Building Upper Ridge Over The Eastern Pacific Spells Cooler Weather This Weeks Second Half….More Snow On The Way!
Sunday December 26, 2010
Posted at 12:24 pm by Howard
Building HT 500 Hts over the Eastern Pacific the next few days will change the upper flow from more out of the NNW while a long wave trof is carved out over the Great Basin in the 5 Day Means. There will be at least one and possibly two significant systems that will effect the Mammoth area through weeks end. The most significant system is associated with a 130knot upper jet that becomes more NNW-SSE orientated as the the upstream ridge builds between 160w and 140w. Mammoth becomes in the front left exit region during the day Wednesday. Additionally, there appears to be two jets with this system. One associated with a dampening short wave in the anticyclonic flow in the mid latitudes Tuesday, and the other stronger system associated with the upstream amplification that actually over runs the mid latitude upper jet. The primary jet seems to prime the atmosphere, prior to the stronger short waves arrival on Wednesday. Mammoth could get 2+ feet of powder over the crest between Tuesday night and Wednesday night. Additionally, cold modified Arctic air gets pulled down from north of 60N Thursday for a day of teens in Mammoth Lakes. With night time lows in the single digits and minus zeros Friday am.
New Years Eve System:
In addition to the above……There has been several GFS ensemble members indicating a short wave coming through the upper ridge for New Years Eve. I did not see it on last night EC, but the GFS has several members with it. So for the time being….there is a chance of Snow around News years as well.
First Week of 1011:
Unsettled…..snow showers. The GFS has the Eastern Pacific High still amped around 140W to 145W and shots of energy could continue into the Great Basin (inside sliders) so it will remain colder then normal for January. However, the ECMWF 12z Sunday runs shows a split flow pattern with a pretty strong southern stream for the southern half of Ca. We’ll see how she develops!
The “Wheeler Headon” phase space; See: http://cawcr.gov.au/staff/mwheeler/maproom/RMM/phase.Last40days.html
suggests an increase of tropical convection over the Maritime Continent. However its too soon to say if it will be an MJO. Will check on CPC chatter next week.
If indeed we do have a MJO….watch and see if another block or REX block develops between Hawaii and the Dateline toward the middle of January.
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.