Archive for December, 2010

Snowfall Rates To Increase Again tonight! The Night of Lights should be Spectactular!

So far….snowfall amounts ranged from 5 feet over the crest to 2 to 3 feet near the village. Snowfall to increase again tonight!

Today’s WX pattern is consistent with yesterday. Upper ridge continues over the dateline with weak tropical  low to the south near 22n-179w spinning up moisture. This pattern continues to advect moisture northward from west of Hawaii then NE toward the west coast. The deep vortex over Gulf of AK has now moved SSE to off the Oregon coast. The upper westerly flow is consoladating at the base of the upper low. Meanwhile subtropical moisture is being pulled eastward and as it approaches the west coast it is being energized by the upper jet.

Latest AMSU TPW shows a even higher moisture content within the river with peak values 1.5 to 1.6 inches now.  

Looking at the the NAM 12 Time Height Sections off the 18z Run, ( http://weather.utah.edu/index.php?t=nam212&r=MSA&d=ET#)  UVM was at low ebb over Mammoth Mt. today. DVM will continue until about 7:00pm (03z) then increase into the night. Plenty of deep moisture with this system…..way up to 300mb. Snowfall rates will increase again after 7:00pm…with peak UVM about 15z Sunday. (7:00AM) Plenty of Upward Vertical Motion exists through Sunday afternoon in the saturated air mass. Expecting another 2 to 4 feet at the village by Sunday night.

The cold front will move toward the state early Sunday and reach the coast during the morning.  FROPA for Mammoth should be about 02z Monday. (6:00pm Sunday) The max precip will be from Central Ca south toward Southern Ca.  

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


Potential Bluebird Morning……. December 22nd!


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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.

Snow Now Falling In Mammoth

Snowfall began at 3:00am this morning and is now expected to continue for several days. No surprises this morning with QPF on track. Updated HPC 5 day amounts for the south central sierra is up to 14 inches over the period along the west side and 9 to 10 inches over the crest. This means that Mammoth MT is likely to receive a good 10 to 12 feet in the coming 5 days. (10:1 ratio)

The Town of Mammoth 4 to 6 feet. It still appears that for the most part, it will all be snow for the town. There are several waves within the subtropical fetch now currently connected to the central coast. Periods of strong vertical motion will coincide with heavier snowfall rates. Moisture Flux Divergence within the flow is expected to be extreme.

As far as the models go over the next 3 or 4 days…..the large upper low in the gulf of Alaska will remain pretty much stationary with a swift zonal flow underneath that system. The upper jet at 160knots stretches from 160w to the west coast just south of 40 north. The little eddies or impulses that streak across the zonal flow are enhanced areas of vertical motion and represent potential heavier areas of precip when they move on shore.

Looking at the CIRA TPW loop from AMSU  http://amsu.cira.colostate.edu/TPW/global.htm You can see the juice up to 35 to 40 mm within the stream . A subtropical upper low near 30 north- 175 west is keeping the pump juiced.

Analogs:

There has been some talk around town of this being a pineapple connection. A pattern similar to February 1986.  This is not true. The February 16 through 19th event was a true pineapple connection.

The analog shows that a blocking high became cut off over Alaska while the typical upper jet diverged to the right and dug back an upper trof that became confluent with the subtropical jet which road over a subtropical ridge into California. The 500mb heights over Mammoth went as high as 570dm and we had 6 to 7 inches of rain over a heavy snow pack. That was the winter that the Sherwin’s slid.

This system is totally different. Instead of high pressure in the northern Gulf of AK, there is a  deep vortex.  The blocking high is out near the dateline in a quasi REX configuration. Check out the analog at http://vortex.plymouth.edu/reanal-u.html then compare to current 3 day means.

Better analogs are 1968 11/28; 1971 11-28; 1961 12/22 and 1966 11/29



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.

Mammoth Readies Itself For A “Mammoth” series of Storms!

Just had discussion with Alex…..Leed forecaster with NWS RNO:

One more day “today” to make sure everything is in order.

Check list:

1. If you have a gas powered electric generator, make sure you have gas and it is working properly.

2. Snow blower working, extra sheer pins available and of course shovels handy.

3.   It look like more snow now as the models are coming in cooler. Nevertheless, those that are in low lying areas of town should clear out their culverts to make sure they are free of debris.

5. We are expecting a good 3  to 4 inches of water EQ in the Town of Mammoth between Friday night through mid day Sunday. (2 to 3 feet+)   High winds of 60 MPH in town, coupled with the heavy snow fall will create a loading problem for trees and power lines. Be prepared for possible power outages.

It will be a mess in town Saturday so CHAIN UP for 4WD may become a necessity.

Again the  models have been trending a bit cooler the past 24 hours and so it may be, that the period of rain will be shorter lived for the town, which will impact the town with more snow.  Avalanches may becomes a problem in non controlled areas. You folks in the June Lake loop should be prepared as well as you will get buried…..

Folks…this will be the kind of snow that you get stuck in. Even for 4WD’s. Very heavy, dense, moisture leaden cement. So get your chains ready for your FWD’s Saturday and be extra safe!

Better yet, probably a good idea to stay home!

UPDATE:

A deep Eastern Pacific closed low is forecast to drift toward the Pacific Northwest with the center remaining off shore into Sunday. This cold upper low and associated polar jet will combine with a fetch of tropical and subtropical moisture emanating out of another tropical low located along the date line at 23 north latitude. This tropical low which has been part of an ongoing REX block has been tapping moisture out of the ITZ. The under cutting subtropical jet and associated moisture will combine with the polar jet, north and east of the Hawaiian islands creating a copious precipitation event for both Northern and Central California.  Then into next week……although the models retrograde the tropical low…..the remaining moisture train continues a few more days and continues to be entrained, into the  long wave trof parked off shore.

A steady stream of moisture along with strong upward vertical motion will impact the northern 2/3s of the state. The upper jet aligns from Oregon to Central Ca through the weekend gradually sliding southward.  This mornings the latest guidance still shows that the heaviest precip will be through Northern and Central Ca….with QPF totals, according to HPC, up to 6 inches by Sunday morning. Another 5 to 6 inches is expected between Sunday morning and Tuesday morning.


Outlook:  More storms on the way over the holiday with breaks……

One more thing……although the REX block breaks down the middle of this week…it redevelops the following week…..


Update Friday:


On the realm of Global warming and Global cooling……

Did you folks know that the sun is unusually quiet?

In fact it is spotless again this morning.

Geoff Sharp is a solar scientist.

Below are his comments this morning…..

2010/12/16 8:00 1133  is still just visible but is under the threshold at 240 pixels. There is a small speck region measuring 83 pixels in the early northern region that shows some potential on the magnetogram. There is also another region on Stereo Behind about to rotate on that may be worth watching. Its cold in the NH right now, the predicted massive northern winter is beginning to happen.

Yesterday’s adjusted F10.7 flux figures measured at 20:00 UTC recorded 84.2 (87.5), on the way down again. The DSN value for today is 110 with the previous measurement at 214.


SEE:  http://www.landscheidt.info/?q=node/189


——————————————————————————–
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.