Monday, October 22, 2018

Mixed Signals Today

Today is one where forecast signals are mixed - but at this early hour towers are already bubbling up here and there. North view from campus captures bit of this and also shows thunderstorms to the distance north. Before sunrise I could see flashes to distant north from these storms.

All of the severe thunderstorm reports in the U.S. yesterday were from Arizona (above), including a landspout-type tornado along I-40 in northern Arizona (photo of this event below). Second below shows detected CG flashes (from Vaisala and Atmo) for 24-hours ending at 6:25 am MST this morning. A very active storm day for many parts of state - especially for October. The early morning storms to our north were mostly in Pinal County.

The ALERT rainfall data for 24-hours ending at 6:00 am this morning are shown above and below.  Amounts were all over the place, ranging from nothing measured to almost an inch. Here at the house we were mostly under anvils from the southwest. There was thunder and a few sprinkle showers that left behind 0.04".

Today is one with mixed signals, as I mentioned above. First, the 06 UTC WRF runs, plus this morning's WRF-RR forecast only limited activity over eastern Pima County today - this appears to be due to drying during the afternoon. However, the 12 UTC skew-T plot for TWC (above from SPC) appears very favorable for strong storms, and has a better BL structure than did yesterday's. The wind profile seems even more favorable for severe thunderstorms. The model forecasted soundings look good too - so apparently the shear and dry air from 700 to 400 mb prevent storms from developing in the model forecasts - we will just have to watch what transpires.

Finally, Hurricane Willa (IR image below from 13 UTC this morning) is moving northward and is very intense - just below Category 5 strength. The storm is forecast to turn northeastward and strike the west-central coast of Mexico, as a very dangerous storm.

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