Archive for January, 2011

Cooler today with decreasing winds over the crest…..milder Friday then next inter mountain slider Saturday to bring more upper elevation wind and cooling….The strong MJO no help in changing current pattern so far….

The weather the remainder of this week will remain fair with temperatures Thursday a bit below normal….then warming to a bit above normal tomorrow…then cooler again. Winds will not be a factor except over the higher elevations where ridge tops will still gust 50 to 60mph.

High latitude blocking is now gone from the picture over Greenland and AK.  Now mid latitude blocking is the rule. With the PNA in its positive phase…California weather will remain fair with occasional Santanna”s for Southern Ca and periods of NNE wind for the upper elevations. This pattern is likely to last at least another week or possibly two. The extended maps progress the upper ridge closer to California later next week for above normal temps much like what we experienced Martin Luther King JR Day.

In the coming weeks…the Hudson Bay Low will strengthen as more and more ice and snow forms within that region and then south through the eastern half of the country. The East will be in the Deep Freeze for some time while the west will enjoy a period of excellent weather. The cold surfaces over Central and Eastern Canada south down through the CONUS will likely begin a thermal feed back process that may perpetuate the pattern into February.

Will the AO and NAO become negative again? Probably at some point in February.  High latitude blocking can be favorable or unfavorable for California rainfall depending upon where the teleconnecting anomalies set up.


So far….the strong MJO over the western pacific has had no effect in the numerical guidance in setting up a wet pattern for California. This is one of those times that forecasters can say that you can not guarantee that the MJO will always be a pattern changer to wet for the West….although the CPC indicated that signal certainly favors a colder stormer east in its current phase.


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.

Dry Dry As Far As The Eye Can See…PNA Pattern Likely To Rule The Western Hemisphere The Next 1 To 2 Weeks! (Wednesday AM MJO Update)

Skiing is fabulous up on Mammoth Mountain. The groomers are out nightly mixing it up on an 11 to 16 foot base!  Temperatures to cool the next few days as our upper ridge retrogrades to 140W. Highs will cool to the 30s again. It will be breezy Wednesday and NGT.

The 3 to 5, 6 to 10 and 8 to 14 day forecasts and outlooks are all singing the same tune.  It’s called “The PNA”. The Pacific North American circulation pattern. It is one of the most common teleconnection patterns over the northern hemisphere.

The positive phase of the PNA pattern features above-average heights in the vicinity of Hawaii and over the inter-mountain region of North America, and below-average heights located south of the Aleutian Islands and over the southeastern United States (Hudson Bay Low). The PNA pattern is associated with strong fluctuations in the strength and location of the East Asian jet stream. The positive phase is associated with an enhanced East Asian jet stream and with an eastward shift in the jet exit region toward the western United States.

Plain and simple…the positive phase  PNA is a dry pattern for California in December, January and February. The West Coast ridge will shift back and forth between 140west and 110W. 

When the upper Ridge is between 130 to 140 west, Mammoth is cooler and dryer then normal with windy periods and sometimes snow showers…..(inside sliders) Even a cut off low can develop over Nevada.

With the upper ridge just off shore or over the Great Basin….California is warmer then normal with  ocassional Santana winds over Southern Ca  Once the upper ridge slips east of 110, the  door can open to pacific moisture for Ca. 

The Dweebs have said it before and they will say it again……La Nina winters are highlighted by intense stormy periods with long breaks in between.  Winter will be back!

Quick MJO UPDATE:

The enhanced portion of MJO is quite strong over phase space 7 of the Wheeler Hedon Phase Space.  The numerical guidance of the GFS from the 00z Wednesday Jan 19th is just beginning to reflect the signature of the inter-seasonal oscillation. Although very *incipient…it is encouraging…however, it was not reflected on the 06Z run.

CPC did cite that the pattern over the high latts was not favorable for an west coast wet event. Additionally, the cold waters of La Nina would also diminish MJOs effects.

The Dweebs see some slight evidence of amplification toward the end of January of amplification and then undercutting of the westerlies. The Eastern Pacific Ridge becomes pinched off and bubbles up along the coast of BC, Canada about February 1st. The timing does teleconnect with MJO and its location.

We will have to have many more model runs as well as much more development in this pattern before any serious confidence can be attained for a California wet MJO related event.

 

 

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.

High temperature records fall in big numbers……MJO Update

What a day! Mid January in Mammoth and temps like early spring!

The high today was 56 at the Village at Mammoth breaking the old record of 53 set back in 1994. As of 2:40 pm the high in Bishop was 75 so far today with higher temps still possible. The old record was smashed by 4 degrees set back in 1958. Another warm day for January is in the cards for Tuesday.

The eastern pacific ridge is set up along the west coast and so record highs are occurring over Southern Ca as well.  A mild off shore flow is coupled with unusually high heights for this time of the year.

An inside slider will intensify the off shore flow Wednesday night for LA. So more of a strong Santana will result.

Over the next few days the eastern pacific ridge will retrograde westward allowing for some Great Basin cooling to move in from the North Wednesday into Thursday. Night time lows will return to the single digits and teens during Mid week.

Over all, we are in a typical positive phase PNA pattern that is common during Mid January. This pattern is highlighted by strong temperature inversions…warmer then normal temps over all with little in the way of precipitation. This pattern often times can last 21 days.  Dry weather is expected through the next Weekend.,

MJO:

The inter-seasonal phenomena convective portion has moved into the Western Pacific…and although a strengthing upper jet is in process….it has not progressed into the Eastern Pacific.  Its location in phase 6 often times is associated with above normal precip in Central California. It is still progressing eastward. Phases 7 and 8 are even more favorable for increased storminess for Central and Northern California.

CPC is not encouraged as there has been thus far, no indication from the numerical guidance (GFS or ECMWF) (Week 2) of a pattern change to wet for California.  The Dweebs comment….There is still plenty of time. Will keep weary eye on the subject!


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.