Archive for December, 2012

The weather over the weekend looks to be mixed with some sun, some light snow….and some Excellent Ski Conditions……The “AR” Drums are beating louder this morning for the West Coast later this month………..

Some decent weather this weekend with a great base of snow, set up on Mammoth Mountain…..

The Snow is squeaky and dry this morning…..ego snow as they say……  Expect snow showers possible later today and tonight with a dusting to an inch or so.  The next weather system is really moisture that is over running the flat ridge building into our area. Expect some light snowfall Saturday night and especially Sunday and Sunday night. Could be 1 to 3 inches over a 24 hour period. There may not be too much, if any, of a break between snowfall producing systems Sunday and Tuesday with additional light snowfall possibly Monday.

The next significant system for late Monday/Tuesday/Ngt has a “good” subtropical tap so it will begin warmer with snow levels rising to about 7000 feet Monday PM. The freezing level will then be falling to 3000 feet by Tuesday night.  As an estimate….It looks to be between a 1 to 2 footer at this time for the upper elevations above 8000 feet by midnight Tuesday. Will fine tune snowfall forecast amounts over the weekend…..

There will be a break Wednesday through at least Thursday. The 12z GFS was slowing the next weather system slowing down until later in the weekend. The Dweebs believe that the models do not have a good handle on the timing of this next storm for the end of next week yet. However, it looks very potent, slow moving and includes “The Possibility” of a tropical connection for the Central West Coast and thus a lot of precipitation..

By the end of next weekend…..the Dweebs have noted that the GFS deterministic run this morning has indicated quite a bit of tropical convection developing SSW of the Hawaiian Islands. Additionally….About Christmas Eve, there seems to be a Kona Storm developing to the NW of Kauai with the entrainment of a lot of Tropical Moisture as well. So Hawaii may be in for a lot of rain over the Holiday!

If the pattern REX’es up along 165W between Christmas and New Years, we will have to keep a weary-eye out for a more significant “AR” event for the west coast. A lot will depend upon if indeed the subtropical system develops, and how it phases with the northern branch with time. At this time, it is unclear what part of the west coast would be effected.

 

The Dweeber……………………..:-)

Stalled Front Over Southern Mono County Late Yesterday Afternoon Dumps 9 Inches at the Village and 16 inches On Old Woolly…..Apparently…..Storms are lined up Next Week for Best Christmas Ever!!!

An active weather pattern is expected to continue for the next week. However, there are still a few more parts of the current pattern to keep the weather unsettled through the weekend.

Here are the WX players both today and through the weekend:

1. The weather for today Thursday will be highlighted by an exiting upper low at 700mb that will wrap some moisture back into the sierra this afternoon and evening bringing the possibility of some light snowfall later today.

2. The next piece of energy from the remains of the current pattern comes into California late Friday afternoon. Although the main energy slips to the south, well to the west of the Sierra Crest, there may be some light snow or snow showers from it.

3. There appears to be a break in the action Saturday before an elongated flat ridge builds east into California. The ridge is so flat that a pretty good chunk of moisture comes over it in a northwest flow….and may give some light “warm advection” type snowfall to our area Saturday night and into Sunday. So as you can see, the weekend is expected to be unsettled. However the Dweebs do not expect heavy amounts of snowfall.

4. Stronger short wave ridging is expected Sunday night through Monday morning with the clouds on the increase again Monday afternoon with a more significant storm Monday Night into Tuesday. The new Thursday 12z GFS has a good moisture tap from the subtropics for the Monday Night/Tuesday system and has plenty of “UVM” upward vertical motion, for a foot or better storm. The Freezing Level with this system will be higher than the last.

Fantasyland:  (Best guess at this time; using only today’s GFS Deterministic Guidance…..Highly Subject to Change)

5. The Dweebs see yet another storm with strong UVM slamming the Central Sierra Wednesday night into Thursday after which the pattern goes into transition to give us possibly a few days break before a new weather type develops. Although the Dweebs see some kind of system for Christmas eve/day……it appears that there will be one more multi-day storm that will be the “Grand Finale”, beginning the 26th and ending that following Friday. Again, this is not for planning purposes…..just for fun!

 

Dr Howard and the Dweebs………………………:-)

 

Spliting Trof to Bring Light Snowfall Today and Tonight…..Then another weakening system is expected later in the weekend…..Stronger, Better Snow producing Weather Systems are expected to begin about the middle of Next Week………

The ECMWF is in……

The Saturday Sunday storm is a dud…..

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Not much has changed from yesterdays thinking as the current trof is well into splitting SSEastward. A weakening cold front will bring the possibility of a few inches of snow today, however, it is expected to stall over southern Mono County tonight with additional snowfall a possibility. This stalling is a Maverick to the current forecast and may produce more snowfall over night than expected.

As the upper trof splits and slows today, it spins up a rather amorphous closed upper level low both at 500mb and 700mb near the Bay Area, then drops south during Thursday to near Bakersfield. This will create both divergence aloft in its NE quad and up-slope flow to the north along its axis.  Precipitation in the form of snowfall could be heavy in parts of Western NV like Tonopah; However, the Sierra from Tahoe south will benefit from the up-slope later Thursday as well as Mammoth by Thursday night as it pushes east along  35N into Nevada.  Overall, the pattern and its UVM Favors Arizona as well as New Mexico. Snowfall amounts should be in the 2 to 5 inches range by morning Thursday or a bit more if the stalled front remains active. Additionally, there may be a bit more snowfall accumulation with upslope Thursday night.

This is a very complicated pattern that the models are dealing with. They are still out to lunch on the late weekend system.   The new 12z GFS is non existent for the system late Saturday into Sunday. The Dweebs will take another look at the EC this afternoon to see if the model is consistent with earlier runs. However, unless it is…the feeling now is that there is only a slight chance of showers now from that Saturday night Sunday system.

So…..there is a weakness in the mean heights over California. However, the long wave is still having issues with wave length which is causing a split off shore…probably due to the REX block down stream over Greenland and South. I believe that this has forced a positive height anomaly over the Mid Atlantic states with the upstream effect a split off the Ca. Coast.  The good news is that this mess will be progressing out of our region early next week as the wave length relaxes. This means in this case, there will be a higher degree of forecast visibility for the longer term once we get past this weekend.

What the 500mb GFS means are showing is that the REX Block south of Greenland is forecasted to break down beginning this Sunday with the upstream wave length stretching out across the US next week. At the same time, across the pacific, amplification occurs with the Central Pacific 500mb High building northward at about 170W mid week. The results for the Ca. West Coast is that the upper flow gradually Consolidates next week. Thus we get rid of the current pattern to one which should be much more dynamic for the Sierra. By Monday, the Dweebs feel that much better visibility and agreement will be in both EC and GFS global models. Better timing as well is possible, as larger snow producing storms will be able to move onshore as we near the solstice.

 

PS the Idea of a strong southern branch of the jet stream hitting California is still in the cards for later in the month!!!!

 

Next update for the late weekend system later today or in the AM.

 

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