Archive for February, 2012

Snowfall Headed For Mammoth Mtn…..Colder 1st half of Next Week……

Quick Update For Friday:

Windy over upper elevations today: With little temperature change:

1st WX system to bring a dusting to an inch or two Saturday/Ngt

2nd System Sunday night/Monday Ngt about 3 to 6+ inches

3rd system For Valentines Day/Wednesday is splitting on the new 12z Friday GFS….so

the energy and precip may remain off shore as a coastal slider with main effect

upon the immediate coastal sections of So-Cal.

“At this time”, the Dweebs expect the Sierra to have some showers from it

Valentines Day without any significant accumulations.

PS:

March Still Looks Wet!!!!

Quick update Thursday AM:

The next couple of weather systems are likely to bring some badly needed snowfall. First estimate for Mammoth Mtn….is 1 to 3 inches Saturday afternoon. The following system for Monday and Monday night is wetter and more dynamic (-30C cold pool at 500mb) with amounts possibly in the 3 to (6+) inches range for Mammoth Mtn Monday into Monday night. Will fine tune this Friday…. Then, showery weather with below normals temps will continue into Tuesday with additional light amounts. Fair weather is expected the 2nd half of next week.

MJO:

Today’s MJO update supports yesterdays changes from the previous 3 to 4 days….

See: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/ensplume_full.gif

Comments added to yesterday’s discussion show MJO headed toward circle of death in Phase 8 before reaching Phase 1. This is not good for storminess….or retrogression of long wave ridge west of 140W.

I have found that true drought years are more consistent with “precipitation events” during periods of transition between dry patterns that last about 21 days. (21 days cycle?) This winter has followed that trend. 

Will update on MJO and Air Sea Coupled model next Tuesday. Who knows…it may flip back….

Teleconnection indices:

http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.pn.png

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.

A Gradual Pattern Change….1st to Cold and showery….then possibly to wet, 4 week of February and beyond…

Mammoth Mt picked up about in inch from yesterdays wimpy system. It split and headed south down the Baja Coast. The 3 day period beginning with today looks dry. However, some signs showing up for some snow showers this weekend as a tweek in the pattern begins to take shape that will bring colder weather with an increasing chance of some light to even possibly moderate snowfall for Mammoth Lakes next week.

Meteorology:

Both the 12z and last nights 00z EC shows a series of NW sliders into the state as the upper block over Ca weakens and allows undercutting of energy into the Ca state. It is certainly not the ideal situation. The mean ridge position is still over the far west. However, there is still strong blocking ridge over the northwest territories and the energy has to go somewhere. Especially since the wave length opens up, as the Hudson Bay low is forcasted to move east. So the Dweebs look at it as a weakness under the block which should allow some northwest sliders to bring some snowfall shots to the Eastern Sierra. The sliders should be able to bring shots of cold air with fairly meager jet energy. Moisture will be limited. However, some of the new guidance is suggesting some decent dynamics…enough for some fast moving shots of light to “possibly moderate” precip next week. So stay tuned>>>>>>>>>>>>

Now for the fun stuff!

MJO! Yes that illusive bugger is quite strong in Phase space 7. That phase space is not favored for precipitation in California. As mentioned in the past, there has been anomalous rainfall late 7 into 8 during times when the AAM changes. Like during the epic 1-1-97 event. However normally phase 7 is El Nino like which actually promotes amplified ridging in the PNA sector, which is what we have been getting. Now the big question is where are we headed?

The MJO is forecasted by several models.

Below are some very useful links…..

First is a snap shot of where the MJO is and how strong it is. SEE:

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

Now here is yesterdays NCEP ensemble forecast:

Yesterdays NCEP ESM: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ncpe.shtml

Here is todays NCEP ESM: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtml

Here is the lastest ECMWF ESM: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmf.shtml

The million dollar question is will MJO stay strong and move into and through Phase Space 1 and 2?

Today’s forecast is not showing that but yesterdays did.

Currently the pattern over the pacific ocean is amplified with probably moderate Meridional Rossby Wave Dispersion. Phase spaces 7 and 8.

IF/When the MJO moves into phase spaces 1 and 2, the eastern pacific ridge retrogrades. This usually results in the FLIP of the PNA sign from positive to negative and we get a nice long wave trof off the west coast bringing storms to the state from north to south. The Northwest will probably turn wet first with the jet shifting south thereafter. The beginning of the intensive observational period for California based upon yesterdays forecast is about 19th of Feb.

Here are the current composites for California for February. As you can see, the significance is high for precipitation and below normal temps in phases 1 and 2 of the MJO phase space.

Temperature Composits and Significance for Feb:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Temperature/JFM/combined_image.png

Precipitation Composites and Significance for February:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Precipitation/JFM/combined_image.png

 

Another supporting model is the “CFSv2 Forecast”

http://www.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/images1/wk3.wk4_20120207.z500.gif

Week 4 (Feb 29th through the 6th of March) Clearly showing the HT 500 height anomaly retrograded west to northwest of Hawaii with below normal 500 heights over the West Coast. This is a flip of the current PNA index.

 

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.

Upper Block Firmly in Place with a Weak Under-Cutting Attempt by the Westerlies…..Some Light Snow Possible Tuesday with Majority of Precip Expected along the California Coast South & Westward……Possible Major Change in Pattern Showing Up Very End of February…..

Like so many systems this year the next weather system will weaken rapidly as it comes on shore Tuesday. Precip forecast shows about an inch along the immediate coast and lesser amounts inland. The suggestion is that on the west side of the Sierra realitive to Mammoth MT, there may be up to 4 inches of snow with amounts in the 1 to 3 inches range over the area between the Crest and highway 395.  Again amounts fall off rapidly as the energy splits and sheers SE off shore. Southern Ca coastal sections may actually do well Tuesday into the evening, especially over the channel islands and Santa Catalina. Beyond the next few days…we ridge up again and that should hold the weather dry through the rest of this week. Both 6 to 10 day as well as 8 to 14 day charts continue the dry trend into the 3rd week of February.

Something to look forward to:

The Air-Sea coupled global models for the 3rd day in a row is showing retrogression of the upper high westward the 2nd half of the last week of February. This mornings run suggests an upper 500Ht anomaly along 150W, negative tilt up through the Aleutians the 7 day period beginning March 1st.  The is the 3rd run in a row that the *air-sea coupled model has been retrograding the upper high with above normal precip south through Central Ca, beginning the end of February into early March. The temp graph show -2 deviations below standard so it would be snow to lower elevations.  Lets hope for the “Miracle March”!

Dr Howard and the Dweebs…………………………:-)

*The Air-Sea coupled model is experimental, and “should not be” relied upon for planning purposes.

————————————————-
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.