Archive for December, 2011

Dec 31…Happy New Year.

Latest 12z Run shows the January 6/7 short wave an inside slider now…..so the system is not likely to bring much more then snow showers and cooling……Still waiting for Mid Jan  change to get into shorter term for better resolution…

The Dweeber…… 😕

Dec 30th.

Mid month pattern change still on with more and more ensembles singing the same tune……..Saving Grace……..

December 29th:

The only item to add to the bullet points below is that the MJO by some of the models, moves into a more favorable position for Amplification then Retrogression of the large scale features that one would hope for to give us a significant storm.  In “Fantisy Land” (beyond day 10 of the GFS) there is a powerful upper low in today’s 12z run that moves off Asia about the 9th/10th, that pumps up a major ridge at the dateline which becomes closed off north of Hawaii over the Aleutians. The down stream upper flow then carves out a full latitude trof about the 12th/14th of January. Normally, it would be nice and exciting for the Dweeb’s to see something like this in the models, then get up and go about the rest the day. However, the Climate Models have been touting a change about the middle of January for quite a while now. So, coupled with the MJO, this Dweeb can not rule out this possible change. Furthermore, the extended runs of the GFS has been hinting at something involving a closed upper high near AK during the second week of January on and off of several runs now.  If she exists…..I’ll call her “Saving Grace”. 

Quick Update For Dec 28th: 

No change in the short term with windy conditions Friday with some cooling Friday into Saturday…

Warm air advection showing up again around the 6th. New 12z ECMWF has quite the subtropical glob with a split trof or closed low showing up as well with the GFS. We might get some small amounts of Snow on the 6th/7th.

Might be interresting to see how split off trof combines with mid lattitude trof for the possibility of precip for Southern Ca and Central Ca.  (Note) This is not any of the forecasts at the moment. Will watch…wait and see……

Pattern Changes still in the offering by Mid month…..Strong Northwest slider possible with strong winds and cooling….precip still questionable…PNA may become more positive later in the month of Jan we’ll see….

________________________________________________________________________________________________________

The Forecast for the East Central Sierra through the end of the year is for the current pattern of mild and dry weather to persist, according to the short and medium range guidance as well as the outlook models. The current mid latitude blocking pattern is likely to continue through the first week of January as well. On a teleconnection note, the Arctic oscillation (AO) will remain quite positive.

Beyond the New Year….there is some evidence that the WX systems moving into the pacific NW will become wetter with time and that Mammoth will get into a warm advection pattern sometime between January 3rd and the 8th.  Again today, a good sub/tropical tap is developing in the guidance that puts some real juice into the systems from the ITZ later in the first week of January. There is decent climo support for this kind of pattern beyond the new year. This may result in higher elevation snowfall or ???  What ever it is….Any precip falling would be non dynamic and warm air advection driven at best. Updates later>>>>>

Currently, the latest climate model guidance, (Beyond week 2) which the Dweebs have to say are experimental at best, are still touting a change to a colder and some what wetter pattern beginning between the 10th of January and the 16th and again in the 17th through the 23rd time frame.  A glance at the 500mb height anomalies then would suggest a return to a colder then normal pattern with the likelihood of snowfall for the Eastern Sierra. However with that said, it suggests that the mean trof position based on the position of the 500mb anomalies, would be a return to a similar pattern earlier this month with the suggestion that a broader trof might develop with somewhat better over water trajectory. What we need is for the mean trof position to develop about 130W with the upper jet coming into South-Central Ca.

The latest Climate Model data might suggests a mean trof position for that time frame east of 120west for a return to cold weather here in the Eastern Sierra and the possibility of occasional moderate precip producing storms. Essentially, the storms would once again develop and move from the NW and track southeast from the long wave ridge position some where just west of 140W which is a drier trajectory then rounding the base of a long wave trof off shore, and coming at us from the southwest or west. There is a lot of time before such a change occurs. Again, this type of an outlook is very preliminary and based upon experimental climate models……There are not forecasts or even officially outlooks. However, there would seem to be some skill there or the CPC would not bother with it.    More later…….

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.

We actually had a little Frizzle last night! (Upslope).  Normally that would not be mentionable in this report. However, this morning, the Dweebs would like comment that it was a nice thought from Mother Nature. Although thus far, shes been pretty Scroogy as an Ebenezer with the Snow this year.

Pattern Change:

Through Friday, no change in the pattern. We are looking for two more shots of cold Canadian Air to advect into our area. One Late Wednesday night into Thursday and the other more mild shot about on Friday. Thereafter…a significant change occurs for the west coast; one that will bring milder pacific air into Central Ca and rain back into the pacific northwest as early as the beginning of next week. Then there is the possibility that Cold and snow will return for the high country between the 3rd and 8th of January.

Here are some thoughts and then some possibilities:

1. First of all during pattern changes, models are usually playing catchup with the details of the change, so the Dweebs forecast will be fine tuned as we get into early next week.

2. A change in the pattern does not always mean precipitation.

The Change:

1. The Eastern Pacific ridge in the mean is moving to the West Coast. (Comment) (There goes the neighborhood!)

2. That will effectively cut off the cold Canadian air that has been periodically invading the far west, keeping Mammoth cooler then normal.

3. The Pacific Jet will grow stronger next week and extend across the pacific increasing moisture and storminess for the Pacific northwest and possibly Northern Ca.

4. And…….although the upper jet will remain well to our north,” Over-running precipitation is a possibility for the Northern and even Central Sierra, “with time” next week, even though 500 Heights will be over 570dm in the mean. (See day +8 centered upon 192hr GFS) http://www.hpc.ncep.noaa.gov/cpc/cpc_NHEM_f192wbg.gif

Over running occurs and is effective in our area when cold air at the surface is entrenched and a moist flow at 700mb RH associated with the upper jet to the north drags mid level moisture into our area. It can be rain or snow! One thing is for sure, whether we get precip or not, the air-mass over central and northern Ca will be a lot more milder next week, “aloft”.

5. More thoughts….

A.  In that there is no blocking downstream IE -AO&-NAO….the likelihood of a persistant highly amplified upper ridge along the west coast is not likely.

B. It is too early at this time to predict over running, but it is a possibility…we’ll see by Christmas Day, if the short term and medium range moistens up.

6. Longer range:

While Mild Pacific Air invades the West Coast, Frigid Air develops over Alaska and is forecasted to plunge southward over the west coast Between January 3rd and the 9th. See: the 500mb Heights forecast that period at: http://www.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/images1/wk3.wk4_20111219.z500.gif

Then see the precip outlook at:  http://www.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/images1/wk3.wk4_20111219.NA.gif

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.