Archive for year 2014

Mammoth Mt picked up another 12 to 18 inches last night….More on the way tonight into Wednesday…..and even the chance for several more inches Friday/Ngt…..Then a Break Next Week……

Thursday AM:

Weather systems over the past 6 weeks have built up a base depth of between 2.5 and 4 feet over Mammoth Mt. All ski resort corridors are now open including Little Eagle, Canyon Lodge and the Main Lodge. The Dweebs expect a few more inches of snowfall Friday into Saturday before we ridge up Later Saturday into Monday.

The Dweebs Weather update shows a beautiful today with lots of sunshine…there will be clouds as well that will increase over night. Breezes will be light this morning but increase tonight. The next and last in the series of weather systems will move through the sierra Friday into Saturday bringing light amounts of snowfall. Possibly a few inches. Thereafter, we go dry Sunday through Wednesday.

The next weather system for Christmas Eve and Christmas Day is being handled differently by the global models. The Euro brings a cold system down the coast with snowfall for the Eastern Sierra while the American models bringing some wind and cooling but keep the weather dry. Stay tuned to this change. I expect better visibility “in the models” later this weekend for Christmas Day!

Dr Howard and the Dweebs……………………………….:-)

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Wednesday Evening….

A quick look at Fridays system, there are two distinct areas of vorticity. One that comes through Friday afternoon and the other very late Friday night into Saturday AM. All in All….not a system to write home about but enough to get 1 to 3 inches of snowfall by Saturday AM

A warming trend is likely Sunday into Tuesday with a pretty big ridge building in…then…..a high latitude block in the northern branch of the westerlies retrogrades and allows a pretty strong short wave carrying Modified Arctic Air south down the coast into northern and Central CA Christmas Eve.

Quick look at the extended guidance of both the ECMWF and GFS. (Subject to change) They both show a cold system digging SSE down over the far west Christmas Eve. By Christmas Morning the -18C Isotherm is over Eastern CA. That is temps around -2F at 10,000 feet and in the low single digits in town of Mammoth Christmas morning if it verifies.

There could be some light snowfall as well depending upon how much over water trajectory there is with the upper jet. So the Dweebs will keep a weary eye out on this one.  If this is works out, Santa will get great gas mileage over night as the flow is right out of the north.  And….Arctic air will invade the Great Basin as well.  This is quite the cold system and like a giant lake effect of cold air over the warmer then normal waters of the pacific ocean.

More Later……

Wednesday AM:

Another System in the Split breaks up over the Central CA  Interior.   Just a dusting this AM.

Next and last system Friday/Ngt will not split. However, it is pretty weak.  We still could pick up a few inches in town and 2 to 4 over the higher elevations by Saturday AM

After Saturday, we ridge up into Mid Week next week.

The Dweeber……………………..:-)

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Finally, a vort center progressed through the Sierra Early this morning. It was enough to drop some 6 to 8 inches in town and 12 to 18 inches up on Mammoth Mt. Not bad for a system that did not have any upper Jet support in this area. It came in before the split could do its damage. It was a Cloudy day today with some light snow shower activity as well.

The Split Flow pattern is coming to an end by this weekend. However, not before another system comes in tonight and yet another Friday.  There is the possibility of another 5 to 10 inches falling on Mammoth Mt between tonight and Wednesday PM. Then one last weak system Friday into Early Saturday AM.  It all depends on how well we do with that split flow.

 

Weekend Outlook:

The transition from a Split-Flow pattern to a pattern in which the northern branch of the upper Jet dominates will effectively take California out of the Current Storm Cycle by the end of this week. However, not before we tally some 4 to 5 feet of snow as it fell by the inch, over the crest the past 6 to 10 days.

This weekend, all forecast models show height rises over the CA State with a NW flow aloft. This is a dry pattern at this latitude and one that will be a bit breezy over the crest early in the weekend. Further height rises occur as a rather large Anti-Cyclone builds NE from the SW. Thus strong ridging is expected into California, Sunday and Monday. Temps will moderate up over the weekend and especially early next week.

Longer Range:

Officially both 6 to 10 day and 8 to 14 day models are both warmer and drier than normal through year-end for CA.  However, The ECMWF Control has a strong short wave coming into CA, late Christmas Eve and Christmas Day. In contrast, its Ensembles just show a strong WNW upper Jet at that time frame. (Northwest Slider) That would primarily be a Wind and Cooling Event with a slight chance of snow showers.  Looking at the GFS, there is a chilly system dropping into the Pacific North West. That also is a dry pattern for the time frame. At the Moment it just looks cooler and breezy or windy. Now with that said…it is what happens after Christmas and over the last weekend of the year that looks promising, as the Eastern Pacific Ridge is forecasted into Major Retrogression Mode.

 

The Dweebs will keep an eye out for the Christmas Day system as well as the transitional pattern that will follow, the end of the year……

 

Dr Howard and the Dweebs……………………….:-)

A Few More Systems this Week then a Break…….Eastern Sierra still stuck with the Split Flow Blues……

Tuesday Am

 

Mammoth Mt Snow plot picks up about a foot over night…Here near the village about 6 inches….

 

Another 5 to 10 inches by Wednesday morning possible
3 to 5 in town…

 

Monday PM:

Latest QPF from HPC again going hog-wild with a 5 day Bull’s-Eye total near the Mammoth Mtn Summit of 2.2 inches of water.  CRFC updated with 1..36 for Yosemite through Saturday AM which takes in consideration of the mountain effects. The FOUS data from Fresno shows .97 hundreds.  It also show some significant UVM of 25.2 at the 36 hour period based upon the 18Z output. That means that the heavier snowfall would increase toward 10:00PM Tuesday night.  In that there is little Jet support for this storm over the Mammoth area, well just have to hope for a good Deformation Zone to set up.

Here are some thoughts. This system is colder than the last system. So the snow to water ratio will be greater than the last storm. Whatever falls will be all snow for the Town of Mammoth.

Updated amounts for the week…..best guess at this time. (Subject to change)  Snowfall totals of 5 to 10 inches in town and “between” 12 to 22 inches over the upper elevations. (5 day totals) The upper limit is certainly not the main forecast. Rather it is a best guess based upon the spread. The timing is over a period that includes several short waves and their QPF total.

 

Dr Howard and the Dweebs……………………….:-)

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Monday AM Update:

Very Weak UVM coming through this morning with another slightly stronger Vt Max coming through Tuesday AM at 12Z.

Main Shot of energy splits with best dynamic portion diving south “off shore” toward Southern CA. Only sheds of UVM come into interior Central CA Tuesday Night/Wednesday AM

What a Mess!!!!

Given the latest 12Z Run of the WRF and GFS…there is little confidence in QPF or snowfall amounts the next 3 days… We may only see a few inches in town with of course the crest doing the best.  It is interesting to note that CRFC gives Yosemite and Huntington Lake over an inch of QPF the next few days. Normally, that would give us at least a foot over the crest.  With orographic’s two feet. With a split flow pattern like this may be only half!

Comment:   Medium range models are still not doing as great a job as they could of.  The Dweebs will stick with Days 1 thru 3.

 

Outlook:

Both 6 to 10 and 8 to 14 day outlooks are drier then normal. So other than inside sliders….we’ll keep waiting….

 

The Dweeber…………………….

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Even though the skiing is great up on the hill…we want more snow! Why?Because…..we always want more snow right?

Latest QPF from Sunday Nights guidance.  Best guess for snowfall between Monday night and Wednesday night.

4 to 8  inches in town; 8 to 15 inches between 9K and 11K

Note, this system is still splitting. The main upper jet is still well south of us. However, at this point orographically, the first system is better than the last, even though the last system for Tuesday night is stronger….

 

There are several reasons for the split flow pattern that weaken storms over the Central Sierra.  The more common explanation is usually a persistent long wave upper ridge over the west. However,  it’s usually much more than that. The wave length at 500MB across the CONUS may play havoc in forecasting this ski seasons weather. And…..even though the pattern can be progressive, the split can still remain. The good thing these days is that the global models are handling the west coast split better than they did back in the late 1980 and early 1990s. Back then, even the 72 hour AVN model would not show the split. This would drive forecasters crazy when the split did not show up until seemingly the last moment. I remember those days very well and often times the only product that one could see the split show up was the 500mb 5 day means. There…You could see it plain as day. However, that west coast split was often times nowhere to be found in the dailies.

Coincidently, “Weak El Ninos winters” are famously associated for west coast split flow patterns. Yes there is an association, but as usual, not always.  Weak warm event conditions are forecasted to be better than 50/50 this winter, and…..we just happened to be currently experiencing a pattern that resembles past weak warm event winters…..Humm….?

Unless you have a subtropical hose pointed at you, it takes dynamics to get the big snows here on the eastside. In order for that to happen, you must have the upper flow at 500mb consolidated and progressive through the Sierra. That has not happened yet this season. Will it happen? Hard to say…..
But there is a good chance that we will be struggling with this split for sometime to come.

The issue with this pattern over East Central CA, is that short waves (Storms) are being forced to slow down as they approach the long wave upper ridge over the west.  As the systems slow down, the energy because of the physic’s,  diverts to the Right. This causes the storm to actually spin up and intensify while changing course toward Southern CA.  So while Northern CA gets hammered with rain, as well as the west coast south to Southern CA,  the Eastern Sierra gets left with the east edge of the systems UVM with weakened dynamics at best.  The other big issue is, as these system split and head for SC, the upper flow becomes southerly. So not only do you not get the UVM energy (Upward Vertical Motion) through the Sierra, you also lose the orographics as well.  We may be forecasting several of these types of systems approaching the west coast this year.  This will diminish the accuracy of both the QPF as well as timing. So we will have storms this year that are forecasted to bring a lots of snow that will actually bring little. There will also be times when we get a lot of snow when little is forecasted. This is going to be a tough year for the forecaster here in the central sierra, especially on the east side. The models will be saying trust me…but can we?

 

CURRENTLY;

The next two short waves approaching CA shown on the models a few days ago were expected to perform with the 1st system progressive through the sierra and the second splitting and heading south.  The latest 00z Monday GFS modeling shows the first system holding on better further east, with more lift actually through the Sierra. Is this another head fake? Should one believe it?  I’ll take a good look at it Monday. Either way, the system is still splitting. The question remains as how much energy gets through….

 

On another note, we can get precipitation from other patterns even with the west coast split. For one, storms that come out of the NNW. As long as the upper jet has over water trajectory, we can get some decent snows. Additionally, remember the Tonopah Low? We have not had the effects of a good Tonopah Low for a log time here in the Eastern Sierra. Maybe 2015 will be the year for it.  The Tonopah Low can give fabulous upslope snowfall for the Eastern Slopes…..

 

More later………………………..:-)

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

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.

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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….

 

Outlook:

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.

WHY?

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!!

 

More Later..

 

Dr Howard and the Dweebs………………………….:-)