Sunday, October 02, 2011

Fall Showers And Thundershowers Continue Today

It's a beautiful morning here in Tucson - as view of Catalinas a bit after 7 am MST indicates above. Shower and thundershower activity did return to southeastern Arizona yesterday, after a very suppressed day on Friday. Across the ALERT network a bit more than 25% of the 93 stations had rainfall. Amounts across all of southeastern Arizona were generally quite light (mostly less than 0.20"), however, most stations did have thunder. We had some very light rain and a rumble of thunder here at the house - only 0.01" in gauge this morning. Marshall Gulch in the Catalinas had 0.51"; while the Carr RAWS reported 0.50" and Rucker RAWS had 0.76". Most interesting here in the metro area was that another small, and quite localized, thunderstorm developed near the airport - Summit Elementary south of TUS had 0.91" and DM AFB to the northeast had 0.72" - airport however had only 0.03".

The small wave that went by yesterday may have been the middle-leval remnants of Hilary, but I've not gone back to try to verify that. Below is the morning analysis at 250 mb from NCAR - note that the subtropical jetstream is far south, over north-central Mexico and the subtropical ridge appears to be down around 20 degrees north. The subtropical mT air has also been pushed far south, with PW amounts of only 1.00 to 1.25" across southern Arizona and south past La Paz. So, we continue to hold on to just enough moisture here in southern Arizona to work with the continuing cool, middle-level temperatures to get some afternoon convection going.

This morning the Tucson sounding (above from SPC) appears to be a bit more favorable for convection, with CAPE values considerably increased from yesterday morning. The early run of the Atmo WRF-GFS model forecasts storms again today over southeastern Arizona. The total rainfall predicted by the model though midnight tonight is shown below. The new 1200z run of the NWS NAM forecasts are similar to the GFS-WRF. Perhaps we'll get a real echo over the house later today?

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