Who Said I’d Be Bored?

Some computer models show around an inch of rain in Palm Springs by Monday morning. That’s a lot in a place that floods easily. I spent time tonight explaining ‘washes’ to the tourists and snowbirds watching.

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I’m forecasting the weather for the Coachella Valley at KMIR. The physics of weather are the same, but there are different tools to use.

Satellite imagery is a lot more important here. Anything coming from the Pacific is out of radar range nearly all the way to the coast.

I’ve been looking at a plume of moisture from north of Hawaii curving up the Pacific then back down the West Coast. It’s the big weekend weather maker for SoCal. The only way to see it is from the bird.

Saturday, while it’s raining in LA and San Diego, there will be partly cloudy skies over Palm Springs with a few sprinkles. We are protected by steep mountains, some over 11,000 feet tall.

On Sunday the moisture heads in from the south. No protection there! That’s when we get the bulk of our rain.

Some computer models show around an inch of rain in Palm Springs by Monday morning. That’s a lot in a place that floods easily. I spent time tonight explaining ‘washes’ to the tourists and snowbirds watching.

On top of the rain we’ve got wind for Saturday and as much as a foot and a half of snow in some mountain locations.

Who said I’d be bored forecasting here?

I Love Time Lapse

The sky was actually quite dull and featureless. It’s only when in motion this way that you see two opposing layers of clouds and all sorts of action.

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Among the things digital photography unleashed was the easy ability to shoot time lapse. It’s the technique which speeds up action so you to see patterns and movements not normally noticeable.

It looks tough to do… and there certainly are a lot of steps… but it’s really simple. The camera automatically clicks the shutter every ‘x’ seconds. Software combines the stills into a movie. Boom, zing. A little polishing in the editor and here it is.

The sky was actually quite dull and featureless. It’s only when in motion this way that you see two opposing layers of clouds and all sorts of action.

I expected blah, but got one of my new favorites.

A Different Kind Of Time Lapse

“Don’t you get bored,” Stef asked after seeing my latest time lapse. In a way she’s right. Just clouds passing by.

On the other hand you can actually watch and see physics in action! Everything happening is happening for a well defined reason.

Tonight is the full moon and we’re close to perigee. That makes the Moon big and bright and very visible as it moves past the window.

I like this one especially. I like the night.

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The Marine Layer

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I took Doppler out for a quick walk this morning at 3:30 AM. She looks down. I look up.

The stars were mainly gone. A low gray cloud deck had moved in. Nothing unusual. I went to bed.

By the time I woke up the clouds were gone. It’s like this a lot in SoCal–sunny days/cloudy nights.

There is a reason. It’s called the marine layer. Let me explain.

Let’s Look At Clouds From Both Sides Now

If it looks like the clouds are boiling, just like a pot of water on the stove, it’s because the dynamics are very similar. Heat is being transferred upward through convection.

NWS EDD

We seldom get the big picture of what’s on the radar by just looking at the sky. Not today. Today is different in SoCal.

The atmosphere is unstable on the the other side of the Santa Ana Mountains, around 30 miles east of me. That’s where the radar (at the top of this entry) shows strong thunderstorms.

What’s striking in the time lapse below are the mid and upper levels of the clouds producing the storms. There are no clouds in the way blocking my view.

If it looks like the clouds are boiling, just like a pot of water on the stove, it’s because the dynamics are very similar. Heat is being transferred upward through convection.

The heavy rain and lightning bolts are out-of-sight behind the mountains. Here, I only see the signs. Everything is moving north and will soon be gone.

Beautiful Sunset Even Without Seeing The Sun

From my office window I can see south and west. What I can’t see is where the Sun sets! It’s behind another home.

It didn’t make any difference tonight. As the Sun went down the few clouds above lit up. Usually it only happens in the western sky. Not tonight. Tonight every cloud was brilliantly illuminated.

I wish I was at the beach to see it all unobstructed!

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On Most Days It’s Red Sky At Night

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This time of year the setting Sun is easily seen from my second floor office window. I look out and make a judgement–what kind of sunset it will be? It’s photography think. Do I want to take my camera out for the daily sky show?

This afternoon the sky was already turning red a half hour before the Sun disappeared. Good sign.

We’re supposed to get showers later tonight and Thursday. I’m used to the sky being a lot more full of clouds this close to precipitation.

As soon as the Sun was out-of-sight, I did a 180 to take the shot below.

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Things You Can Learn From Clouds

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I’m going to put on my science teacher hat for a moment. I saw something cool. You might enjoy understanding what’s going on.

An hour ago I propped my tablet against the bathroom window to take a timelapse movie of the clouds&#185. The sky was filled with beautiful puffy cumulus clouds. On a realtime basis they were majestic and seemed to hover in place.

Not so when sped up by a factor of 150 (that’s one shot every five seconds). Now the sky is turbulent. Roiling!

Gil Simmons, who I used to work with at Channel 8, calls these COW clouds. COW for “cold-over-warm.” I’ve also heard the effect called “self defeating sunshine.”

There’s a larger than normal vertical temperature gradient over SoCal today. Earlier this afternoon the temperature dropped almost 10&#176 Fahrenheit between 5,000 and 7,000 feet. That’s the cause for the clouds–the cold-over-warm.

Later tonight you’ll have to climb from 4,500 to 11,000 feet for that same drop.

Since warm air is more buoyant than cold, it rises and condenses forming clouds. This warm air moving toward the cold is called convection. It’s how heat moves when you put a pot of water on the stove.

If you look carefully at the very top of some of the lower clouds in my timelapse you’ll see the convection in action. The clouds grow upward looking very much like the bubbles of water rising in that hot pot of water!

If it looks like the clouds are moving multiple directions at once, you’re right.

There is wind shear overhead. As the clouds gain altitude they move from a southwesterly flow to northwesterly. It was even more pronounced earlier today. That shear adds to the convective cloud buildup. In fact wind shear is a major factor we look at when predicting severe storms.

Too much for one day? I’ll stop now.

The atmosphere is amazing when you watch it up close. There is so much going on and explanations within the laws of physics for all of it.

&#185 – Try as I might I can’t figure out how to keep the Nexus 7 camera from refocusing from time-to-time. That’s why the shot goes out-of-focus a few times.