Archive for March, 2014

Platinum Powder Alert continues for the high country for Tuesday Morning with a foot plus expected over the Crest.  The Dweebs use the Crest because of the temperatures expected their in qualifying at for least 15:1 or better for the Ratios. Also needed is at least a foot+ of fresh….that is expected by Tuesday AM. (The Storm is coming into our area in two parts)

Part 1. Precipitation will be the heaviest averaging between .5 and 1.00 over the orographically-favored terrain of the sierra. The most favorable area from the exit region of the front left quad with its forcing and upper diffluence and lower level moisture transport puts Mammoth in the Bull’s-eye,  today and tonight. Snow to water rations of between 15&17:1 will be centered over the higher elevations of the sierra tonight.

Part 2.  The upper low, now well west of the Columbia River will continue to drift SE toward the Bay Area with a well-defined mid level short wave. This feature shows a jet streak ejecting out ahead through Central CA and into the  Great Basin. The progs locate the upper low over SFO 12Z Wednesday AM as it opens it into an open wave and kicks SE through the Sierra in the AM. There may be a short period of time where there is a weak circulation center at 700mb over/near Tonopah, NV for about 6 hours of upslope for a few more inches of lee side snowfall Wednesday.

Although this storm does not have nearly the PWAT that the last had….It is much colder and more dynamic than our weekend system and so snowfall amounts could be greater by Wednesday PM  Between 1 to 2 feet over the upper elevations.

Longer Range:

There is a splitting system that will be effecting our area Friday PM….In which we may get some show showers. Based upon the new 12Z GFS guidance there does not appear to be much of any accumulation for our area.

Inter Seasonal Precip:

Took a look at the latest CFS long-range:   It shows 4 inches of QPF for the month of April and .5 for May through mid-month. So Spring may have another 4 feet of snow left in it through the middle of May.

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

Sunday AM: 12:22

Snowfall rates now 1 to 2 inches an hour.  Back edge of front now moving east through San Joaquin Valley

Lower end of snowfall estimates now likely for the Towns of Mammoth and June.

Update Mid AM

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WINTER STORM WARNING IN EFFECT FROM 5 PM SATURDAY TO 5 AM PDT
SUNDAY…….PLATINUM POWDER ALERT FOR TUESDAY AND WEDNESDAY

10 to 15 inches in town and up to two feet over the crest.

*PLATINUM POWDER ALERT FOR Tuesday and Wednesday. Ratios:   (Snow to Water  20:1)

18 to 24 over the higher elevations Monday into Tuesday.

Friday AM:

Two Significant storms headed for the high country.  Each has a good chance to bring about 2 feet over the crest and a foot+ to the Towns of Mammoth and June.  What is interesting about the 1st storm is the coupling of both subtropical and polar jets off the Ca coast.  The best focus for the heaviest precip will be over the west-facing mountains of Northern CA where the upper jets focus the highest moisture transport near the front left exit region of the Polar jet for a longer period then the Central Sierra.  The upper jets do sag south with time, into the Central Sierra later Saturday and into Early Sunday AM.

In looking at the new CRFC QPF data, they give Yosemite only .90 of QPF.  The Dweebs believe this is way under done as that amount would only put about 10 inches to 12 inches over the crest W/orographic’s.  Considering the pattern…I like HPC’s QPF of between 1.50 and 1.75 for the Mono County Sierra and so amount up to 2 feet over the crest seem more reasonable considering the pattern.  Sunday looks snow showery with little if any additional accumulation.

Next System:

The Monday storm is the last in the series. Although it does not have the STJ coupled with it, the upper jet is cyclonically curved and punches in from the west, right over us.  It is cold as well with 500MB temps of -30C and 700MB Temps of -10C to -12C Both Tuesday and Wednesday

Although the QPF is similar….I expect more from that storm because of the higher Snow to Water Ratios….

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Upper long wave reloading tomorrow, in back of a short wave upper ridge moving through California Friday for a dry day.

The Saturday afternoon and night system has changed considerably now. The screaming message here is that a significant development has shown up in the latest modeling that involves the coupling of both subtropical and polar jets off the California coast.  This leads to the possibility of a tropical connection and pseudo atmospheric river event for mainly Northern CA and will include Central Ca, but for a shorter period. This moisture transport and 700-850MB moisture flux will range 3 times above standardized anomalies into Northern CA.

The Central Sierra will get plenty of heavy snow fall with this system, however, not to the excessive degree as the Northern Sierra.  Will have a better handle on things in the morning as far as the QPF and the effects of this storm on the Mammoth area.

Dr Howard and the Dweebs………………………:-)