After a Quick Shot of Light to Moderate Snowfall Tuesday….Modified Arctic Air Invades the High Country Mid Week and Stays into the following Weekend……
Saturday November 30, 2013
Posted at 9:54 pm by Howard
Tuesday Evening Update:
Upper trof axis slowed as it moved through Mono County as forecasted. At the moment the axis is near Lone Pine and will remain over the Owens Valley moving at a snail’s pace through the early morning hours…..reaching Kern County 12Z. Another ripple moves through in the northerly flow late Wednesday for another round of snow showers from upslope Wednesday night into Thursday AM.
The next important Arctic short wave dives south, and is west along the coast of the pacific NW Thursday night…….700mb RH in the NAM increases rapidly Friday with another round of snow by Friday afternoon and into Saturday.
This particular wave looks interesting. As the upper ridge that currently extends up into Alaska gets pinched off with the break occurring on tonight’s 00z Wednesday NAM at 45 north. If this break occurs in the ridge in this spot at that time, the timing may allow the next short wave to bow way out off the coast and cyclonically really pick up some moisture from the pacific.
However, the 00Z Wed GFS does not pinch off the Upper high at that time. What we get is another cold outside slider with a period of light snowfall Friday night. So it is too soon to get too excited about another foot yet.
It look like Mammoth Mt picked up about 8 to 12 inches past 15 hours. Actual tally in the morning from Mammoth Mt.
This particular system is through now….just some snow showers remaining. Do not expect much more than another inch over night.
Cold is now the main message with lows in the low single digits here near the village and -10 to -15 in some of the colder valleys.
Will update in the morning………………
PS I do not remember the models having this much difficulty in handling Pacific energy and the upper flow like it has this fall!! The spaghetti in the Ensembles is pretty unruly after about 7 days…..
I think that were all good on the snowfall prognostication for Tuesday based upon the last discussion. Tomorrow Tuesday Morning, the Arctic Front is expected to slow as it moves into Mono County and that should give us a bit extra Precip as reflected in the forecast amounts.
Looking down the road there will be several ripples in the flow that are out of the Arctic this week. Any one of them can potentially kick up some snow showers. There is one short wave in particular, off in the distance with this same pattern, that will come in Friday night worth watching. The Upper jet seems to have a double structure with it, with an apparent part over Water and the other coupled with it over land. That is expected to come into Mono County Late Friday night into Saturday. That may be good for several more inches then.
The longer range outlook is greatly subject to change, shows the possibility of the upper high pinching off into a closed upper high over AK, with a significant branch of the westerlies undercutting into the central west coast. If this works out, this may be initially, an isentropic lift precip producer, flowed by some dynamics (UVM) afterwards. This is not a forecast……just looking down the road a week away…..
Have a nice day>>>>>>>>>>>>>>
Dr Howard and the Dweebs…………………………..:-)
10:00 AM Sunday
Everything on track for a very cold week ahead with upper teens and low 20s in town. Even Tuesday’s weather will be cold with high temps near 27F……and that will occur fairly early in the day.
Strong winds will preceed the arctic front with gusts Monday afternoon through the night 30 to 50 MPH in town.
Snowfall: The new ECMWF QPF is out for Tuesday painting .6 over the crest and there is even a few isolated areas that show .80 Considering how cold the air mass will be and the higher snow to water ratios of at least 15 to 1, it is not unreasonable to expect 5 to 10 inches between 9K and 11,000 feet by Wednesday AM, and 3 to 5 inches in town. In a few of those isolated spots, up to a foot could fall.
Well, we could have had a bonanza of snowfall this week if earlier model runs would have stayed consistent. The Current Arctic Low off the coast of Northern BC will instead move into the Pacific NW then become east west orientated across the northern tier states. I have to say that by December, the longer range global models usually do a much better job a week away.
You would expect a longer range outlook in November to bust, but by late November that’s unusual. So until the Dweebs see better performance in the longer range, well stick to the short-term and medium range, highlighting that the extended guidance is an outlook rather than something that is more believable. It may be that during this winter, the longer range guidance is one that the Dweebs will use more cautiously.
As far as snow fall goes…light amounts are expected. Will fine tune in the morning….
What we lack in snowfall we will make up in cold weather…..Modified Arctic will invade Tuesday and by Wednesday we will struggle to get out of the teens at 8000 feet. Night time lows will range from the single digits to below zero in some areas. The cold will be prolonged into next weekend. No doubt there will be broke pipes in town……so do what you have to keep the house warm….
I do see another pattern change during the 2nd week of December….hope its a wet one!
Weakening system over the southland may give some snowshowers Thanksgiving day and night….Cold Arctic System makes its way into the Pacific Northwest with Arctic air to Accompany….Snowfall may begin as early as Monday for the Mammoth Area…..
Wednesday November 27, 2013
Posted at 6:25 am by Howard
Wednesday AM Update:
The Thanksgiving holiday weather looks mostly cloudy with a slight chance of snow showers both during the day and night. Daytime highs in the 40s and nights in the teens and twenties. The rest of the weekend look party cloudy with little temperature change. Winds will be light……
Last several runs (Tuesday and Wednesday) of the ECMWF and GFS still have quite the powerhouse coming into the pacific northwest early next week. However, an adjustment eastward in the pattern suggests that the upper center is likely to remain over land now and not out over the sea. Nevertheless, plenty of upper jet energy will bow out off shore and then into the Sierra next week, so still a good possibility of significant snowfall. There are even some signs of a tropical tap later next week. The Key on all this is this. Recent models run of the GFS has the upper ridge axes at 140west through Alaska. The ECMWF has the axis about 145 west. The 140W longitude line for California is Critical. Often times when a long wave highly amped ridge is east of 140W…Storms take a track over land, where by if the ridge axis is west of 140W the track is offshore. The ECMWF is still west of 140W, however, not by much. So a lot will depend upon the eventual placement of the upper ridge when it sets up next week for how much snowfall we get. The Dweebs have noted that the ECMWF is a better global model when looking out a week then the GFS….
This is an evolving situation in which it will probably not be known, how much snowfall will occur until Sunday for the up coming week. There is no doubt that we will get snowfall. The question is how much and….there is plenty potential for Footage IE 1 to 3 feet over the crest……The Dweebs will not update again until Sunday…….
Have a Great Thanksgiving and Travel Safe!
Dr Howard and the Dweebs……………………………………..:-)
Monday November 25, 2013
Posted at 11:30 pm by Howard
Tuesday PM Update:
12z model runs out with GFS still bullish with plenty of over water trajectory. 12z ECMWF has less over water buckling on its deterministic run than last night and yesterday. So it is not as wet. Will update as soon as the new 06z GFS run is finished….
Confidence still plenty good for a cold sierra snow storm, early next week….
Tuesday AM Update:
Confidence increases this morning for the set up of a major Sierra Snow Pattern that will begin Monday morning and continue much of next week. Last night’s 06Z GFS follows the trend of earlier runs of the ECMWF model.
If the weather works out a progged, this will be our Christmas Holiday set up for several feet of snow and a hard grueling week for the snow plowers in town……
The latest 06z GFS is actually showing more over water trajectory now for the pattern, and continues the pattern of heavy snowfall through much of next week……
I hear that reservations for the Christmas holidays in Town were off to a slower start….that should change rapidly as news get out about major snowfall in Mammoth Lakes arriving next week.
Dr Howard and the Dweebs…………………………:-)
Monday Night Update:
The new 00z Tuesday ECMWF is consistent with its previous run in developing a major Snow Storm for the Sierra Monday through Wednesday next week. As the pattern develops this weekend…..The upper high builds over the Alaskan Pan Handel Sunday Night to an astounding +4.1 Sigma ( Deviation from Climo). The Arctic Upper Low deepens as in moves down the coastline and by 06Z Wednesday the SDC is a whopping -4.0 Sigma!
There will be plenty of over water trajectory and upper jet support. If this all works out…a major snow pattern is in the cards from Tahoe south down the sierra beginning as early as Late Sunday night or Monday AM though Wednesday or Thursday AM. The snow will be cold and fluffy with high Snow to Water Ratios.
WSFO’s may put out WSW over the Thanksgiving Holiday for the following week……
Typically forecast models underestimate the QPF with a system like this. Several feet are possible next week…….
Will Fine Tune in the days ahead………………………