Where are you, Monsoons?

By in Prescott AZ with 0 Comments

Even though there have been some sporadic storms across the Prescott and Quad City areas, many of us have been either feeling left out of the torrential downpours with nothing to show from dark clouds except a few sprinkles, or left wondering when the real Monsoon season is going to hit.

Compared to years past, when the Monsoon season has generally started the first week of July, we now sit in the first week of August with little moisture to show for it. Curious about when we might be getting that jaw-dropping, earth-shattering Monsoon season we’ve all been waiting for – where there is practically an awe-inspiring storm every day – we found this article on azentral.com, that gives some possible explanations as to where our Monsoons are and when they might grace us with their presence:

“The heat waves we often get in late June and early July are usually the result of a strong area of high pressure sitting over the state.

Because of the way air flows around a high-pressure ridge (clockwise), the Phoenix area is more likely to experience monsoon conditions when that high-pressure ridge is over the Four Corners region. That allows moist air to flow in from over the Gulf of California.

That moisture helps fuel our summer storms.

However, that high-pressure area hasn’t reached the Four Corners yet and that’s due, at least in part, to holdover weather patterns that brought cooler than normal weather through much of the spring.

University of Arizona climate scientist Michael Crimmins explains that the jet stream (a kind of river of air in the atmosphere) has been hanging around farther south than normal and hasn’t allowed that high-pressure ridge to push north.

‘The (computer) weather models have been really struggling with the monsoon ridge because the jet stream has been so wavy,’ Crimmins said. ‘(The jet stream) has been really active and kind of wintery going back to January and it’s kind of done that through June.

‘It’s only been in the last couple of weeks the models have the jet stream relaxing and pulling north and letting the ridge kind of build in. Whether they are right or not is the big question.’

The National Weather Service’s monsoon outlook has leaned toward a later than normal start to the onset of monsoon conditions. One of the factors in that forecast is the idea that a wet winter and early spring have helped keep temperatures down, which could slow the development of the monsoon.

Crimmins doesn’t necessarily agree that wet conditions earlier in the year are delaying the start of the monsoon.

‘The whole (monsoon) ridge is kind of a chicken/egg thing,’ Crimmins said. ‘I think the cool June is more of a symptom than a cause. It’s more reflective of that the ridge hasn’t rushed in and built up further north because it’s being pushed around by the jet stream. Even the Gulf of California has been turned over a couple of times by the winds blowing through Baja. It’s still not as warm as you’d want it to be for gulf surges.’

But Crimmins also isn’t in the camp of those who think the monsoon will get off to a late start. As a climatologist, he’s more inclined to lean toward historical averages holding up.

From 1948-2018, the most common start date for the monsoon based on the traditional definition of three consecutive days of a certain dew-point temperature is July 3 for both Phoenix and Tucson. The monsoon started on that date nine times during that period in Tucson and 10 times in Phoenix.

While it doesn’t seem likely that things could change enough to bring rain that quickly, it might not be too far off if the jet stream cooperates.

‘If it gets out of the way and can be supported by a kind of more natural circulation pattern, then the ridge could be allowed to build north,’ Crimmins said. ‘That’s what the (computer) models are trying to do over the next two weeks. We’re now into the week-by-week, day-by-day game with the monsoon’.”

Share This

Leave a Reply

Your email address will not be published.