2025 Arizona Summer Monsoon Discussions

  Synopsis Weak synoptic scale ascent combined with modest moisture and instability will generate scattered convection across Southeast Arizona (including Tucson) today. Main impacts from storms will be lightning, gusty winds, and brief heavy rainfall with localized flooding possible. Total precipitation is expected to be between 0.10 and 0.50 inches in the valleys of Southeast Arizona with higher amounts possible over the mountains. Current Conditions Visible satellite imagery overlaid with GOES GLM (Geostationary Lightning Mapper) flashes show scattered showers and isolated thunderstorms moving northward across Southeast Arizona this morning. Visible satellite imagery overlaid with GLM flashes courtesy of College of Dupage. The mid level low that has been anchored over extreme Southern California this weekend is finally lifting northeastward in response to a deepening mid latitude trough in the Pacific Northwest. In addition,...

Synopsis The synoptic scale pattern today is defined by the 500mb anticyclone (Monsoon High) well to the west of Arizona. Moisture and instability is expected to remain relatively modest today as the atmosphere is gradually recovering from several days subsidence. However, thermodynamics will be sufficient for convective initiation over the White Mountains and Sky Islands of Southeast Arizona this afternoon. Strong boundary layer mixing as well as significant dew point depressions will generate DCAPE values greater than 1500 J/kg, so strong outflow boundaries are likely. In fact, t he  Storm Prediction Center (SPC) has issued a slight risk of severe grade wind gusts (> 50 knots) in Southeast Arizona.  Current Conditions 12z 500mb analysis this morning displays a 594 dm anticyclone off the coast of Southern California, a horizontal shear axis extending from Central California into Southwestern AZ, and northeasterly/easterly flow in Southeast Arizona. 12z GFS 500mb...