (This is a path that has sometimes been mistakenly taken in the past in regard to El Niño, where ENSO temperatures were taken out of context relative to other parts of the Pacific. One example was the Very Strong El Niño event in the winter of 2015-16, which is looked at in the following: https://ggweather.com/enso/compare/.)

While the current (September 2019) SSTA for the northeast Pacific does show significant positive SSTA warming in the northern half of the Gulf of Alaska, it is somewhat weaker and farther north that seen in 2014 and 2016. Also of note this year is the strong positive SSTA area west of California, a feature that was weaker and farther south in 2014 and non-existent in 2016.

The bottom line, is that the strength, location and interaction of these anomalous areas, as well as others in the Pacific, and even globally, all affect the circulation patterns of the West Coast differently; thus great caution should be used in drawing any simple (i.e., 1 + 1 = 2, or "blob" = California drought) conclusions as to their impact on the upcoming winter.

This post is also available at: https://ggweather.com/blob.htm

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Phone: (408) 379-7500
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweater

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In the SF Bay Area, the moist southwesterly flow coming onshore from the Pacific Ocean is often perpendicular to the Santa Cruz Mountains, which are oriented from northwest to southeast. After ascending the mountains and producing sometimes copious amounts of rain, the air dries out as it descends downward into the Santa Clara Valley. This produces about fours time more rain near Ben Lomond (~60 inches) than near San Jose Airport (~15 inches) which is only 22 miles away. (Click here or on the map for full-size image)


Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Phone: (408) 379-7500
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

San Francisco
POR begins 1849-1850
2018-19: 25.50, 109%
Rank: 40^th of 170 seasons

San Jose
POR begins 1892-1893
2018-19: 16.63, 112%
Rank: 36^th of 127 seasons

Eureka
POR begins 1886-1887
2018-19: 41.00, 102%
Rank: 50^th of 133 seasons
 
Redding
POR begins 1892-1893
2018-19: 39.92, 115%
Rank: 38^th of 127 seasons
 
Sacramento
POR begins 1940-1941
2018-19: 24.57, 133%
Rank: 12^th of 70 seasons
 
Fresno
POR begins 1881-1882
2018-19: 11.44, 99%
Rank: 32^nd of 138 seasons
 
Los Angeles
POR begins 1876-1887
2018-19: 18.82, 126%
Rank: 39^th of 143 seasons
 
San Diego
POR begins 1850-1851
2018-19: 12.41, 120%
Rank: 36^th of 169 seasons
 
8-Station Index
Northern Sierra Nevada
POR begins 1921-1922
2018-19: 68.44, 126%
Rank: 19^th of 98 seasons
 
5-Station Index
Central Sierra Nevada
POR begins 1913-1914
2018-19: 49.79, 117%
Rank: 22^nd of 106 seasons
 
6-Station Index
Southern Sierra Index
POR begins 1922-1923
2018-19: 37.06, 122%
Rank: 23^rd of 97 seasons


Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Phone: (408) 379-7500
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

With the rain looking likely over the next week or so, below is some May rainfall climatology for the Bay Area and California.






 Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Phone: (408) 379-7500
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

For the past 5 months, the Oceanic Niño Index (ONI) has been stuck in the middle of the Weak El Niño category (i.e., +0.50 and +1.0) and the models are keeping it in that range through the end of the year!  Going back to 1950 (https://ggweather.com/enso/oni.htm) there are only three back-to-back years with kind of similar patterns, but none close enough in my estimation to be reasonable analogs. They were 1968-69 to 1969-70, 1986-87 to 1987-88, and 2014-15 to 2015-16.  California precipitation patterns related to El Niño years can be found at https://www.ggweather.com/ca_enso/ca_elnino.html. 


 


Current SST Temperatures with Niño Region insets


Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

After well above normal February and March rainfall, percentages in April across most of California dropped to well below normal. However, season-to-date numbers are still mostly above normal, and in many locations their seasonal (July 1 to June 30) normals have already been reached. See https://ggweather.com/seasonal_rain.htm and https://ggweather.com/water/.





Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

“ STORM” by George R. Stewart, should be REQUIRED READING if you are a meteorologist, meteorology student, deal with or communicate California weather on a regular basis, or anyone whose day-to-day activities in California are impacted by the weather.  I have just finished rereading it for probably the 5^th time and couldn’t put it down.

I first read “Storm” when I was an NWS meteorologist intern in 1975 and identified with one of the characters in the book, the Junior Meteorologist (JM) at the Weather Bureau in San Francisco. Over the years, I have given or loaned copies to over a dozen friends and colleagues and even though it was written in 1941, the meteorology is still sound and incredibly insightful. Likewise, the impact of a storm across California for 12 days in a winter where there had been early talk of a drought resonates strongly with this year’s headlines. Interwoven throughout the book are the interactions between the weather, the utilities, railroads, commerce, the airlines and people, which are just as relevant today as they were almost 80 years ago.



Please, do yourself a favor and track down a copy. It’s in many libraries, plus I often find copies squirreled away in used bookstores and there are numerous versions available on Amazon. (And when you finish “Storm”, read Stewart’s “Fire” which looks at another timely topic, the impact of a wildfire in the Sierra Nevada.)

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Phone: (408) 379-7500
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather 

How did the 2018-2019 Winter Outlooks that were issued last fall compare with reality? This year, in addition to looking at the CPC forecasts, several outlooks from the private sector were added for comparison. In all of the outlooks I see big-time errors; begging the question is there "skill" and "value" in these products? See http://ggweather.com/cpc/2019/


Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Phone: (408) 379-7500
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

2018-2019 CALIFORNIA WATER BY THE NUMBERS

It's should be no surprise that abundant rainfall this season has translated into a pretty bright picture for water supplies across the Golden State. 

The latest Drought Monitor shows California with its least amount of drought-impacted area since 2011. With only 0.60% in the Moderate Drought category (D1) and 9.56% in D0 (Abnormally Dry), California is at its most drought free since 8-30-2011. 

 The latest California Precipitation Snapshot shows rainfall already approaching or above normals for the entire is rainfall season (July 1 to June 30).

Of particular note is the 8-Station Northern Sierra Index, with state's largest reservoirs, which is now at 128% of normal and just 2.33" shy of their seasonal normal of 54.52".

  
And all of the above translates into California reservoir levels close to or exceeding historical averages for this time of year. 


Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

Historically, February 5th is the snowiest day of the year in San Francisco and the Bay Area. Of the 11 days when snow has been recorded near sea level in San Francisco, twice before on February 5th. In 1887 and again in 1976. (https://www.ggweather.com/sf/snow.htm)


The event on February 5, 1887, was the snowiest on record with over 3 inches in the downtown area of the City.  This is well documented in Mark McLaughlin's wonderful  "San Francisco Snowstorms" document (http://thestormking.com/Sierra_Stories/San_Francisco_Snowstorms/san_francisco_snowstorms.html)


And the last time there was an accumulation of snow near sea level in San Francisco was on February 5, 1976, with up to an inch downtown and 5" on Twin Peaks. (Spectacular photograph below: Art Frisch, SF Chronicle), 



The forecast conditions for tomorrow, February 5, 2019, do NOT look like a repeat of either one of the previous snow events. But the combination of much colder air moving into the region and continued bands of showers overnight should at least whiten the hills above 2000' and in some areas, especially inland possibly down to into the 1000' to 1500' range.

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather