Wednesday, November 07, 2012

Midnight Runs Of WRF-GFS VS NAM

Now that election day is over, I can focus more on the weather - hopefully the posturing and attack ads for the 2014 elections won't start for a few weeks.


The graphic above is an IR image for the northeastern Pacific from 6:30 am MST. The system in the Aleutians is kicking up a ridge that is driving the short wave off the west coast of Canada southeastward. Possibly of more interest to us in the Southwest is the weak, closed low off to the west-southwest of San Diego. This system is pulling moisture northward, as indicated by the enhanced cloudiness near and west of Baja. The blended PW product for 2:00 am MST (below) also shows this moist air, and loops indicate that it is moving northward. The digging short wave to the north is forecast to kick the lower latitude system east-northeastward tomorrow.


The midnight run of Atmo's WRF-GFS model today forecasts showers over eastern Pima County as early as midnight tomorrow (Thursday) night - above is forecast of composite radar valid at midnight. However, these echoes are mostly aloft with only very slight amounts of precipitation forecast for tomorrow night.


However, the WRF-GFS forecasts more substantial precipitation for Friday afternoon and night. The above is WRF-GFS forecast of accumulated rainfall through midnight Friday night. However, the NAM forecast from midnight (below) forecasts lesser amounts of precipitation, with little indicated over southeast Arizona. We can watch how the situation evolves the next couple of days and hope that the WRF-GFS is superior to the NAM.


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