High Cloudiness Invades Mammoth This Afternoon With Dry Cold Front On The Way…..Warm Advection Snowfall Still On The Way For Tuesday And Beyond…..

What does January 4th, 2011 and January 4th, 1983 have in common? They both have very nearly the same amount of water content upon Mammoth Pass to date. Some other interesting notes…  The winter of 1983 was the wettest winter on record according to DWP for the Mammoth Pass.  Now for the Irony. The winter of 1983 was associated with the strongest El Ninos on record! The winter of 2011 is so far associated with a La Nina that’s one of the strongest on record so far.  Wet La Nina….Wet El Nino!    See:   http://www.ladwp.com/ladwp/cms/ladwp013390.pdf


Current Weather:

By 8pm or 9pm tonight a dry cold front will push south of our region……Aided by an upper jet approaching 150knots by Sunday PM across Nevada. Temperatures at 700MB are forecasted to be as cold as -10C on the east side of the Whites and on the west side… -6.5C. Nevertheless another dump of cold air is destined for the high altitude valleys that just got done with temps as cold as -20F.  There will be some -10F locations by Tuesday Am.  

The big forecast challenge is whether or not the valleys get some freezing rain next week along the highway 395 corridor….. Or will it be below freezing through the column?

For the Mammoth and June area, the Dweebs expect periods of light snow fall on and off through the end of the new week. Some days possibly an inch or two, others days 3 to 6 inches within any 12 hour period. Thursday looks a bit better for a system that may bring a bit more.

The Big picture:

Overall this coming week, the models maintain and agree that the high latitudes will remain blocked up with a strong -AO. The big Alaskan block will drift slowly west northwest from northeast AK into Eastern Siberia. Through the process…..the westerlies will undercut the big block and merge with a deepening trof in the mean over southwest Canada.

The tempo will pick up later this week as the storms will move faster under the block.  At this time….it appears that the Town of Mammoth Lakes will be mostly south of this storm track. Precipitation should be Light to at times possibly moderate later in the week.  The Dweebs Snowfall Criteria for Mammoth…..Light: 1 to 6 inches within any 12 hours period; Moderate: 6 to 18 inches within any 12 hour period.

With all that said there are some ensemble members that have the storm track further south into Central Ca later in the week. However, for the time being….the majority keep the brunt well to our north.

Again it appears that Mammoth will have a week of warm advection precipitation. IE…..isentropic induced snowfall.

Note:

There will be something to watch out for after the 15th:

Is the the Dynamical Model MJO forecasting a rapidly strengthening MJO later this week that will move well into the Western Pacific the following week?

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

Never a Dull Moment!

Dr Howard and the Dweebs…………………………..:-)


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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.

Northwest Slider To Bring Cooler Air To Mammoth By Sunday….Some Light Snow Possible Tuesday Into Thursday…Then January Thaw A Possibility Thereafter…..

Inversions weakened over the past 24 hours and Mammoth AP Thursday morning which was -20F. This mornings over night low only was only +1F.  The strong upper ridge and surface high that kept the cold Arctic air from the previous storm trapped in the lower high elevation valleys this week is weakening…..

The next changes to our pattern:

1. Upper cut-off low off LA is currently ejecting through Southern Ca today bringing a few showers possible to the higher terrain.

2. A Northwest slider off the Southern BC coast is acting as the kicker. This system will develop quite an impressive upper jet the next 48 to 60 hours, after which couples with a mid latitude jet  into NW California  Saturday. No doubt there will be an increase of wind over the Sierra Crest later Saturday Afternoon with stronger winds Sunday into Sunday night.  The new 12z Friday GFS shows 300mb isotachs over NW Ca at about 70 knots which then increase to 110knots by 4:00am Sunday.

By late Sunday afternoon, the upper jet at 300MB is diagonally slicing through Central NV with a 135 knot upper Jet. This will keep the upper elevations of the sierra crest winds going….bring further cooling to our region and even the slight chance of some flurries or snow showers as the right rear entry region passes off to the southeast on Monday. Daytime highs for Monday in Mammoth will drop to the low to mid 20s.

3. In the systems wake…colder air will advect in. This will eventually be the lifting mechanism for several mid latitude short waves coming up from near Hawaii Tuesday….Wednesday….Thursday and Friday. These will be all warm advection precipitation producers. Will it be light or moderate in amounts?  Too so0n to tell. Warm  advection precip is some of the most difficult to forecast here in the Eastern Sierra as far as amounts. So for you snow plowers…..don’t take that trip to Mexico just yet. Your hall passes are canceled until we see if the  proposed “January Thaw” is going to be real or not!

4. The long range models are deepening the Hudson Bay Low in last nights 0000 UTC GFS  500mb Height/Anomaly Forecast 7 Day Mean, Centered Day 11 (10 days out). This looks like a January Thaw Pattern.  However, looking at the new 12z Friday deterministic run of the GFS , I have my doubts on how long any period of fair weather will last, as that key negative height anomaly (Hudson Bay Low) does not seem to like the Hudson Bay area very much this year. Thus, any strong loading of the +PNA will probably be short lived?


As usual…we’ll see how it all develops……………;-)

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.

Mid Latitude System Lurking Toward The Middle of Next Week!

Just a quick update for the longer range……..

Both the 12z GFS and the 00z Wednesday ECMWF have a subtropical system coming into northern and Central Ca about Tuesday. The GFS has it a little earlier with the main punch further north. The ECMWF has a good part of it effecting Central Ca. This is a fairly warm system with high snow levels about 8000 to 9000 feet.  The EC is pretty wet with it Tuesday night/Wednesday a week away. It may be warm advection precip.

This system  is currently approaching north of Kauai and is part of the pattern of concern that the Dweebs discussed over the weekend. The fact of the matter is….The Greenland block is still going to force a pattern change over the next week with the ultimate result a cut off upper high over Western AK  and an upper low to the south of it, north of the Hawaiian Islands. There is short wave activity that will come out of the westerlies associated with the big vortex north of Korea.  By this Saturday afternoon, the ECMWF has a closed anticyclone centered over the Aleutians with a Subtropical closed low directly south/north of Hawaii at 30 N. This completes sort of a REX block with two distinct streams with the split between Hawaii and the dateline. 

By Sunday night, the remains of the Greenland block merges with the cutoff high over AK, while a strong short wave coming out of the Asian/Siberian Vortex boots the current closed low north of Hawaii toward California.  The short wave thus replaces the current system north of Hawaii as it too becomes cut off. The big question arises on whether or not the subtropical system makes it into California, as it has to fight a subtropical ridge between the mainland and Hawaii. The ECMWF has a pretty wet storm for California Tuesday the 11th of January with 90% HR at 700MB. 

see: http://www.met.sjsu.edu/weather/models/ecmwf-00/ec_relh700-ani.html 

As a Note: The GFS is not nearly as wet.

There will be subsequent short waves coming out of that mid latitude weakness north of Hawaii later next week. However, the cut off upper high is supposed to retrograde, thus allowing heights build over the Eastern Pacific again, pushing the moisture further north……….stay tuned.  The Dweebs got you covered!


PS.

Please no 12 foot Rumors…..It is too soon….

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.