Sunday, February 12, 2017

Weekend Update

I have been having some PC problems which is making it difficult for me to update the blog posts here. But have a chance right now to show some current info and forecasts.

Graphic above shows GEFS QPF plumes for TUS from 12 UTC data this morning. The members all forecast a very light precipitation event at the airport tonight, as 500 mb closed low heads east across northern Baja and continues tracking along the Borderlands. A more interesting event is currently being forecast for next weekend.

Current (11:00 am MST) NWS forecast for the airport shown below - this will be updated within next couple of hours.

The 12 UTC run of the WRF-GFS at Atmo is drier than the GEFS forecasts. Forecast sounding for TWC above is valid at 06:00 pm this evening - PW 18 mm and CAPE of more than 600 J/kg. The low-level winds are strong from the east and cloud bases are very high. The CAPE value analyzed for the sounding is based in the surface layer and has little chance of being realized. The layer below cloud base and above 850 mb has a small amount of CAPE and is saturated - this mid-level layer could produce some light showers and perhaps thunderstorms. The WRF-GFS forecast of precipitation through noon tomorrow (below) produces little over Pima County.

The pressure gradient for easterly winds from eastern New Mexico to our area is on the order of 15 or more mb, and the WRF-GFS forecasts strong winds later this afternoon and through the night. The 10-m wind forecast above is valid at 08:00 pm this evening.

The forecast sounding for just north of Sonoita (below) indicates strong easterlies that veer to south-southeast below the tops of the Santa Ritas. Winds will be strong at the Mt Hopkins RAWS station - but the maximum speeds are difficult to anticipate. My guess based on the forecast sounding would be in the 40 to 60+ mph range.

Finally, here are the current NWS hourly grid point winds forecast at TUS (above) and Mt. Hopkins (below). Whatever process generates these forecasts has again produced gusts that are fairly close, both down at airport and up on the mountain. I would certainly like to understand more about what procedures generate these forecasts of grid point winds - technical references seem not to exist, so any help much appreciated.

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