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……………………………….:-)
Strong Inversions to Hold Through Weeks end with Milder Weather over the Weekend into Early Next Week……Another fridged system is lurking for Friday Next Week…..
Wednesday December 11, 2013
Posted at 9:36 am by Howard
No Surprises.. Warmer weather the next few days then cold pattern to repeat with a couple of very cold California sliders bringing some light snowfall Thursday into Friday. Very cold temps with highs Thursday the 19th into the teens and 20s and lows in the zeros and single digits. possible snow showers Thursday. Maybe an inch or two.
This is a drought pattern……for the time being>>
I have to say that it is one of the ugliest I have seen in several years……
Thank Mammoth Mountain for all their great snowmaking, They are doing a fabulous job!!!!
Dr Howard and the Dweebs……………………….:-)
Temperatures will remain mild here in the high country today with daytime highs in the low to mid 40s…Nights in the teens. Although there was no wind yesterday, a weak trof of low pressure will move through Friday morning, kicking up some upper elevation wind from the NW, 25mph to 50mph, and bringing some cooling to the tune of 5 to 7 degrees. This is certainly good news for the snow making program on Mammoth Mtn. In speaking with Cliff Mann from Mammoth Mountain. All runs that are part of the snow making program will have great coverage. Even the Little Eagle Area will be ready to go for the Christmas holiday! June Mountain has trails ready to go as they open tomorrow the 13th. They will continue to open additional trails in the future.
Although Mother Nature has not cooperated in the snow department, the cold wave of last week created perfect snow making conditions on Mammoth Mountain and so skiing and boarding conditions will be excellent for the holiday!
Weather-wise, as noted above, some short-term cooling is expected Friday. However, temperatures will rebound Saturday into Monday. It will stay mild through Wednesday. Thereafter, another inside slider is expected the 19th next Thursday. *Should it track a bit further west, then we could get some light additional snowfall. However at this time, the track is through the great basin and it is dry meaning some snow showers are possible but no significant accumulations. It will also be windy and cold. Note…..the change from yesterday is that fridged air or Arctic air in no longer in this outlook period as the upper ridge is not as amplified on this morning run, as was the case yesterday. Additionally, no over water trajectory is noted on either the ECMWF or GFS. So outside of some snow showers, it is a typical December inside slider.
*9:10am update….The new 12Z Thursday GFS is a bit west with a short wave offshore, but the GFS splits the trof and the energy stays off shore going south. IE (No Effect for Mammoth)
Longer Range: Week 2 (Subject to Change)
Looking at the ECMWF ensembles and controlled forecast for week two,
There is another slider expected about Christmas Day. This does look colder with Arctic Air. Cross Polar Flow into the Nations mid section is indicated as well, so some of the coldest air yet this season is expected over the west and especially the Midwest. Other then that, the Dweebs will be following this development…..If it trends west “over water.”….It would be a similar system that brought about a foot last week.
Stay Tuned…………….The Dweebs have you covered!
Looking out over the pacific….The split in the westerlies off the pacific coast will keep CA dry. The details show the eastern pacific ridge shifting east and weakening while a small slider drops through the west/central Great Basin Thursday night. While none of the models bring any precipitation with this system for the Mammoth area, the models handle the feature different enough that there is a question on whether or not the it may generate enough wind to mix out the valleys. I think that what ever happens, it will be a cooler day here in Mammoth Friday. Temperatures Saturday into Sunday warm again…… Of note, there is a cluster of ensembles that feature a cut off Low……off the Southern CA coast early in the weekend. That may affect the Southern CA coastal areas but not Mammoth Lakes.
Of note, both the 6 to 10 day and 8 to 14 day outlooks were dry for Mammoth, while at the same time…..there was beginning to be some ensemble members showing up on the GFS and ECMWF that showed another round of amplification (ridging) into the Gulf of Alaska between 140W and 150W and a responding short wave affecting the Central West Coast Between Wednesday and Friday next week. I suspect that if we continue to see this feature today in the next 4 runs and especially again tomorrow, the outlooks will change. As a comment, the GEM does not have this feature at all! But sometimes the Canadian is not as good on the west coast as the other two.
Some Guess Work:
For what its worth…the ECMWF has a pretty sharp positive tilt upper trof approaching the west coast Wednesday night with ample over water trajectory for moderate snowfall. A very cold area of Arctic Air stretched between Washington state north to the NW territories shows coupled with the offshore Trof. The upstream feature over BC is phased to an Arctic Low even north of 60N over Central Canada. (Continental Polar). By Friday, the EC has the an Arctic low over Washington State poised to slide south behind the lead short wave Friday. If this sets up as shown…..high temps would be back into the low teens, Friday and Saturday, possibly setting us up for another extended cold wave as subsequent short waves from AK/BC are indicated..
Again……not all the models are handling this the same way. However…..in that we have seen this pattern recently, it would not surprise the Dweebs of it recurring again later next week VS if this had not happened at all. If this verifies, and at this point it is a big if…..another possible 6 inches to a foot could fall on Mammoth Mt. This would be followed by the return of the Deep Freeze. The Cold Air-Mass over the Great Basin is depicted by the ECMWF on the 20th over Northern NV Friday as a -3.2 Sigma. (Standard deviations from Climo)…Thus as we approach the coldest time of the year for Mammoth that would be significant.
Dr Howard and the Dweebs…………………………..:-)