Storm System Winds Down Over CA…..Drops between 1 and 2 feet over upper elevations…..The Next Storm Tuesday, Although Weaker…May Bring More Snowfall Than todays
Friday December 12, 2014
Posted at 1:53 pm by Howard
Saturday AM UPDATE
QPF in the Models were drier over night. Possibly because the 2nd impulse is coming in with more of a split flow. CRFC paints about .9 for Yosemite and shows within QPF, the second impulse with much less contribution for the two storms. So the 1st system has the best SW flow and orographics. There is still plenty of time to finalize the QPF forecast, however the Dweebs are expecting from this point in time, between 12 to 18 inches over the upper elevations. This is less then yesterday, but the models have changed a bit. The issue this AM is that while the 1st impulse comes through the Sierra with decent orographics….the 2nd does not .
Update Sunday AM.
Getting through the Hype:
1. The Storm today had no Pineapple Connection like the media purported! Just a lot of Subtropical moisture entrained in the initial system.
2. This was a moderate storm at best for the Central Sierra….
In my previous discussion I said…snowfall amounts 1 to 2 feet, no problem (Verified); 2 to 3 feet possibly….3 to 4 feet unlikely.
Why then was the QPF going bonkers for this past storm? Why did we not get all that the QPF indicted.
If you looked at the upper level winds, dynamics and the upper jet, it told the story of the nature of the storm. The nature of the pattern in general is a pattern where the energy in the westerlies upon approaching the coast diverts to the SSE (digs down the coast) thus diverting the UVM (Upward Vertical Motion) to the SW of the Crest. It’s like putting the peddle to the metal in a car, going down hill, then as the car reaches the bottom of the hill the motor is turned off, and the car stalls out as it moves higher. This all the while as the following cars in back speed south.
This is the pattern. The winds are more southerly with traverse Mt Ranges being favored. Mammoth Mtn virtually had no dynamics or orographics with this system.
Looking across the CONUS….there is a ridge over the intermountain west and another trof over the East. That will change with the next system….
What the Dweebs see is that the wave length will relax somewhat as the east coast storm moves ENE. that will cause more of a weakness in the western ridge.
Thus the “QPF” for the Tuesday is now more “believable”, which is more in the 2 to 3 inches range or a couple of feet for Mammoth MT. I will fine tune this later, but even though this is a weaker storm and has a weaker upper level jet, I think that the next storm for Tuesday/Wednesday from the perspective of this timeframe will bring more snowfall then the one that is wrapping up today Friday.
Because of the Screaming message that we get DYNAMICS! At this time…..the models push the short wave through the Sierra, and the upper flow is more natural to the sierra. IE its more Southwesterly! Why? Becasue the wavelength down stream opens up because of the east coast storm moving out!!
Dr Howard and the Dweebs………………………….:-)
Powerfull Mid Pacific Jet Finally making its way into the Eastern Pacific with Strong Winds in the Mid and Upper Levels….Series of storms to continue into the following weekend…..
Wednesday December 10, 2014
Posted at 7:53 pm by Howard
Thursday AM Update:
Just had a peak at the new 00Z ECMWF Control and Ensembles. What is really nice to see and may I add different this year, is that although some storms are splitting a bit as they approach the central west coast, the systems are progressive. The Dweebs certainly hope that the pattern remains active through years end and beyond. This is a different pattern than last year!
Lets chat about the further outlook. There are two distinct short waves that will impact California next week.
1. According to the new ECMWF control….One that will come through the Sierra Monday afternoon, and a following short wave that will dig more down the coast Tuesday night and Wednesday AM. The first may bring us a foot plus and the other….hard to say at this point. Best guess light amounts. There is a 3rd wave for that following Saturday and now another wave the day before Christmas. Remember, strength and timing will be different over the next week or two.
2. Now…lets have a look at the new 12z GFS/X.
a. The model also has two shorts waves, however, the first wave is stronger and has better orographics as the upper flow is SW for a while. However, just after the wave clears the crest the next upstream short wave splits and heads down the coast bringing the west side a glancing shot of snow as well as more rain to Southern CA and Northern Baja.
b. The following Short Wave rolls through Friday PM the 19th. It splits as well, but not off shore according to the GFS, so there is some promise of more snowfall from it. Remember, a split flow is ok as long as split is not on the top of you.
c. There is now yet another wave for Christmas Eve.
Word of Advice. Remember, both the ECMWF and the GFS/X are guidance. Not a forecast. It is the experienced forecaster that has to make sense of it all, usually within 72 hours before the event!
From Wednesday Night: (Current Storm) High Wind Warning now in effect for Mono County through late Thursday Afternoon.
We have already heard most of the hype on this storm. Now lets take a look at other details that will give a different perspective on this first storm.
1. It is slowing down and may not get into Southern Mono County until later Thursday Night.
2. The biggest flaw in this system is the upper flow to the sierra. The upper level winds are more out of the south than SW or WSW which is “less preferable” orographically speaking. So the Dweebs are being careful about going crazy on how much snowfall this system will bring. With that said, it does have a lot of moisture with it…. and “lots of dynamics”. So….1 to 2 feet? no problem; 2 to 3 feet possibly over the upper elevations. 3 to 4 feet….unlikely. With all that said, it will bring a lot of wind and what we need to get it going up on the hill. The best news of all is that there are at least 2 more short waves the following week going into the following weekend. The first two are also orographically challenged. So, 1 to 2 short waves Monday into Tuesday night and yet possibly another the following Friday or Saturday. So with these other systems, we may at the end of “this storm cycle” and end up with four or more feet total….maybe….Lets get the first one in here!!!!
3. To recap timing and amounts…..
The Storm will slow down Thursday south of Alpine County with the heavier snowfall possibly being delayed until after midnight Thursday. IOP will be between 09Z and 18Z Friday.
Mammoth Snowfall Est. Between 1 to 2 feet in town and between 2 to 3 feet over the upper elevations…..
Active Upper Jet Across the Pacific is Moisture Leaden…..Will take Aim on West Coast Thursday…Main QPF to Saturate Northern CA with diminishing amounts for Mono County…..However this system could still dump another 1 to 2 feet up on Mammoth Mtn by Friday Night…..Active Pattern to continue with more storms in Mammoth’s Future the Following Week…..
Monday December 8, 2014
Posted at 12:21 pm by Howard
Models trending wetter……..This looks like a good old fashion Mammoth Storm…..will up date Wednesday,,,,,,,,,,,,,,,
Tuesday AM Update:
Strong Upper Jet of 180Knotts at 300MB will drive the first powerhouse storm in two years into the high country. The system has plenty of moisture and dynamics to dump a good 3 feet on Mammoth Mtn, and between 12 and 24 inches in town. Most likely this storm will be all snow for the Town of Mammoth. Road crews will be busy Thursday night with the highest precip per hour rates coming in around Midnight. Heavy snow to turn to showers Friday Mid Morning with snow showers lingering into early Saturday. After a partly cloudy weekend, another 2 system will bring more snow to the high country….Monday night into Wednesday……It looks like a break after mid week next week…..
A fast Zonal Flow pattern has set up across the pacific as it progresses off the Asian Coast, all the way to about 140West. To the west of Mammoth is an inter mountain ridge that will give way to the belt of Westerlies Thursday. By this Wednesday, clouds will be on the increase along with an increase of Wind over the upper elevations. Snowfall will begin later in the day Thursday with heavier snowfall Friday…… At the Moment, snowfall accumulations look to be in the 6 to 12 inch range for the town of Mammoth Lakes and between 12 and 24 inches over the upper elevations. This begins the next storm cycle with at least another 3 to possibly 4 systems over the following 6 to 10 days. Some will be colder with less snowfall. Some will split and favor Southern CA. Some will give our local area footage. The details as always may be found here at Mammothweather.com.
In that the main Bull’s-eye of moisture is still Northern California and the Pacific Northwest, it is considered more of a normal precipitation pattern for the west coast and not ENSO related.
That may still change in January…..
Comparing both the ECMWF and GFS, the QPF with the GFS is a little drier then the EC….However, not enough to change the Dweebs thinking of 1 to 2 feet over the higher elevations. There looks to be a break with improving weather toward fair WX later Saturday into Sunday. However, the winds will come up again later Sunday afternoon over the crest and develop over the lower slopes later that night into Monday AM. Snow looks likely to return again sometime during the day Monday next week. That system will weaken as it comes and split Tuesday. The opportunity for some moderate amounts of snowfall looks good. This is the timing of the new 12Z ECMWF as of 1:12 local time Monday.
The Dweebs see yet another system the following Friday the 19th.
The timing for all system systems next week are subject to change of course……..
Dr Howard and the Dweebs…………………………….:-)