1 to 2 feet on Mammoth Mtn now with some additional accumulations possible today through Thursday AM….Earlier Forecast of 2 to 3 feet over the Upper Elevations still in Sight!
Wednesday December 3, 2014
Posted at 9:59 am by Howard
Although Snowfall ended early last evening, more could still occur over the next 24 to 36 hours….. Mammoth is between two dynamic systems. One to the southwest associated with a very active subtropical jet and the other associated with a weakening closed upper low off the coast of Eureka, CA. That system is expected to shift north over the next two days.
A vort center was moving north over Northern CA bringing heavy precipitation to the north of us and the Moisture Plume to the south promises more heavy rains for Southern CA before the day is over… In that the upper low off the northern CA coast is drifting north, as it weakens…..the Subtropical jet will shift north as well bringing more rain to Southern CA by late today.
In that the upper flow is still SW and very moist, there will be plenty of showers today and tonight enabling the Dweebs forecast of 2 to 3 feet above 10,000 feet to be reached. In that the snow level will rise to 8,000, Only light accumulations if any are expected for the town. The best chance will be this evening…..
The over all picture highlights the East Asian Upper Jet that had extended close to the west coast. However, it should be noted that it did not cross the sierra and so we did not get a cold sector and an upper trof passage. The EAJ is expected to retract now through early next week leading to partly to a partly to mostly cloudy weekend but dry. Early next week will be partly cloudy as well but milder. The Dweebs see the East Asian Upper Jet make a run for the coast again about the 11th or 12th. This is according to both week 2 ECMWF and GFSX global models. The storm track looks progressive and should cross the sierra. While storms of this weather type, like the one we just had, are typically more moist and are mostly absent of wind over the lower elevations, the ones that cross the sierra often times bring more snowfall as they have both warm and cold sectors.
As a note; Jan Null a retired Meteorologist from the NWS-SFO reported that through 7 am this morning….San Francisco had received 1.36″ of rainfall since midnight, which combined with 1.61″ received yesterday gives a 2-day total of 2.97″. With more rain on the way this looks to be the rainiest 2 days in San Francisco since at least January 2008.
As mentioned above…these two longer range models are more consistent at this time the extension of the EAJ through the sierra, beginning the following weekend/11th/12th. What is also interesting is that the new ECMWF EPS ensemble control; 200mb hpa upper jet, shifts south to between 30 and 35 North during the week 2 period. Within the upper jet are Jet-lets with speeds of 180+ knots at 200mb. Looking at some of the Canonical Ensemble Means…More and more are looking like an El Nino Influenced pattern. This is giving consideration of both pressure fields over the north pacific to the slightly higher latt’s and the development of a strong East Asian Upper jet and its extension to the west coast. IE the -(TNH) Telelconnection Pattern for our not to distant future. It appears the next wave of systems the 2nd half of this month may be even stronger than what we have now….A lot will depend upon the strength and location of the MJO and GWO.
Dr Howard and the Dweebs………………….:-)
Heavy Snowfall now occuring in the Town of Mammoth with 4 inches on the ground……8 inches at Main Lodge…..More heavy snowfall expected tonight!
Tuesday December 2, 2014
Posted at 1:28 pm by Howard
What is different this year….MJO wise.
That’s Right! We got MJO!! …..so far!
Latest update shows a nice mid Latitude upper jet off Asia today that extends pretty far east through the eastern pacific. Toward the weekend, it does contract some what and so the Friday system splits and we ridge up a bit next weekend into the following week.
By Thursday the 11th a fairly strong short wave approached the central west coast. At the moment the ECMWF is a bit slower with it while the GFSX has it faster as it brings it on shore Thursday the 11th.
So for the time being…..After this storm is over this Thursday…the next one is about a week away!
In the meantime, heavy snowfall continues here in Mammoth with a lot more on the way!!!!
Moderate Winds over the upper elevations with very light snow falling at the 8200 foot level Sunday Evening…..Slower Evolution to storm system underway….Net result the same……
Sunday November 30, 2014
Posted at 9:53 pm by Howard
Comment: Nice Fetch developing out of the ITZ this afternoon. This fetch is getting juicer by the hour……Quite the rainfall event coming for LA Tomorrow/Night. Great news! But problems for the Foothill Burn Communities….for potential mud flows….
Monday PM Update: Some clarification due to phone calls today….
The biggest problem by far this morning is with snow levels with this storm. Not as much an issue after midnight Tuesday, but more so Tuesday afternoon and night. The temperatures are pretty much isothermal through the layer, which could mean that there is the possibility of microphysical processes going on….which would create quite the problem for forecasting amounts, “In town”…not on the mountain!
Snow levels could vary between 8500 and 7000 for this storm. The thinking this morning is that during the heaviest portion of the storm, the snow level will be around 8K. So for a period of time, it will be pretty sloppy in town, Tuesday afternoon into the night.
In simple terms….if you have 2 inches of water possible and the snow level is at 8000 feet, you could get 2 to 4 inches of sloppy wet snow on the ground at 7500 to 8K. However, the snow level will fluctuate between 7K and 8500…..So it will be problematic for forecasting for the Snow Pushers.
If by chance the iso layer goes down all the way down to 7K, will end up with 2 feet in town. That is not impossible, but unlikely. So 6 to 12 inches still seems reasonable. If we get more…great! As far as the upper elevations go…..2 to 3 feet will set us up for the Christmas holidays……Remember, this is dense heavy base building snow. It is absolutely the best type of snow that we could want. It becomes more difficult to ski it out! So…. Go ahead and book it for the holiday…you will not be disappointed…. And……The Dweebs see another series of storms about mid month. That will be the icing on the cake!
A moist SW flow pattern will continue throughout much of this week until the eastern pacific ridge strengthens next week. There is some strengthening and better organization to the next short wave Friday night and Saturday that now track into the Sierra south to Southern CA. This now appears to be a better storm for the Sierra then earlier thought. So….more rain could fall for CA as well as snowfall for the high country. Thereafter we ridge up for a while next week with the next series of storms likely colder based upon the position of the MJO and its composites for December. This appears to begin as we approach mid month……
Upper long wave cold core closed was spinning at 140 west and will end up ejecting a few short waves before coming through mid week. Today, showers and moderate rain fell over the LA basin and into the mountains of the Southern CA. In Mammoth only a dusting has fallen so far with very light snowfall occurring this evening with mild temperatures at the 8200 foot level. 30s…
The latest guidance shows the passing of the first short wave today, and short wave ridging following on its heals for Monday and Monday night. Although there are height rises ahead of the main upper low, the upper flow is very moist and so plenty of over running moisture will occur with little precipitation if any Monday/Night. The Freezing level Monday will be about 10,500 to 11,000 feet. Again little or no precipitation is expected Monday and Monday Night.
Height Falls begin Tuesday AM as the main upper low approaches the coast. By later Tuesday morning or afternoon, Precipitation rates will pick-up with about a 12 to 36 hour period of potentially moderate to heavy precipitation expected into Wednesday. The Snow Level looks like 7500 to 8500 feet Tuesday until it begins to come down later in the afternoon. It should be all snow Tuesday Night in town and well into Wednesday. The snow that falls will still be wet. We still could get “between” 2 and 3 feet of heavy snow over the upper elevations. (9K and above) and 6 to 12 inches at 8000 ft. The cold core or should I say cool core is only about -18C at 500MB as it comes in. So this is going to be a wet storm for the high country with good sierra cement. This is actually just what we need for the upper mountain for base building. I will add again that there is a coupling of the Subtropical Jet and a Weak Southern branch of the westerlies Tuesday and Wednesday. Coastal sections of Southern CA potentially could get a lot of rain this coming week. IE (several inches)…in the foothill communities….
Beyond this particular storm for the upcoming week are additional short waves in this moist SW flow that may effect Southern CA more then the Central Sierra. It will be showery the second half of this week here in Mammoth. There is a tremendous amount of moisture up at 700 MB associated with the subtropical jet that is progged to flow over the state this week. More dynamics will be focused further south later in the week for Southern CA as the upper flow splits and become difluent. So there may be another period of significant rainfall to watch out for after mid week.
Looking down the road the MJO is moving through the pacific and will reemerge back out over the Indian Ocean toward Mid month or about there after. After this week we may have to wait awhile for another opportunity for significant snowfall. This is not to say we will not get more storms, but stronger west coast ridging will return eventually between now and mid month. Watch the MJO as it approaches phases 8/1. Sometimes AR events are associate with that phase for CA. Getting caught up with the WX this week….The Dweebs will update mid week or sooner if necessary.
By for Now…..