Upper Low west of San Diego working in combo with continental southern Four Corners upper high…..is channeling up some monsoon moisture…..air mass less stable this afternoon and Labor Day for some isolated thunder….Weather will continue to be highlighted by above normal temps….
Sunday September 4, 2011
Posted at 10:56 am by Howard
The weather could not be better here in the high country. Temps in the mid to upper 70s…low at night in the 40s. The Weather today and Labor Day should produce afternoon cloudiness as well as a chance of a few thunderstorms over the Crest and Eastern Ca. Tomorrow Labor Day PWAT is forecasted to be about .5 to .6. So although there may be showers….we do not expect a lot of rain. Additionally, the Rt Rear entry region is over the Southern Sierra Labor Day, so tomorrow will have the best chance of a little rain. Either Way odds of measurable precip .01 or better is only about 10% to 20% today and Labor Day for Mammoth.
Early Next Week:
The upper low opens up and comes through Labor day and is east of the area leaving a dry southwest flow by Tuesday. GFS plots from the 12z run this morning has HT 500 Heights over Mammoth at 590DM by late Wednesday AM. Thus Wednesday will be well into the upper 70s.
Longer range: The second half of next week shows a weakness developing within the long wave upper high over the west. An upper low develops over the Great Basin Friday and retrogrades toward the Central Ca coast next weekend. It is possible that a more divergent upper flow pattern may occur effecting the Mammoth area, with some showers and thunder next weekend especially if the upper low is SSW of Mammoth near PASEO ROBLES or FAT. Although the atmosphere may be dynamic for our area, so far, there is little moisture showing up in the pattern at this time……that may change…..
Beyond next weekend….the upper flow deamplifys across the pacific and a fairly strong band of westerlies develops between 40 and 50 north…The pacific northwest will begin their rany season. This is well north of the Mammoth area. Ht 500 Heights remain in excess of 582DM that following week for our area.
SSTA”S Sunday update:
Warmer water continues to modify the persistent -SSTS of the past 12 months well off the Ca coast and up along the coast of the pacific northwest into the Gulf of AK. The cold -SSTA’s are also warming in the Gulf of AK. Although the SSTA;s are still in negitive terratory, this modification has been rapid since the middle of August. If the trend continues we may observe +SSTA’s off and possibly along the Ca Coast northward then northwest into the Gulf of AK. If so, odds may increase for a later start to the Fall rainy season here in the Sierra. Warmer water tends to support higher heights aloft and a stronger upper high especially during the colder half of the year…..thus it tends to weaken west coast storms. Of course there are other stronger forcing factors hemispherically.
If this is going to be a light La Nina year, then I would expect a later start to the season with a colder winter than last, with some large powerful storms during the winter.
Again typical La Nina Winters usually start later and end earlier here in the south central Sierra. I said that last year, and of course the winter was totally opposite, because of the combination of a strong -PDO, strong La Nina and strong northern hemi blocking.
At this time last year, La Nina was already cranking. Today, the CPC is in La Nada mode with La Nina not showing up until the end of October at the earliest. So it is very weak at best and will probably take until wintertime to strengthen.
The storms of La Nina years can be quite impressive during the Dec, Jan, Feb into early March. Average La Nina winters usually bring somewhere between 80% to 120% of normal. (354”) is the average for the past 41 years. Last year was about 185% of normal. So pretty much off the chart!
1000 inch winter? We may be lucky to get 400 inchs!
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.