Cold Upper Low Now Exiting through Northern Mexico…Leaves some light snowfall in the Process…Gusty winds over the Crest….Cooler Temps……
Friday December 20, 2013
Posted at 5:58 am by Howard
Friday Update: official word 4 to 6 inches on Mammoth Mt….. storm total with snowmaking going on all day Friday and Saturday weather permitting….
Next update Tuesday AM…..
Mammoth received some light snowfall Thursday. Although it was at the lower end of what was hoped for, about 2 to 3 inches accumulated here near the Village at Mammoth. Mammoth Mountain probably received between 3 and 5 inches. However they will update a bit later this morning.
the upper flow over the weekend will be out of the north with the upper jet over Nevada. this is a cool dry pattern. the best that can be said about it is that it will remain cold enough for snow making every night and some in the daytime today Friday as well.
By Sunday the an upper ridge builds in for the west and we become inverted again early next week. It appears that although there may be a few small systems that will modulate winds and temperatures from time to time, it will remain dry through the end of the year according to the guidance. There is some suggestion by some of the guidance that a slight shift in the pattern will occur by years end. That a weak storm or two might slip through the mean ridge position or a slight retrogression in the long wave ridge position may occur in the first week of January. However, whatever change occurs, it will most likely not be significant as there are much less ensemble members that are showing it as compared to others that are just plain dry.
For you long rangers that have the need to know what the future may hold, the Climate Forecast System (CFS) has indicated the following. (I will add as a caveat, that this experimental at best and is not to be relied upon for planning purposes).
For Mammoth Lakes (QPF)
1. From the 22nd to the 27th of December (Dry)
2. From the 27th to January 1st (Dry)
3. From Between January 1st and the 3rd. Between ( .1 and .15)
4. From between the 1st and the 5th of Jan (.3)
5. Between the 5th and the 8th (.25)
6. Between the morning of the 6th and the morning of the 11th ( . 2 to .25)
7. Between the afternoon of the 8th and the afternoon of the 13th. (.35)
8. Between Jan, 13th and the 18th (1.2)
9. Afternoon of the 18th and the afternoon of the 23rd (1.3)
10. Afternoon of the 23rd to the afternoon of Jan 28TH (.75)
11. Afternoon of the 28th of Jan thru Feb 2nd. (.7)
Total for January (QPF) between about 4 inches ( This does not include the first few days of Feb.)
Again this is experiential and not to be used for planning purposes
The average snow to water ratio is about 10:1 here in Mammoth Lakes.
Based upon the CFS guidance we might think that the chances of significant snowfall might increase about the middle of January.
In that I do not have access to the ECMWF Monthly Precip I can not compare to the CFS. However, my access to the upper height pattern at 500MB FOR 30 days and the 500MB ENSEMBLES suggests that
the CFS is too Wet…
Dr Howard and the Dweebs………………………:-)
Weak little Subtropical Low Ejecting through Sierra This AM….. bringing a few showers ahead of Main Coastal Slider For late tonight into Thursday Night….A few showers are possible Friday Night as well…..Weekend to be partly cloudy with moderating Temps…..Then possible back door cold front Tuesday…….
Wednesday December 18, 2013
Posted at 9:19 am by Howard
According to Jan Null CCM
As 2013 comes to an end it is very likely that this will be the driest “calendar year” in San Francisco since records began in 1849. So far only 5.59 inches have fallen since last January 1st; almost three-and-a-half inches less than the previous driest of 9.00″ in 1917.
For the present “rainfall season” (July 1st to June 30th) the total is 2.08″, which is the 4th driest on record.
So if you think that it has been strangely dry…you now have a clue…..
Thursday 5:30pm update..
Storm is mostly over but linger snow showers is a possibility tonight…..
Received about 3 inches at the 8200 foot level….a little more over the upper elevations…..good news is that its cold and snow making is in full swing tonight! Should stay cold through Friday night with snow making continuing…..
Nothing on the horizon at this time….Back door cold front idea has shifted east into the Rockies…….
Thursday AM: BACK TO REALITY!
All long range models were dry again for the first week of January 2014….this is what weather folks have to deal with…. That is why we just watch and wait for something that sticks within the 5 to 7 day period….
Snowfall was increasing this morning across the Eastern Sierra….for Southern Mono County the heaviest period of snowfall will be between 11:00am and 3:00pm. The heaviest Precip is indicated by the models over the Southern Sierra with upslope enhancement combining with a deformation zone from Southern Mono County south to Olancha. Temperature’s bottomed this morning at 26 degree at the 8200 foot level. I do not think that it will get much warmer then that today. As usual the strongest winds will be up over the crest to 60 MPH.
Here is your forecast for Mammoth at the 8300 foot level….
Today: Snow showers. High near 26. Northwest wind 5 to 15 mph becoming north in the morning. Chance of precipitation is 100%. Total daytime snow accumulation of 2 to 4 inches possible.
Tonight: Snow showers, mainly before 10pm. Low around 16. Northwest wind 5 to 15 mph. Chance of precipitation is 80%. New snow accumulation of less than one inch possible.
Friday: Mostly sunny, with a high near 36. Northwest wind around 5 mph.
Friday Night: Mostly cloudy, with a low around 23. North wind around 5 mph.
Saturday: Mostly sunny, with a high near 42. North wind around 5 mph.
Saturday Night: Mostly clear, with a low around 22.
Sunday: Sunny, with a high near 45.
Wednesday PM: 2:00pm
Seems like todays 12Z run of the ECMWF control ensemble has a pattern change in early January to wet. While this is certainly nice to see, at this distance….it is pretty dubious at this time. Will watch….follow and report as time goes by…..
5:00PM Wednesday: New 18Z GFS has closed upper high in Gulf of AK on January 3rd. Another promising sign but again too far out for anything serious…..
Some light showers developed over the Sierra this morning from a weak subtropical low being picked up by the main system coming in late tonight and tomorrow. The Upper low this morning is more of a nuisance forecast wise then anything else. A very small area of divergence aloft develops mainly south of Mammoth, produced a few reports of very light rain. QPF is up to a .1 max along the Inyo Mono Boarder. Although the models have had it for days…no QPF was associated with it until last night for today. Again this little wave will be through by this afternoon. Some snow showers possible over the higher elevations in the AM. No big deal….
Next stronger coastal slider is headed south tonight. This is one of those systems that will produce snowfall after the cold pool arrives. It will be the cyclonic upper flow that develops once the closed low forms that wraps back and gets us.. Upslope snowfall is likely and will produce precipitation during the morning hours and peak during the afternoon. Of note, the 500mb low center is on the coast and the 700MB upper low is east over the Central Valley in a better position for us.
Timing wise the snowfall is later then yesterdays thinking and light Snowfall may continue into Thursday night. Thereafter….were in an insider slider pattern which may actually produce snow showers again Friday evening or night……well see. Over all…..these are still storms in a dry pattern that shows no signs of changing. Snowfall estimates…….2 to 5 inches for Mammoth Lakes between 7000 and 8000 feet. As much as 5 to 7 inches up by the crest by Friday AM.
Extended range shows a back door cold front through Christmas Eve. It may or may not happen. If it does we may get a few showers………………and it will turn cooler again after warming up Sunday into Monday.
Dr Howard and the Dweebs……………………….:-)
Very Mild Condition to Continue Through Tuesday then Cold Showery System expected for Late Wednesday Night through Thursday Night……Ridge Returns by Weeks End……….
Monday December 16, 2013
Posted at 9:37 am by Howard
It still looks like an upslope event. We seem to usually do better in upslope events as compared to how much snow is forecasted because of Mammoth Mt orientation to 700MB /NE flow. so 2 to 4 inches might to be conservative….
Opinion and food for thought……
Short, Medium and Long Range guidance are about as ugly as it can get. I think that it takes more then just a few teleconnections and oscillations to make up a winters pattern. Some of the oscillations are probably more important in the longer range then the teleconnections which they can effect. For instance, the QBO….. is in its westerly phase which has been shown to be associated with more of a positive AO (less stormy for the east) then its brother the negative phase. Strato winds west to east are associated with the (+AO) Pressures are lower up in the Arctic and help to contain the cold up in the higher latts. (Less Blocking)
Here is something to think about. We should be nearing the end of the positive phase of the QBO within the next few months. As soon as the index gets below +8 there should begin to be more blocking over Greenland and a possible flip in the sign to the AO as well as the NAO. Now a flip in the sign does not necessarily mean that we will turn wet here in California as the PNA may go strongly positive as well. That is why the effects of the QBO are non linear over California as compared to the east. But I think that it is a significant part of the structure of “this winters make-up” and any kind of change I say is good. The only thing is…this index may not begin to change until February or March……currently the index is a +12.45 for November. Based upon what I see in the arctic, I’d say that is it still quite positive in December as well. But again…we are nearing the end of that phase of the oscillation….the westerly phase should be weakening within the next month or two. After that, the east at least should turn colder. Remember, statistically, the best high latitude blocking with the QBO is associated when the 30mb index transits between positive and negative or negative to positive, rather than just the negative phase. So in this case, going between +12.45 down to at least +8. It will be fun to follow and see.
Considering a link to an article that was posted on another blog….see: http://climate.nasa.gov/news/997
It should be noted that so far, the PNA (Pacific North American Circulation Pattern) has been fairly negative this fall. The blogs article mentions that it is rare but possible that when the AO is negative and the PNA is negative that the infamous AR can occur over California. Since the PNA is and has been at least somewhat negative this Fall so far, might it be of interest if the AO flips to negative because of the weakening QBO by say March, and at the same time the PNA remains negative? Just something to think about………
To follow the QBO index…. go to http://www.cpc.ncep.noaa.gov/data/indices/qbo.u30.index
As far as the weather goes, it does not look good for a major storm before year’s end. We have a system expected in Wednesday night that will bring light amounts of snow through Thursday night, then dry over the weekend. The longer range does show several inside slider type systems that could bring a few inches here and there. This is a cold pattern and although there may be some light snowfall here and there, it is still considered a dry one. Hopefully January will be a different story.
High temps the next few days will be in the 50s and upper 20s at night. A cooling trend begins Wednesday with light snow beginning about midnight Wednesday then into Thursday.
It looks like Mammoth Mt will be able to keep the snow guns going….more often than not right on through the holiday!
Temperatures by Thursday will be in the low 20s for highs….. and Thursday night in the single digits…..
The ECMWF model has an weak inside slider type system; (upslope) for about the 23rd of December so more snow showers possible then….
There are additional sliders expected before years end.
Dr Howard and the Dweebs……………………………….:-)