Snow Showers possible Thanksgiving Day….Then Fair…Breezy…But Dry Over the Holiday Weekend…….
Wednesday November 23, 2011
Posted at 10:27 am by Howard
Wednesday morning update:
CRFC QPF update this morning gives Yosemite .01 of an inch of precipitation Thanksgiving Day. So the idea of some snow showers is ok. Mammoth Mt might pick up a trace to an inch or two. That would be the most that I can see. I do not expect much more then a trace or an inch for the town in snow showers Thursday.
The next system will split further west around 138W. A Cut off low develops well off shore on Sunday….that system will aid in ridging us up over the weekend.
The next short wave to effect the west will approach the pacific northwest on the 1st of Dec. This is beginning to look a bit more interesting from the prospective that this mornings ECMF had this system splitting up over the Pacific NW dropping a cold upper closed low down over Ca. Wednesday night/or early Early Thursday for some light snowfall and much colder temps. The new Wed Nov the 23rd 12z GFS has now come round similar to the ECMWF’s scenario but is about 12+ hours slower, bringing it in more like Thursday the 1st. Back to this mornings EC. Ecmwf moves the split over the far pacific Northwest, brings a southern branch of the polar westerlies down the coast next Wednesday night and then cuts off a deep closed upper low (543dm at 500mb) over SFO at 00z Fri the 2nd….IE Thursday late afternoon. It is then ejected late Friday into the Rockies via the Sierra. The next upstream kicker is shown to have a better over water trajectory coming SE into Ca the following Saturday the 3rd of Dec.
The point is…the EC scenario would produce snow for the sierra both with the 1st system and with the 2nd. The new 12z GFS handels it differently though…..in that it brings a weakening front to the Sierra early Thursday evening then washes it out as an upper low forms over the Central Ca interior (over land). It then drops it SE right down the San Joaquin Valley during the day Friday the 2nd. By Friday night, it is pretty much cut off over Southern Ca Friday night:
This scenario gives Mammoth:
1. Snowfall with the upper low itself.
2. a 2nd chance of up-slope flow and possible some up-slope snowfall Saturday.
In that there is no short term upstream kicker like EC, the cutoff remains over So-Cal until early the following week. The GFS’s kicker is pretty much worthless unlike the ECMWF. The EC’s kicker has better potential for more snowfall in Mammoth the following Saturday the 3rd.
So, here are my thoughts:
1. In that we are in a transitory pattern the faith an any scenario a week away is not particularly good.
2. However, with that said, there are two global models that are suggesting more snowfall the 2nd half of next week!!! Say tuned! and Think Snow!!
Next update Monday the 28th.
Have a Happy Thanksgiving Holiday to All!
Dr Howard and the Dweebs……………………..:-)
Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.