Wednesday, June 07, 2017

Isolated Thunderstorms Southeast Arizona Again Today

Yesterday afternoon there were two small thunderstorms over the northeast corner of Santa Cruz County during the evening (above plot shows detected CG flashes for 24-hours ending at 11:00 pm MST last night - from Atmo and Vaisala).

Chart below is 12 UTC 500 mb analysis this morning (from NCAR RAL/RAP) showing the large ridge over the western U.S. There does appear to be a small, closed anticyclone just off to the northeast of Tucson. Middle-level temperatures are around -8 to -10 C, which is quite cool given the 100+ F surface temperatures expected, so that high-based convection continues to be possible.


SkewT plots of the 12 UTC morning soundings are shown here (TWC above and ELP below). The local sounding exhibits basically no CAPE, while there is a bit more moisture and small values of CAPE to the east at El Paso. The model forecasts keep the better moisture mostly to our east, as winds over the metro area stay southwesterly much of the afternoon.

The 06 UTC WRF-GFS forecast of composite radar echo (below from Atmo) forecasts an isolated storm at 05:00 pm this afternoon, very near where the storm occurred yesterday. The other 06 UTC and 00 UTC forecasts from the WRF variants indicate slightly more activity that is shifted a bit westward. Impacts at low elevations again appear to be mostly wind, with perhaps a light shower and thunderstorm within sight. Would be a good idea to check the 12 UTC WRF forecasts when they become available.

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