Archive for November, 2013

Back Peddling Continues as Central Pacific Upper Ridge now Forecasted to Set Up Too Far West……Major Storminess for the Central Sierra Now Unlikely Mid Week…..

Short term: Short wave passing to our north today has brought in a thin high cloud deck. However, 500MB heights are high enough for a few more degrees of warming. Additionally, 700MB winds will come up a bit today with gusts over the crest to at least 50 MPH. Local breezes will reach into the 25 to 30 mph range. The Dweebs are expecting a high of 58 degrees at 8000 feet.  Temps on Mammoth Mt for the opener will be in the upper 40s to low 50s. Again it will be breezy this afternoon.  The skiing should be great as a lot of Man Made snow was laid down…some natural snow was mixed in as well! The forecast for the following few days will indicate light winds until Saturday night or Sunday when it will become breezy again. Expect little change in temperatures with highs in the upper 50 and lows in the 20s and low 30s.  It is a dry 3 to 4 day forecast.

Outlook: The back peddling continues as the upper ridge that governs the down stream pattern to a major degree is now progged over the dateline instead of between 170W to 175 West. It is amazing when you think of it, that an adjustment of a few hundred miles either way in this feature can make a huge difference in the results of how much precipitation we could get. As it stands, with the amount of amplification pronged for that feature, there is the chance of some light snowfall here in Mammoth Monday night and Tuesday. I would say at this point somewhere between 1 and 6 inches to cover it top to bottom. Thereafter, it will be unsettled for a few days with breezy conditions, partly to mostly cloudy sky’s and at best very light precipitation.  The bulk of the deep moisture off shore shifts to the North of Central CA Next week. In looking at the GFS means this morning, Day 11 shows some hope for that positive height anomaly shifting slightly east again by the very end of next week. Additionally, there appears to be a Kona Storm to the NNW of Kauai.

See: http://www.hpc.ncep.noaa.gov/cpc/cpc_NHEM_f264wbg.gif    The Kona feature is part of the REX block in that area. It has the potential to generate a lot of Subtropical moisture that would flow out of that area for confluence off the west coast.  Just something to watch the end of next week.

Remember, just an eastward shift of three hundred to five hundred miles in that 500MB upper positive height anomaly would make a huge difference precipitation wise for us…..

Time to get the Snow Dancing Going……with sacrificial effigies………;-)

Will update next Monday…..

Have a nice weekend….

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

Milder temps on the way today and Wednesday then gusty winds Thursday for the opener followed by a Fair Weekend with Seasonal Temperatures……Next Week we will get snow…Maybe……Timing possibly Mid-Week……

Wednesday 5:30PM

Here lies the problem..

See the Mean Height Anomaly at 175W: http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

420DM at 52N-175W

Here it is again in the 8 to 14 day outlook:

About 390DM at 50N 180W

It’s moving in the wrong direction as the wavelength if correct will force ridging to develop near the west coast and most of the moisture stays off shore and moves north…..

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

The Dweebs sincerely hope that this is not what the future holds for us next week.  We can still get some light precip but not much if this Multiple Model ensemble mean is correct……The weighting according to the CPC is this….

10 PERCENT OF TODAY’S  OPERATIONAL 6Z GFS CENTERED ON DAY 11…30 PERCENT OF TODAY’S GFS SUPERENSEMBLE
MEAN CENTERED ON DAY 11…40 PERCENT OF TODAY’S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11…AND 20 PERCENT OF TODAY’S 0Z CANADIAN ENSEMBLE MEAN  CENTERED ON DAY 11.   (What a Mess)

 

 

 

Wednesday AM:

Note: Latest 12Z GFS is pure Junk this AM……

New Deterministic ECMWF retrogrades the Key height Anomaly west of the dateline by a week from this Thursday.  This is not good for any kind of precipitation for Central Ca.   This mornings 12z GFS was probably signaling a change as well. Again both of these are the deterministic runs. We need more time, more runs…into the weekend for a better analysis…..

 

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Quick update this morning based upon the ECMWF ensembles show a mostly dry period until about the middle of next week when Central California becomes under the influence of the Subtropical jet. As mentioned before, the pattern change seems to be highlighted by the subtropical jet where even at times there is a coupling of the polar jet to our north. So the cold air for lower snow levels remains mostly to our north. Snow levels will be high with this event later next week and the Dweebs are doubtful at this time that the snow pushers will have much to do during the meat of the storm if the air mass over Mammoth becomes saturated.  If you Dweebs have access to the ECMWF Ensembles….look at the 5-9 and 6 to 10 day means. With the closed upper high at 175W and a positive tilt long fetch from near Hawaii, this has the potential to be a very wet period with the polar jet over well over northern California and the Subtropical jet over South Central Ca. There is even the “potential” for an Atmospheric River set up later in the 6 to 10 day period. This is pretty unusual for Central Ca in Mid November……however, so is the Upper Height Anomaly at 175West that will develop in excess of +400DM, while at the same time the subtropical high is pinned over south-central Baja. CPC is favoring the EC Ensembles putting the greatest weight on its members at this time. The long fetch, “should it develop” from near Hawaii with a strong subtropical jet will make for a lot of Rain and snow over the highest elevations later next week. Remember, we still have significant differences in the GFS and EC. I expect them to come together on a solution over this weekend.

Comment: In a discussion from Hanford, mid shift, one Met commented about the positive AO being responsible in part for the pattern. The Dweebs have also read publications about the Non Linear relationship of the AO to California WX.   Looks like more research is needed…..

 

 

2:15PM   Tuesday

Looked at the 6 to 10 day and 8 to 14 day outlooks.

CPC puts the upstream height anomaly of +300 DM in the 8 to 14 day period and +420DM for the 6 to 10 day period in the same place. Both centered between 170W and the dateline. That is quite a ridge out there. Too Bad it is anchored between 170W and the Dateline.  This definitely put the Bull’s-eye up along the CA/OR or even further north for the next too weeks.  Although above normal precipitation is expected for the Central Sierra, the 564 Mean iso height contour is over South Shore Tahoe. This means that the polar Jet will remain mostly north of Mammoth with just occasional deviations to the south.  Orographic’s will play an important roll.

For the most part, it will be the subtropical jet that brings us precipitation and so expect high snow levels much of the time. Of course Sierra Cement is exactly what we need early in the season…….

 

The Dweeber……………………:-)

 

More later…………………….

 

 

Tuesday Am Update:

The Dweebs are beginning to see and understand the differences between the EC and the GFS now as the new 12z GFS run arrives today. The main differences “has been”:

1. The GFS’s earlier timing of precipitation due to the emphasis upon the lead short wave for Next Monday into California.

2. Whether or not the emphasis by the EC on a significant Subtropical Connection is warranted.

This morning’s 12Z GFS run is beginning to “dampen out” the lead short wave into California which weakens at best that short wave.

Additional energy develops a deep positive tilt upper trof with quite the subtropical fetch like the ECMWF.  As is the case this time like many times……The ECMWF seems to have a better handle on eastern pacific energy in my estimation 10 days out then the GFS.  So if you only look to the GFS, your missing at least half the story, 6 to 10 days out.

One thing is certain, there are no guarantees at this time of how much precip we will get or when it will begin. However, it looks more likely later than earlier like the ECMWF. Northern California still looks favored over Central CA and Southern California does not get much at all at this time. Another concern is where the up stream ridge is developing……about 170W.  That allows for the downstream subtropical ridge off the west coast to be a hinder on the digging trof. Would like to see the upstream ridge progress to 160West which would be better….

More later today or tomorrow AM

 

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

 

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Chilly beginning of this week to be followed by Moderating Temps Wednesday with system to the north Thursday then Party Cloudy but Dry Weekend…..Increasing snow pack with Wet Base Building Storms to begin possibly Middle of Next Week….

 

 

The Dweebs will continue this discussion later this morning….   A series of major storms look likely to hit the northern California Coast first next week with the storm track shifting south as the week progresses.  A negative tilt upper high will set up east of the dateline and north next week with a full latitude long wave trof down stream over the eastern pacific. The upper long wave trof will become both deeper and dig further south with time, tapping potentially high amounts of subtropical moisture for the west coast. There will be wet storms with heavy wet base building snowfalls for the upper elevations, eventually for Mono County as well…..

The Dweebs want to stress that this is very early in the game of pinning down any particulars. The best point one can make is that there will be a pattern change highlighted by an important positive height anomaly set up between Hawaii and the Dateline with a lot of amplification that will dig a significant long wave trof over the eastern pacific. Once the upper long wave is carved out, the upper jet associated with short waves will take aim on the central west coast.

Because of the depth and tilt of the long wave there is the potential for significant subtropical moisture becoming entrained  in the pattern associated with the eastern flank of the upper trof. The actual track of the systems will determine what areas of California will get the brunt of the precipitation. At the moment, Northern California is favored through 360 hours by the ECMWF as it paints a bull’s eye just to the East of Chico, Ca of 6.4 inches accumulated over the 360 hour period. This also suggests that snow levels will be on the high side down here in the southern portion of the Central Sierra.  Again this is subject to change dependent upon where the 500mb heights end up in our area.

At the moment, between 2.5 and 3 inches is being forecasted for the same time period for the Mammoth Crest. That could be 20 to 30 inches of snow up on the crest. This will change daily…as every model run is different. So this is just a snap shot from last nights Run of the EC.

In the meantime it will be a dry week….Cold today, chilly Tuesday and milder Wednesday through Saturday. Early morning Temps will be in the teens tomorrow, then moderating back to the 20s by mid week. Little change in temps there after through Saturday. Wednesday night into Thursday will be breezy. Sunday partly cloudy and dry.

Interseasonal:  MJO- location of tropical forcing… Phase 3 is highly favored for precipitation in central and Southern Ca  for November.

See:  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Precipitation/OND/combined_image.png

The EMON (Seasonal Prediction Ensemble Forecast System) Looks Interesting……

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/EMON_phase_51m_full.gif

I like the fact that it goes along with the Dynamic Statistical Model:

http://cawcr.gov.au/staff/mwheeler/maproom/RMM/fcsts/pd.MW05.Last.gif

 

Teleconnections;  The PNA teleconnection is forecasted to take a dive through the 15th of Nov. (good news)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.fcst.gif

 

 

More later……..

 

The Dweeber….