Saturday, January 30, 2016

Short-Range Forecast Little Change And Long-Term Doldrums

The short-term model forecasts for the impending late Sunday - Monday weather event have changed little during past 24-hours. Shown above are GEFS QPF plumes from 06 UTC last night - the operational member (blue) is now second driest of all the ensemble forecasts. The models forecast the precipitation window to be from about midnight Sunday night to noon Monday.

Graphics below show two forecasts from the Atmo WRF runs at 06 UTC last night. Directly below is the WRF-NAM forecast for precipitation amounts through 5:00 pm MST on Monday. The WRF-GFS forecast is very similar, and both models forecast a fast-hitting event with mostly light precipitation for southeastern Arizona (higher amounts over mountains, especially to northeast of Tucson). The models continue to indicate a windy event, and graphic at bottom is from the WRF-GFS and shows the forecast for 10-m wind speeds valid at 2:00 am Monday morning.

Looking beyond the Sunday/Monday event is not very encouraging. Shown here are the GEFS forecasts of average 500 mb heights: above valid at 120-hours (5:00 pm February 3rd) and below at 240-hours (5:00 pm February 8th). The west coast ridge strengthens as 500 mb heights remain very high over the northern polar regions. The ridge extends across the pole into the eastern hemisphere, almost breaking the northern hemisphere pattern into two circulations. We are stuck in the near ridge doldrums, while active and cold weather impacts the eastern US and Europe. 

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