Archive for year 2011

Windy…Cooler Today with Cold Front flushing through by the end of the day….Upslope Snowshowers Thursday…Chilly weekend…..

12:30pm Update:

New 12z EC run now follows the GFS lead by taking the 2nd short wave further east. So no strong reinforcing shot of cold air expected this weekend. However with that said, it will be plenty cold to make snow.

 

Just a quick update:

Cold Front moving very quickly southward. It passed Tahoe at 15z. It should clear the central sierra by early afternoon. Some showers possible this afternoon but far and few.  Winds will highlight the day with gusts 30 to 40 in town today.  Temps have already peaked for the day.
Expect some upslope developing after midnight then through Thursday.  It will be cold Thursday with highs in the mid 20s….and Wind chills in town from 0 to 10 above at times.

MJO:

The convective area of MJO is over the Indian ocean at about 70E. It is in a position that would be conducive to a negative PNA…however, as of late, the teleconnection has been weakly positive to neutral.

See: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml

As you can see….The current forecast for the teleconnection is for a negitive PNA over the next week.

 

Furthermore…the dynamic MJO Forecast shows a strong progression into Phase 4.

See: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

Between 70E and 120E is where we would expect the negative phase of the PNA. IE West coast trofing associated with the MJO and -PNA.

So over the next few days….look for retrogression in the long wave high over the eastern pac, if the MJO is going to have an effect, as beyond 120E the PNA usually trends Positive again.

What are the models showing during week 2?

The latest deterministic 12z run of the GFS has the current position of the long wave ridge centered at 135W. By Dec 2nd it retrogrades to 140west. Further retrogression occures to 143W on the 6th of Dec which then retrogrades the short wave track westward back over California….. which is still over land. Further retrogression is suggested but not conclusive.  So…..We are still waiting to see….

 

 

The Dweeber……………..:-)

 

 

 

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.

One more nice day today then winds and cooling to begin Wednesday with dry cold front flushing through Mammoth Late afternoon Wednesday as Blocking pattern develops over Eastern Pac…..

Something to Watch:

The new ECMWF just arrived…1:15pm

It has the next short wave for the weekend digging back in the same trajectory as the Wednesday to Thursday one and it is just as cold! So the current Run as well as the last EC run is consistent. If another run or two shows the same thing….this will create a problem for the weekend as do we go with the EC and call for a cold showery weekend or do we begin warming it up like the GFS then break down the block like wise the following week.

More importantly…. The new 12z EC run has rapidly rising heights over Southern Greenland the 8th into the 9th and cold arctic air piling up over central Canada stretched south into the nations mid section…about the same time.  Could this be the beginning of a reversial in the +NAO? Not that I am a fan of the combination +PNA and -NAO…. But at least it is a change.

 

From this morning…..

Expect similar temps today Tuesday in Mammoth. A major change to windy and colder weather is expected Wednesday. Highs in Mammoth will occur earlier in the day Wednesday as a strong dry short wave/cold front plunges south through Nevada and Eastern Ca. Timing of the wind shift is expected about 4:00pm Wednesday here in Southern Mono County. Once the cold front comes through, winds will shift from the NW to the North then NNE then eventually Easterly.

There may be some snow showers with or shortly behind the front. Then….up-slope showers as the winds come around from the NE. Strong Mono Winds on the west side and eventually the cold will be the big news.  Winds in the Town of Mammoth will be 30 to 40 with gusts to 50MPH possible. Ridge tops will gust well in excess of 100MPH….

By Thursday, NE up-slope will make for a chilly day, even for Mammoth residents as ambient temps combines with NE flow and snow showers to create wind chill factors of 0 to 10 above. 

*Beyond Thursday, the two Global models have the next cold short wave handled differently. The EC brings it down over Nevada Saturday while the GFS takes it south over Utah. The difference is significant as the EC would bring another reinforcing shot of cooling and possible snow showers to the Sierra through the weekend whiled the GFS has moderating temps into the following week. At the moment, the NWS is going along with the more progressive GFS solution….. 

GFS deterministic and Ensemble Spaghetti:

The GFS has a full latitude Block once established over the Eastern PAC Friday, breaking down early next week, much faster than the EC. In that there is no high latitude block in the Greenland area, the pattern is pretty progressive…thus the sale of the GFS solution next week.  Beyond the first half of next week……amplification of the long wave occurs again with a pretty strong upper ridge forming out at 135west about Thursday the 8th.  The upper anti-cyclone that is forecasted to build offshore is expected to move into Calif the following weekend for another one of those fabulous warm Santa Ana events like the past holiday weekend. Mammoth got into the 50s and LA into the 80s with off shore flow then. If the Dweebs dare to look further…..the next weekends big ridge breaks down again as a strong pacific jet progresses across the pacific ocean….while the long wave pattern over the western CONUS remains unchanged with a flat mean ridge over the far west.

Looking the the GFS ensembles/spaghetti

Pattern remains similar through the 7th in the positive phase of the PNA and no west coast trofing….

The other teleconnection is the AO which is in the positive mode. Lower pressure over the high lat’s. A flip to the negative phase would shift arctic air into the mid latitudes.

MJO:

The MJO is the only wild card at the moment as it is strengthening in Phase Space 3 and projected to remain strong into Phase Space 4. If the system remains strong and progresses into Phase Space 5, that may be a game changer to the pattern we want. It it dies in the hole, it will do nothing….

Although the GFS does not show a change in the next 6 to 10 days, tropical variability and its effects are only in the models for 5 to 7 days max. The week two forecasts with the GFS would not take into account the effects of the MJO for another 5 days or so.

All in all, the GSDM and its GWO show the big differences between this year and last at this time. Last year as well as this were/are La Nina years, but this year with the way the GWO has been behaving the atmosphere is acting more like in a weak La Nina/weak El Nino state. IE split flows, +PNA pattern which in itsself is more El Nino like…unlike the negative phase of the PNA which west coast trofing is more the norm.

The Dweebs feel that with the forecast of La Nina rapidly strengthening through December, and peaking in mid January, winter will come on strong later in December and continue strong through February.

Will take another look Friday……

 

The Dweeber……………………………:-)


 

 

————————————————-
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.

Subtropical flow up from the SW to keep lots of high clouds in the area today…..Otherwise warm mild pattern to shift to cold dry pattern 2nd half of week……MJO may be moving into more favorable area week 2……

It was a fab holiday weekend here in the high country. Temps on Sunday hit upper 50s….about the same as Bishop some 4000 lower in elevation. Now that’s an inversion! We’ll its no secret….we want more snow! So what are the prospects for that in the near and distant future?

1st SSTA’s

The Dweebs like them even more now than where they were earlier in the Fall:

The Sea Surface temps over the eastern pacific are much cooler than normal now as compared to the warming that came in late last Summer. That is important because in the subtropics and tropics, cool water creates sinking air. Further north, it  promotes  lower  1000mb-500 mb thickness and with it,  the tendency for deeper troughs in the winter. The current pacific SSTA set-up calls for more trofs over the west and just offshore than last year, when the core of cold was well west off the coast. So the SSTA set up is quite good off the west coast for California.

2nd progression.

The pattern is not blocked negatively for California up over the higher Lat’s.  I think in that the Arctic oscillation is strongly in its positive phase…. and that much of the real cold air is concentrated up over the higher Lats.  That will change later in the season. Something will trigger that cold air to break up and move south like a possible strato-warming event or a strengthening negative QBO which favors higher pressure over the cold northern Lat’s.

More importantly….there is a strong MJO over the Indian Ocean that is progressive. If it make its as far east as the Phase Space 5 then the Odds for an IOP event increase. Look for retrogression in the long wave features sometime next week.

 

Currently, we are beginning to experience more longitudinal flow over the eastern PAC. We will shift to a colder patten later this week with storms dropping much of there moisture over the PAC NW then dropping south through the great basin. The first system that will effect us will be this Thursday. It’s a Cold…snow showery pattern with strong NE winds and light up slope precip. (Closed or cut off low over So-Ca possible

Later in the month the pattern may intensify with the possibly a cut off low near Tonopah, NV (Tonopah Low). “If” the MJO gets into phase space 5, we should have retrogression then west coast trofing in December. However….although the MJO phase space is hinting at that…the GSDM (GWO) is not.

 

Stay Tuned…..

 

 

The Dweeber………………………..:-)

 

 

 

 

 

 

————————————————-
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.