Wednesday, March 11, 2009

Back to Normal......

Another sunny & cool day with lots of snowpack.

A piece of energy that is cut-off from the main flow will slide into CA on Thursday, but it is a very weak piece of energy so it shouldn’t create more than just some clouds & keep cooler temps around. Meanwhile, a storm gets cut-off from the jetstream & spins out in the Central Pacific. This will cause a ridge to form over us with sun & slightly warmer temps near 40 on the mtn. for Fri. & Sat.

Retrogression of the ridge back towards the Central Pacific on Saturday may allow for a storm hitting the Pac NW to come far enough South to bring snow to Tahoe on Sunday. Models in a little bit of disagreement on how far South the storm comes, but it Doesn't look like much if we get any, just some light snow showers.

Meanwhile, the cut-off storm moves backwards slightly & is sitting over Hawaii right where we want the ridge to be sitting, therefore displacing the ridge to the Eastern Pacific & blocking storm activity. A blocking High pressure may form over the North Atlantic similar to the first week of February which digs a big trough into the East & dams up the progression of the flow & holds the ridge in place over the West. Latest models suggesting that the ridge is flat and storm activity will continue to impact the Pac NW. The ridge may get flattened enough by the end of the week to allow a storm to affect the area. Mon.- Wed. would have lots of sun with temps in the 40’s on the mtn. & 50’s in town, before the chance of a storm on Thurs/Fri.

The flip flopping of the long range models this week makes me not want to look much further out than 10 days with any confidence right now. Latest models suggest the ridge re-emerging for the weekend of the 21st, & then retrograding allowing for another storm that week. This pattern looks like the typical La Nina pattern where the cold Ocean loves to put a ridge off the coast, only to occasionaly shift West enough or be crushed by big enough of a storm to allow us to get some snow. In La Nina we are always right in the middle as the Southwest is drier than normal & the NW is wetter than normal.

We have had La Nina type conditions for the past 3 winters which is why CA has been so dry. Good news looking towards next season is that the Pacific looks to start warming this summer & current thinking is for a possible "Mild" El Nino for next season. This would definitely return wetter conditions to the West Coast. BA

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