Rest Of The Week

I will start with the short term, since there is already substantial high cloud around this morning. The water vapor image at 6 am MST this morning (above) shows that another area of mid-to-high clouds is intruding from the Pacific (see post from Sunday afternoon). The system that will eventually bring another storm event to the Southwest is currently spinning over the Pacific west of Oregon.

The WRF-GFS early forecast from Atmo (on the 5.4 km grid) indicates weak radar echoes across much of southern Arizona at 6 pm this afternoon (above). Thus, another chance for mid-to-high level buildups, virga, mammatus, and perhaps light sprinkles later today.

By late Thursday, the model forecast valid at midnight (below - again from the 5.4 km grid) indicates the west coast cyclone centered near San Francisco, with two major bands of precipitation to its southeast and a large area of precipitation over the Great Basin.

Edited to add: The Tucson Festival of Books is scheduled for this coming Saturday and Sunday and is to large degree an outdoor event (see   http://squidinkbooksblog.blogspot.com/ ). The timing of the next weather event and the Festival seem to be on a collision course at the end of the week!

The global models continue to handle the evolution of this event somewhat differently. Both the ECMWF and GFS forecast a strong front and showers Friday afternoon into Saturday for southern Arizona. However, the ECMWF has now become less progressive than the GFS, which clears the system eastward considerably faster. The 144-h 500 mb forecasts from the ECMWF (above) and the GFS (below) are shown here. These are the operational forecasts from 00 UTC last evening and are valid Sunday (10 March 2013) at 5 pm MST. The ECMWF forecasts a large closed low centered near Denver, while the GFS forecasts the closed portion of system to be over eastern Kansas. The GFS forecast trough is very positively tilted; much different than the ECMWF system. The forecast for the Front Range of the Rockies from Wyoming to New Mexico will be a challenge for Sunday.