Thursday, July 30, 2015

Yesterday - Storms For East Side

Thunderstorms yesterday stayed mostly on the high terrain around and north-to-east-to-south of Tucson. Several storms tried to come off the Rincons into lower terrain but slowly weakened before they got very far. The plot above of detected CG flashes though 11 pm MST last night (above from Vaisala and Atmo) shows this clearly. Several rumbles of thunder here during late afternoon but only some brief spits of rain.

Across the ALERT network 71 of 92 sites had measurable rainfall for the 18-hour period ending at 6:00 am this morning. Amounts were heaviest over the eastern part of the network from the Catalinas around to the Santa Ritas and generally very light over the lower elevations of the network. Debris cloud rain produced 0.07" here at house after dark.

Precipitable water has been decreasing during the night (time series above is from on campus), with values falling to about 1.25 inches this morning, down almost half an inch according to the GPS estimates (only minus a quarter of an inch from the 00z sounding to this morning's). The TWC skewT plot for 12 UTC this morning (below, from SPC) indicates much reduced CAPE, with almost none likely at low elevations this afternoon (models do bring PW up some from the southwest later today). Winds are mostly light except in the upper troposphere. Not a very good start to the day, and the WRF model runs from 00 and 06 UTC forecast only isolated mountain storms for this afternoon. Most interesting thing I noticed looking at the model forecasts was that both the NAM and GFS versions from 00 UTC forecast showers before sunrise over eastern Pima County tomorrow morning.

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