- Partly cloudy, slightly breezy
- Cooler and drier tomorrow through Thursday, highs in the lower 90s
- Chance of Thunderstorms minimal this week until Friday - Suday
- Deeper monsoon moisture expected to be in full swing next week, hopefully
Forecast Table:
https://www.wrh.noaa.gov/forecast/wxtables/
Navigate on the map to your location and click for a detailed local forecast.
Discussion:
With high temperatures pushing 100 degrees on Saturday and Sunday and morning – early afternoon dew point temperatures as low as the upper 30s each day, it was surprising that we were able to receive as much rain as we did this past weekend. The air was so hot and unstable that high-based, slow-moving thunderstorms were able to form and produce locally heavy rain, small hail and gusty winds. The airport only reported a trace of rain, and rainfall amounts from Dewey-Humboldt to PV to Chino Valley were all very light or zero. However, in and around Prescott, rainfall totals were in the 0.5” to 1.5” range.
Hot temperatures will continue today, but it will become slightly cooler and drier through Thursday as the winds at all levels become a bit more westerly. The chances for thunderstorms will therefore be minimal.
By Friday through the weekend, high pressure will rebuild over the Four Corners region circulate deeper monsoon moisture into Arizona. Thunderstorms that form over the weekend will drift toward the north-northeast at about 10 mph and be capable of locally heavy rain, gusty wind (from microbursts) and occasional lightning and thunder.
The North American Monsoon is such an enjoyable time of year, and my favorite time of year here in northern Arizona. After the dry heat of May through early June, when the monsoon moisture arrives the temperatures become cooler and it most often rains in the afternoon to evening. The storms usually first form over the Bradshaw Mountains south and west of Prescott or over the Black Hills or Mogollon Rim north and east of Prescott, then slowly propagate into the Quad City area depending on the wind and the shear of the wind with height. In some cases, the wind shear can be strong enough to support severe storms (multicells, or rare supercells) capable of producing larger hail and weak tornadoes. Flash floods, lightning, and gusty wind are the main hazards during the monsoon, however. It is important to stay indoors and away from washes when monsoon storms are in progress.
Monsoon rains are an important part of our climate, because they bring relief to the dry wildfire conditions and allow our forests to survive the heat of summer. When the moisture arrives, the cicadas start to buzz and the toads emerge from the mud. The vegetation greens up nicely and the smells of the vegetation and soil reacting to the rain are also very pleasant.
The word “monsoon” comes from the Arabic word “mausim” which means season. It is a seasonal wind shift that arises from temperature differences between oceans and continents. Normally, the prevailing wind across North America is westerly, but during July – September each year, the prevailing wind becomes more southerly and in some cases southeasterly because the continent is warmer than the ocean. This brings moist subtropical air across the Southwest, leading to showers and thunderstorms.
It appears that the monsoon could get into full swing next week, but the long-range forecast models have been wrong before!
Curtis James
Met Mail is an unofficial weather discussion and forecast transmitted once or twice a week via e-mail by the Embry-Riddle Department of Meteorology (http://meteo.pr.erau.edu/). Embry-Riddle offers an undergraduate bachelor-of-science degree program in Applied Meteorology. Please spread the word to all potential qualified candidates!
Further Information:
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Official National Weather Service forecast
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