Monday, January 28, 2013

January Closes Out With A Fairly Dry Evenet

The current surface plot (above from NCAR RAL) for a bit after 6 am MST shows that the approaching cold front is about half way across Arizona. Precipitation is mostly confined to northern parts of the state. Snow has returned to Flagstaff and the Grand Canyon area after the heavy rains of the weekend. Gusty winds behind the front for much of the state today.

The blended PW product from CIRA at Colorado State is shown above for 5 am MST this morning. This analysis indicates that the current system is fairly starved for moisture, with amounts of 0.50 inch just into southeast Arizona (the light blue indicates amounts over half an inch). Much different than Saturday's system which had significant moisture inflow from low latitudes.

All of the GFS ensemble members (from forecast run initialized at 5 pm MST yesterday) forecast precipitation across southeastern Arizona for period ending at 5 pm this evening. However, Atmo's early run of the WRF-GFS, with its high-resolution grid, indicates that most of that precipitation is from the
coarse grid GFS smoothing mountain precipitation into lower elevations. So it looks windy and cooler, with some light showers about. Some spots in the lower elevations may get enough rain to wet the roads while other places will get spits and sprinkles, as more significant amounts stay at higher elevations.

In the longer range, some GFS members are predicting a system at 8-9 days that taps into low latitude moisture - but of course, that's off in February.

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