Wednesday, June 27, 2018

Looking Ahead To Friday Evening

The 500 mb analysis this morning (above from SPC) indicates an anticyclone is over northeast New Mexico, with a band of 20 to 25 kt east winds from El Paso to Tucson, along with quite cool temperatures in mid-levels. The pattern is a bit chaotic with a weak trough inching across southern California and an inverted trough far to the south over west-central Mexico. The inverted trough will likely help increase thunderstorms over northwest mexico and also play a role in the large increase in PW forecast by the models - this begins today and continues through Friday night. See the 00 UTC GEFS plumes for PW at TUS below. By Saturday the PW here is forecast to reach to around 30 mm (1.2 inches) and hold steady through rest of forecast period. The same forecast for QPF at airport (second below) indicates periods of light showers, and probably thunderstorms, from Friday evening (the 29th) through the Fourth of July.

A forecast skew-T for TWC (above from 06 UTC WRF-GFS at Atmo) valid at 5:00 pm MST on Friday shows an interesting sounding with west-northwesterly winds through the well-mixed boundary layer and southwesterly winds above (due to the slight eastward progress of trough over California). The forecast mixed-layer CAP is just over 800 J/Kg due to increased BL moisture and cool mid-level temperatures continuing to hold off much warmer air out to the west.

Forecasts here are from the 00 UTC operational GFS and are also valid at 5:00 pm on Friday - above is 850 mb and below is 500 mb. The flow at 850 brings higher PW from GoC anticyclonically into southeastern Arizona (a situation that occurs frequently during summer). The 500 mb is chopped-up but is open to low-latitudes, which allows the push of low-level moisture into Arizona.

All-in-all, it appears that we'll have interesting weather to watch as June draws to a close. 

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