Mammoth Weather

A 17 foot base on the upper mountain, fair weather, very light breezes, with highs well  into the 40s…..it does not get much better then that in January! 

No surprises this morning.  Strengthening upper ridge off shore….the remains of a great basin slider exiting through the desert southwest. Highs today with light breezes will be in the upper 40s in town with temps 5 to 10 degrees cooler up on the hill. Lows tonight will be in the teens and 20s.

The next short wave to come through the upper ridge with be Sunday with an increase of Sierra Crest wind. (50-60MPH)

Heights to continue rising as the upper ridge snuggles up to the Ca. coast this weekend. Low 50s are expected Sunday and MLK-JR Day Monday. Lows in the 20s and 30s.

The next change in the pattern comes Wednesday/Thurs. Looking at the determanistic EC and GFS….the EC is sharper with the upper ridge as it retrogrades toward 135 west. The GFS is not as sharp. The differences will be reflected mostly in wind and amount of cooling.

MJO:

Reading through the lines of the CPC discussion Thursday, it’s apparent that they do not like the “Set-Up” of the High Lat’s as far as where the anomalies are that would support an MJO enhanced west coast storm event. They also sight the moderate to strong La Nina Conditions that tend to weaken the MJO as it moves over the colder then normal waters of the eastern portions of the western and central pacific. However, with that said, the Dynamical Model MJO Forecasts were again insistent that a strong MJO in the critically teleconnected area, could effect the west coast with the beginnings of storminess around the end of this month but with the more likely event in early February. The eastward movement has slowed by a few days from earlier forecasts, and so the timing would tend to be pushed back a bit. The next 5 days or so will be important I believe.

Once again…..this will be an interesting scenario to follow for those that have interest in the interseasonal aspects of forecasting. (Beyond week 2 and outside the time frames of the (GFS Fantasy Charts)

Currently the GFS does have an eastward migrating lower latitude upper jet toward the west coast over the next 10 days. The pattern is pretty much zonal across much of the pacific.  Watching and waiting  for Amplification!

For some basic concepts of (AAM) Atmospheric Angular Momentum see the link below:

http://www.examiner.com/climate-in-raleigh/atmospheric-angular-momentum-aam-oversimplified

The Dweeber…………………..:-)

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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.

The key feature in the western hemispheric pattern over the next 7 days is the big Bering Sea-Alaskan block that is retrograding westward toward and over Siberia, Russia. This teleconnects well with the west coast rising heights forecasted by the global models. This should give us a nice period of January thaw the second half of this week into early next week.  Temperatures will climb to the mid 60s in Bishop by Saturday and into the 40s beginning today for Mammoth.  There will still be a few periods of over-running about Thursday/NGT and again some clouds Sunday.  The models only give us a scant  of QPF Thursday/Ngt (.01 to .02)

Here is your high temperature forecast for Mammoth through weeks end. This is for the Town of Mammoth (TOML).   Wed43/Thur43/Fri44/Sat45/Sun48/Mon48/Tuesday48.

Night time lows will be in the 20s for the most part this week until Sunday and Monday morning when they may only get down into the low to mid 30s…hence the January Thaw!

Good time to plan to break up ice dams and ice and snow off areas of decks and walk ways as the ice will be much more easily removed by this weekend!

Longer Range:  (Next Week)

The models sharpen the west coast, upper ridge the early part of next week. All models have an inside slider type system that will dive into the Rockies mid week.  The warm temps over the Eastern Sierra for the time being is expected to hold through next Tuesday afternoon. However an abrupt change in the pattern will send a blast of cold Arctic air into the Great Basin a week from this Wednesday. An Arctic Front  is expected to enter the Pacific Northwest Tuesday and move through Mammoth Thursday morning. This will probably bring  increasing winds as early as Tuesday night with stronger winds Wednesday into Thursday morning. There may be a period of up-slope snowfall Wednesday night. Strong “convergence aloft” in the left rear entry area of the upper jet and NVM should build a pretty strong surface high over Idaho (1040mb)with a tightening NE gradient along the Eastern Slopes of the Sierra. Strong up slope North Easterlies? It appears to be a quick event in any case.  What is additionally interesting is that this is but a very small chunk of modified Arctic air compared to the monster frigid Arctic air mass that is forecasted to come slamming down from the Arctic later next week over the North-Eastern US. It appears to be the Coldest Arctic Air Mass in a long time.  The coldest air will effect areas like the Great Lakes region south and eastward. A 500mb-1000mb thicknesses pool in the Mid 460s is impressive over Central Canada Thursday afternoon a week away! Today’s 12z Wednesday GFS has the 474Dm  Thickness clipping the northern Great Lakes area a week from this Friday…then heading for upstate NY into New England……..Brutal!

MJO:

Still Intensifying and even growing stronger then forecasted for this time. The Dynamic models are adjusting.

What does the MJO (Madden Julian Oscillation) do to the pattern over the pacific?  It depends upon where it is, and how strong it is.  As the “enhanced portion” (rising air….enhanced rainfall) moves into the western pacific, it modulates the westerlies. The GFS should begin to show a change in the pattern later this month. 

If it all works out…..As the enhanced state of MJO moves into the Western Pacific, (About the 25th of January} watch for strong amplification of a Trof-Ridge pattern with a large jump in amplitude in the west coast ridge. This feature should then build north up over Alaska with time….eventually becoming a large cut off upper Anti-Cyclone  over AK.

Phase space 7 into 8 the Atmosphere is in the Pseudo El Nino State. Expect a lower latitude upper Jet splitting off and under cutting the westerlies during the mature stage with the chance that a precip event will come to the west coast. Timing….sometime between the end of January and the first week of February. Good reading below…..

Remember that there is no guarantee at this time that this will happen. It is still quite speculative. However….this will be a lot of  fun to follow!

MJO Education:

1. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/MJO_1page_factsheet.pdf

2. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/MJO_summary.pdf

Specifically in the #2 PDF file, there are some excellent visuals toward the very end of the file.

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.

A strengthening upper jet into the pacific northwest brought light warm advection snowfall to the eastern sierra this morning. About an inch has fallen on Mammoth Mt and a dusting in town. Expect another inch or so to fall throughout the day today and tonight. In that heights will be gradually rise this week, we can expect warmer temperatures. Highs in Mammoth in the mid 30s today then low 40s Wednesday and Thursday followed by upper 40s over the weekend and approaching 50 by Sunday/Monday. This is setting the stage for a possible January thaw.

Precipitation will be very light all week with periods of gusty winds mostly confined to the upper elevations……hence “Nuisance Weather”!

MJO:

Yes…there is confirmation now that we have a strengthening MJO.

See: http://cawcr.gov.au/staff/mwheeler/maproom/RMM/phase.Last40days.html

Note:  The location within the graph of the MJO is on the border between phase space 5 and 6. It is possibly 1 to 2 standard deviations of normal.  The number 10 represents the day of the month which is currently January. The further the distance between the center of the chart to the outer end the stronger the MJO.

Now look at the Dynamic Model MJO Forecasts:

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

One can see that the GFS forecasting system is forecasting quite an impressive MJO.

And just as importantly……

The location of the MJO moves into a very-very favorable teleconnected area, Phases (7 and 8 ) (El Nino Like).  Historically, this area has teleconnected well with strong west coast storms, including but not limited to the dreaded Pineapple Connection.  Although it is still to early to make forecasts and the fantasy charts of the GFS has of yet,  not picked up on any significant amplitude. They do have quite the strengthening lower latitude upper jet beginning to extend eastward north of Hawaii toward the west coast by the 21st.  

Again..the dynamic MJO forecasts indicate a strengthing signel during the upcoming week with eastward propagation through the end of next week. Most importantly….the “Enhansed Convective Phase”  is forecast to be entering the western hemisphere about the 25th of January. This may set the stage for a possible stormy period for the west coast toward the end of January and into the first week of February.

Stay tuned WX Dweebs……It may get quite fun!

A comment from the Climatic Prediction Center:

1/10/11

ANOTHER CONSIDERATION FOR THE WEEK-TWO PERIOD IS  THE POSSIBILITY OF A SIGNIFICANT MJO EVENT WHICH IS STRONGLY SUGGESTED BY GFS  FORECASTS.  THE PHASE OF THE MJO IS FORECAST TO BE IN A REGION OF CRITICAL  TELECONNECTIONS TO THE CIRCULATION OVER NORTH AMERICA, HOWEVER AT THIS TIME,  IT IS JUST TOO EARLY TO FACTOR ITS INFLUENCE INTO THE FORECAST WITH ANY DEGREE OF  CONFIDENCE, OTHER THAN TO REDUCE CERTAINTY.

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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.