Tuesday, January 10, 2017

Damp Weekend On Tap?

It was a mostly cloudy day yesterday - above view from campus was at 5:00 pm MST. Unfortunately, the automated observing system used by NWS indicates that yesterday was perfectly clear (see ASOS observations below). I think that surface observations were actually more accurate, and useful to aviation and other users, back in the 1960s, when I was learning to take observations at the St. Louis Weather Bureau. Higher technology can sometimes make things easier by taking humans out of the loop, but result in degraded quality. Note - the ASOS system does not detect clouds above 12,000 AGL, thus it was "clear" yesterday.

The current NWS forecast for the airport (above) indicates chances for showers and measurable rain at the airport from Thursday night through Sunday, with highest chances of 40 % for 0.01" on Saturday.

The ECMWF and GFS global models are in agreement, forecasting a closed, 500 mb low into the Southwest - the two forecasts here are valid at 5:00 pm Saturday afternoon. The ECMWF (above) has the low further north than does the GFS (below), which has the circulation center over southern Sonora. The ECMWF forecast would bring better chances of rain to our part of the state - but the weekend is still several days off.

The GEFS plumes for QPF at the airport (below from 06 UTC forecasts last night) forecast 100 % chance of measurable rain at the airport but there is considerable spread in the timing of the event (as reflected in NWS forecast above), as well in amounts of rainfall possible. The operational GFS (blue) is very dry, possibly because of its southerly track forecast for the low. Another let's wait and watch situation.

No comments:

Post a Comment