Models Forecast Huge Increase in PW

South view from Kitt Peak this morning at about 7:00 am MST shows high clouds at top right corner - these are approaching from the southwest.

Two forecasts, from the 06 UTC run of the WRF GFS on 5.4 km grid, of PW (in mm) shown here: Above is valid at 6:00 am this morning, while below is valid at 6:00 pm this evening. There is forecast to be a large increase (nearly tenfold) in PW during the day across southwestern Arizona. 

The moisture increase comes along with a significant precipitation event for southeast Arizona during the night. Forecast of QPF for TUS (bottom) is from the SREF system at EMC. The members forecast the event to produce most of its precipitation during the night tonight. The range in forecast amounts is from about 0.15" to about 1.20 " - very large spread, but most of members are clustered more tightly around the ensemble average of about 0.60". We'll have to watch the details as the event evolves today and tonight.