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.