Prediction: Arizona Monsoon Season Start Date

For those chasers in AZ, we are probably waiting for the start of the AZ monsoon season. Although for a few storms last week it seems that the season still hasn't shifted into gear. It looks dry for another week. So, the question I would like to pose is for when you think the monsoon season will arrive in Tucson?
Thought it might be otherwise a few weeks ago, but it's really sucking rocks (literally) now. By the usual local definition my guesstimate is July 15th, and it won't start out strong.
I had two really good nights last Wednesday and Thursday in Scottsdale. I chased until 2am last Wednesday. Although it was literally a CG fest for hours, technically these were pre-monsoon.

I'll go with 7/13 for the PHX metro. That was the night of the first real blow up for PHX last year. At 6pm I started in the Central Deserts, and wrapped up in the McDowell range at around 2:30am. Fantastic chase 7/13/04.

Where in Arizona are the preferred target areas for lightning during monsoon season? Also, what time of day do they usually originate?
Hey all. I've lived in the desert northwest of Tucson since the first grade....which was 1961! I've been a wx. freak ever since then, and the monsoons (or NONsoons as I often call them) have been the one thing that's made this desert life halfway tolerable....that and chasing for 2-4weeks in my native Nebraska and the rest of the alley every year for about 20 yrs.
I've come to tell people that ask me that I really consider it an annual safe bet that the monsoons really don't get going strong until the 3rd. week of July. Yes, certainly...we'll get some earlier starts than that, but what we're more likely to experience is a series of "teaser storm days" that begin around the first week of July. These teasers days tend to offer a couple of days a week with storms...prior to the REAL start as previously mentioned. And....these teaser days early in July basically only hit the southside of Tucson with storms.....they don't really push up to thru to the northside and beyond until further in July. Also....those first teaser day storms of the season will usually start with a bang....I.E. the southside gets blasted with a huge dust storm and 70-80mph winds. It's not unheard of to have reports of funnels during this period, however.....I've tornado chased Arizona quite a bit as well....and there is a very small window for monsoon tornadoes...and that's the very last part of August and then however long the monsoon continues thru September.
If anyone is interested in hearing about central / southern Az. tornadoes and the associated "mini-alleys" within this area....I've got the skinny. Feel free to respond, and I'll fill you in.
Joel Ewing
Jay.....were you out chasing this past May and into June? Did you and I meet somewhere in the alley. I remember meeting some gentleman from southern Cal somewhere out in the alley a few weeks ago. It might have been in southeastern Colorado, or the Texas panhandle...or even southwest Kansas...near Hugoton. Was it you?

At any you ever "work" Arizona during the monsoon? I'll tell's really tough going...and there's rarely any advance notice of tornadic severe prior to the event. Oh sure, you can get some wicked butt-kickin' storms.....but naders.....they're pretty rare. But not as rare as one might think.
Originally posted by Jay Press

Where in Arizona are the preferred target areas for lightning during monsoon season? Also, what time of day do they usually originate?

Hi Jay,
Lightning can strike in any part of the state, however, there are a few places where lightning is more prevalent.

Here is a bit of monsoon info for those who have a week or two to experience chasing it:

Monsoon season: 7/7 - 9/13 give or take

What to expect: Sporadic activity in a burst and break pattern.

Weather features:

High winds to 57 mph plus. The plus is key here. A top wind gust that I remember was taken at the Deer Valley Airport in Phx, I believe in 1996, clocked at 115mph. There was a lot of damage that day in the metro area. Microbursts also occur with the collapse of the thunderstorms, leading sometimes to lines down, trees uprooted and structural damage.

Sand and dust storm known as "haboob". Seen pictures in the Middle East? Same thing. Wait until it passes, the sky will clean up and chasing will be better.

Lightning. Type: Branchy, wild, unpredictable CGs, CAs, CCs. The forest service warns hikers in the Chiricahua mountain range in SE Arizona with a small lightning index sign mounted in their visitors center. The scale ranges from None to Constant. I have seen Constant a handful of times. Arizona's lightning is all over the place, often from high based thunderstorms in extreme desert heat. Twice I have photographed bolts from the blue, reaching for miles (go to my gallery if you want to see them on, Gallery, then the images "bolt from the blue" and "caprice") Unpredictable stuff.

High heat. Desert air temps go from about 105-115 F degrees in the summer, with the ground temps much hotter. There are three things you'll need to bring in the desert...water, water, and water 8) In the open desert (non urban areas) the temp will drop 15 degrees at sunset, and another 15 or so over the course of the night.

Speaking of water, monsoon rainfall is isolated but torrential. One part of a city can get inches and street flooding, the other part stays dry. The cloudbursts are very obvious.

Flash flood. There's a law out here...literally called the "stupid motorists law". In some cases, if you get yourself stuck in flash floodwaters, you may have to pay for your own rescue. That's a couple grand at least to wait it out. Don't forget the contents of flash floodwaters are a veritable milkshake of dirt, brush, thorny plants, critters, cactus and barbed wire ranch fence. Just let the thing recede or turn around and find another way!

Tornados are rare but not out of the question. Generally though, the above are the prominent features of the desert monsoon. It can get pretty wild, and it also can stay calm for a few days. I chase mostly at night, and it is kinda nice not having to worry about funnels dropping in the dark and large hail that can't be seen. This aspect of Plains chasing is much more dangerous. I can work around the monsoon features at night, and it is nice not having to worry about large hail.

Here are some of my favorite places to lightning chase:

The Lower Verde Valley. This area includes Rio Verde, Fountain Hills, Cave Creek, Carefree, McDowell Mountain Range. Terrain: Upper Sonoran Desert foothills and mountains. Prominent feature - 8,000 ft Four Peaks Wilderness, giant Saguaro cactus, Mazatzal range to the north, Superstition range to the east, Saguaro Lake. This is part of the Tonto Natl Forest, and one of the areas I chase regularly. Distances are vast. The TNF alone is the size of Connecticut.

The Verde Valley and Prescott, Camp Verde, Black Canyon City. These are north of PHX heading up I17 toward Flagstaff. Terrain: Upper Sonoran Desert foothills and mountains. Very dramatic scenery and vegetation.

The Central Deserts. This includes Casa Grande, Maricopa, Stanfield, Eloy, Marana. Terrain: Wide open desert with valleys and jagged mountain ranges. I often start out there and work my way north. Visibility is awesome and there are services along I-10.

SE Arizona from Tucson east to the Chiricahua Mountain Range. I would chase the I-10 corridor near towns such as Benson, Willcox, Tombstone. I would definitely stay away from the border and towns along the border due to border running, crime and political problems. Terrain: Lower Sonoran Zone, desert to yucca and prairie grassland with very pronounced sky island peaks (such as Mt. Graham at almost 12,000 ft). Lightning prospects very high here, area gets a touch more moisture than other areas. Do be careful though when chasing anywhere in the southern part of the state until the border issues are resolved. It is serious stuff down there.

Another favorite - Payson to the Mogollon Rim. The Rim is the edge of the Colorado Plateau. It is a massive landform - a shelf of 1000-2000 foot cliffs that stretches SE-NW across the state, generally. This would offer extremely dramatic terrain and overlooks for alpine chasing in Payson, Pine, Strawberry, Heber, and the Apache-Sitgreaves forest lands. Advantages: cooler temps, incredible country. Disadvantages: storms build during daylight more often - bad for lightning photography, trees can obstruct view depending, and smoke from wildland fires might be present. Still, those issues are minor compared to the gorgeous scenery and storm prospects. Watch for elk while driving (really, they are huge and plentiful).

I also enjoy the Superstitions - Lost Dutchman state park, Apache Junction, Queen Valley to Superior. From there, you start to climb. It is a windy, two-lane mountain highway to Globe and beyond. Can be very generous lightning-wise!

The North Rim of the Grand Canyon is also a lightning hotspot in the state.

Time of day for Monsoon chasing in general - I start about 6pm and can run until 2-3am if storms are about. Monsoon chasing is an evening activity if you're going for the lightning.

Have fun!
Thanks Susan, this will help a lot. Pretty detailed stuff that only a local would know... Do you think that tools like wxowrx or swiftwx help out there?


Yes, I'm from CA and was chasing in the panhandles with my brothers around May 10-15. I have never been to Arizona but would like to check out some boltz there this summer...
Jay, I'm not Susan, but I stayed at a Holiday Inn once. Last year there was a similar thread... see:

I posted then
The Monsoon is a general term for a number of factors (some quite subtle) that combine in varying degrees during the summer season to produce convection. The various factors interact with the geography in different ways, though the mountains in general tend to initiate and focus the convection as you'd expect.

In my (non-professional) observation there are two basic categories: diurnal insolation-driven and disturbance-driven.

In the first, the convection responds mainly to sun heating. It will initiate over the \"sky-islands\" of Southern Arizona (Catalinas, Santa Ritas, Pinalenos, Huachucas, Chiricahuas, etc.) and on the Mogillon Rim ( around noon or a little after. It will then move off the mountains with the mid-level flow and cycle as multi-cell air-mass storms. As sunset approaches the storms tend to clarify and settle enabling those beautiful photo opportunities. Nighttime usually stables out surprisingly fast.

In the second, the multi-cells tend to coalesce into lines and into larger clusters with mesoscale and occasional synoptic scale disturbances. Last night in the Phoenix area was such a case, and you can still see the disturbance in the WV loop approaching Las Vegas this morning. Other than the occasional easterly waves the experts can see coming for a long time, these disturbances seem usually to be generated by the subtle upper thermodynamics of the \"Four Corners High\" mechanism that characterizes the monsoon flow. The disturbances seem to surprise everybody -- including the NWS. Watch for persistent linear storm formations perpendicular to and traveling with the flow for early warning. These tend to move smartly along, can occur at all times of the day (though nocturnal seems preferred), and are more classically chaseable.

WX-Works, SwiftWX, and the like should work for the more organized storms and not so well for the "popcorn" type up-and-down storms. I've noticed, and I think Susan might agree, that the better monsoon storm nights happen with the mesoscale disturbances.
The best lightning shows out in the west are generally associated with
large MCS's moving south out of Mexico. Timing is king. If the show starts
early -- then it's cloudy and overcast with reduced lightning chances in the prime PM timeframe. If the show occurs overnight (in Mexico) the next day is usually nuked because of cloud cover. If a MCS moves into the desert SW during peak heating in the late afternoon -- the show can be fantastic. In the ABQ region, some of the best summer lightning occurs as storms move off the mountain range.

Monsoon start date = 3rd consective day of 55+ Tds = ...July 16 for PHX/TUC.

I agree that the best storms have a little help aloft for organizing a strong line. Orographic storms often go early and peter out by the time it's dark enuf for lightning photography. Persistent orographic storms can cause flooding and make chasing a bit too exciting (AZ flow aloft is often quite weak during the monsoon). Desert floor MCSs are where it's at, what with their giant haboobs, longevity, and intense lightning.

Hopefully we have a strong monsoon. No one likes to chase a nonsoon...
It will initiate over the "sky-islands" of Southern Arizona (Catalinas, Santa Ritas, Pinalenos, Huachucas, Chiricahuas, etc.) and on the Mogillon Rim ( around noon or a little after.

Although I'd give half an arm to experience the monsoon, no ten wild horses could drag me anywhere near Mogollon Rim... especially not after dark! :oops: :lol:

Unless ofcourse Susan will hold my hand hehe :p
Actually I think I stood in the same place. I think it's granite not sandstone. Anyhow, look at gfs it looks like the dew points are starting to creep up on the 8th. I know it's a ways off but hey check it out.
Yes... it is starting to look like a poor monsoon for the SW. I have talked
to people out further west (Phoenix) and I'm often told the "good old days" are long gone -- when storms would roll into the valleys almost everyday. I wonder what large scale pattern change has caused this or is it global warming?

Could it be? Could moisture be making it into the state at last?

NELY flow can be the precursor to good SELY flow with the real juice. PHX Td is up from 33 earlier today to 48, and I see some upper 50s and even a 70 near the Sea of Cortez. Perhaps early next week the monsoon will be officially on.

Oh look; as of 10:16 MST the temp at Bullhead City was a measly 112F.
Well, according to some records, the latest date that the Arizona monsoon ever started was July 25. We're comin close!
I've lived in Tucson since '61, so I've seen all kinds of monsoons. To tell you the truth....this non-soon has got me scared. I think we're poked. This is eerie. And remember, the official "start" of the monsoon is not the first good thunderstorm's 3 successive days of 55 degree dewpoints.
I sure hope I'm wrong....but I am truly worried that we're not really going to have much of anything this season. And let me tell you.....this 'ol desert is just as brown as can be.....and we're in for a long long fire season.
Pray for rain.
Originally posted by joel ewing
I've lived in Tucson since '61, so I've seen all kinds of monsoons. To tell you the truth....this non-soon has got me scared. I think we're poked. This is eerie. And remember, the official \"start\" of the monsoon is not the first good thunderstorm's 3 successive days of 55 degree dewpoints.
I sure hope I'm wrong....but I am truly worried that we're not really going to have much of anything this season. And let me tell you.....this 'ol desert is just as brown as can be.....and we're in for a long long fire season.
Pray for rain.

I talked to a park ranger friend of mine who has been living in Arizona his whole life and he said one year things really got going but not until August and when it did, September as well was extremely stormy and rainy and there was some damage, pretty substantial activity. Actually, early September is my favorite time to shoot monsoon storms, many of my shots come from that time of year because late Aug/early Sept is after that mid-August break that typically comes and last a week or so.

All this waist-high chaparral we have out here this year is a result of very heavy winter rains. The fire season was going gangbusters during the month of June, esp with that big 250k acre Cave Creek Complex blaze in the Upper Sonoran desert foothill zone. The native desert plants - we want those - either stay green all year or lay down each summer. The brown ones you're talking about are the pesky non-native plants that grow like crazy in the spring then die out and sit there. They are not desert plants, they were brought here.

If the monsoon comes in another week or two that's ok with me, as long as it comes. I have had chasing until early October in the past. I still think it will get started here before the end of July.

There are towers with overshooting tops in Flagstaff today and up in the Mogollon Rim Country. Maybe I'll have something roll down the Beeline Hwy 87. Weather forecast on the radio today said that could happen, storms might come down off the Rim next couple nights. Pretty typical in the beginning.