Very Quiet Week Ahead with it being Very Mild the first half….Then a few inside sliders during the 2nd half to chill it down some…..Long Range Models looking Pretty Dry for much of November……
Monday November 11, 2013
Posted at 10:27 am by Howard
Quick Update Tuesday Afternoon:
The new 18Z GFS is trending back to an inside slider while the 12z run of the EC is most consistent as a Great Basin slider.
So for the time being this is a cold dry system with some snow showers at best for the weekend. It will definitely be cold!
Tuesday AM UPDATE
12Z Tuesday GFS just finished its run. It shows the strong subtropical ridge centered west of Cabo San Lucas amped north to the front range of the Rockies. This upper ridge will retrograde in the coming days and redevelop out about 140west. The results are a sharp cold short wave that digs out of western Canada and brings some of the coldest air of the season….and possibly some light snowfall. Once again like the system in October, the Precip will depend upon if the upper jet gets out over the Water as it digs south. So Yes…there is now a chance of snowfall, at least according to the new 12Z GFS run. However, the earlier runs did not show this system this far west and the EC either. So well have to wait until we see more model runs to see if this change sticks. The New 12z GFS paints about .5 to .6 inches of QPF over our area for several inches of snow Saturday/NGT.
For now, try not to get too excited…..as again this is only one run of an ensemble of dry runs. What is positive, is that Saturday is only 4 days away and so this change that is occurring in this model, time frame wise, is more significant.
Dr Howard and the Dweebs…………………………..:-)
Long wave pattern becoming a little more receptive to energy reaching the west coast by this weekend as mid pacific closed low north of Hawaii weakens thus allowing less destructive phasing or deflection of cold air advection (ie digging) into western US via back door cold front or slider. Also cold trough over eastern US ejects ewd into north Atlantic creating an excessive wavelength to allow more troughing over Western US as an adjustment wave. An incipient wave forms off Japan on 00Z 13th with energy reaching west coast using Hovmoller timing of 10 deg long/day or 4 days later on 00Z 17th late Saturday into Pacific Northwest and early Sunday into Great Basin.
Interesting to watch this energy propagate via tightening gradients and cold air advection over western Canada and off BC coast. Latest 12Z GFS latches onto this energy and carves a deeper trough further west over California than previous runs. Will be interested to see if ECMWF and ensembles begin to trend toward this deeper and colder system digging over the area this weekend. While the effects on sensible weather may be in question… what is certain is much colder temps by Sunday with a chance of snow showers or more depending on how far west the upper jet and cold air pool aloft moves over water along the west coast. another low develops off Japan near 150E on 00Z 17th with energy forecast to come across west coast longitude 00Z 21st. This next slug of energy may be deflected well to north if long wave pattern reverts back to normal PNA (west coast ridge/east coast trough). Keep an eye on the long range ensembles for a consistent trend or converging solutions.
Thanks Tom for your contribution….
Monday Afternoon Outlook:
New CFS finally updated. If you want to believe this stuff…this is for you! Actually, in its defense, it accurately forecasted the big snowy December last year, back in early November.
The Climate Forecast System is calling for a wet last week of November and a wet first week of December……
The temps are Seasonal which mean snow not rain.
What is the most interesting is how the models do it. In looking at the 500mb for weeks 3 and 4 you will note a continuation of the block central Pacific block. However it appears to be both stronger and further north. -(EPO) The AO and NAO appear to be in positive mode which works for the Pacific Block better…..and so that would bode well for us. Additionally, for week 3, the minor block is over Scandinavia. (Not too exciting) but week four looks especially interesting as it is both stronger and just east of Iceland. (Nice excessive wavelength!)
We’ll see if this forecast holds as we get closer to that time frame.
I will post it here for all of you.
(Negative Phase of the Eastern Pacific Oscillation)
A bit over a week ago there was lots of promise for a major change to a wet pattern for Northern and Central Ca. However, the models for whatever reason got it wrong. What weather enthusiasts’ have to remember, is that philosophically, weather is perfect. What happens today or next week is exactly what is supposed to happen. It is man’s inability at this time to not have all the information for the models to get it right all the time! The good news is that (The Models) are getting better every year with more and more improvements. As examples, Today’s 3 to 5 day models are nearly as good as days one and two 15 years ago. Today’s 6 to 10 day outlooks are probably as good as todays 3 to 5 day forecasts, 15 years ago.
So it is all moving in the right direction. Additionally, during the Spring and Fall, models have to deal with the change in the differential heating of the oceans and the continents. The models use different equation’s to base there calculus on in the Winter as compared to the Summer. That is why model verification is so much better in say January and February and again in the Summer than October/early Nov or March. Additionally, in the Fall you have a big factor going on as we have all heard recently…….Typhoons in the Western Pacific. They can totally change a long-range outlook with in a day, if they change direction and re-curve to the north or phase different because of upstream short wave timing. Lots of variables.
Obviously there were too many and the best forecast long-range models blew it big time……It happens…..but much less frequently then 10 years ago.
As long as folks want to know what the weather is going to do a week or two away, there will be outlooks for them to find out. However, remember, an outlook is different then a forecast! The ability to get it right is much better 5 to 7 days out today then in the 6 to 10 day period.
The Upper ridge at the dateline has found a home for a while. The wavelength of 60 degrees from ridge to ridge has set up some fine weather for most of California. There is a stalled out storm off shore that will spread some subtropical moisture through the ridge over us. Lots of high clouds are expected the next day or two. Temperatures will remain much warmer than normal for the next few days. Low 60s and 30s.
The second half of the week will be dry as well. However, the upper height anomaly that is currently anchored out at the dateline will weaken as an eastern pacific ridge re developed far enough west to allow a weak inside slider pattern. This pattern will bring enough cooling for better snow making conditions and possibly a few snow showers later in the week. By Sunday, highs will be back in the low 40s.
The Western Hemispheric pattern is not showing any significant high latitude blocking. Teleconnections are pretty weak on each side of zero. So a polar recharge is going to occur for a while.
The 21 day cycle I used before the long-range CFS was available would suggest not much change in our weather until toward the very end of the month. That is contrary to some California forecasters that painted about 6 feet of snow on Mammoth Mountain for the Month of November. Maybe well get it all the end of the month? Will check with CPC and report tomorrow……
PS Some nice Satellite picts showing long wave trof off shore and short waves rotating to the NE bumping into west coast ridge…
Dr Howard and the Dweebs……………………………………:-)
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…..
Thursday November 7, 2013
Posted at 8:55 am by Howard
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……
Tuesday November 5, 2013
Posted at 9:12 am by Howard
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…..
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)
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…..
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…..
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…….
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………………………………….:-)