Friday, July 20, 2018

Storms Likely To Try To Come Off Mountains Today

View above from campus yesterday shows some buildups over Catalinas at 5:00 pm MST, as well as heavy high cloud overhead. Plot of CGs below (from Atmo and Vaisala for 24-hours ending at 1:00 am this morning) shows storms over Cochise County extending to the San Pedro Valley but not getting into much of eastern Pima County. This was just as most all of WRF variants forecast beginning Wednesday evening. Two ALERT sites in Catalinas reported rainfall right around a tenth of an inch. So essentially zero coverage for metro zone and about 10 percent or so for mountain zone. Second day in a row with high CAPE that was not realized at lower elevations. 

The nasty, shallow, well-mixed BL forecast for 3:00 pm yesterday by 06 UTC WRF runs (above) was extremely similar to the observed 5:00 pm sounding data (below). Quite amazing forecasts by the WRF versions yesterday.

Visible satellite image at 6:30 am this morning shows cloudiness and showers over southwestern New Mexico, as well as some storms in northern Mexico. The 12 UTC plot of TWC upper-air data below (from SPC) shows the strange two layer structure again below 700 mb - so question today is: can heating over lower elevations lead to a single, well-mixed BL extending up to 700 mb? The WRF runs indicate that this happens, so that storms are more likely today in eastern Pima County. The vertical wind profile, however, is not very good for the metro area, as the stronger southeasterly winds at high levels will tend to spread anvils out directly ahead of any thunderstorms.

The 06 UTC forecast runs at Atmo for composite radar coverage valid at 2:00 pm this afternoon are quite a bit different - WRF-NAM above and WRF-GFS below. The NAM forecast indicates thick anvils over the metro area and storms skirt around the low elevations. The WRF-GFS also forecasts anvil over much of metro, but with a very large and strong storm over the southern half of the ALERT network.

Appears to be at very best a flip of the coin for measurable rain here at house - will again wait and watch.

1 comment:

  1. It looks like that cloudiness and showers in SW NM has become a well defined Easterly Wave... hope it makes it to Eastern Pima Co. this afternoon!!