Persistence

Weather persistence is when today's weather is about the same as yesterday's. This explains why LA's carbon footprint is so small. Read more about this report at the Brooking's institute website.

Visit The Varying Impact of Gas Prices to see the percent of income spent on gasoline by US county. The recent jump in gas prices has increased the amount our household spends on gasoline to nearly 1% of our income. I guess this means I should drive less and bicycle more.

Wild Weather and Wild Fire in CA

The jet stream almost exactly traced the coastline today, not a typical pattern for us.

The Santa Cruz mountains wildfire injected a plume of smoke into the middle of the jet stream.

My sister says that there was no way I could have been feeling the effects of the smoke from the Santa Cruz fire by 8:30 AM when we IM'd. Jet stream speeds of 120-150 knots could travel between Santa Cruz and LA in 3 hours or so. The fire started around 5:30 AM. She's right. But what could it be?

Perhaps I was experiencing respiratory effects from the Santa Clarita fire closer to home? Santa Clarita is NE of me; the smoke from that fire is unlikely to travel this far west. It was such a small fire compared to the Santa Cruz one.

After discussion with my sister, I realized that the unusual wind pattern put me downwind of the Chevron refinery 5 miles NE of home.

It rained between 6 and 7 PM today and it sounds like the rain has started up again. Rain in late May in a non-El Nino year is rare. Could the soot from the fire have nucleated raindrops?

Links:

• CRWS Jet Stream Analysis (CA Regional Weather Server)
• MODIS Fresno (central CA) Subsets Moderate resolution imagery from NASA's Terra and Aqua Satellites
• Tornadoes, hail and snow in Southern California today
  

Weather and Beauty

Speaking of weather and news readers and the importance of looks, Daisy Fuentes got her start in television as the weather personality at WXTV. I found this on her Yahoo movies bio:

A neighbor employed in fashion asked a 16-year-old Fuentes to serve as a substitute for a sick model at a photo shoot, launching a career as a print model. While still a college student and not yet out of teens, she landed a gig as a weather girl at Manhattan's Univision affiliate (WXTV Channel 41). Switching to rival Telemundo, she graduated to news reader.

Yes, she became a news anchor at 19 while still a college student.

Years ago, she was interviewed on a late night talk show. I was surprised to learn that she wasn't given a weather forecast to read; she had to write her own forecasts. She was worried about appearing like a fool, so she would buy several newspapers and read all the weather forecasts. She then forecast the average of the temperatures she read. She had stumbled upon ensemble forecasting!

She designs clothes, too.

Frickin' Freakonomics

That whole How Valid Are T.V. Weather Forecasts? story just sets my teeth on edge. It is another example of "gotcha" news stories about how scientists are idiots that can't get anything right.

For starters, the statistical methodology was not explained. How does J.D. Eggleston define "Degrees Missed"? You need to put a sign on the temperature deviance in order to rule out systematic bias. If there a consistent temperature bias, could he and his daughter have placed their backyard thermometer in a place that gets radiated heat from a rock or their house foundation? Was their house at a higher or lower elevation than the official elevation for their city? This matters because meteorologists use the predicted height at 850 mb and extrapolate downward to the official elevation.

If you want to know the value added by a forecast, you take the difference between the forecast and no forecast.

What does that mean? You can set the baseline as either persistence (what was the weather like yesterday?) or climatology (what was the average on this date over a long period of at least 50 years?). Then calculate the differences between the actual observed weather with the forecast and also against no forecast. The change in forecast skill (hopefully, a reduction in error) between the forecast and no forecast is the true value-added of the forecast.

Studies that handle statistics more carefully show that today's 15 day forecast is about as accurate as the 3 day forecasts made 30 years ago. This is primarily due to improvements in numerical weather prediction and the use of satellite data.

What methodology did they use for verifying rain forecasts? Did it rain in their backyard? That's not meaningful. The precipitation forecasts give a probability over a broad area. Their home could be in a micro-climate. In addition, how does their methodology handle when the forecasts were off in the timing of the precipitation, but not in the areal extent?

Furthermore, TV weather readers are as likely to be meteorologists as the news readers are likely to be journalists (whatever that means now). Most majored in communications, not meteorology. No professional qualifications are needed to read the news on TV other than good looks.

Some weather readers sought and received the American Meteorology Society (AMS) Seal of Approval or "Certified Broadcast Meteorologist" (CBM) designation. The AMS Seal of Approval was so contentious among AMS regular members, that the program is being phased out. The CBM designation was an attempt to tighten up the standards.

The main difference between the two programs is education and the exam. To apply for the CBM, applicants must hold a bachelor’s or higher degree in atmospheric science or meteorology (or the equivalent) from an accredited college/university. Current AMS Sealholders (those that earned the Seal prior to January 1, 2005 ) are not required to meet this criteria. These Sealholders may qualify for the CBM designation if they pass the written exam. All CBM applicants must pass the written exam to earn the CBM designation.

Go read the requirements; you could get the seal of approval by sending in videos of yourself reading the weather and looking good while doing it. Even with those loose requirements, most weather readers don't even hold that qualification. Current seal holders can get CBM designation by passing a multiple choice exam with a score of 75 or more. They better hurry because this deal expires next year.

Digression about TV weather forecasts:
A while back, Bulletin of the AMS (BAMS) published study of TV forecasts. The study determined that TV forecasters overplayed the likelihood of extreme events, particularly precipitation, for ratings. They would play teasers all night long, "Is there rain in your commute tomorrow?" and make people wait until the 11 o'clock news to say that there was a 10% chance of precipitation.

FYI
I am a regular member of the AMS that qualified under this category:

hold a baccalaureate or higher degree from an accredited institution of higher learning in some other science or a related field and be currently engaged in a professional activity in which his or her knowledge is applied to the advancement or application of the atmospheric or related sciences

If I recall correctly, another regular member of the AMS had to vouch for my scientific competence and that my job was substantially meteorology before they admitted me. They'll let anyone in. ;-)

Afterthought

Why is Eggleston so deeply involved with his daughter's science project?  Like I blogged about earlier, Mark and I were probably the only parents in Iris' first grade class that let her turn in a diorama that SHE created.  Don't be a helicopter parent.  Let kids do their own homework.

Vortex Streets

I found this moth-eaten cashmere sweater at Goodwill (a thrift store). It was too nice to trash so I decided to refashion it with an asymmetric scarf collar a la Norah's Cabled Cardigan from the Fall 2006 Issue of Vogue Knitting.  Some may recognize the cabled panel as the center panel for the Vortex Street Pullover in Norah Gaughan's book, Knitting Nature.

I plan to cut off the ribbed portions and hem up the bottom and sleeves. Of course, a portion of the center front and the V-neck ribbing will be trimmed away, but I may need to add some clear elastic to stabilize the back neck.

A little bit of darning will be required. I don't have the right color wool and may tea-dye the ecru wools auditioning in the above photograph.

While I was at it, I darned the 20 year old fuchsia wool sweater below, in holey state. I didn't have any wool the right color, so I took one ply of Encore (100% acrylic, sacrilege!) and darned away. You can't tell from a galloping horse.

I became melancholy while repairing this sweater because my stepmother bought it for me when I was in college. She used to moonlight as a bookkeeper for several Benetton stores. When stuff I might like was about to be marked down, she would sometimes set it aside and buy it with her employee discount.

It was supposed to be a one day a week job, which it was initially. Math and bookkeeping was not the store owner's forte and he had given her the books in quite a state. After she straightened out the mess she inherited, it took her only 3 hours a month to maintain the books. When the owner found out, he wasn't miffed at all. He told her that she was saving him more than one day a week so she could keep the same pay and leave whenever she was done.

The part that makes me cry is that she was an artist that worked as a bookkeeper. She would get back to her painting "someday", in retirement. Her someday never came. She died of complications of cancer when she was 60.

Aside about Vortex Streets

One of the things I love about my job is walking into lab in the morning to see that morning's satellite overpass. In Los Angeles, the most recent overpass often flew over Guadalupe Island, off the coast of Baja California. When the cloud deck and wind speed and direction are just right, we see a double von Karman vortex street on the lee side of Guadalupe Island.

This image of a vortex street near Guadalupe island (as does the next two after it) comes courtesy of Earth Science World Image Bank. Go visit their site for more images of Vortex Streets.

Vortex streets form near the Canary islands off the coast of Africa.

And near the Kuril islands.


NASA's visible earth site also has vortex street imagery.


Don't miss the CIMSS Satellite Blog's entry about vortex streets near Guadalupe island. Follow this link and watch the GOES imagery vortex street video!

Space.com on von Karman Vortex Streets

Topography and Rainfall Bands

This week, I took a bit of time each day to clean up my desk at work. The stack of unread issues of Eos, Physics Today and BAMS (Bulletin of the American Meteorological Society) was about to topple over.

BAMS wrote a short piece about Corene Matya's research, combining meteorology and geography. Science Daily has a good synopsis here. She showed that the most intense rain bands (aka rain shields) of hurricanes after landfall coincided with the underlying topography. She combined GIS information about terrain elevation with radar measurements of rain shields and discriminant analysis methodology.

With hurricanes crossing Texas hill country, the rain shields tend to line up parallel to the main axis of the hills, running west to east. Storms near the Appalachians also line up parallel to the mountains, whose axis runs southwest to northeast, with the heaviest rain consistently occurring to the west of the track.

West of the Appalachians is the leeward side. This agrees with Rob's simulations and my rain gauge observations in February 2008 Rainfall II. Although we aren't talking about hurricanes here in LA, we do have a similar situation when the Pacific storms' airmasses encounter colder and dryer continental air as they cross the coastal hills and mountains.

February 2008 Rainfall II

The raingauge at Chez BadMom read 1.5" this morning even though it was slightly tilted over. Had it been perfectly upright, it might have held even more water.

The California-Nevada River Forecast Center shows that nearby spots received just under 1" in the last 24 hours. Breathing Treatment also wonders why my gauge readings are a little bit higher than at his house, only a few miles away.

My house is on a relatively flat area about 2 miles from the ocean. Two bands of hills (really sand dunes) stand between us and the ocean so there is no hope of ocean views unless we build an 80 foot tall house. If we were on the seaward side of a hill, we would expect higher rainfall due to orographic forcing. (That's fancy talk for the air moves uphill and the water condenses out of the air as it rises and cools.)

Rob of Are you cereus? explained that the area behind a hill also receives elevated rainfall. The water doesn't condense and start falling right away. In that time lag, the wind will carry the condensing water droplets downwind.

Additionally, the air that comes up and over the dunes can come slamming back downward in a bouyancy wave. So, there is an upside to living in Felony Flats, leeward of 140-160 foot sand dunes (Hermosa View, RB's Golden Hills, Manhattan Hill District and Manhattan Heights. I get more free water falling out of the sky and require less irrigation water.

[Incidentally, developers have been razing the small beach shacks in those areas and erecting massive houses on those sand dunes. Not surprisingly, those homes develop foundation problems very quickly.]

Past posts in the LA rainfall series:
February 2008 Rainfall
When is a moderate drought good news? Lots of rainfall statistics links there.
The whole meteorology thread.

February 2008 Rainfall

I haven't been keeping careful track of the running rainfall total at my house like Breathing Treatment. I often forget to check and empty it out for weeks at a time. Mine is on a stake and sometimes blows over, making the readings lower than the actual rainfall. It is probably not very accurate. However, I emptied 0.5 inches from the rain gauge yesterday morning.

I listed a bunch of useful Los Angeles rainfall statistics links in When is a moderate drought good news? The good news is that the the US Drought Monitor shows our area has been downgraded from moderate drought to abnormally dry. (The map is clickable if you want to see a regional map.)

When is a moderate drought good news?

When the drought is downgraded from severe to moderate.

See more at the US Drought Monitor. Click on the 6 or 12 week animation link at the bottom of the page to see the widespread and extreme drought in the southwestern US recede to moderate.

Our rain gauge showed another 1.3" between Saturday and Monday. There might have been more rain, but the gauge tilted over slightly--either from wind or the neighbor's cat.

I wasted spent some today to collect rainfall statistics links, with an emphasis on LA rainfall statistics:

• California Nevada River Forecast Center is a good place to start.
• Click on Precipitation Data over on the sidebar on the left.
• The Climate Precipitation Summary gives data for the most recent two years.
• Or check only Or data for the past 6-24 hours.
• Scroll down to see the Gridded Precipitation Maps.

• Or scroll nearly to the bottom of the page to Monthly Observed Precipitation - NWS Cooperative Observers.
• See the data for the current rain year, Monthly Precipitation Summary Water Year 2008. It is not yet updated to reflect January.
• It looks much better than Monthly Precipitation Summary Water Year 2007.
• The Climate Precipitation Summary is updated daily and shows data for the past 2 years.
  
• The LA County Department of Public Works has an excellent precipitation website.
• Angelenos will be especially interested in the near real-time precipitation map. The java applet allows the user to select a time period to view (1-96 hours). Single stations are also clickable for a twice daily 30 day history.
• http://water.weather.gov/ has tons of useful information. You can generate maps for specific regions of interest (at the state level, not finer), times of interest and by variable (observed, normal, departure from normal or % of normal precipitation.

For instance, I am a big fan of desert wildflowers. See our Death Valley trip in 2005. And Death Valley in 2006.



First, I check Desert USA's Wildflower Reports.
I look at the individual area reports and refer back to the AHPS precipitation analysis of those areas. Desert flowers tend to follow the rains by a some weeks (time varies by temperature). Take your best guess at the most promising desert area and book your hotel or campsite early. When the bloom reports say the desert is a carpet of wildflowers, all the hotel rooms will be gone.

Rain Followup

Our rain gauge showed another 1.5" fell from 9 am 24 Jan to 9 am 25 Jan 2008.

I've been thinking about the impact of weather on traffic safety, especially after reading Unsafe trucks stream out of L.A.'s ports.

Miguel had more reason than usual to be anxious as he drove his aging big rig out of the Port of Los Angeles' bustling China Shipping Terminal.

By his own admission, his 24-year-old truck was dangerously overloaded. The suspension was shot, the tires nearly bald. Over his CB radio, other drivers barked warnings that the California Highway Patrol had set up several checkpoints nearby.

"If I get inspected, I could get put out of business," he said, easing into traffic while scanning for the CHP. "Something real bad could happen at any moment on the road. I'm doing the best I can. It's a vicious cycle."

Most of those trucks are traveling over mountain passes (with faulty brakes!) to inland distribution centers for big box retailers. What is the true cost of the lower prices? Is it any wonder Angelenos spend so much time in traffic, trapped behind truck "accidents"?

Even under the best of circumstances, we are hemmed in by the unending truck traffic. People who live near L.A.'s ports can see America's growing addiction to cheap imported goods.

Profit margins for the independent operators who serve the Long Beach and Los Angeles ports are thin -- so some, like Miguel, cut corners whenever possible.

For example, because a gauge showed that the weight of his load exceeded regulations -- and because he views his truck's brakes as untrustworthy -- Miguel used the trailer's brakes to stop the entire rig. The CHP considers that maneuver particularly dangerous -- and illegal.

Like many other independent haulers, he contracts with licensed motor carriers, or a trucking broker, linked to shipping companies and cargo owners, such as big-box retailers. Each morning, Miguel shows up at the broker's dispatch window to solicit jobs.

Like other drivers serving the ports, he's a "short-haul trucker," ferrying containers to distribution centers across Southern California.

He gets paid by the load -- the equivalent of about $8.90 an hour -- and works 65 hours a week.

Real Rain (and Hail, too!) in Los Angeles

The rain gauge at Chez Bad Mom this morning, 24 January 2008. It reads ~ 2.3". (It is clickable if you want to read it yourself.) Unfortunately, I forgot to empty it out before this week's storms hit; I am not sure if there was residual moisture in the gauge from the rain 2 weeks ago. Things slip when you are fighting jet lag.

[Aside 1: If you got here by searching on Los Angeles Rainfall or LA Rainfall, you will find all sorts of interesting links to relevant rainfall statistics websites by clicking on the Meteorology tag link.]

[Aside 2: No, I do not work at the company barely visible in the corner of the photo. I picked up the freebie rain gauge at their booth at an American Meteorology Annual Meeting. The 2008 meeting is currently going on in New Orleans, but I didn't attend this time. If you can look at the program you can see that my work is being presented.]

Right after I took the picture of the rain gauge and emptied it, I set out to work. The rain was awfully loud. I looked down and saw little white ball bearings hailstones. Here's the proof. I know these hailstones are puny by Midwestern standards, but it is an extraordinary occurrence in coastal Los Angeles.


We are in for a few more days of rain. See how the jet-stream is sitting over us, steering the storms right into southern California? (Jet stream analysis courtesy of the California Regional Weather Server. Thanks, again, Dave!)

Now look at the 72 hour forecast. Over southern California, the scenario looks awfully similar, huh? It will be a wet three days.

Note that, by Sunday night, the winds jet stream will be from a more southerly direction than now. Because the lower-level air will likely also travel from the south, over warmer ocean water, we will probably get more (and warmer moisture). That is not good news for skiers or the snowpack that we depend upon for summer water supplies.

[Aside 3: The plots show Universal Time or UTC and LA local time is UTC - 8 hours.]

Did I mention that the rain gauge held another 0.25 inches when I came home from work today?

Los Angeles Rainfall: Dec 2007

Brent has been sharing his rain gauge readings. Our house got 1.4" this week through Friday evening when the rain slowed to a drizzle and I emptied the gauge. Then Mark went to the grocery store without a jacket and walked home in a miserable downpour. The gauge showed another 0.2 inches from that brief rain band. Add the inch we got the previous week and the early storm in October, and LAX rainfall is at 106% of normal for this time of year. Still not enough to make up for the severe drought last year.

For the latest rain year data, see the California Nevada River Forecast Center page for data for the most recent two years. Or data for the past 6-24 hours.

Some thoughts on water policy.
[LA] Mayor Villarairgosa called for voluntary water conservation, but only if it does not involve sacrifice or inconvenience for anyone. I suggested to Mark that we let our small patch of lawn in the front yard go brown in anticipation of replacing it with EasyTurf like in the backyard. Mark was adamant that we will not do any more conservation of any sort because we will be punished again.

(Remember Stick that Up Your Light Socket? We conserved electricity in 2000 so we weren't eligible for $ credit in 2001 when people were rewarded based upon how much they reduced their electricity usage between 2000 and 2001.)

If we conserve water now, we will be punished again when water rationing is implemented for real. They are suggesting baseline water allotments based on historical use. If you used more in the past, you will be given a higher allotment. There will likely be an appeal process, which will be as inconvenient as possible to discourage people from using it. Unlike Brent, I object to being put through administrative hoops to get a reasonable water allotment. (I am busy enough.)

It will be galling to watch profligate water wasters be given a higher allotment because they "need" more, based upon prior history. Consumers do learn--the wrong lessons. Perhaps we should fill our jacuzzi tub for nightly bubble baths for everyone to establish that we have a "need" for huge amounts of water. Or maybe I will wash our cars in the driveway twice a week.

Links
Los Angeles Rainfall
California and Nevada Precipitation Data both real-time and archival long-term history

Please Send Rain

We are burning up.

This image of the wildfires in southern California was taken by the NASA Terra satellite during this afternoon's overpass. I am not sure if the plumes in northern Mexico are dust or smoke. The color shift occurs when images from two satellite overpasses are stitched together. Areas which are very bright in the infrared (hotspots) are marked in red.

The largest and waviest plume comes from the Witch Fire in Poway.

See more imagery by visiting the NASA MODIS Rapid Response System website:
Global Subsets: click on your region of interest
USA5 Subset
The subset data has a slight time delay. For the latest imagery, use the Near Real-time Imagery Browser page.

Hint: Aura flies overhead at roughly 1:30 local time. Convert your local time to UTC time to obtain an approximate time to browse first. Then go a little earlier or later until you find what you want. Remember that visible imagery will be available during the early afternoon overpass but not the post midnight one.

The CIMSS Satellite Blog shows an animation of smoke plumes seen from the GOES (geostationary) satellite. It is kind of mesmerizing to see the smoke plumes undulate.

Blog Action Day: Walking My Watershed

Years ago, I attended a lecture by a noted member of the "Deep Ecology Movement". I can't remember his name or all the things he talked about. But I do remember that he sounded much more reasonable than detractors of the movement had led me to expect. In his closing statement, he implored the audience to "walk your watershed".

How can such a simple idea lead to a whole new way of seeing my relationship to the world? Today, on Blog Action Day, I would like to take you on a tour of my watershed.

(New readers may also be interested in the Green Party and Fire is a river that runs uphill.)

We begin with a familiar picture.

Lucky urban dwellers don't have to think much about water. Clean, safe water just comes out of our taps. (I know that it is clean and safe because my water district encloses the results of water analysis with the bill.) The bill is paid with hardly a thought. It takes 1-2 hours of my salary to pay for a whole month's water for our household. Contrast that with the 5 hours per day a woman in sub-Saharan Africa might spend providing her family with water (which is not necessarily clean and safe).

Where does our water come from? I live in a semi-arid region with about 15 million other humans. Once, there were wetlands which did provide water for a small human settlement and an estuary for wildlife. But the wetlands are mostly paved over now.

Ballona Wetlands used to cover over 2000 acres, but only about 800-1000 remain and much of that will disappear under the Playa Vista development which is being built now.

Another large wetland area became Los Angeles and Long Beach Harbors, two of the busiest, and most polluted, ports in the entire world.

Our natural watershed can't provide sufficient water for the population here. Read Revisiting ‘toilet to tap’ to learn how the Hyperion water treatment plant below provides recycled water to the beach cities. In the picture below, you can see some of the water that the Hyperion plant releases into the Santa Monica Bay. What you can't see is that treated waste water is also pumped into the aquifers from which part of my tap water is derived.

But even recycling can't provide enough. We have to look much further to meet our voracious appetite for water. Some of it comes from the Colorado river even though we are hundreds of miles from the natural Colorado river watershed pictured below. In fact, the Colorado River no longer flows to the sea. All of the water is used and reused until the river disappears in the desert.

This favorite campsite is near the confluence of the Green and Yampa rivers, in Dinosaur National Monument. A few miles downstream, they will join the Colorado river.

In the morning, we rode our mountain bikes on a jeep track along the Yampa Bench overlooking the Yampa river.

On another trip, we visited Black Canyon of the Gunnison, also in the Colorado river watershed.
The Colorado river is a shared resource. We cannot take enough from it to satisfy our needs. We also tap the Owens valley watershed picture below. The extent of Mono lake used to be much bigger and this valley used to be much greener.

See the dust devil below from June 2007? Los Angeles lost a lawsuit because it diverted so much water from Mono Lake, that dust storms became common. This created unhealthful air quality for the people living in the Owens valley.

Los Angeles did not live up to its past agreements. The water line agreed upon in a court settlement in 1994 is here. Doesn't look very wet here at all.

All of these tufa formations used to be underwater. If the agreement above were honored, many of them would be underwater again.

I walked my neighborhood today to show you my watershed up close. Our household sewage goes here. Note that I live in an urban infill townhouse. Two identical townhouses share a single lot, hence the two sewer lines.

Storm runoff goes into a separate system which flows, untreated, into the ocean. Here is our backyard storm drain.

The storm drain in the front driveway.

The storm drain by the street. Note the graphic reminding us not to dump nasty things into the drain.

A sign at the park tried to educate the populace.

Some of the storm drains are above ground and attract wildlife.

This ersatz creek flows into Polliwog Lake. Note that our recent rainfall caused the lake to overflow its concrete banks. The benches are not normally in the water.

It is a sad fact that, around here, only low-lying areas are turned into parks. But at least Polliwog is a very attractive park. This catchment basin is not as attractive.

It all ends up here. Read the environmental scorecard for the beaches.

Or maybe it all ends up here, in the clouds. The airshed is connected to the watershed... (sung to the tune of the funny bone song)

Which then rains back down. And so it goes ad infinitum. The global watershed is all connected. Take good care of your watershed.

Rain Dance

Or maybe it is the happy dance. Our rain gauge held 0.9 inches (23 mm) of water this morning! Add that to the 0.5 inches in late September and those two storms resulted in roughly 50% of the total rainfall of the whole water year (counted July 1-June 30) prior to that.

I feel like such a geek for blogging about small amounts of rain comparable to mere fog in other parts of the world. But, I noticed that Grandma Ann of Sitting Knitting and BAM of Breathing Treatment also blogged about the rainfall and gave their rain gauge readings. Don't miss the photos of the sunrise before the rain at Sitting Knitting. Actually, don't miss any of the photography over there.

(Aside: Mark and I were discussing the geekiness of owning a rain gauge. I said that most of our friends have them, too. He said that our friends are our friends for a reason, but they are not typical. So show of hands. Do you have a rain gauge? Leave a comment.)

Mark and I mucked around in the yard today. We neglected it so during my last health setback. I had to trim back half our lemon tree due to an aphid infestation. We also trimmed quite a bit off the (healthy) bay laurel tree and the rosemary bush. I put the trimmings out by the sidewalk with a sign saying, "FREE Rosemary and Bay Leaves (but leave the basket here)". One lady actually took some Rosemary. I went into the kitchen to get a plastic bag for her.

Maybe I will even knit tonight. My sister just bought another spinning wheel. She swears that she NEEDS them all, for different types of fibers. Yeah, that's right. I NEED all the stuff in my stash because they have different uses, too.

Surf

The surf was up last Friday. Remember how placid it looked in the photo in Pleasure?

Sure looks different in the video I took Friday, 5 October at lunch. Listen to the roar of the wind and watch the flapping of the palm fronds in the video.



Look at the jet stream analysis (courtesy of the California Regional Weather Server). Ripping winds aloft usually mean big winds below. Big winds bring big waves.



By the next morning, the water was considerably less choppy.

Big News

The rain gauge shows 0.5" of rain last night and this morning.

Late Arrival

It is actually raining now! I am posting the current radar as proof. Earlier, we saw lightning. I opened the windows so we can enjoy the sound of rain falling on the leaves of the tree outside our bedroom window. Ooh, I just heard thunder.

It is so tough to be a weather geek in LA.

Many people were making fun of Angelenos and meteorologists today. I can explain everything. There is a perfectly reasonable explanation why so many traffic accidents occur when it rains here. It is because it rains so seldom.

Road grime is greasy. It builds up on the roads unless rain washes it away. LA is a desert. When the first rain arrives after a long dry spell, and we have a lot of long dry spells, the roads become incredibly slick. Accidents can happen even to good drivers (not that I am saying we are uniformly good drivers here). People from wetter parts of the country don't properly appreciate the difficulty of living in a desert with so much traffic and, hence, road grime and so little rain.

About the other matter. People have been making fun of meteorologists all week because it seemed like the predicted rain would never come. First, it was supposed to arrive Wednesday. Nope, Wednesday was sunny. Then it was supposed to arrive on Thursday, anther bright sunshiny day. Why can't we get the day right?

It has to do with the difficulty of predicting the behavior of a cutoff low, an area of low pressure hemmed in by surrounding higher pressure areas and removed from the jet stream. For technical reasons that I don't completely understand but my coworkers do (it involves technical terms like isobaric and hydrostatic), cutoff lows don't have any place to go. So, they tend to stagnate over areas. When they do move, their motion is highly unpredictable, depending on slight pressure differences. (They can retrograde!) It is much harder to make landfall predictions for a cutoff low than for a big old hurricane with lots of momentum.

The Missing Guest

On the northbound drive from LAX to SFO last month, tiny pellets fell on the windshield. They appeared dark silver or gold, depending upon the peekaboo sunlight. They rolled UP the windshield. I looked up to see if farmers were spraying some kind of nasty chemicals on the fields from crop dusters. I saw nothing but a few dark clouds off to the east.

It took me a few minutes to figure out that those pellets were actually rain. It had been so long since I had actually experienced rain, that I forgot what it looked like. Additionally, I had never experienced rain in the Prius, which has a sharply raked windshield. The car is so aerodynamic, and the droplets so small, that the force of the wind actually overcame gravity and moved the raindrops UP the windshield.

Technically, it was virga, not rain; the droplets evaporated almost immediately and the road surface was dry.

Wisps or streaks of water or ice particles falling out of a cloud but evaporating before reaching the earth's surface as precipitation.

Anyway, there is much weather excitement in LA because it might actually rain here this week. I took the Prius in to the car wash yesterday to make sure that it would rain. Note, I did not wash the car. Everyone knows that driveway car washing is the largest contributor to groundwater contamination and runoff pollution into the ocean in LA, right?

Asides:

• No, it is not narcissistic to believe that I can cause rain by getting the car washed. It is merely a statement of fact. The car was washed in preparation for the trip to SFO and it worked like a charm.
• It was news to me that driveway car washing is so detrimental to the environment. I learned it a few years ago at a groundwater workshop at UCLA's Institute of the Environment.
  
• I go to a car wash where they recycle the water. In fact, the stuff coming off cars is so toxic, that the sediment in the water holding tank at the car wash has to be hauled away by a toxic waste hauler. That's right. Road grime is toxic. In addition to the organic alphabet soup of petrochemicals, they also contain lead residue and heavy metals that escape from catalytic converters.
• Commercial car washes are required by law to recycle water and properly dispose of the sludge. The heavy metals can even by separated and recycled. It makes me feel better about my laziness environmental responsibility.
• Numerical weather prediction (NWP) models estimate we will get 1/2 to 1" of rain out of this storm. Rob at Are you cereus? was able to show convincingly that NWP models sometimes precipitate out the moisture too fast. They estimate too much rain on the windward side of the mountains and not enough on the lee side. In at least one instance, he was able to convince people to change their model. So don't just complain about bad weather forecasts. Do something about it. Document the bias and show it to the forecasters.
  

Nature's Casino

The cover story in last Sunday's NY Times contains many elements that fascinate me. It mixes an immigrant story, mathematical modeling of statistically improbable but extremely damaging events, risk analysis, meteorology, a motherhood story and human behavior. Read Michael Lewis' In Nature's Casino. It is delicious.

I especially like the part where a visibly pregnant modeler, Karen Clark, explained to a roomful of men at Lloyd's of London that they faced extremely high financial exposure when an Atlantic hurricane hits a heavily populated area. That one had not done so recently was just dumb luck and the luck would eventually run out. They told her that they understood their risk quite well, thank-you very much. Then Hurricane Andrew hit and bankrupted many of the Names of Lloyd's.