Upper ridge to hold steady this week with some flattening of the ridge next weekend leading to some cooling aloft…. Slow discontinuous retrogression is hinted at by the models the next few weeks…..The Forecast is still dry for a week to two weeks……Anomalous warm waters in the Bering Sea hold hope that long wave ridge may gravitate to that area during weeks 3 and 4…..

The forecast and outlook are still pretty much straight forward this upcoming week with the dry weather trend holding with strong temperature inversions, due to the persistent west coast ridge. This ridge will actually strengthen Tuesday through Thursday with the freezing level topping out at about 14,000 feet by Thursday afternoon..  Thereafter, a passing short wave Friday night will flatten the ridge somewhat, bringing some breeze over the upper elevations and some cooling aloft. It may be enough to mix out the valleys by early Saturday AM…well see.  Temperatures this week in Mammoth will rise to the mid 50s with lows in the upper 20s to possibly low 30s in the upper elevations of town by Thursday morning. Some cooling is expected over the weekend. Lows at night have been running about 10 degrees cooler in town than at the Village. So 15 to 25 degrees as of late. These lows will come up a bit by Mid-Week.

There really is not anything in the models that look striking different from what has been said of late.  Those that follow the 21 day cycle of pattern change might be interested in knowing that this current pattern began on the 5th of December as indicated by reanalysis 500mb charts. 21 days would put the next pattern change or “transition” about Christmas.  This does not mean that we will not see any moisture until then, as within this pattern we could still get something that sneaks in here bringing something light. It just means that a meaningfull transition is not expected based upon this theory until about Christmas. Furthermore, with that said, it is not really known what we are going to transition to.

Optimism:

Let me chat about Sea Surface Temps.

What I like out over the pacific is the increasingly warm pool in the Bering Sea.  Whether it’s the Chicken or the Egg, these anomalous warm Sea Surface Temperatures often times attract large-scale high pressure systems in their vicinity during this time of the year.  This may cause  the current long wave pattern to retrograde with a good solid block developing in the WPO region either later this month or most likely in January. If/when this happens it could get quite wet in California. The warmest positive sea surface anomalies are currently in the Bering Sea and south of there. On the negative side, SSTAs along the California coast are getting pretty warm as well. This may tend to keep Southern CA drier, I do not know.   The CPC Climate models are showing 500MB Heights retrograding to this area during the Weeks 3 and 4 period. See Graphics below.

Based upon the 21 day cycle, were probably going to have to get through the next two weeks being dry, as today is only day 5 of that period. However, if the Climate Models are correct from the CPC, showing a block developing in the southern part of the Bering Sea -(WPO);  Beginning the week following Christmas and Week 4 “New years Eve through Jan 6th”.  We could get some badly needed precipitation. Week 3 looks cold temperature wise, with week four looking more moderate in temperature as there is more over water trajectory with the upper jet. . On another note, other graphics which I am not authorized to display from another model is trending wetter as well for the northern half of California in January. I hope they all verify!

 

Think Snow!!!!

 

 

 

Easterly Winds have greatly diminished over the Upper Elevations…..Upper Ridge will hold steady over the region untill about mid-month when cooling will arrive……Pattern Continues dry into the extended….

Looking at the models this morning, it is evident that the earlier forecast guidance has been correct in setting up the strong Ridge-Trough pattern over the CONUS this week.  This pattern has legs and will persist for some time.  It appears to be, that with a moderate La Nina and the QBO in its negative phase, meridional flow will dominate the weather this winter and there is likely to be long periods of quite between active weather patterns.  The next opportunity of a change will be mid month December, as the forecast models do move the Big Eastern Trof out into the Atlantic. That should open the wavelength and allow at the least some weak energy for some cooling, wind and a slight chance of some very light snowfall. I say slight chance as even through the current Eastern Trof is forecasted to move out, the mean ridge position still remains over the far west.  So any short wave action will weaken from the west and is more likely to back door us from the northeast. This is usually a dry pattern with upslope snow or something of that sort.  The ridge then redevelops over the far west again.  The Dweebs are still hopeful that a more significant change will occur the end of the year as the pattern is forecasted to go into full transition. The Dweebs just hope we do not go from one drought pattern to the next!

As a note, this pattern is horrible for the fires in Southern CA. Although LA is not likely to experience those very strong winds as earlier this week in the near future, there will still be periods of increased off shore flow over the next 2 to 3 days as the cold temps over the Great Basin combine with a persistent surface high over the same area diurnally.  The off shore gradient does greatly relax next week. However, there is the potential for another off shore event late the following weekend into early the following week. That is the time frame that we may see our change to cooler weather. (17th-18th)

 

Dr Howard and the Dweebs……………:-)

Gusty East Winds will slowly diminish later today with warming aloft later this week and strong temperature inversions expected….The Weather will likey remain dry for a week or two…….

Thursday December 7th:

There is not much to add to the previous discussion other than to emphasize that this pattern is all about the big Trof in the East and the other Trof in the mean north of Hawaii. The Dweebs know that when the big Trof in the east moves out to sea, the west coast ridge will weaken and some energy will more through. Whether it brings just wind and cooling or some light snowfall it is not known at this time. However, the timing appears to be about the middle of December for this to take place. I have been writing about teleconnections a lot lately. During a winter like this, they really can give a better picture to what is happening, as well as to add support to what the models are doing with our future weather.  Things to watch for:  Feed back mechanisms like wide-spread snow cover developing over the Great Lakes Region and Eastern US. Also the development of anomalous warm water along the west coast.  These two feed back systems if established would be a future concern to the persistence of a dry southern and central west coast winter pattern.  The current pattern if it persists could be perpetuated into the winter if anomalous warm water develops along the west coast (+PDO) in conjunction with a large-scale snow pack in the mid west and east.

On a positive note, the *Climate Forecast System”  is still consistent in a break down of the current Ridge Trof pattern over the CONUS and develops a teleconnection of a strong negative phase EPO and WPO.  This along with at least a neutral “PNA” should return storminess to California with needed precipitation toward the end of the year and into January.  The Global models EC and GFS should have decent visibility as to this change in about 6 to 10 days. Although it is always possible to go from one drought pattern to the next, I trust the EC quite a bit as its physics are better at long distance than the GFS.

By the way, I have chatted lately with several locals here in Mammoth that have been up on the hill skiing and boarding. All have indicated that snow condition are very-very good. Comparing ski reports over California,  Mammoth Mt certainly has the very best snow conditions in California with the most snow pack reported of all the resorts. Mammoth Mt reports a 5 foot base over the upper elevations due to receiving more than 6 feet of snow during one of the AR events of November. The lower slopes has about 2 feet and they have been adding to that base with their extensive snow making system nightly. Over the past few days, it has been cold enough to make snow during a lot of the daytime hours and all night.  This includes The Little Eagle area as well as Canyon Lodge. Skier’s and Boarder’s are going to be amazed how good the skiing is when they are up for the holidays! 

 

More Interseasonal outlooking….

Below is the Weeks 3 and 4 500MB outlooks from the Coupled Forecast System/Upper height anomalies at 18,000 feet; Note the Red (Positive Height Anomaly (Blocking) over Alaska and Siberia and the Green (Negative Height anomaly) on the week 4 chart at the bottom. Also note the Blue Color “The Polar Vortex” becoming stretched out shifting well east. This is far from where it has been.  Note the Green (negative height anomaly below the Red on the week 3 chart, (Rex block) morphs to a full high latitude block in the WPO and EPO region. The Negative Height anomaly gets established over the Pacific Northwest.  If this verifies, this should be a good pattern in late December and early January for badly needed precip over the Central and Northern Sierra. This looks to be a colder pattern as well.

 

Dr Howard and the Dweebs………………………:-)

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It is another clear cold morning here in the Eastern Sierra. As the western ridge continues to build over the entire west coast and even up into Canada, a strengthening cold surface high over the Great Basin with a general off shore flow pattern is expected to prevail for several days.  Air Quality will diminish for those who live in the Eastern Sierra. Expect hazy conditions both day and night beginning Wednesday. This new pattern initiates with a strong east-west gradient. Gusty easterly winds over the Sierra Crest will slowly diminish over time, then briefly increase again Wednesday night. Mammoth Mt was reporting easterly gusts to 70mph range this AM. Again, winds will gradually diminish over the upper elevations as the gradient relaxes. At the Same time, warming aloft will begin today with the freezing Level expected to go up beyond 11,000 by tomorrow Wednesday. Once reached, an 11,000 foot freezing level will continue through the weekend. High temps will climb into the 50s later this week at resort levels while lows at night will rise to the 20s and 30s.

This pattern over the far west is part of the infamous positive phase of the Pacific North American (+PNA). Its key teleconnection lies over BC, Canada were it is anchored. When teamed up with a strong negative phase of the Arctic Oscillation (-AO) (Anomalous high heights over the Arctic) This pattern along with a northern hemispheric four wave, (long wave pattern) is very stable and unlikely to change anytime soon. The Climate Anomalies from todays run of the CFSv2, shows a 500mb positive height anomaly remaining anchored over the far west for both week’s 1 and 2, or through the 18th of December.  During week 1, the 500mb Height anomalies axis is located about 120west or over the Sierra. During week 2 it may shift east to about 110 west.  This eastward shift may bring further warming to the Owens Valley as there maybe periods southerly flow. By week 3 the interseasonal climate model shifts the northern part of the upper height anomaly over Canada further east to about 100West away from the PNA region, while the southern portion of the block remains strong over the Desert Southwest. This change will allow the westerlies to move back into the west coast from about Northern CA northward to Washington State. So the potential of an “AR” exists for the coastal regions of the PACIFIC Northwest. It would be primarily warm air advection precipitation over Northern CA, and most likely rain except for the highest elevations. Based upon this mornings run, most of it remains to our north and that may be a good thing!

The week 4,  500MB height anomaly if we choose to believe it, definitely shows the Break Down of the +PNA pattern over the far west and SW Canada. So the pattern goes into transition, the last week of December. Yesterdays European EPS, PNA region showed the +PNA dropping to neutral by the 28th of December. What is even more encouraging is that the Western Pacific Oscillation goes negative about the first of January and the Eastern Pacific Oscillation goes negative beginning the first week of January as well. These two Teleconnections indicate that high latitude blocking high pressure aloft will develop between Alaska and the Bering Sea during the first week of January and into the 2nd week.  PS. The AO goes positive the first week of January, and so there is the possibility of less Meridianal flow. This may allow the pacific jet to make its way to the west coast again.

Just using these teleconnections along with a negative PNA, tells the Dweebs that a stormy period will take place possibly beginning sometime toward the end of the month of December. The odds will then increase through first half of January. Of course, the Dweebs will have better visibility in about 1 to 2 weeks.

Stay Tuned……………………..>>>>

Dr Howard and the Dweebs………………..:-)