WeatherWhys Blog

April Showers Blossom as El Nino Wanes

April Showers Blossom as El Nino Wanes

The El Nino southern Oscillation is still occurring in the equatorial Pacific. But its days are numbered- like the certainty California’s rainy season will eventually end.

Following a break in the action most of the month of March, low pressure has brought wind and rain to the Golden State. The past several days have been very active with thick dust conjured up by 50 MPH winds on Sunday afternoon that did a fair amount of minor damage in the region, primarily downed trees. It is axiomatic that such dusty affairs as what we dealt with on Sunday are often the calling card of a wet period to follow. It was something you might see in November or December that would herald approaching winter rains.

The record setting .41” that fell on Sunday evening, together with a few other day’s rains, have now established April as an “above normal” precipitation month prior to the mid-point of the month itself. We now have 4 of the past 5 months wetter than average. December through February finished 218%, 154% and 146% of normal, respectively. And who could forget the late January storm that broke all former atmospheric pressure records (Storm Ares)? This has been a good water year. And speaking of that, the 2009-10 water year (July to June) total is now at 6.22”, lacking only .27” to hit the magic 6.49” average annual precipitation for Bakersfield. I am confident that mark will be exceeded before it is all done. If it stopped raining entirely this month, we would still finish April at 118% of average. The lingering showers which fell on Monday dropped a little bit of small hail in the area. It also dropped .04” of rainfall which marked the 39th rain day of this water year. Bakersfield normally gets 39 rain days, so on that count we have just accomplished the quota. Any additional rain days will be gravy.

I am forecasting some of that gravy to push not only Bakersfield’s rainfall fortunes into the black (surplus) but also most other cities in the state. Only in the far northern reaches of the state (Redding, Eureka) are water year percentages in the negative, even though the actual amounts are higher than southern California. This is typical of an El Nino event, i.e. wetter in the southern US and drier in northern portions. But all those characteristics are predicted to come to an end by the middle of May. In fact, long range computer models are showing what looks to be a hotter than normal summer coming up. With all the rain we’ve had, that could portend an active wildfire season.

In the meantime, the rest of April is looking very cool and wet. I would not be surprised to see Bakersfield end the water year with over 7 inches and perhaps 8 if a few heavy showers visit the city. A deep low pressure configuration is coming for Sunday and Monday of next week with the prospect for thunderstorms. Heavy mountain snows of late have boosted the Sierra snowpack to over 120% of average statewide. Significantly more snow will be added in the coming 2-3 weeks. El Nino is ending worldwide which means different things to different regions. The Australian and Polynesian drought will cease, bringing much needed rainfall to those areas. All good news as we prepare in California to shift gears from what has been a bountiful winter to a predictably unforgiving hot summer.