20160722, part 2

An active day is being forecast for Sunday as the surge continues to import high IPW into the state while the mid level high moves to an optimal location over the Four Corners.  The latest model runs (and NHC) have TS Frank moving a bit more to the west than previous forecasts, but the model runs seem to think it was close enough.  Disclaimer!  Be aware that confidence in this forecast is low as it's more than 48 hours out, the path of the tropical system is uncertain, and outflows need to converge in a specific way.

A moderate surge is underway on Sunday with IPW values increasing into the mid 30 to mid 40mm range. 

Mid-level steering is from the east to southeast as the high center is located over the Four Corners.  Wind speeds are still not great as they are only 10-15 knots.  Temperatures are also OK as somewhat cool air is present at 500mb.  It could be worse as -5C and warmer are on either side of the state.

CAPE is very impressive with up to 2000 J/Kg over southern Arizona. 

By late in the afternoon, scattered strong to severe storms are moving from the high terrain towards the deserts.

An impressive vertical profile late in the day at Tucson.  CAPE is high and low-level winds are strong from the NW providing excellent low-level convergence with the eastward propagating outflow boundaries - a tropical squall line situation.

Storms are producing strong outflows and during the early evening, they intersect over the Tucson area, providing the mesoscale lift needed to initiate deep convection.  Note the 15-knot inflow at KTUS.  There is a similar situation setting up for the Phoenix area.

Let the model speak for itself.

Outflows converge in eastern Maricopa and Pinal counties during the evening triggering additional convection in Maricopa and Pinal counties.