Hot Weather to Start Week
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07 August 2018
  Dr. Curtis James

Whew! Hot!

Forecast Discussion:

Last week brought some severe thunderstorms and flash floods to Yavapai County, especially with Monday and Thursday. On Monday, as you might recall, we had that squall line that moved through Southern Yavapai County and into the Phoenix area from the Mogollon Rim, causing many reports of wind damage and wind gusts up to 70 mph at Sunset Point and 74 mph at the Deer Valley airport. On Thursday, thunderstorms around the Prescott area produced rainfall rates up to 3” in 45 minutes and up to quarter-sized hail. The vertical wind shear wasn’t great, but the air was moist and very unstable that day, which made up for the lack of vertical wind shear. Plus, the light winds made for slow moving storms that dropped a lot of rain in some places. Flash flood warnings were issued, including for the town of Mayer, where a mandatory evacuation order was issued due to flooding along Big Bug Creek. An unoccupied vehicle was washed down the creek, but luckily no one was injured in the event. Mayer apparently had about 2” of rain in a short amount of time. 

Drying took place over the weekend, eliminating the chance for thunderstorms today. High pressure is now located overhead again, leading to much warmer-than-normal temperatures for today and tomorrow. As a result, of the dry and hot conditions, and the sinking motions within the high, the chance for thunderstorms today to tomorrow will be virtually non-existent, though a couple of forecasts for tomorrow are indicating a slight possibility for rain tomorrow. Areas below 4,000’ elevation are expecting high heat indices near or above 106 (which could lead to heat exhaustion/stroke), so stay in the high country these next few days! J

     Beginning Wednesday, the chances of precipitation gradually return as the upper-level high builds north of Arizona over the Great Basin and northeast winds begin to stream across northern Arizona. Meanwhile, moist airflow is expected to return to the lower atmosphere from the southwest, increasing the surface dew point temperatures once again into the upper 50s or lower 60s. This pattern will create good wind shear for Wednesday for the weekend, with the possibility for lines of thunderstorms to move into the Prescott area by mid afternoon to evening each day from the northeast at speeds of about 10 mph. Expect the potential for locally heavy rains, small hail, gusty wind, and frequent lightning with the storms that form later this week. This could be a wet monsoon pattern for Prescott from Wednesday or Thursday on. The Climate Prediction Center continues to predict that wetter-than-normal weather is more likely than not for the remainder of the monsoon, and the long range forecasts are indicating anywhere from 5” to 10” of additional rainfall across the Prescott area in the next couple of weeks. The predictions for above normal precipitation also extend into the coming winter season as El Nino conditions are expected to develop this fall. This is all great news to help relieve the drought conditions that we experienced early this summer.

     To monitor the past weather throughout the year, Dr. Mark Sinclair, Meteorology Professor here at ERAU, has created time series of observed weather on the Embry-Riddle campus for the current and previous day, month, and for the entire year  so far. We have two weather observing systems on campus, one that is adjacent to the RC field and one on the roof of the Academic complex. To view these time series, see the links at the bottom-left corner of our meteo website (http://meteo.pr.erau.edu/).

C. James