Wednesday, June 22, 2016

Monsoon-Type Pattern Continues But ...

The graphic above (from Atmo and Vaisala) shows detected CG flashes for the 12-hours ending at midnight last night. There was a bit of thunderstorm activity yesterday along the Borderlands and in the Santa Rita Mountains. 

The MIMIC PW analysis (from CIMSS at University of Wisconsin) for 4:00 am MST this morning is shown below. PW values are generally over an inch across southern Arizona and southern California, but the boundary layer (BL) is very deep with low RH near the surface. Much high PW is lurking over the southern 2/3rds of the GoC.

Even though we are in a monsoon-type summer pattern, there has been only isolated storm activity due to limited CAPE. Needed is an influx of higher moisture and/or cooler middle-level temperatures. A bit of both would be a big help. 

There is nothing much showing up in the long-range range forecasts that would trigger a serious push of deeper moisture into southern Arizona (culprits are usually TS near Baja or deep inverted troughs moving across northern Mexico). Second graphic below shows the GFS ensemble average 500 mb chart valid next Sunday afternoon. It appears that we will have to rely on MCS outflows to get the moisture up some - these can come directly into southeastern Arizona from Mexico, or they can push westward into the GoC and force low-level flow up the gulf.

The GEFS plumes provide forecasts for a number of parameters and the two plots here show PW above and CAPE below (both from 06 UTC last night). The models forecast PW to stay around 1.1 inches or a bit below 30 mm. The CAPE jumps up and down some, but the average generally stays below 400 J/kg - not very exciting for low elevations. So, best we can do is watch day-by-day and hope for some large MCSs in Sonora. (Disclaimer - I do not know how the GEFS algorithms compute CAPE and have to admit that I don't have the energy to try find documentation - my guess would be some that it's surface based but that's just a guess.)

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