Yuletide Season Approaches…..Still No -NAO or -AO in Sight…..-WPO and -EPO to Rule West Coast Weather into the New Year and possibly beyond…..
Thursday December 5, 2013
Posted at 7:40 am by Howard
Friday Update: Mammoth temps Highs 20s today and teens Saturday…..low 20s Sunday
Lows below Zero Sunday AM again…..
Warmer Next Week:
Not much change but to slow the current system down 6 to 8 hours. QPF is slightly less than the previous storm but we’ll get more snow because it will be colder during the snowfall. Snow to water ratios are expected to be 20:1 over the Southern Mono County Sierra. Thus…….4 to 8 inches is expected in town with 8 to 12 inches between 9K and 11K. Although some light snow may begin later this evening…..Most intense period of precip will be 5:00am to 11:00am Saturday with showery WX during the afternoon into the early evening hours. Sunday AM will be very cold again with early Sunday AM temps below -0F. Temperatures at resort levels will moderate slightly by Monday AM with single digits..however, the high elevation valleys like Bodie will go -20 to -25. Like Thursday Am there is a surface gradient for the NNE flow over Mono Lake Sunday afternoon into Monday AM. So another Lake Effect snowfall is not out of the question for Mono City and Lee Vining. As the high pressure portion of the AK block progresses east into CA, There will be moderating temperatures Tuesday into Thursday with highs in Mammoth returning to the 40s and lows in the teens. The Freezing level is expected to temporarily rise to 9300 feet by Wednesday Night. Expect a brief reduction in air quality the middle of next week due to temperature inversions.
There after….the next weather system for late Thursday and Friday the 13th is being handled differently by the two most popular global models. The ECMWF has it as a coastal slider with less moisture then the GFS which actually brings in the western flank low from the current Omega Block which is most likely wetter. Either way the system will be fighting the trend….
Outlook: (Subject to change)
The trend according to the Ensembles is the transition from the current -EPO to its western cousin the -WPO. Once the -WPO sets up in the Bering Sea it is indicated to retrograde westward even further out over the Western Pacific. That will increase heights over the mid lattes of the eastern pacific. Without any cold deep trof in the Gulf of AK or BC to suppress the westerlies south week 3, the Anti Cyclonic tracked Rossby Wave Train will most likely remain too far to the north to bring us precip during weeks 3 and 4. This would be a return to milder weather for the high country. However, there are some ensemble members showing the possibility of the pattern reverting back to the -EPO which puts us back into the deep freeze and cold storms down the coast much like we have been having, toward the end of the year.
More later…………………….Dr Howard and the Dweebs
Looking at the latest teleconnections the next 6 to 10 days it is quite possible that the Positive numbers in the QBO and low solar are putting the KABASH on negative phases of the NAO and AO. The Dweebs like that as those teleconnections do not usually favor stormy weather on the central west coast. Easterner weather junkies love the negative of the NAO and AO as those telelconnection’s often create a blocking pattern that buries the cold in the east while the west is often times ridged up with the +PNA.
With the strato winds of the QBO blowing stronger west to east last month as compared to the month before, it is unlikely that long-term blocking will come anytime soon to the Greenland area this year. This is good news I think in a neutral ENSO year for the central west coast. Exception….the GEM has a block in the Greenland area but is the Maverick compared to the other models.
It appears to this WX Dweeb….that over the western hemisphere, the negative phases of the WPO and EPO are taking turns in their reign over the Pacific. As of late…..the GFS has shown that amplification has come to the -WPOs Eastern Cousin, the -EPO and an adjustment wave is slowly becoming more and more evident in the pattern, west of the BC coast. “It maybe” as the upper jet out over the pacific gets stronger climatically…..a stronger southern branch under these blocks will become confluent with the strengthening arctic jet later this month…..radically changing Mammoth’s landscape……
Snowfall Estimates Update:
Update on the QPF from the 00z Thursday ECMWF for the Friday/Saturday system (.70) for the crest. CRFC has .46 for Yosemite and .40 for Huntington Lake. The New 12Z Thursday GFS has .50
So it appears that this snowmaker will be similar in amounts to the last system that dropped 7 to 10 inches on Mammoth Mountain.
Looking down the road… is it quite evident that the highly amped upper ridge responsible for the Arctic Air will break down rapidly early next week and collapse in response to the Morph of the -EPO back to the -WPO. This will allow milder pacific air to invade the far west by mid week. Sometimes you can get isentropic lift type snowfall if there is a moisture channel, however this is not in the cards at this time.
The epo/wpo teleconnections are very similar in that they are blocking patterns highlighted by positive height anomalies over the northern latitudes and negative height anomalies to their south over the mid latitudes. The only difference in the teleconnection is location. The WPO is in the central and western pacific and the EPO is situated in around the Gulf of AK. When under the influence of the -WPO, the main upper height anomaly can be too far west for major storminess for the central coast with ridging instead. With the -EPO as are experiencing, the upper height anomaly is too far east. What we may get is a sort of hybrid of in-between…and if the southern branch of the westerlies is strong enough…..It may merge with the polar branch and become confluent. This can lend to a wet pattern for the central west coast with possible “AR” implication’s….
At any rate, there is lots of Winter Left and this candle is just getting lit…..
Dr Howard and the Dweebs……………………….:-)