Golden Gate Weather Services

The updated CPC ENSO Discussion is now available: www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html
and it has raised the likelihood of El Nino occurring in Fall 2014 exceeding 50%.

Of particular note is the dramatic increase in sub-surface temperatures shifting east and moving toward the surface: www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/figure4.gif

These changes are reflected in the "plume" of Nino 3.4 forecasts: www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/figure6.gif and
iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso_tab=enso-cpc_plume

BUT keep in mind that the there are no guarantees of more rainfall in California during an El Nino event and that climatology is NOT a forecast. See: ggweather.com/enso/enso_myths.htm

For more El Nino links see: ggweather.com/enso.htm

Jan Null, CCM
Golden Gate Weather Services

Despite outward appearances, it was NOT a Miracle March.  In reality only Eureka and Redding had above normal rainfall with 110% and 119% respectively. Most of central and southern California were less than 50% of normal. See ggweather.com/calif/mar2014.htm

This means that there will be no mitigation of drought conditions statewide and given the "summer drought" which characterizes our Mediterranean climate things will not change for the better until at least next winter. See droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?CA

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I have been using Twitter more frequently to post brief updates to weather and climate info that do not merit an email "blast". My Twitter handle is: @ggweather

Also, I am posting these email into a blog that can be found at ggweather.posthaven.com/

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Jan Null, CCM

Let the hype begin.  CPC has issued an El Nino Watch for the 50% possibility of a weak El Niño next fall from the IRI/CPC forecast ensemble.   A similar Watch was issued in 2012 but El Niño never materialized.

Already there are headlines about El Niño being the answer to California's drought which only perpetuates the myth that El Niño definitely means lot of rain for California.  To put aside this and some of the more prevalent misconceptions see The Myths and Realities of El Niño. 

Also see:
El Niño and La Niña Winter Historic Precipitation &Temperatures

Comprehensive Climatology of ENSO Events and California Precipitation

The bottom line is that climatology should NOT be used as a forecast tool.  An "average" El Nino is made up of a very broad range of past events!

If I were grading this past winter's CPC precipitation and temperature forecasts they would not receive a passing mark.   Except for Arizona, New Mexico and the northern Rockies, the forecast bore little resemblance to what was ultimately observed and in some locations was 180 degrees out of phase!

A graphical comparison of both the Winter 2013-14 (i.e., December-February) seasonal and monthly forecasts and actual conditions can be found at http://ggweather.com/cpc/2014/. 

Comments welcome.

Despite several recent significant rainstorms, most of Northern and Central California ended up with February rainfall totals only near normal.  The exceptions were wetter than normal across the northern tier of counties and near the Tahoe Basin. In Southern California it was mostly below normal.   See 
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dPpct.gif

Likewise temperatures were near normal with the exception of the southern half of the Central Valley where Sacramento and Fresno average maxima were 3.2 and 5.1 degrees above normal respectively.   See http://ggweather.com/calif/feb2014.htm

Jan Null, CCM
http://ggweather.com
jnull@ggweather.com

The overnight rainfall (through 7 am Friday, Feb 28)  has pushed San Francisco's seasonal rainfall to 7.57".  While still a paltry amount, this means that the 2013-2014 rainfall season (July 1-Jun 30) will NOT be the driest in the 165 years since rainfall records began in SF in 1849.  And given the expected rainfall through the rest of the day, this season may jump into 3rd place.   The Ten Driest Seasons were:
1850    7.42"
1975    7.95"
1897    9.38"
1863   10.08"
1958   10.46"
1919   10.46"
1876   11.04"
1976   11.06"
1971   11.06"
1917   11.47"
(See http://ggweather.com/sf/season.html)

And it should be noted that the normal San Francisco rainfall for the remaining four months (Mar-Jun) is still another 5.60".

The rainfall totals across northern California were very impressive, but 4-day totals dropped off rapidly into central California.  Many locales in the north more than doubled their season to-date totals, jumping from percent of normal (PON) values in the teens to PON's in the 30% to 40% range.  See http://ggweather.com/feb2014rain.htm

But the important takeaway is that while this is a great start, the north half of the state would still need on the order of 4 more equivalent storm systems to get close normal.

The very important Northern Sierra 8-Station Index also jumped significantly; doubling with over 5 inches to 9.58" to-date.  This is approximately 35% of normal, up from 18% on Wednesday.  See http://cdec.water.ca.gov/cgi-progs/queryDaily?s=8si&d=today

There have been some rain totals of over 20 inches being reported for Mt. Tamalpias.  However In light of surrounding locations this seems to be a bogus.  Kentfield's big-time 96-hour total of 11.83" would appear to be more representative.  See https://marin.onerain.com/sensor.php?site_id=1555&device_id=1&view_id=3