Dry with Some Record Warmth for February Across California

 

See http://ggweather.com/calif/feb2016.htm

Average maximum temperatures across California for February 2016 ranged from "just" well above normal (i.e., Eureka at +2.5 deg F) to downright toasty with average monthly maxima anomalies of between +6.1 and +9.4 degrees.  Four of the eight major stations set records for all-time warmest maxima for the month. 
                                       2016    Prev record
    San Jose                    69.0    67.8 in 2015
    Sacramento Ex AP    67.6    67.1 in 1988
    Los Angeles - City     77.5    75.6 in 1954
    San Diego                 74.4    72.1 in 1954

At the same time, rainfall across the Golden State was paltry at best, with values ranging mostly between 10 and 20% of normal.  The exceptions were at opposite ends of the state with 58% of normal in Eureka and only 2% of normal in San Diego.

This allowed rainfall season (Jul - Jun) totals to drop below normal for most of California, though prog charts for the next two weeks should produce  very strong upward movement to back above normal.  Currently: http://ggweather.com/seasonal_rain.htm 

Likewise, snowfall totals have slipped below normal, but should also show a strong recovery in coming weeks. Currently: http://cdec.water.ca.gov/cgi-progs/snow/COURSES

Jan Null, CCM
Golden Gate Weather Services  

 

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El Niño 2015-16 becoming Poster Child for "All El Niños are not the same!"

El Niño 2015-16 becoming Poster Child for "All El Niños are not the same!"

 

Among the mantras from the past year by myself, SF State Professor Dr. John Monteverdi and many other responsible meteorologists, are that 1) each El Niño is unique, 2) the number of past events is statistically very small for comparison, and 3) that there are "no guarantees". To date many of the blogs, webpages and associated articles have look at the similarities to previous strong and very strong El Niño events.

However, as the El Niño 2015-2016 and its impacts continue to unfold, Dr. Monteverdi and I felt it's important to look at how this year is dissimilar in many ways to previous events.  To that end we have co-authored the following page: Differences Between 2015-16 El Niño and Previous Strong and Very Strong  Events.   

Below is one of the figures from that page, which breaks down the Sea Surface Temperature Anomalies (SSTAs) for each of the strong and very strong El Niños for all four of the Niño sampling regions in the tropical Pacific. Other data includes how the circulation patterns are different along with how the November through January precipitation and temperature patterns don't match very well with previous events, 



Coming soon, will be a separate page with how the second half of the winter during these events has looked.

Jan Null, CCM
Golden Gate Weather Services

Dr. John Monterverdi, CCM
San Francisco State University

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January 2016 Wet and Mild Across California

In the major cities across California the January 2016 rainfall ranged from "just" 102% of normal in Los Angeles to over 200% of normal at Redding (213%) and Fresno (202%). Rain in the critical Sierra Nevada watersheds ranged from 175% of normal in the Northern Sierra 8-Station Index  to 119% of normal in the Tulare Basin 6-Station Index. (See http://ggweather.com/calif/jan2016.htm)

 

The rainfall season- (July 1 to June 30) to-date totals and percentages of normal for 46 California stations are available at: http://ggweather.com/seasonal_rain.htm.

Monthly temperatures were generally warmer than normal though maxima in Redding and LA slipped in as cooler than normal.  (See http://ggweather.com/calif/jan2016.htm)

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

 

 

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What's Different with El Niño 2015-16?


 

As we turn the corner into the second half of the rainfall season, it is becoming increasing apparent that the ongoing El Niño is becoming the poster child for "all El Niños are not alike!". While it is still way too early to know what this will ultimately mean for California's rainfall season, it is noteworthy to look at some of the differences.

While most attention has been focused on the Niño 3.4 region (see map) which has been very similar to the very strong El Niño event of 1997-1998, there have been some significant differences in the adjacent regions. The Niño 4 region to the west alongthe equator has been warmer than 1997-98, while Niño 3 and Niño 1+2 regions have been cooler.



There have also been significant differences in the monthly rainfall patterns compared to previous strong and very strong events.  The following sample is for the San Francisco, Los Angeles, the Northern Sierra Nevada (8-station index) and the Central Sierra (5-station index), with monthly totals for November and December and for January through the 26th.



Please insert the usual caveats, that it's still only the midpoint in the rainfall season and we don't know how these differences will impact the remainder of the rainy months. But it is different, so stay tuned.

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

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Comparative Monthly Rainfall Climatology of Strong and Very Strong* El Niño Events

Comparative Monthly Rainfall Climatology ofStrong and Very Strong* El Niño Events

 

As the current very strong El Niño continues, it's time to examine how the current event looks in comparison to past similar strength events.  The following is breakdown of the precipitation anomalies on a month-to-month basis for the previous strong (1957-58, 1965-66, 1972-73) and very strong (1982-83, 1997-98) El Niños. 

- December 2015 across the Pacific Coast states was almost a reverse image of the 1997 and there are really no good analog event for the West Coast. 

- Recent discussions have centered on Southern California being "left out" of the January mid-latitude storm track, but an examination shows that only in January 1983 was Southern California above normal.


The full analysis can be found at http://ggweather.com/enso/strong/.

This page will be updated monthly through March as the each month's data becomes available.  Send comments and questions to jnull@ggweather.com.

 

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Maybe Not So Super Super-Bowl Weather 

 

Maybe More Soupy Than Super

The first week of February 2016 will see the eyes of the world focused on the San Francisco Bay Area for Super Bowl 50 on February 7, 2016.  If past Februarys, and the recent impacts of El Niño, are any indication, the odds are pretty high of that some of the outside activities will be wet.

During the first week of February, over the past 49 years, it has rained on average two days with an average rainfall amount of 0.81 inches at San Jose Airport, just 3 miles away from Levi Stadium in Santa Clara, CA. That rained occurred on 37 of the 49 weeks, or 76% of the time.  It is also interesting to note that the two wettest Super Bowl Weeks were during the strong El Nino events of 1997-98 (6.76") and 1972-73 (2.23").

Over the past 49 February 7ths it has rained 20 times, or 41% of the time.  And on those occasions the average rainfall has been 0.22 inches. 

The last time the Super Bowl was played in the San Francisco Bay Area was Super Bowl 19 on January 20, 1985.  That day was clear, cool and crisp with a high temperatures of only 52 degrees.  And the San Francisco 49ers beat the Miami Dolphins,  38-16.

The average high temperature during the 1st week of February is 61 degrees and the average low is 43.


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

 

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How Much Rain Is Needed to End the California Drought? 

How Much Rain Do We Need to End the California Drought? 

 

First, drought, like beauty, is in the eye of the beholder. Each different user group has their own metric for how much is enough for them to breathe easier.  For some activities just a normal rainfall year in their local area might be enough, while much of the state needs at least 150% of normal and some users may need on the order of 200% of normal.  Of course all of these solutions are complicated by California’s complex water delivery system which means that where the rainfall is measured is not necessarily where it is used! [The Drought Monitor and Drought Termination and Amelioration pages give some insight, though both are biased by factors related to agricultural drought.]

A simplistic way to look at the water shortage in California is to look at the rainfall deficits around the state from the past four seasons, and then add in the current rainfall season. In doing so (see table below) the deficits range from almost two times normal to about three-and a half time normal.

Or to look at it another way, all but Salinas would need an all-time record rainfall year to erase the 5-year deficit.



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

 

 

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Seasonal Rainfall Page

Seasonal Rainfall Page

 

I have begun producing an (almost) daily update of California Rainfall Summary, based on the long-established rainfall season of July 1st to June 30th. The data is based on the raw summary put out by the CNRFC, which unfortunately and unexplicitly changed to the October 1st water year (WY), but with the more climatologically sound July to September period added in. An example of the product is below, and the link to the actual daily summary is:  http://ggweather.com/seasonal_rain.htm

Also included on the page is a link to the Excel spreadsheet (with instructions) that you can use to create the seasonal summary yourself if I am unable and/or you are impatient. Enjoy!


Questions and comments welcome.

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

 

 

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Why This Isn't Really the First El Niño Storm of the Season

Why This Isn't Really the First El Niño Storm of the Season

 

Many headlines in recent days have been touting the current and upcoming rain as the first El Niño storm(s) of the year.  In reality, every weather system we have seen in California, and elsewhere, have been influenced by El Niño; going back to its strengthening in the eastern tropical Pacific last fall. And every storm will continue to have to some "El Niño DNA" in them, well into spring.

The pattern that we saw in December, with a series of colder storms from the Gulf of Alaska, were not as characteristic of El Niño, but they were certainly related as distant cousins.

The current pattern, with a series of storms moving almost directly west to east (i.e., zonal flow) across the Pacific in the middle latitudes, is what is more commonly thought of as a "typical" El Niño pattern.



This pattern is more closely related to the impact of El Niño on the jetstream pattern in the Pacific; and to extend the familial metaphor are more like brothers and sisters.  This is very reminiscent to what we saw in January through March of 1998.  It should be noted that during those months in 1998 that while there were lots of rainy days, most of the daily amounts were in the moderate category and not heavy rain days.

Jan Null, CCM
Golden Gate Weather Services

 

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December California Summary and Wet Weather Forecast Tools

December Summary and Forecast Tools

 

The December California Summary was highlighted by some stark contrasts in rainfall around the state while temperatures were pretty close to normal. In the SF Bay Area, downtown San Francisco rainfall was 14% above normal while San Jose was 15% below normal. (So the average of the two would be normal?)  Elsewhere north of the Tehachapis, rainfall was generally well above normal, with 180% of normal at Eureka, 168% at Fresno and 131% at Redding; but Sacramento was the outlier with only 50%of normal. 
 


I have put together a simple map interface to access the "sampled" GFS for locations around California. See http://ggweather.com/gfs.htm.  

While the GFS is not always the best model,especially out past about 5 days, the sampled data gives a good quick "first guess".  For example the "Total Precip" column is an easy way to see the timing of an approaching system. And if any of the values on the page are underlined, you can click through to see the associated charts. Previous QPF amounts can also be compared at http://wxweb.meteostar.com/sample/compare_qpf.shtml?text=KOAK.
 


The QPF page has been updated and hopefully all the links are working. Lots of rainfall and river resources to be aware of and hopefully used often in the coming months.
 



Happy New Year.

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

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