Archive for January, 2012

Current Strato-Warming “In Process”and the flip of the QBO to Easterly Suggests That Arctic Air Will Decend Upon NA..

Quick Update Saturday 1:15pm

*Today’s Operational 12z Run of the ECMWF and the EC ensembles have the ridge ridge axis at about 166 west. This is much more encouraging then last nights 00Z run of the GFS. the Differences is a location of about 240 miles further east which results in the heights being about 50 to 60 meters lower for the Mammoth area. That would likely mean a lower snow level.

Checking in on the current state of the well advertised strato-warming event…..the data via (EC Ensembles 360hr) at the 10mb level is pretty amazing showing the warming over the N pole going from -68c to -18c at 10mb over the current 15 day period. (360hours). Check out the GFS over the upcoming 240 hours period. http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/

Additionally, the QBO’s easterly flow continues to deepen in elevation and is now over much of the hemisphere near the equator in which relevance supports strato-warming and the GFS upcoming AO flip in the next (6 to 10 days) The GFS is forecasting the AO to be in negative territory by the 15th of January. Remember, that there is a correlation to a positive AO and dry weather in California.

This all adds up to a forecast that Arctic Air, via Siberia and Alaska should invade North America the second half of this month. The exact timing is uncertain but best guess is about the 3rd week of January.

*The key to what Mammoths weather will be like always revolves around where the pacific ridge set up. Set it up too far west and we ridge up. Too far east and we ridge up. Too far north near AK, you get under cutting of the westerlies. If it is too far west and north we may get rain as the wave train comes up from the lower latts  (Subtropics).  The GFS 00z 7th sets up the mean ridge over the Bering Sea at 170 west. It closes off an anticyclone at 500mb with 300 meters of the southern branch (wet) by the afternoon of the 17th. http://www.hpc.ncep.noaa.gov/cpc/cpc_NAM_f264wbg.gif

That is a relatively warm wet pattern for the Central Sierra as the mean heights over Mammoth would be in the mid to upper 560sdm. The 564 line at 500mb cuts across Tahoe.  Snow levels in saturated air 8.5K to 9.5K? depending upon micro physical processes/sounding. Again the key will be where the upper ridge sets up. The Dweebs would like to see it closer to 160west so we get more energizing from the polar jet and a cooler air-mass. (confluence)

The good thing is that the pieces to the puzzle are coming together and although we have another good week before we can nail it down, the light continues to grow brighter that a change to a wet pattern is nearing and the end to a very long dry spell……

Latest Climate Model anomalies show it going dry again week 4.

 

 

Dr Howard and the Dweebs…………………………..:-)

 

 

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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.

Pattern Change still on track for about the 15th…..Odds beginning to increase for precip between the 15th and the 18th…..big question is…..what happens afterwards…..

Friday Am update:

Pattern still highlighted by inside slider Saturday morning so breezy and cooler this weekend. Temps probably back more toward Climo 30s during the day. Good snow making conditions. Ridging with inversions setting up again Sunday night into Monday…then another slider or splitting system, middle of next week. Bottom line is…the mean ridge position over the far west and Eastern Pac is still keeping the central and southern west coast dry. Of interest this morning was week 3 of last nights Climo runs. Jan 20th thru 26th showed wet for Central California north through Washington.  This is a reversal from the past 5 to 7 days.  Well keep eye on this……hopefully something will give. For what it’s worth, today’s run of the Climate models are dry for Central Ca, the week Jan 13th Through the 19th.

Last night:

There was good ensemble support on today’s 12z ECMWF run for a decent system between the 15th and the 18th of January. The operational run looks impressive for a good precip producer with a fairly wet system, beginning about day 10. (the 15th)  Even the new 8 to 14 day outlooks from CPC are now backing to normal precipitation amounts for Central Ca.  However…..this is still a long way out and should be looked at with skepticism. During true drought type winters, many models do not handle the deep rooted underlying factors that support patterns, like the ones we have been dealing with. Case in point….notice how the new 00z Friday operational flips back 180 degrees to a ridge the same time frame. Not good….but it will interesting to see what Fridays 12z and this Saturdays 00z ECMWF shows, for the time frame around the middle of the month as that will effect the ensembles and the outlook period.

The GFS fantasy charts are a bit more conservative and elusive, however do bring in some sort of system about mid month. The big question this evening is….. “Is this just a transitional storm between another dry pattern or will this continue into January”. The Jury is still out on this one. Not jumping on the ECMWFs 15 and 30 days at this time. Climate Models are still dry through Feb 1.  Only supporting index at the moment is that the AO, which is still expected to drop off into negative territory the 2nd half of January.  Stay Tuned!………………..>>>>

 

 

Dr Howard and the Dweebs………………………………:-)

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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.

Another Dry Week Ahead As We Begin The New Year…..Mid Month Pattern Changes Still In The Picture…But Nothing Conclusive…..

January 4th update:

The strato warming event in process is certainly effecting the NH polar regions with the forecasted movement of both PVs. The Dweebs are watching changes that are supported by the GFS ensemble means this morning as well as the ECMWF…

The movement of the large upper low/polar vortex over Alaska back to Eastern Siberia allows for a significant ridge to develop over the Bering sea and Alaska in the 11-15 day period. This ridge builds into Alaska and far Western Canada and also ensures that the vortex over Eastern Siberia can not progress into Alaska. This is a significant change in the pattern to last December. Additionally, the trend in the phase of the AO and NAO is downward toward neutral by mid month.  That as compared to the super positive readings of December and November. More later…..

JAN 2nd:

It’s the 2nd day of January and Tioga Pass is still open. That in itself is a record breaker going back to 1933. High temps were in the mid 80s in the San Gabriel Valley in So-Cal New Years Day. Mammoth Lakes had highs in the low 50s….40s on Mammoth Mtn.

A good point to be made is that Mammoth Mt has got some of the best skiing on Man Made snow of anywhere in California and probably the west. The pacific NW has a higher base, however, the storms have been either rain or snow producers. To the point…..Mammoth Mt has 17 lifts operating and over 45+ runs open. They will remain in full operation. Skiing is always better in the morning because of the fresh corduroy so get up on the hill early!

The forecast is for little change in the pattern this week. Highs through Thursday will continue in the 40s on Mammoth Mt and low 50s in town. Over night lows in the 20s.

Discussion:

Upper ridge over the intermountain west will flatten today as a system moves through the pacific NW. This will have the effect of kicking up winds over Mammoth Mt today, 25 to 35 with stronger gusts possible over the ridges.  The mean ridge position over the far west Re-Amps again Tuesday night and sets up another weak off shore flow pattern for Southern Ca…..and so more 80s possible mid week for Southern Ca. Mono County will experience a bit stronger inversions by mid week. Expect little change in temperatures at 8000 ft through Thursday.

By Thursday, the upper ridge begins to flatten again and redevelop a bit further west. This will have the effect of setting up a brief NW flow aloft pattern and bring cooler air back into the Sierra. Although this is still a dry pattern, A good shot of cooling is expected to lower high temps down into the 40s by Friday and nighttime lows into the teens. The colder and a drier air-mass will create better conditions for snow making just prior to the weekend. Then by the 8th, anticyclonic flow aloft will move into Northern California strengthening inversions with warming temps at 8K ft back into the 50s by weeks end.

Now….the longer range…..

With much anticipation in the week 2 period of a pattern change, the models are at best chaotic in there resolution.  The GFS is all over the place in where they redevelop the upper eastern pacific ridge to…..and what they do with with the remains of the current ridge. So yes….there is a pattern change going to happen. However at this time it is not clear how it will set up.

MJO is diving into the circle of death once again. The AO is trending negative which is good, and so the dam of cold air currently over the pole will get the chance to move south in the next couple of weeks. The climate models have not been updated since the 31st, assuming because of the holidays. The Dweebs believe that we will know a lot more by the end of this week.  Keep good thoughts but stay away from the 1000 inch Jinx!

 

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.