July 3rd - Hot And Dry

Yesterday was almost a totally down day. There were early, very high-based buildups over the Catalinas around 9:30 am - these produced virga and a bit of thunder. Katie heard thunder here at house about 9:45 am. These buildups moved off to the southwest and that was it. The WRF-GFS forecasts yesterday were considerably less active than the WRF-NAM forecast, but were still an over-forecast. There were no reports of rainfall in the ALERT network during the past 24-hours. The TUS sounding from 5 pm yesterday is shown above - the sounding has almost no CAPE and only 28 mm of PW. The PW values continue to be holding around 30 mm at the Univ. of Arizona GPS site, except when storms were moving overhead - a time series for the last 7 days is shown below. I'd really like to see PW up around 40 mm or higher for significant, heavy thunderstorms. It is interesting that the old NWS start definition for the monsoon (3 consecutive days with average Td of 54 F or higher) has not yet been met. Today's morning sounding (the Fourth) is similar to yesterday's. I do note on the standard level charts very hot temperatures and a distinct trough to our northwest below 500 mb. With 500 mb temperatures holding around -7 to -8 C the thermal instability will be substantial - not good news for fire fighters.

The early WRF-GFS forecasts another totally down day for most of southeast Arizona. Above graphic shows total rainfall through 6 am tomorrow. I will check the 12 UTC forecasts and watch the PW values later today, since their is always the possibility of a model zig-zag from yesterday to today

The IR image below is from 1330 UTC this morning. Note that Dalila is almost gone. This storm remained very compact during its life and didn't impact the southern end of the GoC. The remnants of an Mexican MCS have moved over the north-central GoC. Outflow from this convective system has moved into southwestern Arizona - note the higher dewpoints and strong, south-southeast winds at Yuma this morning (bottom). The next tropical storm is just at the right side of the image.