Big Storm Event Today In Phoenix?

Yesterday Atmo's early run of its high-resolution, WRF-GFS forecast model predicted the day's trend correctly for the third consecutive day. In eastern Pima County there were only isolated storms. The storms did produce some gusty outflows, Here at the house we had an outflow from the north during the afternoon and then a much stronger outflow from the south around dark - no thunder and no rain. Across the ALERT network only a bit over 20% of the higher elevation sites had rainfall - metro Tucson was pretty much suppressed except for a later afternoon storm south of the airport. Today the early WRF-GFS forecasts another substantial upturn of thunderstorm activity. This occurs as the 500 mb anticyclone is pushed toward the east because of a trough in the westerlies approaching the west coast. Winds become southerly to southeasterly aloft and increase in strength above 500 mb. Today I'll focus on Phoenix, since that's what the model forecast does (note that the new run of the NAM also seems to focus on Phoenix).

The model forecasts CAPE at almost 3000 J/Kg by mid-afternoon at Phoenix (above). At 3 pm MST (below) the GFS-WRF forecast of composite radar echoes has Phoenix essentially surrounded (good for converging outflows in the Valley), and substantial storms in eastern and central Pima County.

By 8 pm storms have exploded over eastern Maricopa County (composite radar at 8 above). The model forecast of rainfall through midnight is below - nice increase over Pima County, but serious rainfall predicted in the Phoenix area (bright red indicates over 3 inches!). If model has this right today - batten down the hatches in the Valley!