Monday, September 26, 2016

Windy Sprinkles Now - WRF Forecasts Wet Next Several Days

The morning sounding data from campus (above skewT plot from SPC) indicated saturated conditions above 700 mb, with strong east winds through the troposphere. The composite radar depiction (below) at about 6:40 am MST this morning indicated light showers over much of southeastern Arizona. Here at house we have been having sprinkles with wind gusts around 30 to perhaps 35 mph.

The NWS has a wind advisory in effect for today, and I've been out front picking up paper trash that's been blowing in the wind.

Winds are very strong at some of the nearby observatories. The RAWS site on Mt. Hopkins (near the Fred Lawrence Whipple Observatory) have been gusting over 80 mph since a bit after 3:00 am this morning, with a max gust so far to 91 mph (see plot above).

Out west at Kitt Peak the weather station at the 4 Meter telescope site has been recording winds of 50 to 60+ mph for the last few hours (below).

I would love to see a very high-resolution modeling study of strong wind situations around the Santa Ritas and the Huachucas (strong winds impact the observatory and the military activities in/near these Sky Islands - how many multi-million dollar blimps have been lost at Ft. Huachuca?). It is not at all obvious why the winds on Mt. Hopkins reach such extreme speeds during strong easterly flow. The sounding from campus certainly doesn't seem to indicate a classic mountain wave situation - so what exactly goes on up there?

The current 500 mb analysis above (12 UTC from NCAR) indicates the maverick closed-low now over central Baja. This feature, and its interactions with the trough to its west, will affect our weather here in Arizona at least through Thursday. Tropical Storm Roslyn is forecast to remain well off to west of Baja (i.e., to remain west of 155 degrees W through its life) and thus may not get into the various interactions impacting us.

The 06 UTC runs of the WRF models at Atmo forecast mostly light rainfall around the metro through midnight tonight (just below). But both versions of the model forecast more significant rainfall for our area, and all of state, through 11:00 am on Thursday the 29th (bottom panel). 

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