Few Storms Yet Again

Yesterday's early WRF GFS forecast the down trend to continue and was quite accurate again. Lightning strikes for 24-hours ending at 7 am this morning are shown above - very little thunderstorm activity in all of southeast Arizona, except for some parts of Cochise County. More activity in far southern California and some severe storms in the Central Sierra Nevada. There were some warm rain showers again in eastern Pima County. During past 24-hours 21 (23%) of 92 sites had rain - mostly before 5 pm yesterday and with mostly very light amounts (two high elevation sites had more than 1/2"). Phoenix Sky Harbor did pick up over 8/10s of an inch just before noon yesterday, for its first decent rain of the summer.

Little change today - 12 UTC TUS skew-T plot below shows: slight CAPE, high moisture, warm mid-level temperatures, and a very chaotic wind field (essentially light and variable through the troposphere). So, not a good setting for organized storms here in southeast Arizona. Showers again at higher elevations and showers at low elevations at places where they might develop nearly overhead.

The early WRF forecast of composite radar echoes valid at 6 pm MST today is above (this is the most activity in the model forecast for today). Forecast of rainfall through midnight is shown below - model forecasts a little bull's eye of heavy rain up on the Catalinas and also heavier rain amounts in Cochise County.

Above is this morning's NAM forecast for 500 mb valid at 5 pm MST on Wednesday afternoon. Very large anticyclone covers much of the US from south Florida to west of California. Note that winds are quite weak over about the southern 2/3rds of the anticyclone - so we will continue to see a moist atmosphere but with little steering flow. CAPE will probably remain low until cooler mid-level air comes around the high and combines with warmer boundary layer temperatures. Seems very similar to the pattern we fought with for much of last summer.