UA WRF Forecast Discussions

  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 ...

  Overview: The area continues to be under an unusually amplified flow pattern with a deep upper-level trough centered over California and a strong ridge of high pressure stretching from the Southern Plains to the Canadian Prairies. Broadly speaking, this places the Intermountain West in a region of upper-level cyclonic vorticity advection which should support scattered thunderstorm activity from southeastern Arizona into central Colorado. While southern Arizona is close to the southern extent of the West Coast trough, the right entrance region of an upper-level jet streak should aid in upper-level divergence over southeastern Arizona today and to a lesser extent tomorrow. In the meantime, drier air in the southwesterly flow ahead of the upper-level trough is settling into Arizona from NW to SE over the next 48 h which should limit convection to areas east of the Tucson Mountains. Destabilization in the valley locations of the Tucson metro area today will be somewhat problematic du...

  Synopsis A mid latitude trough is expected to deepen along the West Coast today causing broad mid level flow to turn southwesterly across Arizona. Another embedded shortwave is expected to lift northward across extreme Southeast Arizona and combined with sufficient thermodynamics will promote a chance of showers and thunderstorms mainly east of Tucson this afternoon and evening. Main impacts from storms will be strong winds, hail, and brief heavy rainfall. SPC has Southeast Arizona in a marginal risk for severe grade wind gusts and hail today.  Today's Forecast Synoptics/Dynamics The broad synoptic scale mid level pattern is characterized by a deepening mid latitude trough off the Pacific Coast, a high amplitude ridge over the Plains, and brisk southwesterly flow across Arizona. 12z GFS 500mb cyclonic vorticity valid for 5PM MST this afternoon courtesy of Tropical Tidbits. Zooming in, there's an embedded shortwave expected to lift...

  Synopsis Mid level flow is gradually turning southwesterly today as a mid latitude trough deepens along the West Coast. A subtle, embedded shortwave is forecast to lift northward across the Eastern half of Arizona this afternoon/evening and combined with sufficient thermodynamics will support a chance for showers and thunderstorms across the region (including Tucson and potentially Phoenix). Main impacts from storms today is strong wind gusts, blowing dust, and heavy rainfall which could lead to localized flooding. Current Conditions Mid level water vapor imagery this morning showed a high amplitude ridge over the Great Plains, a plume of moisture across the Eastern half of Arizona, and drier air beginning to move in from the southwest. Mid level water vapor imagery as of 9:45AM MST courtesy of College of Dupage. Arizona remains in between two large synoptic scale features which are a deepening trough off the West Coast and a subtropical ridge over t...

Synopsis CAMs forecast an active afternoon and evening across much of Southeastern Arizona as an inverted trough moves northward across the region. The amount of buoyancy and associated storm coverage and intensity across the area will be primarily dependent on mid level cloud cover throughout the day. If clouds can clear by early afternoon, strong storms are possible across Southeast Arizona (including Tucson), but if clouds persist then there will likely be much less activity. Storms that develop have the potential to produce strong winds, blowing dust, and heavy rainfall that could lead to flash flooding.  Current Conditions At 9:45AM MST, visible satellite imagery and lightning detection displayed scattered showers and thunderstorms in Southern Arizona (south and west of Tucson) associated with a robust MCV. Visible imagery overlaid with glm flashes courtesy of the College of Dupage. The broad synoptic scale mid level pattern remains quite busy wit...