Winter Returns to Tahoe

One of the scenarios for the weather changing in my January weather posting was for the ridge that was over us to regress; or if you prefer "move west", and that has occurred in the last 36 hours.  This has allowed the upper atmospheric flow to move southward and over our region.  It has regressed far enough west that there is ample moisture advection over the Pacific Ocean before being orographically lifted by the Sierras.  Wind speeds in the upper atmosphere are very strong and the lifting and cooling effect is amplified by the increase in velocity, resulting in snowfall rates of 4 inches an hour.   There is a strong trough evident from 750mb to 300mb that will provide instability, and pull in cold enough air that the snow should continue for the next week.  The 14 day long lead forecasts show this flow to continue, so stay tuned for updates.  Since the time the snow started this morning at 5:00am the course has gotten over 2 feet.  It is now 3:30pm The official forecast is for another 2 feet in the next 48 hours.  Check some of the weather links I have provided and pay particular attention to the 500mb heights, and how far the bottom of the trough stays off the coast.  If you can find the times that the highest wind pulses will move through the bottom of the 500mb trough and then over the Tahoe area, you will be able to predict the times of heaviest snow fall.  Or you can simply look at the NOAA link and go to the QPF (Qualtitative Precipitation Forecast).

Now, I need to clean the snow off my truck and go home!!!!