20160617

I'm doing a post today as the WRFGFS is now starting to show increasing moisture and some storm activity by early next week.   At this point, confidence in the forecast is low as only the WRFGFS runs out far enough to cover the period in question and run to run consistency of the location of convection and intensity is poor.   However, the last few runs do advect enough moisture into parts of the to support convection by Monday.

A narrow strip of moisture is present across south central/SE Arizona and the resulting CAPE forecast indicates enough is present to support convection during the afternoon on Monday. 

The PBL is mixed deeply and the skew-t forecast for Tucson has a large inverted V signature thus very strong/severe winds are possible with outflows.  Tucson is in unidirectional easterly flow, unfavorable for storms here, but to the NW, flow is less unfavorable.  Additionally, moderate ENE flow is favorable for steering organized convection from the higher terrain into the lower deserts.

Convection does form by afternoon and moves to the SW, toward south central Arizona.

Very strong to severe winds associated with the outflow are possible.  As the previous day's forecasts are devoid of convection (and complexity) WRF can make fairly good long range convective forecasts.    Still, confidence in this particular forecast is low until this solution is mirrored by the WRFNAM (once it comes into the time range) and additional WRFGFS runs.

Moisture continues to trickle in and slowly increase throughout early next week and by Tuesday-Wednesday, enough is present to support isolated showers and storms over much of the higher terrain of Arizona.  Storms will be accompanied by very strong winds due to the continued high cloud bases/inverted V profiles.

 As a side note, some WRF runs are forecasting mid 90's lows for the urban areas of Phoenix on Sunday night-Monday morning as winds increase out of the SE during the night, keeping the lower PBL well mixed.