California Exceptional Drought Worsens

I keep hearing from some people how the storms at the end of February and the start of March had to have helped the California drought.

That all the rain that fell in the lowlands and snow in the Sierra had to have had an impact. Right after the storms in my , I was already pointing out that this was not the case. One set of storms does not end a three-year drought. In that post I stated, "The drought in California did not just develop this year, or in the last 12 months, but over the last three years. It is unrealistic to think one series of storms is going to have a huge impact on the long-term drought..."

Now, two weeks later, here is more evidence that the short period of rain and mountain snow had little impact.

Below is a comparison of the Drought Monitor maps for California from Feb. 18 (before the storms) and the one released today.

Over this span of time the area coverage of D4 drought conditions (exceptional) has actually increased substantially from 14.62 percent to 22.37 percent of the area, covering the rich farming area of the Central Coast to the San Joaquin Valley. The D3-4 area (extreme drought) did come down a little from 68.30 to 65.89, mostly in southwestern California.

I have already shown that many reservoirs in central and northern California are still at near-record low levels. The graph below shows the daily Sierra snowpack this year, compared to the previous two years and to normal.

With no substantial rain and snow expected for at least another week, and a round of near-record temperatures likely in the Central Valley and southwestern California coming for this weekend, all of these stats are not going to get any better. In fact, there is a good chance of below- to well below-normal precipitation over the next couple of weeks.

 

 

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Heat Wave May Threaten World’s Hottest Temp. Record

A brutal and potentially historic heat wave is in store for the West as parts of Nevada, Arizona and California may get dangerously hot temperatures starting Thursday and lasting through next week. In fact, by the end of the heat wave, we may see a record tied or broken for the hottest temperature ever recorded on Earth.

Statistics for Las Vegas, Bishop and Death Valley

The furnace-like heat is coming courtesy of a “stuck” weather pattern that is setting up across the U.S. and Canada. By midweek next week, the jet stream — a fast-moving river of air at airliner altitudes that is responsible for steering weather systems — will form the shape of a massive, slithering snake with what meteorologists refer to as a deep “ridge” across the Western states, and an equally deep trough seting up across the Central and Eastern states.

All-time records are likely to be threatened in normally hot places — including Death Valley, Calif., which holds the record for the highest reliably recorded air temperature on Earth at 134°F. That mark was set on July 10, 1913, and with forecast highs between 126°F to 129°F this weekend, that record could be threatened. The last time Death Valley recorded a temperature at or above 130°F was in 1913.

Las Vegas and Phoenix, two cities well-known for their hot and dry summers, are also predicted to approach record territory. Last Vegas’ all-time high temperature record is 117°F and Phoenix’s high is 122°F. Excessive heat warnings are in effect in both cities from Friday through Monday.

Las Vegas could come close to tying its record for the longest stretch of days at or above 110°F, which is 10 straight, set in 1961. Phoenix may approach its record for the number of consecutive days at or above 116°F, which is four, set in 1990. Reliable weather records began there in 1896. Forecast highs in Phoenix range between 115°F to 120°F for Friday through Sunday.

“While hot temperatures are a regular feature in this part of the country, a heat wave of this proportion and duration is not common,” the NWS forecast office in Phoenix said on its website. “Several days at or near 100°F are common for the southwest Arizona [and] southeast California deserts in the summer. But periods of temperatures at or above 115°F are more rare."

Forecast atmospheric pressure dpeartures from average (geopotential height anomalies) at about 18,000 feet for Saturday, June 29. The red area shows the "heat dome" or area of higher than average pressure, across the West.

While each heat wave has ties to short-term weather variability, increasingly common and intense heat waves are one of the most well-understood consequences of manmade global warming, since as global average surface temperatures increase, the probability of extreme heat events increases by a greater amount. Data already suggests that heat waves have are becoming more common worldwide.

One study, published in the Proceedings of the American Academy of Sciences in 2012, found that the odds of extremely hot summers have significantly increased in tandem with global temperatures. Those odds, the study found, were about 1-in-300 during the 1951-1980 timeframe, but that had increased to nearly 1-in-10 by 1981-2010.

The heat during the weekend and during the first week in July will also affect inland areas of Southern California, where excessive heat watches and warnings have been issued. The NWS said on Thursday that the strong heat dome may migrate northward through the 4th of July holiday, potentially locking the near-record high temperatures in place for a week or more, raising the risk of wildfires, and bringing a heat wave to places like Portland and Seattle.

The heat is also likely to aggravate already dire drought conditions in the Southwest. Fortunately, the hottest weather is not likely to affect Colorado and parts of New Mexico, where the largest wildfires have been burning to date. More