doppler radar mexico and southwestern united states

But if you look past the thermal lows and examine the isobar patterns, you’ll notice it paints out a much larger low-pressure area covering the western states. This is a thermal low, which often wanders over to Phoenix or up to Las Vegas. You’ve probably noticed the semi-permanent low that always sets up over Yuma, Arizona, in July. The strong heating in the deserts also leads to the development of a broad low pressure area at the surface, due to the low density of hot air. Combined with the lack of air-mass contrast polar jet formation is unlikely, so upper-level winds are usually weak. This helps produce an upper-level high pressure area, or an upper-level ridge that often persists for weeks. This results in widespread, slow-rising motion, on the order of centimeters per second on average, and transports lots of mass to the top of the troposphere. This is a testament to the vast amounts of heating that take place across all of the western states, from Washington and Idaho all the way to the border of Mexico. Adjusted adiabatically to sea level, this translates to a temperature of 118. But consider Salt Lake City, which reaches an average of 93 degrees in July and lies at an elevation of 4200 feet. We often think of this heating as being strongest in Phoenix, Las Vegas, and Death Valley. This changes with the seasons, so weather forecasting is categorized according to the time of year.ĭuring the summer, strong heating dominates the western states. This region has an average elevation of about 4000 feet and effectively radiates its heat away during the winter, making it a cold desert.īut to truly understand in detail how weather in the western states works, we must start with the temperature balance between the two great source regions: the Pacific Ocean and the inland desert regions. These mountains are also prolific generators of clear-air turbulence (CAT).įinally in between the Sierra Nevadas and Rockies is the Great Basin region, a vast plateau region stretching from Las Vegas, Flagstaff, and the Painted Desert northward to Spokane and Boise. These north-south barrier ranges are known for their orographic effects, as air masses flow across the wet windward side and the dry leeward side. We also have the Sierra Nevada and Rocky Mountains. It is shielded from the cold Pacific current, making it an important moisture source, mainly in the late summer when this moisture gets entrained in southerly flow and advects to Arizona and California. Measuring 700 miles long, this is found south of Arizona, dividing mainland Mexico from Baja California. It provides a powerful moderating influence on Washington, Oregon, and especially California, where it tempers summer heat along the coast.

This is because a large cold current originates from Alaska and flows down the coast all the way to Mexico year-round. If you’ve ever jumped into the water at a California beach, you know the water is rather cold. This produces powerful thermals that aggregate into convective updrafts. Due to the rock’s low specific heat, this radiation is put back into the atmosphere as heat through conduction. Incoming sunlight overwhelmingly hits rock and sand, which effectively absorbs solar radiation. This includes not only the Sonoran and Mojave deserts but the Great Basin Desert further north in Nevada and Utah. So let’s outline the important players.įirst is the vast desert region itself, devoid of much tree cover. Tall mountains, cold ocean currents, and hot deserts are all strong influences on the weather, and must be factored with the basic weather patterns themselves. Weather in the western states is heavily shaped by the effects of land and ocean. And the effects of climate change have also brought with it some new flying problems which we’ll discuss later. Forecast models have always had difficulty factoring in these effects. The landscape and nearby oceans complicate the forecast picture, so when things go downhill, things can get quite difficult. Most likely you’ve also done some cross-country trips in those areas and had no problems.īut this area is not without its hazards and peculiarities.

This is partly why the military has its air combat training centers in Arizona, Nevada, and California. Without a doubt, the western United States offers the best VFR flying in the nation. Southwest monsoon storms like this can pop up on the California-Nevada state line.

Doppler radar mexico and southwestern united states