A CHRISTMAS WISH...

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Merry Christmas to all who celebrate!

The North Bay forecast for the week ahead has many of us hoping and wishing for rain and snow. And, it looks like we will get our wish, at least in part.

SHORT TERM FORECAST

The dry weather with occasional high clouds will continue until Wednesday, when a storm system will arrive bringing rain throughout the North Bay and Northern California. And then a second storm is on track for Friday.

Overall the North Bay may receive over 3 inches of rain in total from the 27th to the 31st, with even more possible in the wettest spots.

Here is the rain forecast for the first storm, from Wednesday the 27th through Thursday the 28th. You can see that this is a coastal storm focused on Northern California, with very little rain or snow expected to reach the Sierra. And, the North Bay may be on the southern fringe of the heaviest rain.

The second system (below) should be a two day storm from Friday the 29th to Sunday the 31st.

Like the first, this storm is forecast to weaken as it approaches the West Coast and encounters strong high pressure extending from Canada over much of the West and Midwest U.S.

However, the first storm may flatten the high pressure ridge a bit, allowing this second storm to push further inland and further south. Here is the forecast rain from the 29th to the 31st.

Overall, with high pressure in place over the U.S. through much of Christmas week (below), low pressure systems will have a hard time pushing into California from the North Pacific.

This logjam may be changing a bit in the 2nd week of January. There are signs that both the Madden Julien Oscillation (MJO) and the Pacific North American pattern (PNA) may be moving into phases that support stronger storms along the West Coast. Without getting into too many details, this “teleconnection” support in the atmosphere has so far been lacking…thus our weak storms.

The long range forecasts suggest a deep trough of low pressure over the West Coast for the 2nd week of January.