Like a broken record here in north part of City - moist and sultry but only a Trace of rainfall for past week. The 6:00 pm MST view from campus yesterday shows very distant Cbs to the north. ALERT rainfall map (below - for 24-hours ending at 7:00 am) shows a bit of rain up in higher elevations and zilch at low elevations across the City. The flash density map (second below for 24-hours ending a bit before 7:00 am from weather.graphics and Vaisala) shows thunderstorm activity occurred yesterday from north to east to south, while most of southwestern Arizona was totally suppressed.
The current 500 mb analysis (above from SPC) shows the ridge amplified over the West, with anticyclone centered over Nevada's famous Area 51, with even a hint of inverted trough to our west. The SPC 250 mb analysis (below) has shifted the anticyclone center off toward Puerto Penasco.
Morning conditions in our area remain similar to yesterday: high moisture and CAPE but with a chopped up wind profile. Yesterday afternoon radar loops showed many storms propagating along mountains flanks, exhibiting apparent movement from all directions.
The WRF variant forecasts from 00 and 06 UTC last evening/night each forecast different convective outcomes today for eastern Pima County. Most spectacular forecast is from the 06 UTC WRF-GFS which forecasts a severe line of thunderstorms to cross the metro area at around dark. Least active forecast appears to be from the 00 UTC WRF-NAM - but bottom line is that high uncertainty regarding when and where storms might occur at lower elevations continues.
Below is the 06 UTC WRF-GFS forecast skew-T for TWC, valid at 6:00 pm this evening, with substantial CAPE above a well-mixed BL. However, the vertical wind profile is pathetic. The model forecast indicates strong storms moving rapidly off higher terrain toward the southwest - so outflow propagation seems to be the dominant steering force in the forecasts. Another wait and watch kind of day.
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