Saturday, September 14, 2019

Complicated Situation Today


Above is a morning outlook statement from NWS - this is interesting since it is somewhat out-of-phase with the 06 UTC WRF-GFS forecasts (more re this below). Thunderstorms and rainfall remained mostly east of Tucson yesterday afternoon (plot of CG flashes from Atmo and Vaisala - below for 24-hours ending at midnight last night). Not much in way of rainfall amounts - three ALERT sites had rain reports of up to 0.08" in mountains; St. David had 0.42" off to east, and Nogales had 0.50" down to our south.




Visible satellite image above shows the heavy cloud cover present this morning at 7:00 am MST over much of Arizona and southwestern New Mexico. The cloud cover is associated with a weak cyclone at 500 mb (12 UTC 500 mb chart below from SPC) centered somewhere south of New Mexico bootheel.



This morning's TWC upper-air plot (above, also from SPC) shows PW of 1.24" and nice easterly steering winds, but almost no CAPE. The 06 UTC WRF-GFS forecast (all forecasts shown here are from this run) of TWC sounding for 3:30 pm this afternoon has little CAPE with two capping inversions above the well-mixed BL, as well as weakened winds around 500 mb. The 500 mb forecast (valid at 4:00 pm - second below) shows the 500 mb low centered just to our east, but with warming 500 mb temperatures.





WRF-GFS forecast of rainfall through midnight tonight (above) has huge donut hole over our area. Forecast of 10-m winds (below for 5:00 pm this afternoon) shows severe winds with storms over northeastern  Maricopa County, as well east winds around 20 kts our area.

I would like to see some rain this afternoon, but forecasts are uncertain and quite a mixed-bag!





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