Temperatures are a little cooler at 500 mb over the region, but warming has occurred at 700 mb. The temperatures at 700 mb are very hot over the Great Basin. Moisture has increased since yesterday in the Valley, but a Gulf surge apparently did not occur and dew point increases yesterday at YUM were probably associated with the overnight MCS in Mexico. We still are in a distinct McCollum Type II pattern, but lack the low level moisture to cause severe weather in the Valley. P chart of the 12 UTC sounding from Luke Air Force Base on July 28, 1994.
Wind speeds are in knots.
The small box indicates the location of Phoenix, and the Salt and Verde River Basins are outlined. This morning, a thin layer of cirrus covered the valley along with some mid level clouds to the northwest. Temperatures reached 109 at Sky Harbor before severe thunderstorms entered the Valley. Dewpoint temperatures increased dramatically after 1400 UTC, reaching 68 F at 200 and 2300 UTC - winds during this period were only 7 to 10 kts from the southwest to west. The most significant outbreak of severe thunderstorms occurred since the start of the project.