WeatherWhys Blog

Lucky Sevens !

Lucky Sevens !

With our latest rain event that brought .10” to Bakersfield, we have now received over 7 inches of rain for the water year. Only 27 out of the past 122 years have been wetter.

The 7.05” of rain so far this 2009-10 water year places Bakersfield in the 78th percentile of wet years. This is more than half an inch above normal for the water year, which runs for another 6 weeks through the end of June. Water is running through the Kern River again, testament to our wet winter marking the end of a three year drought. The last time water flowed in the Kern was 5 years ago. Not co-incidentally, the 2004-05 water year yielded more than 9 inches of rain. This wet winter has been chiefly produced by El Nino enhancement, the heralded and storied Pacific Ocean phenomenon that appears semi-regularly. It doesn’t always bring heavy rain, but this year it did. We also usually see cooler than average temperatures for an  event of this type. During our 2009-10 winter every month has been cooler and wetter than normal, except March. May is only .02” shy of achieving the expected monthly rainfall tally.

Cool weather often persists into the summer months with El Ninos. Our Hot Times Contest has allowed viewers to guess when they think the first 100-degree reading will be reported at Meadows Field. Weather records indicate that the average first 100 occurs on May 31st, the earliest ever was April 23, 1910 and the latest was July 16, 1998. That latest date (only 12 years ago) was also during an El Nino year. In fact, the 1997-98 water year was the wettest on record with 14.73”, more than double what we’ve seen this year. But don’t think that the late start to triple digit heat means the summer will be cool. On the contrary- there were 5 heat waves, 5 days with lows in the 80s and highs that hit 110 degrees in 1998. August and September were particularly hot. The lesson again is that a slow start does not portend the intensity of a summer season. And I believe something similar will take place this year.

We are currently locked in to a cool pattern by virtue of significant ridging in the middle of America. The easy answer has been “El Nino” for most of the winter when explaining why it was cool and wet. But over the past 2 weeks I’ve noticed a dramatic cooling in the equatorial Pacific bringing an end to the 2009-10 El Nino event. By next month it will be declared as having expired. Dynamic computer models continue to show sea surface cooling through early autumn. Most ensembles bring the sea temperatures to near normal, but a NASA model swings temperatures to sub normal and thus predicts a La Nina event for this next winter. If that happens, we in Kern County would probably see a warm and dry water year for 2010-11. For what it’s worth, I don’t believe that the NASA model will pan out (although long term forecasts of any kind are inherently problematic).

So, taking it all one step at a time, let us enjoy our current fortunate status of greater than 200% of normal snowpack, water in our rivers, recharged aquifers and the prospect of another year Californians can get by- thanks to the generosity of nature.