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The official start date of the Arizona Monsoon season is June 15. In 2008, the National Weather Service determined the AZ Monsoon starting date along with the ending date of September 30.
storm clouds Monsoon season
What causes monsoon?
Traders sailing the Indian Ocean and Arabian Sea used the word monsoon to describe a system of alternating winds which blow from the northeast during the northern winter and from the southwest, during the northern summer. Therefore, the term monsoonrefers solely to a seasonalwind shift, and not precipitation.
Arizona Mexico Border storm clouds
Arizona happens to be located in the area of the United States that experiences a monsoonal circulation. During the summer months, winds shiftfrom a west or northwest direction to a south or southeasterly direction.
Microburst clouds during Monsoon
This wind shift allows moisture from the Gulf of California and the Gulf of Mexico to stream into Arizona. A monsoonal circulation produces a radical change in moisture conditions throughout the entire state.
Monsoon storm clouds over Coronado Mountains
Thunderstorm or cumulonimbus clouds are very familiar during monsoon season. These storm clouds cause lightning, hail and heavy rain.
dark thunderstorm burst clouds
What Arizona experiences during the summer months is only a small part of a larger circulation that encompasses much of the southwestern United States and northwestern Mexico. Thus, it sometimes is also known as the Mexican monsoon. The National Weather Service calls it the North American Monsoon.
Monsoon clouds Mexican Arizona Border
This adjustment in wind direction is the result of two meteorological changes:
the movement northward of the huge upper level subtropical high pressure system, known as the Bermuda High,
and the intense heating of the Mohave Desert creating rising air and surface low pressure, called a thermal low
Monsoon Storm clouds on top of mountains
The southerly low-level winds help to bring in moisture from Mexico. When this moisture encounters the higher terrain of Arizonamountain ranges, it gets lifted and forms thunderstorms.
Monsoon storm Coronado Mountains
Small driving factors such as: atmosphere interaction, land elevation, soil moisture and vegetation all play a part in what drives the Arizona Monsoon; but it is also why predicting storm intensity is so difficult.
When such high volume rain descends upon the Arizona desert the ground and the surface streets flood. Quite often the rain pools on streets during monsoon storms causing dangerous driving conditions.
Storm burst clouds at Arizona Mexico Border
The monsoon circulation does not produce thunderstorms every day during the summer months, but rather monsoon storms occur in a pattern known as “bursts” and “breaks”.
Monsoon microburst cumulus cloud
This cycle of bursts and breaks will continue from the onset of the monsoon (typically June), until the time when cold fronts begin to move across the state of Arizona (typicallySeptember), which will return our winds to a westerly or northwesterly direction.
We hope you enjoyed this article. Our goal was to make Monsoon Season easier to understand.
One of Arizona’s most majestic, lovable desert cactus plants is the Saguaro,Carnegiea gigantea. Being aware of the saguaro’s history and incredible internal design, it is an honor to walk close to the Giant Saguaro that is over 150 years old and standing tall.
Giant Saguaro Cactus of Arizona
These desert cacti are large, tree-like columnar cacti that develop branches (or arms) as they age.
Saguaro Cactus can not tolerate freezing temperatures in the winter and this is what limits their range.
Saguaro Cactus
Saguaro FACTS: Saguaros are a very slow growing cactus. A 10 year old plant might only be 2 inches tall.
How tall can a Saguaro Cactus grow? It can grow 40 to 60 feet tall.
Saguaro Cactus on Mica MountainA Tall Saguaro Cactus
Below are Saguaro cacti at the bottom of Mica Mountain in Saguaro National Park.
Mica Mountain Saguaro National Park
Saguaro cactus roots are only 4-6 inches deep and travel out as far from the plant as it is tall. There is one deep tap root that extends down into the ground.
A Saguaro Cactus can gather enough water through its remarkable root system, duringa significant rain, to last a year!
Holes in Saguaro Cactus for birds nest
Why are there holes in the Saguaro Cactus? The gilded flicker and Gila woodpecker excavate nest cavities inside the saguaro’s pulpy flesh.
Birds nesting in the Arizona Saguaro Cactus
Cactus Wrens are common birds that live in the holes (nests) of the Saguaro Cactus.
Saguaro Cactus Flowers bloom, then turn to fruit
When a saguaro reaches 35 years of age it begins to produce flowers.
Saguaro cactus Bloom – Flower
A Saguaro can only be fertilized from a different cactus – cross pollination. Only a few bloom each night awaiting to be pollinated and close by late morning.
red fruit on Saguaro CactusA living and dead Saguaro Cactus.
Because the major part of a desert saguaro cactus is made up of water, an adult plant may weigh 6 tons or more. This tremendous weight is supported by a circular skeleton of inter-connected, woody ribs.
After the saguaro dies its wood ribs can be used to build roofs, fences, and parts of furniture. The holes that birds nested in are called saguaro boots.
Saguaro Boot used by Native American
Native Americans used saguaro boots as water containers.
Saguaro Cactus next to a biker to compare the size
Saguaro branches normally begin to appear when the cactus reaches 50 to 70 years of age.
The average life span of a saguaro is approximately 175 years of age. Experts have estimated that a Saguaro Cactus with more than 5 armscan be 200 years old.
Yellow Palo Verde Tree is a nurse tree
Young saguaro cacti can be very hard to find because they grow under the protection of a “nurse tree”. The nurse tree releases nitrogen in the soil which the Saguaros and other desert cacti use to grow healthy and strong.
Saguaros sometimes grow in odd shapes or forms. The growing tip of the cactus occasionally produces a fan-like form which is referred to as crested or cristate.
Cristate Saguaro Cactus
These crested saguaro cacti, Carnegia gigantea forma cristata, are rare. Biologists are not sure why these Saguaros grow this fan-like shape.
Crested, Cristate, Fan-like Saguaro Cactus from AZrare Saguaro in Tucson
Arizona has strict regulations about the harvesting, collection or destruction of The Arizona Saguaro Cactus. It is illegal to harm a Saguaro in Arizona. During building or construction, precautions must be taken to move every saguaro that may be affected.
Arkenstone Cave was discovered near the RinconMountains of Southeastern Arizona in the 1960’s. This livingcave is protected by the county and accessible only to a few scientists and researchers.
Arkenstone Cave in Arizona
We have spent a great deal of time investigating information regarding Arkenstone and La Tetera Caves. Our most important finding has been the fact that Pima County regards these living caves as treasure troves of precious, immeasurablescientific information.
Access is extremely limited; but a visit to Colossal Cave Mountain Park Museum can provide the curious with results of the past and latest research conducted inside Arkenstone Cave.
Here are some of the research highlights provided from the Museum Caving Rooms at Colossal Cave east of Tucson, AZ.
Arkenstone Cave is used for research
ARKENSTONE is an active KARSTCAVE, which means the breaking down of limestone has produced fissures, sinkholes, caverns and underground streams.
Most caves are formed in limestone. Simply put, it dissolves from precipitation mixing with carbon dioxide and the decaying organic material in the soil. This dissolution process is extremely slow. Thousands upon thousands of years!
Arkenstone, La Tetera and Colossal Caves are located in Colossal Cave Mountain Park, Arizona. Colossal Cave is dry and considered a dead cave. La Tetera and Arkenstone are alive and adorned with calcium carbonate formations produced through slow precipitation.
Arkenstone Cave Crystal formations
Mineral deposits in caves are called SPELEOTHEMS.
ARKENSTONE CAVE is called:
a WILD cave
a WET cave
a LIVE, “active” cave
What does this mean… A wild cave has no provisions for the general public and is dangerous without expert equipment and experience. A wet cave has precipitation.
Tower Coral, crystal formations on the floor of Arkenstone Cave
A live cave has life forms, insects, faunal, animal, species and unusual speleothems.
Pima County and Colossal Park employees have an overwhelming desire and responsibility to protectLa Tetera and Arkenstone living Caves.
species found in Arkenstone Cave, Colossal Mountain Park, AZ
Several new species have been found in Arkenstone that are endemic to Arkenstone, meaning they only exist in Arkenstone Cave. A few researchers have special grants to work in these living Arizona Caves.
In recent years, 7 new species of fauna have been found. The Arkenstone Cave exhibit at Colossal Mountain Park Museum gives detailed descriptions.
research at Arkenstone Cave
Animals that live in caves are often put in the category called TROGLOBITES. Troglobitic species tend to be very unusual organisms. For example, they may have loss of pigment or no eyes. These characteristics would be adaptations to their subterranean life.
Pseudoscorpion found in Arkenstone Cave
A previously unknown species of pseudoscorpion was discovered in Arkenstone. The pseudoscorpion has since been listed as one of Pima County’s priority vulnerablespecies!
Bat Bones found in Arkenstone Cave
A small, late Quaternary, (about 2 million yrs ago), deposit of degraded bat guano (poop) in Arkenstone Cave yielded thousands of fossil bat bones.
Arkenstone Cave Exhibit and research
Rarer bones in the deposit represent a smaller species of bat (Myotis) and the extinctvampire bat Desmodus stocki.
This is the first record of D. stocki in what is now the Sonoran Desert and the second location for the vampire bat species in Arizona.
Extinct Vampire Bat found in Arkenstone Cave
Due to leaching in the alkaline cave environment, the bones could not be dated by radiocarbon, but the fossils probably date to the late Pleistocene Age — (Late Pleistocene Bats from Arkenstone Cave, Arizona by Nicholas Czaplewski and William Peachey, December 2003)
The Late Pleistocene age was dominated by glaciation Many larger land animals, MEGAFAUNA, became extinct over this ICE AGE. Experts estimated that 30% of the Earth’s surface was covered by ice. Pleistocene vampire bats most likely were capable of surviving in cooler temperatures than the modern bats of today.
The extinction of Desmodus stockiparalleled the extinction of the megafauna.
Photo of Earth during the Ice Age, The Pleistocene
Research indicates that Arkenstone Cave was the site of a maternity colony of Myotis thysanodes. Myotis thysandoes is a larger species of bat, mammal. These bats begin nursing colonies, female nurse bats remain at the roost while other adults are out foraging.
extinct vampire bat, Desmodus stocki
Virtually all of the bones collected were of that species. Remains of Desmodus are consistent with a single individual, and those of a small Myotis (bat) consistent with two individuals (Czaplewski and Peachey 2003).
Arkenstone Cave discovery of extinct vampire bats
Desmodus stocki was 20% larger than the still extant common vampire bat. Lets put aside the scary name, VAMPIRE, and let me share some benevolent behavior of Vampire Bats that may gain your admiration for the Pleistocene bat, Desmodus Stocki.
Vampire Bats are one of the few animal species that show caring behavior for those beyond their family group. They even adopt orphaned bats and will share their food. Look at the photo above for more altruisticvampire ways. 🙂
common vampire bat skull, teeth
Scientists state that fossil records of Desmodus stocki are uncommon because these bats mainly roosted in hollow trees and any remains would decay along with the wood.
new species found in Arkenstone and Kartchner Caves
A new species of Nicoletiidae (Insecta: Zygentoma) has been discovered in Arkenstone and Kartchner Caves. This species pictured above lives in deeper areas of Arkenstone Cave than it does in Kartchner.
The 2 caves are approximately 23 miles apart and in isolated Karst areas with no possible connection to each other.
Caves at Colossal Cave Mountain Park
You would think that these would be different species? But so far the research shows they are the same. How amazing is that?
Arkenstone Cave
Cave species are very fragile and some live in a specific cave and no where else in the world. These TROGLOBITES are accustomed to a near constant temperature and humidity. Even the slightest disturbance can disrupt the life cycles of these amazing species.
Crystal formations in Arkenstone Cave
As updated research becomes available we will add new articles.
fringed myotis is found across the western United States.
The fringed myotis is found across the western United States. It has been found as far east as the Trans-Pecos region of Texas during summer months, as far north as British Columbia and as far south as Mexico.
The fringed myotis is found across the western United States. It has been found as far east as the Trans-Pecos region of Texas during summer months, as far north as British Columbia and as far south as Mexico.
