Thursday, April 07, 2016

Event Off To A Cloudy Start This Morning

The MIMIC PW product for 11 UTC this morning shows the northward intrusion of the broad region of subtropical moisture that the models have been forecasting for a number of days now. There are already virga and mammatus over parts of our area, as north view from campus shows above. 

Various models continue to forecast 100% POPs of measurable precipitation over the airport and indeed all of Pima County. However, the 06 UTC run of WRF-GFS forecasts generally light amounts across of all of Pima County, except for a narrow, south to north band with 0.25 to 0.50" amounts out to the west. There are considerable differences between the GFS and NAM versions of the Atmo WRF model for Cochise County. 

The GEFS range of forecast rain amounts at TUS is even larger this morning than it was yesterday - so much for increased model consistency as the event begins. The current NWS forecast below continues to forecast only a 50% chance of 0.01", or more, at the airport after 5:00 pm MST this evening.

Basically, we are now in the time frame where we just sit back and watch what actually happens.

Although PW in the TWC sounding at 12 UTC was only 13.5 mm, the WRF-GFS forecasts double that by evening. The forecast of composite radar echoes above is valid at 8:00 pm MST this evening. The echoes are strong enough, that when considered with the forecast skewT valid at same time, indicate some chance of thunderstorms later today. 

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