From the Heat to the Rain

It’s now in the record books: for the first time ever, all 30 days in June were greater than 100 degrees in Tucson. 

So if you thought it was unusually hot, you were correct.

Chapter II: The monsoon 

Thanks to the position of high pressure, which also brought us the heat, moisture has already begun moving into the region.

Dew point’s at TIA are now near 50 degrees and forecasted to increase over the next few days.

You may recall that the dew point is the absolute measurement of how much moisture is in the lower levels of the atmosphere.

The following images are high-resolution depictions of projected rainfall across the region for the next 72 hours.

72 HR RPM
72 HR RPM

This image is our 72 hour RPM model indicating a noticeable uptick in our monsoon.

We like to look at other model runs to make sure that there is consistency among our forecasting tools.

WRF UA

This image is from the WRF Hi-Res Model from the UA

Bottom line: The first week of July looks to be at least the beginning of what I hope is a great monsoon.

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Signs Of The Monsoon Before July

CaptureCheck it out. Here is the latest GFS model for June 30th. It’s still awhile away, but if it verifies, we should see good storms developing in  Tucson before July.

Not So Ideal Weather Using ‘Ideal’ High School Chemistry

I hope my reference to High School Chemistry didn’t conjure up painful memories from your past; a la exploding graduated cylinders, or brutal Bunsen burner burns.

If not, please read on with an open mind.chemistry_book

Very basic chemistry explains why the Willamette Valley has been cold, foggy, gloomy and literally unhealthy for those with certain respiratory conditions.

So here comes the ‘hard’ part. Take a deep breath as I now present to you a very simple equation fundamental to science. Does the Ideal Gas Law ring a bell? All of the gasses we deal with in our atmosphere can be described using this handy equation.

P = ρRT

The simple relationship says. The pressure of any gas (P) is equal to the density of the gas (ρ) times the gas constant (R) times the temperature of the gas (T)

Okay, if you’ve made it this far the rest is easy.

Using simple algebra we can easily  rewrite this equation as such:

ρ=P/RT

Since the gas constant (R) doesn’t change – (duh it’s a constant) we can easily rearrange this to read:

ρ ≈P/T

This is an elegant little expression. It can be read like this: The density (basically the weight) of a gas (our air) is inversely proportionate to it’s temperature. Since our air pressure hasn’t changed much, it’s easy to see that the colder our air is (T), the denser it is as well (ρ). 

This relationship represents  the cornerstone of our weather lately.

The cold dense air is heavy and is resting right on top of us  in the lowest parts of the Valley. Since there are no buoyant forces to make this air rise, all of the dust, ash and other particles are trapped in this shallow dense air. We call this stagnant air. The longer this stagnant air sticks around, the more pollutants it adds. It’s kind of like adding a bit more salt to your soup day after day.

It’s unfortunate, because we have a giant ridge of high pressure aloft which would ordinarily give us unseasonably warm, sunny weather. Look at the temperatures on the mountain lately. 53 at Mt. Hood meadows today, 60s in the Coast Range. The low January sun angle isn’t strong enough to warm this layer up so it becomes less dense and lifts away. There is also little evidence of a major pressure change (AKA wind) to help move the gloom.

So here’s the real kicker: we may have to wait for rain to make us sunny again. How the heck can rain make it sunny you may ask?

Well, rain would mean an area of low pressure would move above us, it would also cool the atmosphere from above thus restoring the atmosphere back to equilibrium. A state where the temperature decreases with height, or the exact opposite of an inversion.

Weather Advantage – The Mountains

Check Out This Graphic

ECMWF HEIGHTS

 It shows a massive ridge of high pressure over the entire Pacific northwest. A set-up means unseasonably warm and sunny conditions right? Not so fast.

The weather pattern we’ve been experiencing lately has been characterized by cold, saturated and foggy conditions. In order for this ‘gloom’ to go away we need this air mass to lift. Air that is able to lift is called unstable air. It happens when the air above us is cooler, which is generally the case.

But happening now is very mild air above us. In fact, this morning at 7000′ in The Cascades we are reporting temperatures in the upper 40s, while the Valleys are just above freezing. This creates a stable air mass – or air that is more difficult to lift.

Without geeking out too much, the set-up for the next several days favors the mountains. Our cold Valley air is dense, (cold air weighs more than warm air) and due to the weight and gravity, this air stays in the lowest locations and is locked in place due to the stability.

So this means people hitting the slopes will be enjoying spring-like skiing and coming off the slopes with sun tans.

In the Valley, we get to deal with air-stagnation, poor air-quality and cool temperatures despite the giant ridge overhead.

If we can get enough of an east wind, we could clear out and see sunshine and mild temperatures, but as of now it looks like this won’t happen. Our only hope is some late day sun to heat the air and give it some instability. But in the dead of winter with such a low sun angle I wouldn’t be too optimistic.

So, advantage – the Mountains.

Most Of Oregon Had A White Christmas and A Dry 2013?

Unless you live along the Coast or in the Willamette Valley, chances are good you had a white Christmas.
From the Coast Range to the Gorge, to the Cascades and points east –

snow was in the air. Check out some of these snow totals. Christmas2012

Back in Portland Christmas was a wet day with cool temperatures in the upper 30s to lower 40s.
The front that brought the rain and snow is lifting out and behind it is cool showery weather.

So weatherwise, prepare for scattered showers for the remainder of the night with temperatures falling slowly into the upper 30s. If you are headed out to a movie, grab an umbrella and the rain gear, but overall the heaviest rain has ended.

Tomorrow some scattered showers will roll-in as the next weather maker moves to our south. Highs will be in the mid 40s.

Get ready for this breaking news: Thursday through next year – that’s right I said next year – should be mainly dry! Morning fog, followed by partly sunny skies is the forecast from Friday and beyond – courtesy of a dry east wind.

On A Final And Personal Note,although I was unable to be with my family today, I am grateful that we will all celebrate tomorrow in San Diego. Working with my wife Kacey is always fun, and my in-laws near Dallas, Texas had a wonderful Christmas surprise – A White Christmas. They sent me this beautiful picture which I showed on the 6pm news tonight. Dallas

Merry Christmas to all, and all a goodnight,

A White Christmas? Portland’s Chances Are Better Than Some

Twas the night before Christmas,IMG_2968
And all through the air,

Conditions were dry,

And the weather was fair,

Kids were hoping for snow,
Well into the night,

With the hope of some snow,
Christmas would be white.

Dreams do come true and many parts of the region will see snow on Christmas day – but probably only rain in the lowest terrain.

A strong winter weather storm is moving toward the region and will bring plenty of rain to the region on Christmas day. If you live near the Gorge or in the highest hills, you may see some snowflakes mixing in with rain very early Christmas morning. Otherwise, it’s a wet Christmas for the valley with highs in the mid 40s.

The coast will be wet and breezy, the Coast Range will pick-up 2-6″ of snow before changing back over to rain. The Cascades will pick-up another foot or more of snow and the Gorge east of Multnomah Falls should pick-up plenty of snow.

Here’s a factoid that may make you feel better about our white Christmas chances: The city of Miami has a 1-in-20,000 chance of having a white Christmas. It has never happened and it has been 35 years since Miami has even seen snow.