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Arizona: Monsoon Season is now calendar-based

Note to Monsoon chasers who visit Arizona- as of 2008 Monsoon Season is now defined via the calendar. The old dewpoint system measuring the onset of monsoon as occurring when 3 consecutive days of 55+ dewpoints (PHX), has been thrown out in favor of the new simplified system. Yay.

Monsoon Season in Arizona now starts June 15 and ends Sept 30. Now if only the storms would say, "Okay, it is June 15, time to rock & roll!"


I like the new system. It used to be that even if rooftops flew off but the dewpoint only reached 54 that day...or if dewpoints would hit 55, then 55 the next day, then 54 the next, Phoenix still couldn't declare monsoon, even if there were 100 mph winds and 10,000 lightning strikes. This is much simpler and does a better job of preparing people for violent weather season when they know the date is coming.

Since the word 'monsoon' comes from the Arabic word 'mausim' which means seasonal wind shift in itself, 'Monsoon Season' is kind of a redundancy, but that seems to be okay with most people because of the benefits of having the season defined.

It also means that Monsoon Season can now be declared 1 month from today!! :D
Aren't you glad Warren? The new system is not PHX centric like the 55 3x, which made no sense everywhere else in the state. Seeing as action starts in other parts of the state at 54 easy. All that doesn't matter anymore.

What is unique about this is that Phoenix, Flagstaff and Tucson all regarded monsoon differently. Now we are all on the same page.
If anybody is interested in talking tornadoes with respect to the Az. Monsoon...I'd be game.
I know the world thinks that Arizona doesn't get tornadoes...but this is incorrect. We get the real deal..I've seen several and photographed a few. But usually they are not down on the ground for very long, as their midwestern counterpart. We get both landspouts and meso-induced tornadoes, and here around Tucson we've had people killed by them on a couple different occassions, too.
I believe Warren Faidley, a long time ago, did a study about all the historically documented tornadoes in Arizona. If I'm correct...there was a MILE WIDE tornado near the town of Florence in the late 1800's!
I've photo'd tornadoes in between Florence and Casa Grande...so I believe it.
Like tornado alley....there are what I like to term "mini alleys" within the main alley. Mini alleys have always fascinated me. Although Az. is far from "the alley"....there are areas that seem to receive more action than others.
Just last week I had a customer at my retail business who ranches down in far southeast Arizona...near the New Mexico border. She said she and her husband have seen tornadoes on their ranch land, and they just recently went on a horse-back trail ride to fix fences. She said that they encountered a couple of areas where there was obvious tornadic damage. This included uprooted and downed trees and saguaro (pronounced Sa-war-oh) cacti (the big tall ones with arms that you always see in the movies) that were blown apart and scattered in a rotary fashion. Also...I live in far north Pima county (Tucson) and I've seen tornadoes down several times between the northern Pima county border and northward into Pinal county. There are several more "hotspots" as well.
I'll be chasing the "real" alley in June...then hopefully we'll get a good butt-kickin' monsoon here in Az. this July thru September...and I can bag some of those brief but real tornadoes that "everyone knows we just don't get here in Arizona"..haha.
Wow, that is pretty neat. Its about time that it is Calender based. I can remember last year I was watching the storms pop up in AZ and said "wow the monsoon has started" and then being replied to with "its not the monsoon yet" because of the 55 degree dewpoint not going for three days straight. I do agree that even tho it is now Calender based (while not trying to jinx it) we all know that the monsoon can be picky about starting on time. its about time to start checking the Monsoon forecast page. yeehaw...

Good Luck this year to all the Monsoon chasers, especially you Susan. =)

Thanks Gerrit! =)

On the topic of “little alleys” in Arizona…there are definitely pronounced hotspots of activity that seem to play out year after year during Monsoon. It can get pretty wild.

Here are mine: (Lightning)
Starred* ones have good sandstorm chase possibilities too.

Mogollon Rim #1…Hwy 260 between FR300’s Woods Canyon Lake turnoff & aspen grove to Show Low, that whole stretch

Payson (the Houston Mesa road, specifically)

Verde Valley (Prescott, Sedona)

Wickenburg (gotta put a star on that one…love the town, love the people, love the lightning)

*Places off the I-8 corridor in the Central Deserts

*Florence (one “strike” against it: prison lights)

*Central Deserts between Casa Grande and Marana (although less these days due to light pollution)

Globe/Miami (one “strike” against it: crazy curvy highway)

Queen Valley to Superior

Safford (one “strike” against it: prison lights)

Black Canyon City

The Plateau (under certain synoptic conditions)

*The Willcox Playa

*SR 79 between Florence Junction and Oracle (one “strike” against it: flash flooding)

Northeast Tucson

The McDowell Mountains (and Lower Verde Valley east of Scottsdale)

Saguaro Lake

The Superstition Mountains (of course! It is the birthplace of the Apache Thunder God after all)

The Mazatzal range including Four Peaks Wilderness

4 weeks and counting!
It's always a little frustrating watching the first storms sneak into the far SE corner of the state. For several weeks, Douglas, Bisbee, the Chricahua Mountains, and other far-flung areas enjoy the show while the rest of us melt in the scorching early summer heat. While the old 3 days x dp55 was far from perfect, it was applied on a local basis, acknowledging the progressive nature of the monsoonal flow. IMO, a fixed date is far too arbitrary.

Living and working on the SE side of Tucson encourages southern chase targest. Tucson's highway system is a mess; the thought of fighting the northbound traffic is often enough to scare me off of chasing in Pinal or Maricopa counties. The chasing in the western/central deserts of Az. can be fantastic, but I seldom roam so far.

FWIW, some of my favorite chase locales:

Mt. Hopkins road.
This climbs from the Green Valley area on the way to Mt. Hopkins. The elevation gain gives you a majestic view to the west, where sunset and storms play above the Boboquivaroi and Sierrita mountains cascading into the infinite distance.

Highway 83, between I-10 and Sonoita.
There are good westerly views just S. of I 10.
The central section of the road road runs along the eastern edge of the Santa Ritas so most of your shooting will be to the east. When clouds diffuse the evening light around the mountains, the rolling grasslands of the Las Cienegas reserve can take on fantastic warm colors, while the antisolar sky swirls with subtle yellows, blues, oranges, and everything between. Add lightning for effect! The same mountains often cast striking anticrepuscular rays over the landscape. Take the Empire Ranch road a few miles east, into the reserve, and enjoy some of the prettiest country around. I've seen two funnel clouds in this area. On both occasions winds were from the west, spilling over and around the mountains, creating areas of local shear.
Approaching Sonoita, the views open up to the S and SW, often silhouetting distant storms against the late twilight sky.

East of Benson, I-10 climbs to the foothills of the rugged Dragoon Mountains. You can look back across the valley for a nice sunset view, or catch storms developing over the outcroppings of welded tuff. (Edit - Granite?! DOH!, I was somehow thinking Alabama Hills.)

Chricahua N.P. offers real potential....so long as you're willing to hike narrow twisting trails among the hoodoos by moonlight. Try not to step on the rattlesnakes, and be ready to dodge lightning if/when a storm develops overhead. (Both are real dangers!)

Aaron, if you're stuck for equipment, I can loan you some of my manual focus Canon FD stuff. I must have half a bazillion bodies and lenses. On top of that, my lab partner buys old tired/broken Canon equipment, repairs it, and sells it for very little. I suspect he could set you up with a decent FD body and 2 factory lenses for around $100. (Contrary to popular myth, film still works!) Holler if interested.
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Had another interesting customer at my retail business two days ago. He's a long-time railroad engineer (he drives the trains...not the geeky type of engineer..lol) and last monsoon season he received verbal instructions to slow his train to a dead stop and just wait. This was near Benson, Arizona (southeast of Tucson). It seems that there was tornadic activity near there, and a tornado actually crossed the tracks ahead of him!
Another railroad engineer who came into my business told me basically the same story...he had to slow to a stop, and wait a couple of hours without moving..because there was tornadic activity down the rail from where he was at the time. This episode was near Gila Bend, Az.
Kinda cool, huh? Well, we all KNOW that REAL tornadoes NEVER hit in Arizona....lol.
I agree with Greg. Sorry, but defining the monsoon season by the calendar seems ridiculous to me. What information is being conveyed and what distinctions being made by this? I know for a fact that summer begins about June 22 and ends September 21 ... everywhere. Granted the 55 d.p./3 day standard was a bit flakey, especially on the Rim or the higher terrain of se Arizona, but why not refine it with some sort of atmospheric column-based statistic instead of throwing the whole game.

The good thing is that the NWS will be 100% accurate in their forecast for the start of the monsoon. Really special -- when the low deserts bake in desiccating heat as June 15 comes and goes.
The monsoon is amazing! Being from Southern California when the cu starts popping over the San Gabriels bout mid-late morning on a hot July-August day you know it could be an interesting afternoon!

Some of the most impressive storms I've seen have been summer monsoon storms, and I just finished up my 3rd year at the University of Oklahoma!

SoCal is typically on the western edge of the monsoon ridge so our thunderstorm days are usually more occasional than just to our east, but when they come in they come in! 2003 was a particularly active year for us, we had 10 days of thunder at the house (very active compared to the average of 3-4) and on July 29th Lancaster took a direct hit by a severe thunderstorm. I videoed the microburst as it developed just to the east of my house and then blasted through the neighborhood and into the heart of town. Scores of trees downed and uprooted, a huge steel billboard sign was bent nearly 90 degrees and power was out till nearly midnight.

There have been several tornadoes in and around my area of the high desert / Antelope Valley, several of which occurred while I was away in Oklahoma interestingly enough!

Joel, do you have photos of those AZ tornadoes??

Talking about the Monsoon, might not be the official start of it yet, but an interesting pattern change may be in store for the West heading into next week! Very strong/cold upper trough and 500mb closed low with temps possibly A.O.B. -20 C progged to dig into the West Wed-Thu-Fri. Just posted a fcst thread about it.
Actually the first remarkable monsoon lightning I ever saw was in the California deserts around Indio at 4:30am, in 1994. This was after being pounded by intense CGs for hours in the Inland Empire. I recall the heavy storms started around 11pm. That night was my first taste of monsoon. Although the Sonoran, Plateau and Arizona high country gets the lightshows with more frequency, that night in LA was rockin'.

Preference-wise, I like the new calendar system over the 55 3x. Perhaps the date will eventually seep into public consciousness and serve to boost preparedness. Not everybody is into weather and thus may not track dewpoints. Outages, flash floods, extreme wind, sandstorms, microbursts and CGs will be coming so if there is a hard & fast date, it might remind people that violent weather season is coming up. Funnel clouds are also not out of the question.
Had another interesting customer at my retail business two days ago. He's a long-time railroad engineer (he drives the trains...not the geeky type of engineer..lol) and last monsoon season he received verbal instructions to slow his train to a dead stop and just wait. This was near Benson, Arizona (southeast of Tucson). It seems that there was tornadic activity near there, and a tornado actually crossed the tracks ahead of him!
Another railroad engineer who came into my business told me basically the same story...he had to slow to a stop, and wait a couple of hours without moving..because there was tornadic activity down the rail from where he was at the time. This episode was near Gila Bend, Az.
Kinda cool, huh? Well, we all KNOW that REAL tornadoes NEVER hit in Arizona....lol.

I can't speak for anyone else, but I've never believed tornadoes don't occur in Arizona, or any state for that matter. But while we're on the subject, I've never seen a photo of an Arizona tornado. Should would be cool if you could throw one of yours up here. That's a rare gem, as far as tornadoes are concerned.
Shane's right, "no AZ tornadoes" is a myth.

Here is a list of AZ tors:

Of note is one on Aug 30 1971 F2. I read about that one-it occurred in Tempe; 41 people injured by flying glass and one hundred homes damaged. I live in Maricopa County. Phoenix is also in Maricopa County.

Another one sounded like serious business in Tucson June 23 1974. One fatality and 31 injuries when trailers were destroyed.

One storm I chased back in ’97 spawned 3 funnels near Queen Creek, Arizona.

Things can get funky aside from tornadoes. One August 14, 1996 a wind speed of 115 was recorded north of Phoenix at the Deer Valley Airport. That particular severe storm was noteworthy, causing $160 million in damage.
OK, it's June 15. Where are those lightnings?! ;)

Admittedly, we do have some weak scattered storms blowing up from Mex into extreme southern-central Az. south of Tucson. It's a start!

Forecasts are not offering hope for much more, although the tongue of moist air is scheduled to continue sneaking N. from the Organ Pipe area for a day or so. After that, the models show at least another week of hot, dry misery. :mad:
No Monsoon Here...

I can tell you, being a native of arizona (born & raised here in Phoenix since 1969), that our weather pattern here in Metro Phoenix has changed. When I was young we would get strong powerful storms fairly regularly (much like Tucson gets now). But since the urban sprawl, we have developed a "heat shield", which essentially tears many storms apart before they can reach the city. Last year we recorded less than 1" of rainfall for the entire monsoon season. I think I will have to hit the outskirts of the city or head down to Tucson for any action this year, which I think won'tl happen until mid-July, maybe a dust storm on the 4th. :D

Team Remora
Hey all! I haven't visited this forum since quite a while ago. Kinda forgot about it.
I've lived on the far northern outskirts of Tucson since '61, so I've seen a few monsoons. Pretty much anymore...I tell people that the full-on monsoon doesn't really get going until the 3rd. week of July. Oh for sure...we can get teased with some action prior...but it just seems to me that the really strong flow of moisture from old Mex. doesn't really become entrenched until then.
Gawd, I sure hope we have a good one this year. We've got our own water well where I live...and we're already fightin' water now. As always, my scrawny little trees and bouganvilla bushes are looking pretty damn tepid...AGAIN.
But...that's a small price to pay to live side-by-side with Rattlers, huge Tarantulas and Cougars. lol.
Please folks...pray for rain.
Tucson's DP broke 50 for a few hours today, and is predicted to hover near 40 for the next few days. This is enough to generate some high based convection over the mountains. The clouds - ANY weather - is welcome! Lightning sparked a small fire in the the Rincon range Sunday. Woo-hoo!

Forecasts don't show a huge improvement over the next few days. Even the extreme SE corner of the state, usually the first area to enjoy the moisture, will remain no less dry than us to the north.


LOL - so much for forecasting by DP! It went and rained last night!
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Well I was going to post a new topic but its just a quick question I have. Has there ever been a Moderate risk in Arizona? I lived there in Prescott for 12 years but wasnt super into weather , let alone SPC. Then I got into it and moved to Oklahoma =). If not moderate days are there often slight days there?
We get a handful of SLGT RISK days during the monsoon season. It really depends on how strong the season is; that's a major variable. The risk is almost always for high wind, with the occasional hail threat.

I was coming back to this thread to say that this afternoon has seen a +10Td surge and now PHX has a 10% chance for thunderstorms tonight. Scattered storms are up southeast of the metroplex.
I just came back from my first chase of Monsoon 2008. I followed a lightning/CG-heavy storm in the Sonoran foothills and tried to stay close enough and far enough at the same time. This is early, 6/25 historically is a couple weeks before most Phoenix action gets started. Javalinas (like wild pigs) were out and about, roaming around in the dark nearby. I'll see what kind of storm pictures resulted soon.

Nice to chase late June. It has started this early before. Tonight's lightning though set a salt cedar grove on fire in southwest Phoenix and the blaze is not contained because so much fire equip is tied up right now in Calif. Homes are being threatened right now so that is not a good lightning legacy for tonight. Pray nothing happens. The fire muddied the whole sky over Phoenix today.

The last time a June storm blew in this early was a few years ago and I caught these bolts in some desert mountains. The clouds are reddish because of the sand storm that was happening at the time.

Things were really cooking south of the border tonight. Moisture and higher dewpoints are reaching into Phoenix so there's another chance tomorrow as well...
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Thats great to hear Susan. I highly depend on that Monsoonal Moisture for thunderstorms here in Idaho. This High pressure I figured was gonna get things started quickly. Now if we could get some tropical systems to form off of mexico then things will really get brewing. I had some distant thunderstorms the other night, got 2 bolts but not worth showing cause they were soo far away. Looking forward to seeing your lightning photos.

Stay cool out there,,,,,,,,, Happy Chasing... =)

Normally I applaud the surge of monsoonal moisture up into the Sierra Nevada, as it provides us some pretty mountain storms and welcome clouds for a little heat relief. But the way it looks this weekend, it's just going to add to the little fire problem that NorCal has right now. Last weekend's dry lightning event started 600 fires...hopefully that won't be repeated this weekend, but I'm afraid it will be.

Trying to plan a little weekend trip out to PHX in late July to try my hand at this whole monsoon chasing thing. :D
I lived up north right off I-17... Cordes Lakes to be exact (Junky town). Gah now that I think about it there were always sick supercells building in matter of minutes at one point in the season and being almost central in the state they came from all directions =) Ill go visit my friends and chase all July haha hows that for ya. I love my job.
Brendon, are you sure those were actual supercells and not towering multi-cells?
And that town you lived in....is it near Prescott?? I know that what is known as Prescott Valley does get tornadoes. I've never chased up there.