Very Mild Condition to Continue Through Tuesday then Cold Showery System expected for Late Wednesday Night through Thursday Night……Ridge Returns by Weeks End……….
Monday December 16, 2013
Posted at 9:37 am by Howard
It still looks like an upslope event. We seem to usually do better in upslope events as compared to how much snow is forecasted because of Mammoth Mt orientation to 700MB /NE flow. so 2 to 4 inches might to be conservative….
Opinion and food for thought……
Short, Medium and Long Range guidance are about as ugly as it can get. I think that it takes more then just a few teleconnections and oscillations to make up a winters pattern. Some of the oscillations are probably more important in the longer range then the teleconnections which they can effect. For instance, the QBO….. is in its westerly phase which has been shown to be associated with more of a positive AO (less stormy for the east) then its brother the negative phase. Strato winds west to east are associated with the (+AO) Pressures are lower up in the Arctic and help to contain the cold up in the higher latts. (Less Blocking)
Here is something to think about. We should be nearing the end of the positive phase of the QBO within the next few months. As soon as the index gets below +8 there should begin to be more blocking over Greenland and a possible flip in the sign to the AO as well as the NAO. Now a flip in the sign does not necessarily mean that we will turn wet here in California as the PNA may go strongly positive as well. That is why the effects of the QBO are non linear over California as compared to the east. But I think that it is a significant part of the structure of “this winters make-up” and any kind of change I say is good. The only thing is…this index may not begin to change until February or March……currently the index is a +12.45 for November. Based upon what I see in the arctic, I’d say that is it still quite positive in December as well. But again…we are nearing the end of that phase of the oscillation….the westerly phase should be weakening within the next month or two. After that, the east at least should turn colder. Remember, statistically, the best high latitude blocking with the QBO is associated when the 30mb index transits between positive and negative or negative to positive, rather than just the negative phase. So in this case, going between +12.45 down to at least +8. It will be fun to follow and see.
Considering a link to an article that was posted on another blog….see: http://climate.nasa.gov/news/997
It should be noted that so far, the PNA (Pacific North American Circulation Pattern) has been fairly negative this fall. The blogs article mentions that it is rare but possible that when the AO is negative and the PNA is negative that the infamous AR can occur over California. Since the PNA is and has been at least somewhat negative this Fall so far, might it be of interest if the AO flips to negative because of the weakening QBO by say March, and at the same time the PNA remains negative? Just something to think about………
To follow the QBO index…. go to http://www.cpc.ncep.noaa.gov/data/indices/qbo.u30.index
As far as the weather goes, it does not look good for a major storm before year’s end. We have a system expected in Wednesday night that will bring light amounts of snow through Thursday night, then dry over the weekend. The longer range does show several inside slider type systems that could bring a few inches here and there. This is a cold pattern and although there may be some light snowfall here and there, it is still considered a dry one. Hopefully January will be a different story.
High temps the next few days will be in the 50s and upper 20s at night. A cooling trend begins Wednesday with light snow beginning about midnight Wednesday then into Thursday.
It looks like Mammoth Mt will be able to keep the snow guns going….more often than not right on through the holiday!
Temperatures by Thursday will be in the low 20s for highs….. and Thursday night in the single digits…..
The ECMWF model has an weak inside slider type system; (upslope) for about the 23rd of December so more snow showers possible then….
There are additional sliders expected before years end.
Dr Howard and the Dweebs……………………………….:-)