Friday, January 09, 2015

Unsettled Conditions Continue For Next Several Days


Yesterday's showers turned out to be considerably more than were expected (POPs were 20% for the day as the sun came up) and ended up with more than 90% of the ALERT network sites measuring rainfall. Amounts maximized across the metro area from east-to-west, with much lighter amounts  to north and south. The two ALERT sectors with most rainfall are shown above and below - maximum amounts reached 0.35". Here at house we came in with 0.29".



The Southwest continues to be under the influence, at 500 mb, of a weak, southerly branch of the flow that undercuts the large ridge over western Canada and Alaska. There are a number of short waves and closed lows in this stream that will impact southern Arizona into next week. Graphic above is the ECMWF 500 mb forecast valid at 5 pm MST on Sunday afternoon and indicates another short wave about to cross southern California. The weak large-scale setting means that anticipating the day-to-day details of weather in the metro area will continue difficult. The current NWS grid point forecast for the airport is shown below and indicates low POPs, but for almost all forecast periods through next Tuesday. The WRF forecast from Atmo indicates the possibility of a few more sprinkles today over eastern Pima County as the closed, 500 mb low to our south moves eastward across northern Mexico.


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