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Crunch Time for California Drought

By: Christopher C. Burt, 8:24 PM GMT on October 03, 2014

Crunch Time for California Drought

The most dangerous month of the year for wild fires is underway in California and starting off with a significant heat wave. Last week’s rainfall had little impact on the overall drought conditions but was a welcome respite nevertheless and hopefully a harbinger of some drought relief as the rainy season approaches.

Welcome rainfall of 0.30” to over 3” brought relief to the northern half of California on September 24-26 and helped squelch the massive King Wild Fire but, unfortunately, they hardly made a dent to the state’s overall drought situation and ground moisture conditions, let alone reservoir levels.





A comparison of the Drought Monitor maps at the beginning of the dry season in May and the latest map issued. The latest drought map (top) released on October 2nd shows only an imperceptible improvement in conditions (in the far northwestern county of Del Norte) following the rainfall during the last week of September. Map from NOAA/NCDC et al.

As the U.S. Drought Monitor reported in their Western Regional text summary, ”The rains had little impact on the ongoing drought, especially in California, where deficits are huge and the normal annual precipitation in parts of the northern coastal areas can reach 75-100 inches. Topsoil in a few areas benefited, wildfires were hindered, and stream flow increased, but the stream flow recovery was short-lived as streams rapidly returned to the low flows they had prior to the rain event, and reservoir levels did not improve. Statewide, California soil moisture conditions were the same as last week, with 80% of topsoil and 85% of subsoil rated short or very short of moisture by the USDA.”

To make matters worse, a significant heat wave has now engulfed the state and raised the specter of more wild fires to come. Temperatures on Thursday, October 2nd, broke records in southwestern California where Santee, Ventura, and Fullerton all hit 102°F (38.9°C), the warmest places in the nation. Santa Maria, on the normally cool coastline hit 100°F (37.8°C) breaking its previous daily record of 96°F (35.6°C) set in 1945. Long Beach (in the Los Angeles area) had a record 98°F (36.7°C) beating out the former record for the date of 96°F (35.6°C) also set in 1945. The San Francisco Bay Area was also hot, but not in record territory. Salinas was the warm spot reaching 97°F (36.1°C) and San Francisco (airport location) reached 91°F (32.8°C), its 2nd hottest day of the year so far (following a 92°F/33.3°C reading on May 13th). Although impressive, October often registers the hottest temperatures of the year for coastal locations in the state. Monterey’s hottest temperature on record occurred on October 5, 1987 when a scorching 104°F (40°C) was observed and it was 102°F (38.9°C) in Downtown San Francisco, its October monthly heat rtecord. Eureka’s all-time heat record happened even later in the month, on October 26, 1993 with an 87°F (30.6°C) reading. San Francisco has seen several occasions of 100°F+ temperatures during October. SATURDAY UPDATE: On Friday, October 3rd, record temperatures continued. San Francisco Airport reached 95°F and San Francisco Downtown 92°F, both figures represent the warmest temperatures observed so far this year. Pacifica, right on the coast, reached 96°F. A little further south, Gilroy peaked at 105°F, the hottest place in the nation on Friday. Monterey measured a daily record high of 96°F. Santa Cruz was 99°F. SUNDAY UPDATE: San Francisco Airport reached 91°F on Saturday, October 4th. This was the 3rd consecutive day with temperatures above 90°F. The last time this occurred was over six years ago on June 19-21, 2008. If the temperature hits 90°F on Sunday it would be the first time with four consecutive 90°+ days in 10 years, the last time being September 4-7, 2004. Oakland registered a new daily record high of 92°F.

Here are the monthly maximum temperatures observed so far this year at Downtown San Francisco:

JAN: 72° on Jan. 15
FEB: 69° on Feb. 21
MAR: 76° on Mar. 15
APR: 90° on Apr. 30
MAY: 90° on May 13
JUN: 78° on 2 occasions
JUL: 85° on Jul. 25
AUG: 71° on 3 occasions
SEP: 80° on Sep. 10
OCT: 92° on Oct. 3 (so far)

Notice how it actually got warmer in January than it ever did in August!

The cause for the October warmth is when the first outbreaks of cold air from Canada invade the Rocky Mountain states which causes a high pressure ridge to build over California and strong offshore flow winds to form at the surface. These are the same winds (known as the Santa Ana and Diablo winds) that have caused some of California’s worst wild fires on record. Fortunately, during the current heat wave, very strong offshore winds are not forecast to develop. In any case, the heat wave is expected to last through the weekend with even hotter temperatures expected at most locations on Friday and Saturday (I will update the numbers and new records this weekend).

Needless to say, the hot dry conditions have completely eliminated the beneficial effects of the September rainfall, and conditions have set the stage for a critical month, both in terms of the drought and potential wild fires. Reservoir capacities continue to shrink: Lake Oroville, one of the state’s most important water storage facilities, is now down to 30% capacity, approaching its all-time record low of 26% set in 1977 during the state’s worst drought on record.



Lake Oroville when at full capacity in 2011 (top) and in August, 2014 (bottom) when it had shrunk to 32% capacity. Since August it has declined to 30% capacity. Photos by Paul Hames, California Department of Water Resources and Justin Sullican, Getty Images.

Statewide reservoirs are at 36% capacity, which is 57% of normal for this time of the year.



State-wide reservoir levels as of October 2nd. Map from the California Department of Water Resources.

Meanwhile, the crisis is worsening for the state’s farmers and residents, especially in the Central Valley as this report from the New York Times dramatically relates.

In a normal year, the winter rainy season should begin around the third week of October for the northern third of California and gradually work its way south with each succeeding week until mid-November when regular rainfalls should become statewide. Everyone is keeping his or her fingers crossed!

Christopher C. Burt
Weather Historian

Extreme Weather Drought

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Thanks for the update, Chris. Just shot an email off to my older brother asking him how the weather's been.
Yes, thanks for the update. I have visited that website on occasion to look at the trend line in those reservoirs over the last two years. A poor rainy season would be dire indeed. Not being a California resident, I am not current on any serious initiatives being undertaken to mandate some form of water sustainability use. The state's population has expanded substantially over the last 30 years and it just may be hard for residents and policymakers to appreciate that water availability can no longer be taken for granted. As the New York Times article indicates, waiting until it's gone is quite a shock. Should such a situation encompass larger swathes of the state, the economic and social repercussions will have national consequences.
NASA Satellites Put California Drought Into Shocking Perspective

Newly released images created from NASA satellite data illustrate the staggering effect the California drought has had on groundwater supply in the state.

The images show the amount of water lost over the past 12 years, with different colors indicating severity over time.


Link
I screenshot the NWS reports at 3PM - Pacific time yesterday. Second image note Riverside at 2F dewpoint and 2% humidity.

Are these legitimate figures?








Also went digging around and found this:


The world's lowest recorded relative humidity value occurred at Coober Pedy in the South Australia desert when the temperature was 93 degrees and the dew point was minus 21 degrees producing a relative humidity of 1 percent.



Quoting 4. Pcroton:

I screenshot the NWS reports at 3PM - Pacific time yesterday. Second image note Riverside at 2F dewpoint and 2% humidity.

Are these legitimate figures?
....(snip)

Wouldn't surprise me at all. While single digit humidity is not frequent, this time of year SoCal expects to see it.
Are these legitimate figures?


Yes, A freshly-washed pair of athletic shoes will dry in about ten minutes, if sat on a ledge outside. Grapes turn into raisins in about three days, if left in a bowl on a table. It's kinda creepy.
Thanks Chris for the blog update..
And bringing some perspective..
The map above shows the RPM computer model forecast for rainfall through Tuesday morning local time. The map gives a general idea of where heavy rainfall may fall, but it's important to bear in mind that the official track forecast may differ from the forecast from any individual computer forecast model.

Additionally, Japan's steep terrain often leads to large variations in local rainfall that often aren't captured well by computer models. Indeed, in areas where winds blow perpendicular to the steep terrain, rainfall amounts could easily double what's shown above.

JMA forecast bulletins are predicting anywhere from 500 to 800 mm (roughly 20 to 32 inches) of rain in the Tokai region, including the Nagoya metropolitan area, Japan's third largest, with roughly the same population as Chicagoland. Other parts of Japan's Pacific coast could see generally 200 to 600 mm (roughly 8 to 24 inches) of rainfall.

Some of the areas in Phanfone's path saw historic rainfall from the one-two punch of Tropical Storm Nakri and Typhoon Halong in August. The city of Kochi had over 61 inches of rain in August, its wettest month in records dating back to 1886. The rural hamlet of Shigeto in the mountains of Kochi Prefecture picked up 94.41 inches of rain, crushing its previous all-time record for any calendar month by nearly 40 inches.


Link
Those two images of Lake Oroville are frightening.. certainly keeping my fingers crossed for a truly rainy season.
We were in Palm Springs, CA last week. I saw no indication that water was in shortage. Green grass and sprinklers running everywhere.
Quoting 10. jaxwatches:

We were in Palm Springs, CA last week. I saw no indication that water was in shortage. Green grass and sprinklers running everywhere.


That reminds me of this article by the senior water scientist at the NASA Jet Propulsion Laboratory at Caltech and a professor of Earth system science at UC Irvine.:

Link

The first 3 paragraphs read "Southern California water managers are doing such a great job that you would hardly know we are in the midst of the worst drought since record-keeping began in the late 1800s. Our lush, well-watered landscapes look as healthy and inviting as ever. Our fountains continue to shoot water in great arcs. Our freshly washed cars remain shiny and clean. On the surface, that's amazing. Kudos to our regional and local water districts for an incredible job in 'drought-proofing' Southern California. However, excellence in water management has a real downside: a false sense of security. It is exceedingly difficult to convey the urgency of the situation when most everything around us is green."
Here is the rain that lacks in poor California. - Hmm, third blog entry about record rainfall in Southern France imminent? ;-)





Herault: new episode of intense localized rainfall
Meteo France, 10/07/2014 (translated from French)
A new episode of heavy rain has affected some parts of the department of Herault in the night of Monday, October 6, 2014 to Tuesday, 7. Station Prades-le-Lez, a few kilometers north of Montpellier, measured 262 mm of precipitation (including 223 mm * in 3 hours, 95 mm in one hour). That's more than the precipitiation of two months. This accumulation exceeds the old daily rainfall record of this station which has opened in 1979, all months combined.
Similarly, according to information from weather radar data, a daily rainfall of the same order as that of Prades-le-Lez has hit the west of the town, between Grabels and Juvignac.
This episode was very localized. The city of Montpellier only got 35 mm, and the airport Frejorgues, southeast of the city, 0 mm.




Local town relies on neighbors to ease ongoing water shortage | 89.3 KPCC
(Excerpts follow. Click the link above for the full article.)
The mountain community of Lake of the Woods, about an hour north of Los Angeles, remains vulnerable to the drought – even though the state has removed it from a list of mostly small and rural places critically in need of shoring up water supplies.

How the Lake of the Woods Mutual Water Company has worked to accomplish that task points up potential future problems in larger communities who themselves may grapple with a California growing ever drier.

....(snip) This year, just three of the five wells in Lake of the Woods are producing water, and they’ve slowed to a trickle.

“They aren’t producing a lot – 10, 15, 50 gallons a minute for a community of 400 homes,” says Dave Warner, a consultant for small and rural water services. I ask him how that compares to historic production levels. “For them? It was over 300 [gallons a minute] from all the supplies two years ago.”

....(snip)
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