First in a Series of Storms has moved into Mono County…..First two systems will bring at least 3 to 4 feet by Monday afternoon over the higher elevations as Skiing conditions shift into high gear………Temperatures to really plunge next Tuesday into Wednesday…..
Thursday December 10, 2015
Posted at 9:14 am by Howard
Sunday 10:15 AM…
Snow began to fall in Mammoth shortly before 10:00 AM
RE: Southern California WX
On the 5th of December, the Dweebs brought all our readers the awareness to a change in the WX pattern for Southern California. The ECMWF indicated a major shift in the long wave Eastern Pacific Ridge westward to north of Hawaii later next week. This retrogression is very significant as its “current location” between Hawaii and the west coast is responsible for the current storm track, and a drier So-Cal.
The ECMWF is certainly the best in longer range week two forecasting tool. It has been very consistent in this change in bringing the first major storm to Southern CA in years beginning the weekend of the 19th/20th. A development over the past 24 to 36 house suggests that a relatively deep surface low will accompany this storm centered west of South Central CA. Since there is a lot of sensitivity about precipitation in Southern California, I will be focusing a lot on this upcoming potential event, that is taking shape in the models for late next weekend into the following week. To Reiterate…..The EC and its ensembles continue to be consistent for a Major Storm just prior to and through the beginning of the start of Astronomical Winter….There are two storms. The first has the deepening surface low late in the weekend and the second sweeps in behind the first…as we transit through the Winter Solstice….
PS: Monday Noon 12/14/15
Major Christmas Day/Eve storm in the cards for California….North to South!
As far as the current storm now moving into the Sierra; The forecast shows between 5 and 10 inches between 7500 and 8500 feet elevation and 12 to 18 inches over the upper elevations by Monday Mid morning….
Dr Howard and the Dweebs……………………:-)
So-Cal Storms Looking good…..beginning late next weekend between the 19th and the 21st then a series through the end of the year… ECMWF painting QPF in 2 to 3.5 inches in the coastal mountains with first storm. Nice surface low spins up as well….
There will be a break between storms today as a short wave ridge moving in from the NW, diminishes winds. Over-running cloudiness is expected this afternoon from a system over the pacific northwest and will spread mainly mid and high level warm advection type percip…mostly to the north of our area. However, there is a slight chance of some light snowfall early this evening…. In the higher elevations, the wind will ramp up later today and increase further Sunday as the next short wave digs southeast from the GOA. This system is colder than the last, but not cold enough for a Platinum Powder Alert. Most of the cold air comes in behind the precip. Moderate snowfall accumulations are expected, with between 5 and 10 inches at 8000 feet and between 12 and 18 inches on Mammoth Mountain. Snowfall ratios will probably be between 10:1 to 12:1 so light snowfall yes…but no Platinum Powder.
Mammoth Mt reporting 14 to 20 inches of new this morning. It is still snowing lightly. Looking at the updated HRRR another 1 to 3 inches is possible today bringing snow storm totals within the 1 to 2 feet forecasted. Great Job Forecast models!!
It was interesting to note that although the freezing level was 10,500 feet early Thursday morning, it was snowing down 7500 feet. The next storm moving in Sunday morning shows a freezing level temporarily at 10,500 at 4:00AM. Snowfall forecast models show that by the time the storm starts about 10:00AM, the freezing level is down to 9000 ft. Remember…the snow level is usually between 1000 feet and 1500 ft below the freezing level, unless there are microphysical processes going on, in which case it can snow all the way down to the surface like 7000 feet. The main point is that it will be all snow and no rain for the next storm on Mammoth Mt, Sunday into early Monday AM…… And between another 1 to 2 feet is possible.
The Dweebs wanted to add one more bit of information…..If the air-mass is saturated like in “Subtropical moisture advection”, the Snow Level can be the same as the Freezing level……Again subject to microphysical processes.
System Digging SE….Open Cellular Cu approaching……Get ready for the cold sector of this storm…..Lots of snow coming later tonight!
As usual, our favorite global models have their differences. The Dweebs will comment on these current differences during week two and try to relate them to what may happen in the future.
Just as a quick note….This particular storm was expected to bring rain/snow mix this morning at 8000 feet…. Our daytime high already occurred at 37 degrees at 7:30am. At 9:00 it was down to 31. It appears that it will be all snow where it is snowing at the moment with the snow level lowering the rest of the day…..
So far the warm sector has been pretty Wimpy with the leading front now falling apart. A recent report from Mammoth Mt said that there is 3 to 5 inches of new snow, top to bottom at this time with about .6 of precip.
Looking at the IR motion, a nice pool of Open Cellular Cu is rotating off the Northern CA coast and is now just moving in to the north coast. There is a nice NW/SE Jet streak developing west of Monterrey, CA. The system is still digging SE and so I expect the popcorn clouds to give way to heavy snowfall tonight and into the AM hours. The storm is touted to bring 1 to 2 feet total over the upper elevations by mid-day Friday. I think that we’ll still get there but not exactly how expected. Next storm rolls in Sunday with similar amounts however it will be a colder storm with lighter snowfall.
Based upon all model runs today, the storm track for the most part is north of Southern CA. So-Cal will get clipped with showers, but amounts look light. .25 or ??
Eye on So-Cal
I think that better news is on the horizon for Southern CA which was what I was leading up to when I wrote this morning. The ECMWF and GFSX both have retrogression in the cards week two. That means the eastern pacific ridge in this case is going to set up further west so Southern CA can get on with winter.
In looking at the ECMWF 5 day means, Long wave ridges on both coasts combine over the central pacific during the 3rd week of December. This should get the storm track down into Southern California before Christmas. I can imagine that lots of skier’s and boarders would like to try out their new stuff for the holidays…. Timing wise for you folks down south, calendar “around” the weekend of the 19th. IE (a few days before or after) The long wave ridge is further west and north of Hawaii and that should make a difference. It is possible that a stormy pattern for So-Cal will last several days….Possible but not in stone….
For the record, it is clear that El Nino has effected the Hemispheric pattern in many ways. First of all, the pattern over the CONUS is flipped from last year. It is cold in the west and warm in the east. The Hudson Bay low has not made much of an appearance yet. However, I have to say that it is still pretty early for that anyway.
Dr Howard and the Dweebs……………………:-)
A Transition to a Very Active Pattern by Mid Week is Expected as the nose of a 180 Knot Upper Jet extends to Northern CA by Mid Week……Multiple systems are expected periodically for the Northern and Central Sierra……
Saturday December 5, 2015
Posted at 2:16 pm by Howard
I have had a lot inquires in regards and concerns about when will the big rains will come to Southern California. The Dweebs want you to know that we are watching the models carefully for signs of when that may begin. The new GEFS has been implemented and it a beauty! It’s like buying a new car! 😉
So-Cal folks keep this time in mind…..
The ensemble really amplifies the pattern 10 days out while keeping the Great Basin in the Cold. The models suggest that this ridge will build northward north of Hawaii and become Cut off over Alaska while a rich plume of PWAT imbedded in an atmospheric breaks underneath, and heads for Southern Ca. The model shows an AR knocking at your door just prior to Christmas Day……..Remember this is a long way out and so lets see how this Ensemble Model does……
Tuesday AM Update:
Good Confidence in the upcoming Thursday Winter storm. High winds expected early Thursday AM…..Good warm sector with initial high snow levels. CRFC has freezing level at Yosemite, 4:00am Thursday at 10,500. As the air-mass moistens up, evaporative cooling will initially allow snow levels to fall below the usual 1500 ft difference between the snow level and freezing level. So the snow level may bounce around between 7000 and 9000 feet. By 10:00 AM Thursday we should be saturated and the snow level as solid 7000 to 7500 feet. Latest QPF for the crest is close to 2.00 storm total by late Friday afternoon. Some of it will be at 8:1 and some later in the storm 12:1 to 13:1. Orographics come in to play so odds are good for at least 1 to 2 feet with up to 30 inches in Saddle Bowl. The outlook for the weekend shows Saturday the break between storms…Although there could still be some snow showers….
Just a quick comment on the Sunday/Monday storm: The Tuesday 12Z GFS shows a track more like the 12z ECMWF Monday/Tuesday model runs. So it is not as wet as earlier runs of the GFS. Nevertheless, expect at least a foot out of this one. It may not be platinum powder, but plenty fluffy! The storm is a quick intense hitter Sunday afternoon and Night with showers on Monday. The following system (mid week) is a cold inside slider type with snow showers possible. Week 2: expect a 60% probably of being wet for most of California. The upper flow becomes more zonal. CPC is putting more faith in both the Canadian and GFS ensembles rather than going with the ECMWF solutions which show higher Heights and a jet further north……for the time being…..
As Another Comment….
The GFSX has a series of storms following the Thursday/Friday system fairly close to the coast. The main cold pools move inland between Mammoth and the Northern Sierra. This is a track that is not favorable for major precipitation for Southern California. The Dweebs will update later this week…..
Confidence is increasing that the first storm cycle of the Winter will begin this Thursday as a series of weather systems head for the Central Sierra. The first storm has a light to moderate AR attached to it with a PWAT plume of 1.25 inches. So there will be a moist warm sector that will precede a colder portion of the storm. At the moment, WPC’s 5 day QPF shows 3 to 4 inch’s of Water EQ for the Central Sierra over a 5 day period. About (3 feet of snow over Mammoth Mt). However, most of the precipitation will fall over a 36 hours period. This storm is likely to have a wind event attached to it Wednesday night into early Thursday AM, so travel in the Mono County area Wednesday north and south along the 395 Highway is best before mid to late afternoon. The Snow Level will probably begin around 8000 ft early Thursday AM, falling rapidly by mid to late morning….. Heavy snowfall is expected Thursday afternoon into the night……
A following storm will arrive later in the weekend. That one looks colder with possibly higher snow to water ratios. The new 12z Monday run of the GFS has that system trending to dig further south and west, and so it may actually be the first significant winter storm for Southern CA and their Local Mountains, if that trend continues. I will take another look at that Mid-Week after several more runs…..
Dr Howard and the Dweebs…………………………….:-)
Although the Dweebs are still waiting for the more classic El Nino forced North American pattern to develop….A series of Winter Storms look destined to slam the Sierra from north to south beginning about Mid Week, next week.
So far the most obvious signal usually associated with a strong warm ENSO Winter has not yet developed. This is why Southern CA remains dry. Sensibly, you will know when that change occurs, when the storms come from the West/North West at Mid latitude. Additionally, it will be noticeable, as the presently located fire hose (jet Stream) shifts from the Pacific NW, south to much of California. The upper jet will split out over the Pacific with a wet southern branch into the Golden State. The Dweebs would expect higher pressure over Western Canada and the Gulf of AK, and Lower pressure well south of the Gulf of AK aimed at California. So more time is needed, especially for Southern California.
Currently the storm track remains to our north….A west to east upper Jet at 300MB is expected to sag south mid-week and port into Northern California. The pattern will be preceded by high winds over Mono County. Over the following days….The jet sags south and the Central Sierra receives heavy snowfall. Amounts through Friday AM are not super heavy but between 1 and 2 feet is certainly possible. The Dweebs will update if that changes. The pattern change will be highlighted by the fact that the nose of a 180 knot jet will port on shore over Northern CA with the front Rt exit region effecting Mammoth in the form of strong winds beginning late Wednesday then ramping up that night into Thursday AM. No doubt a High wind episode is very possible for Wednesday night or Thursday. The upper jet is expected to sag south through the Bay area and Mammoth later Thursday allowing the southern sierra to benefit from precipitation. However at this time, Southern California apparently will miss most of this storm, unless the longer range models do something different.
There are subsequent systems in this pattern destined for California. So another storm is possible sometime that following weekend.
One thing seems likely……The snow will be accumulating up in the Sierra! Some of the guidance suggests up to 5 feet of fresh over the next 10 days on Mammoth Mt….
More updates coming next week or sooner if necessary….
Dr Howard and the Dweebs…………………………:-)
Meteorological Winter Arrives Today Dec 1 as a Weak Winter Storm Moves in Late Thursday…..SOI CRASHING LIKE 1997!…….
Tuesday December 1, 2015
Posted at 9:17 am by Howard
The Storm System is a QPF bust in Mono County.
It brought little more than an inch at the main lodge and up to 2 inches over the crest.
Late this afternoon the HRRR had the right idea all along but the Dweebs focused on the QPF of the other models.
We will relay more on the 3K HRRR in the future when looking at a time frame of up to 12 hours….
The Focus now begins to turn to the pattern change shaping up for the middle of next week. A powerhouse “Zonal” 180 knot at 300MB will punch into Northern California Wednesday night and shift south to the Bay Area by Thursday AM. Although this looks like another primarily Northern CA storm precip wise….The Dweebs are not totally convinced at this time that Mono County will not be in for a major storm because of:
- The SOI tanking this past week.
- The distance in time.
One thing is for sure, it is going to get real windy Wednesday Night.
I will update a lot this weekend………………….
8:00 AM Thursday
Some thoughts today about the next weather system…..
The Highlights are as follows….
- Lots of wind Thursday. Wind Advisory hoisted for 10:00AM to 10:00PM tonight
- Light amounts of snow (2 to 4 inches in town); (3 to 6) on Mammoth Mt by Friday AM)
- The leading upper jet has us in the front RT quad with convergence aloft and a windy scenario.
The New NCEP GEFS Ensembles [T574] arrives in a few hours. The first run of it will be for the todays 12Z output. It will be the latest and greatest that NCEP has to date.
I will report on its longer range possibilities this afternoon if it is ready…
- Were still looking at a minor Winter Storm with light amounts of snowfall Thursday night.
2. While I wait for the new 12Z ensemble Runs….I think that it is important to note that later next week around the 10th of December, a powerful jet stream will push into the west coast with strong winds and heavy precipitation. The nose of 180 knot upper jet is on shore around the night of the 9th or during the day of the 10th. This upper jet is progged to sag south with time. Snow levels would be quite high but there is cold air behind it.
This will be the up coming story from the Dweebs later this week and into the next.
Dr Howard and the Dweebs……………………….:-)