Thunderstorms developed over the metro area just before dark yesterday - movement of cells was a bit erratic due to light steering winds (at one time I noticed on radar loops that strong cells were propagating toward house from both east and west). The ALERT rainfall maps - above and below - are for the 24-hours ending at 5:00 am MST this morning. There were many reports of amounts between a half and two inches. Every ALERT site - except for 9 stations - recorded rainfall. Kudos to the morning NWS forecast of 70% POPS - the highest I recall seeing this summer at 6 to 12 hours before any rain was falling. The early afternoon update did reduce the POPS down to 50% - regardless a good storm day.
Reports from other local sites: TUS had 0.98" with gusts to 46 mph; DM had 0.30" with gusts to 44; here we had 0.61" with gusts estimated at least to 50 mph; Atmo measured 0.75" (see their time series of T and Td below with its very impressive drop in T); and Phoenix had yet another rain event at 0.42". Here at the house rainfall has totaled 2.16" for the seven days from last Saturday through yesterday. This was wettest seven days here in a long time.
What will today bring? Given the large area of wet soils, temperatures will be cooler, and usual scenario for day like this is for little storm activity away from mountains. At 500 mb this morning (above from SPC), the weak IT has shifted a bit westward and can still be seen in wind field from southern GoC, extending northward to about the Silver City, New Mexico, area. The cyclone/IT that was pronounced yesterday am at 250 mb sheared apart into two pieces - the northern portion essentially dissipated, while there remains an IT from lower GoC extending southward.
The skew-T plot for TWC's morning upper-air data (below, also from SPC) continues moist and with high potential CAPE - however, the SPC analyses estimate CAPE considerably too high, given the onion character of the profiles, and with the significant cooling below 850 mb. The winds remain L/V below 300 mb, while upper-levels westerlies are increasing due to the trough over the Northwest.
Interestingly, observations at about 4:00 am this morning (i.e., approximate release time of the upper-air balloon flight) indicate that both the airport and Atmo had lower temperatures and dewpoints than were measured at the NWS release site - roof of a three story building. This difference affects strongly the surface-based CAPE calculation shown on SPC analysis.
I took a look at the two 06 UTC and 12 UTC RR runs of the WRF model. Neither the NAM or GFS versions were able to forecast the low level cooling that was observed in the sounding. However the RR version started with an accurate vertical thermodynamic structure. That version of model forecasts only some isolated mountain storms - mostly to the south of the metro in Santa Cruz County, with a quiet day at low elevations.
Finally, as the trough over northwest presses more toward the south, conditions here dry out considerably. Down at bottom is 06 UTC GEFS plumes for PW at TUS - PW drops below an inch Monday morning and stays there for rest of the month. A dramatic change from past weeks heads our way.
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