Category Archives: rain
Even though summer doesn’t officially end for a few more weeks, meteorological summer (June, July and August) is now in the record books.
While parts of Cochise County remain in a major surplus of summer rain – even despite a dry August – Tucson will go into the books hot and dry.
Here is a synopsis of summer 2013 at Tucson International Airport where records are kept.
It’s hard to believe that tomorrow is the first day of August, and Tucson’s largest school district is headed back to the classroom.
If we consider the monsoon a season defined by dates (June 15th – September 30th), then we are almost halfway through with our summer rainy season.
Most locations are way ahead of their average rainfall to date.
Some spots – especially in Cochise County – are breaking all-time records for the wettest month ever.
So how does August look?
According to the CPC (Climate Prediction Center), the odds favor a warmer and wetter month as compared to average.
So if these projections verify, I would say monsoon 2013 was a success if you were hoping for widespread rain.
A severe storm plowed up I-19 and into Tucson today.
Check out the toppled power poles our reporter Sam Salzwadel captured on the South side of town.
Rain was heavy especially on the South & Northwest sides of town today.
The intersection of Country Club & Ajo picked up 1.81″ of rain, and a rain gauge in Oro Valley received 2.05″.
The monsoon is going into a low-grade pattern as we head into the weekend while high pressure sets-up shop overhead.
Dry air in July means hotter temperatures and triple digits are back in the forecast for the next several days.
Monsoon 2013 will take a little break, and perhaps this is welcome news for residents of Cochise County.
Here’s a staggering statistic to consider: 9.67″ of rain has fallen in Douglas during the month of July.
Enjoy your weekend and remember to stay hydrated as we return to ‘summer’
The final flood advisory for Central Pima county has expired leaving all of Southern Arizona advisory/watch/warning free for the first time in a long time.
So now that I have some down time let’s discuss monsoon 2013 and where we stand.
There are plenty of superlatives we can claim already.
Douglas, for example, has received over 8.00″ of rain during the first two weeks of July.
It is now the all-time wettest month for Douglas – and we are only halfway through. Portions of Cochise and Santa Cruz Counties have literally been washed away in the past two weeks.
As you can see, Hereford and Douglas really stand out while the remainder of the region is near average for rain.
One thing I find curious is that TIA, too, is above its rain average – while many ‘midtowners’ have noticed the lack of a good soaker.
So often is the case that, TIA (where rain records for Tucson are officially kept) seems to receive much less rain than other portions of Tucson.
Perhaps this is just a misnomer, but we can accurately claim that as of today, Tucson is above average for monsoon rain.
Okay, just when you thought it was safe to work on the blog a new flood advisory pops-up.
I’ll see you soon!
Have you been a bit disappointed lately with the lack of rain in midtown Tucson?
Would you belive me if I told you that this monsoon has been epic so far? Well it has, and I’ve got the proof.
In fact we are at double in the rain department.
Nearly 700% of average for July.
So despite what you may consider a slow start to the monsoon, we are actually faring quite well.
I expect a bit of a downturn in rain chances from Friday through the weekend, but some signs are indicating another uptick as we head into the middle of next week.
Hopefully the daily round of storms works its way a bit farther to the north.
Here’s my Monday monsoon update.
We’re off to a good start this year when it comes to our monsoon rain. Nearly 1″ of rain fell at TIA on Friday, and way more out toward Vail.
We have two positive factors for the potential of heavy rain this week and one potentially negative.
1) Tropical Storm Erick
A very favorable factor is on our side if you like rain. Tropical Storm Erick is churning to the West off Baja in Mexico. Often times we get what’s called a ‘gulf surge’ from tropical storms – even when they’re well to our south. Essentially, mid level moisture travels up the Sea of Cortez and helps us in the rain category. We still need a ‘trigger” or a mechanism to lift this tropical moisture to create rain. Enter factor #2.
2) A disturbance moving from East to West.
Remember the definition of monsoon? A seasonal shift of the wind. While most of the year we look to the West for our weather, disturbances this time of year come from the East and can help lift our moist air to create the rain. A disturbance is moving our way and should help lift our moist air for good rain chances. In the following picture you can see an area of lower pressure to our Southeast- this would be our trigger.
I’ve seen this too many times during the summer months. Often times despite a ‘trigger’ and good moisture, we do NOT get good rain in the Desert. This can be a function of too much of a good thing.
Ample storms may fire-up, many miles away from Tucson, but they can weaken sending us only clouds. If we are left with leftover clouds, we do not get warm enough at the surface to destabilize the atmosphere for convection (aka storms).
So as of now, I think the two ‘good’ factors outweigh the one ‘bad’ one and parts of Southern Arizona get abundant rain this week. But keep in mind, as contrary as it may sound, waking up with sunshine is a good thing if you are hoping for rain!
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.
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:
Since the gas constant (R) doesn’t change – (duh it’s a constant) we can easily rearrange this to read:
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.