Tuesday, December 22, 2009

Fresh and Cold........

Northstar added 2 more inches and ended up right on forecast with 8 inches of snow from the storm. Plenty of cold air behind the storm, as highs were only in the 20's Tuesday and will stay in the 30's into the weekend.

The cold air is going to stick around as a ridge builds off the coast. Ridge is a dirty word around here in the winter. We have been plagued by the ridge and dry weather the last few winters due to the colder ocean temps in the Pacific. The ridge will move over the Pacific NW by the weekend with a storm approaching the West Coast. The storm is looking pretty weak as it hits the ridge. Only expecting light amounts of snow if any as the storm slides by. The ridge to our North is not quite going to be far enough to the North. Therefore, the jetstream that we have been waiting for to come under the ridge is going to come in down by the Baja and extreme Southern CA.

The ridge will head East as another storm approaches the coast around next Wednesday. This storm may have enough time to dive in Wed-Thurs ahead of what will be a persistent ridge building in off the coast of CA. If the ridge builds in faster the storm may be deflected just to our North. Need to watch this storm because it may be our only shot at snow the next two weeks.

Although El Nino is at moderate strength and holding steady the last few weeks, the pattern is going to take on more of a La Nina look next week. The ridge is going to build in off the CA coast and send storms up into British Columbia and the Pacific NW. This is good for the upcoming Olympics but no good for us. We had psuedo El Nino conditions last two weeks ago with the MJO the Western Pacific helping to pump the jetstream, but now the MJO is on vacation in Africa. Sometimes during a cold PDO (Pacific Decadal Oscillation) like we have now the El Nino signal can be overwhelmed, especially early in the season.

The NAO (North Atlantic Oscillation) is negative which can form a block in the North Atlantic that holds a trough over the East and the ridge over the West. That can be attributed to cold air over the East and storms up the coast like the blizzard they just had. The PNA (Pacific North American) teleconnection has been positive which causes an up and down jetstream pattern across the Pacific and helps contribute to putting a ridge along the West Coast. During El Nino or a strong MJO in the Western Pacific this won't be as bad as the jet can come in under the ridge. Neither of those factors will be helping us going into January. Normally the affects from El Nino become greater as we go deeper into the winter. Looking for that to happen hopefully by the 2nd or 3rd week of January.

Plenty of cold across the country with the AO (Arctic Oscillation) being negative, which displaces the cold in the arctic down into the country. Look here, it has been almost off the chart which can be blamed for all the cold coming into the country. Good news for us is that we should get shots of the cold air so even if we go into a bit of a lull in storm activity it hopefully won't get too warm.

So to re-cap: Cold followed by a shot at a cold storm a week from now and then quieter weather for a week or two thereafter. Stay tuned because I will be happy to be wrong on this forecast if conditions change.........BA

No comments: