Alarming fact: the Hoover Dam is currently at 36% of full!

凤凰城今天115度！
西南内陆地区高温干旱还好理解，怎么加州靠海，也是大半年不下雨有点让人困惑？这太平洋的水汽一点也不施惠于人？

但愿今年不会有雷电。fingers crossed.

加州属于地中海气候。我们这里雨季通常是从十月到四/五月。

我们这里夏天难得有雨点。 十里不同天。 旧金山或海边夏季有时会有drizzles. 有年夏天在金山小住，傍晚时在细雨里散步。路边的树木青翠欲滴花团锦簇，湿润润的空气里飘着幽幽的清香。

zt:
地中海式气候，又稱作地中海气候 (英語：Mediterranean climate)、副热带夏干氣候 (英語：dry summer climate)，其分布於中緯度地區（約南北緯30至40度）的大陸西岸地區，包括地中海沿岸地區、黑海沿岸地區、美國的加利福尼亞州、澳洲西南部伯斯、南部阿德莱德一帶，南非共和國的西南部，以及智利中部等地區。

地中海式氣候分布範圍占全球比例十分稀少，（降水和温度相反），迥異於其他類型氣候，也往往造成作物生長季無法與雨季配合，因此地中海農業區的作物種類往往為耐旱的蔬果，灌溉系統亦十分發達，為其一大特色。其气候特征是：夏季炎热干燥，冬季温和多雨。

What's behind the heat wave in the American West?

PHOENIX (AP) — Much of the American West has been blasted with sweltering heat this week as a high pressure dome combines with the worst drought in modern history to launch temperatures into the triple digits, toppling records even before the official start of summer.

Record daily highs were seen this week in parts of Arizona, California, New Mexico, Montana, Wyoming and Utah. Phoenix, which is baking in some of the U.S. West’s hottest weather, hit a record-breaking 118 degrees (48 Celsius) Thursday and was expected to reach 116 degrees (46 Celsius) Friday and Saturday.

“Very dangerous record breaking heat should continue today across the deserts with well above normal highs,” the National Weather Service's Phoenix staff wrote on Facebook. “A very good day to stay indoors.”

WHY IS THE AMERICAN WEST SO HOT THIS WEEK?

The heat comes from a high pressure system over the West, a buckle in the jet stream winds that move across the U.S. and vast swaths of soil sucked dry by a historic drought, said Marvin Percha, a senior meteorologist for the agency in Phoenix.

He and other scientists say the heat wave is unusual because it arrived earlier and is staying longer than in most years.

“June last year, things seemed pretty normal,” noted Park Williams, a University of California, Los Angeles, climate and fire scientist. “The record-breaking heat waves came in August and September.”

But with such an early heat wave this year, “this could be the tip of the iceberg,” Williams said.

WHAT ROLES DO DROUGHT AND CLIMATE CHANGE PLAY?

A two-decade-long dry spell that some scientists refer to as a “megadrought” has sucked the moisture out of the soil through much of the Western United States. Researchers said in a study published last year in the journal Science that man-made climate change tied to the emission of greenhouse gases can be blamed for about half of the historic drought.

Scientists studying the dry period that began in 2000 looked at a nine-state area from Oregon and Wyoming down through California and New Mexico and found only one other that was slightly larger. That drought started in 1575, a decade after St. Augustine, Florida, was founded and before the Pilgrims landed on Plymouth Rock in 1620.

The hot weather can be tied to the drought drying out the landscape. Normally, some of the sun’s heat evaporates moisture in the soil, but scientists say the Western soil is so dry that instead that energy makes the air even warmer.

“When the soil is wet, heat waves aren't so bad," said Williams, who has calculated that soil in the western half of the nation is the driest it has been since 1895. “But if it's dry, we are under extreme risk.”

HOW DO RECENT WILDFIRES FIGURE INTO THIS?

Scientists say the wildfires that have erupted in recent days have been fed by the excessive heat across the region. Climate change contributes to the drought conditions and makes trees and shrubs more likely to catch fire.

At least 14 new wildfires broke out this week in Montana and Wyoming as the record heat sparked an early start to the fire season. Firefighters also battled blazes in Arizona and New Mexico.

“From a fire potential standpoint, what is capable this year, it is certainly much more severe than we’ve seen in the past," U.S. Department of Agriculture fire meteorologist Gina Palma said in a climate briefing Thursday.

Palma said the drought-related fire risks were especially pronounced in higher elevations across much of the U.S. West, from the Rocky Mountains down into the Southwest and parts of California.

“You will be seeing very extreme fire behavior, certainly conditions that we would not normally see in June,” she said.

IS THIS THE NEW NORMAL?

A growing number of scientific studies are concluding that heat waves in some cases can be directly attributed to climate change, said Kristie L. Ebi, a professor at the Center for Health and the Global Environment at the University of Washington.

That means the U.S. West and the rest of the world can expect more extreme heat waves in the future unless officials move to cut down on greenhouse gas emissions, Ebi and other scientists say.

A study last month estimated the percent and number of heat deaths each year that can be attributed to human-caused climate change. It included about 200 U.S. cities and found more than 1,100 deaths a year from climate change-caused heat, representing about 35% of all heat deaths in the country.

On average each year, Phoenix has 23 climate-triggered heat deaths, Los Angeles has 21 and Tucson has 13, the study said.

“Climate change is harming us now,” Ebi said. “It’s a future problem, but it’s also a current problem.”
___

Associated Press Science Writer Seth Borenstein contributed from Washington.

www.yahoo.com/news/explainer-whats-behind-heat-wave-202659502.html

“CA agriculture accounts 80 % of our water usage, even though California agriculture is less than 2% of our economy.” -- really? wow.

"It takes 9.8/10.8/12.2 gal. of water to grow one lb. of strawberries/tomatoes/oranges, but almonds, 1900 gal. "--- that's why my daughter told me not to buy almonds.   

加州的农业产值占加州的GDP百分之二是有可能的。如果说占全美百分之二恐怕有点少。收获一磅almond要用去1900 gal.水也太过分了，放在加州严重缺水的现实情况下，确实需要考虑限制种植。让民众知道这一点，大家都不买、少买也是一种有效的措施。幸亏我几乎没有买过杏仁这种nut，不像核桃walnut/山核桃pecans两样。
She is a concerned Californian and yet, smart kid. 

Climate change tipping points are upon us, draft U.N. report warns: 'The worst is yet to come'

A draft report by the United Nations Intergovernmental Panel on Climate Change warns that unless drastic and immediate action is taken to limit greenhouse gas emissions and keep global temperatures from rising further, life on earth is poised for a catastrophic reckoning.

The 4,000-page draft, a copy of which was obtained by Agence France-Presse, states that mankind may have already missed its opportunity to keep the climate from passing a series of thresholds that will further spur the warming of the planet.

www.yahoo.com/news/climate-change-tipping-points-are-upon-us-draft-un-report-warns-the-worst-is-yet-to-come-185803244.html

What's wrong with our lovely planet?


Look this! 
The low temperature in Las Vegas on Saturday and Sunday morning is forecast to be 94 and 93 degrees, respectively. In Phoenix, the low temperatures will likely not get below 91 degrees. This is a problem because these temperatures don't allow the body to successfully cool down at night. The temperature needs to drop to at least 80 degrees for recovery to begin. In fact, a person can lose up to 2 liters of fluid overnight through sweating if the temperature doesn't drop below 85 degrees. the heat alerts across western states

这人不是已经死了吗，(May 12, 1937 – June 22, 2008) 怎么还知道正在发生的流行病毒？ 

智者先知也。 加缪在《鼠疫》一书中也有预警：

" He knew what those jubilant crowds did not know but could have learned from books: that the plague bacillus never dies or disappears for good; that it can lie dormant for years and years in furniture and linen-chests; that it bides its time in bedrooms, cellars, trunks, and bookshelves; and that perhaps the day would come when, for the bane and the enlightening of men, it would rouse up its rats again and send them forth to die in a happy city. "

-- Albert Camus:THE PLAGUE

没有想到干旱影响了西红柿的产量：
Get ready to pay more for tomatoes, as California growers reel from extreme weather

12月下旬，加州太浩湖周围下大雪成了全国的新闻。不过坏事也能变成好事。美国干旱监测局（U.S. Drought Monitor）30日公布最新干旱地图，显示过去一周的暴风雨对加州严重的干旱状态有巨大的影响。从地图上可以看出，加州几乎全数地区都已脱离最严重的「异常干旱」状态（exceptional drought），只有大部分中谷地区还是「极端干旱」状态（extreme drought）。过去一周的暴风雨让加州12月降雪量创下历史新高，塞拉内华达山脉（Sierra Nevada）中部测得193.7吋的积雪量，打破1970年创下的179吋纪录。



美国干旱监测局表示，加州干旱情况未来几周还会继续改善，因为气象局预测北加州下周还会有超过正常的降雨。协助制作新地图的国家海洋暨大气总署（National Oceanic and Atmospheric Administration）气象学家普优（Brad Pugh）说：「在12月降下豪雨之前，加州绝大部分地区不是处于极端干旱（D3）就是异常干旱（D4）的状态，最近获得的雨量和雪量让各地的干旱严重程度改善了一到两级，但仍短缺12到24个月的水量，希望接下来几周能进一步改善。」

尽管如此，加州目前还没有任何一个地区完全脱离干旱，53.35%的地区现在处于「中度干旱」（moderate drought），但比12月21日时56%的地区处于「极度干旱」已改善许多。加州目前处于最严重的「异常干旱」级别的地区只有不到1%。