Winter Solstice has past….Monday is Winters 1st full Day…Christmas Eve/Day System looking stronger this evening as GFS Sides With ECMWFs Further Westerly Track….
Monday December 22, 2014
Posted at 12:14 am by Howard
Snowfall Forecast 3 to 5 inches in town between 6:00PM and 1:00AM Christmas Day
5 to 8 inches over the upper elevations…..
1:10PM Tuesday Update:
Models have come in a wee bit drier this morning but based upon QPF we should still get about 6 inches on the Mountain. 3″ to 4″ in town. The fact that this is a cold storm and most of the precip will fall after the front, giving a higher Snow to Water Ratio. The Snow to Water ratio will average about 13:1 to 14:1, Not Platinum Powder Alert Criteria but still light and dry.. So if we get .5 inches of QPF, that would be about 6 to 7 inches of snow over the upper elevations. CRFC still shows .47 for Yosemite by 12Z Thursday and so close to 1/2 inches of water. As far as timing…most of the snowfall will be over by Midnight because of the speed of the short wave. It’s a Screamer! Update either tonight or in the morning…..
Dr Howard and the Dweebs………………………………..:-)
2:00PM Update: Just looked at the new Experiential T1532 1800Z GFS which shows PWAT of between .8 and inch within the Front. The system’s Vt center is also digging into CA about 150 Miles further south. This is really in step with the ECMWF now. WOW the EURO is so good! HPC has just come out with between .5 an .8 on the QPF. CRFC has between .4 and .5 for Yosemite. With good Orographic’s you can often times double that. So here we have a system that could dump in a short period of time about 8 inches over the crest and 6 inches at the main lodge. In town 3 to 6….
12/22/14 UPDATE: 10:00am
The GFS has continued its new trend in a further westerly trajectory of the Christmas Eve short wave. The main idea now is to highlight that this is going to be a quick hitter. I.E. It moves in quickly by 9:00PM Christmas Eve and it moves out Christmas Day. There is still some coupling of the two upper jets to give it an extra shot of moisture and energy but it does not last long. Expect this to be a windy system with the winds picking up during the Day Christmas Eve. Gusty Winds in the 45 to 55 MPH range in town is possible as the system still has a WNW bias with the upper jet. Most of the precip is post frontal.
The Dweebs Estimate about 3 inches in town and between (3 and 6+) inches over the upper elevations by Christmas Day if the Deeper ECWWF verifies. Highs on Christmas Day will be some 25 degrees colder than todays high of 56 predicated at 8000 feet.
Per Vegas Discussion for those traveling the Owens Valley Christmas Eve:
Winds should start picking up Christmas Eve afternoon and strengthen during the evening where a 100+knot upper jet at 250MB moves directly over head. 500 MB Heights show a “hydraulic jump” signature to the lee which looks probable for a Christmas Eve Downslope Wind Event for the Owens Valley and Fish Lake Valley.
Welcome to Winter… It is officially here over the Northern Hemisphere. While we dream of the deep snows to come this winter, we’ll actually have a few very mild days to begin the week as a strong anticyclone sets up just off shore. High temps will range in the upper 40s to low 50s the first half of the week while night-time lows will be in the upper 20s and 30s.
The good news this evening is that the GFS which had been consistent the last several day in keeping the next weather system for Christmas further north and east has flipped this evening to the ECMWF idea all along. The Dweebs were just commenting a few days ago how the GFS had the right idea for quite a while. Tonight, that idea appears to be incorrect. The fact that the change is coming within the 72 to 84 hour period raises a higher level degree of confidence that the short wave will remain on this track. The track is much further west with brief but over water trajectory. And…..this one does not split. In fact it comes right through the Sierra early Christmas Day.
The Dweebs looked at the Winds aloft at 300MB and there appears to a coupling of a small subtropical jet with the polar jet just briefly off the North-Central CA Coast before it swings inland to the sierra. The upper flow at this time is southwesterly for a short period of time. So there is a period of orographics for about 6 hours.
The Dweebs will looking again in the morning at both 06z and 12z to see if there is consistency. If the short wave holds this evenings course, we may end of with quite a bit more snowfall over a short period of time. Like 6 or even 8 inches of snowfall between Wednesday night and Thursday Night.
Stay tuned to this developing weather system that apparently is changing course.
Dr Howard and the Dweebs……………………………………………….:-)