UA WRF Forecast Discussions

  Synopsis A mid latitude trough is expected to continue to dig southeastward along the West Coast throughout the day today and eventually reach Arizona later tonight. This feature will allow 500mb heights to fall leading to much cooler temperatures as well as a chance for valley rain showers and mountain snow across mainly the eastern half of the state. In addition, UA WRF model soundings forecast a relatively shallow layer of instability (CAPE on the order of 100 to 300 J/kg) tomorrow across the region, so an isolated low-topped thunderstorm or two is possible. Rainfall amounts are expected to be light, with between a trace to 0.10 inches in the lower deserts, and between 0.25 and 0.50 inches over the higher terrain with highest amounts possible along the southwestern facing slopes of the Mogollon Rim and White Mountains. Snow levels will remain above 6000 feet with a trace to 6 inches expected with locally higher amounts possible over the tallest peaks.    Current Cond...

  Synopsis A mid level trough will dig southward across the Intermountain West today, and become anchored over Arizona as a closed low by tomorrow. This feature is expected to provide the state with cooler temperatures, windy conditions, and light precipitation chances. The majority of precipitation is forecast to occur over the higher terrain in Northern Arizona, but a brief period of showers and isolated thunderstorms are possible in Phoenix and Tucson tomorrow afternoon. Precipitation accumulations are forecast to be light with a trace to 0.10 inch in the lower deserts and between 0.25 and 0.50 inches over the higher terrain with locally higher amounts possible along the southwestern facing slopes of the Mogollon Rim and White Mountains due to orographic enhancement. Snow levels will remain mainly above 7000 feet with a dusting to 6 inches of accumulated snow possible with the highest amounts over the tallest peaks of the Rim and White Mountains.  Current Conditio...

  Synopsis A weak mid level low will dominate the synoptic scale pattern across Arizona this weekend. Today will likely be the most active day this weekend as Arizona will be within the northeast quadrant of the upper level low where synoptic scale forcing is maximized. Poor moisture will limit strong buoyancy this afternoon, but a dry subcloud layer will promote a risk for locally strong outflow winds and blowing dust.  There's quite a bit of uncertainty tomorrow regarding the extent/timing of synoptic scale forcing as well as the amount of instability. At this time, expect a chance for scattered showers and thunderstorms across mainly the higher terrain with isolated chances in the lower deserts. By Monday (Labor Day), the upper level low is forecast to lift northeast with the 500mb anticyclone rebuilding across the Desert Southwest. This will lead to dry weather and increasing high temperatures next week, with some lower desert locations potentially reaching ...