Weather to turn cold and windy tonight with snowfall……Light to Moderate amounts expected…..A rather windy period is expected for the next 5 to 7 days…..

As of 1:40PM, The next weather system that will affect our area has spread precipitation south to the Bay Area. However the band of precip has yet to reach the sierra, north or south.  Snowfall projections are now on the low end of the forecast with a foot expected on the sierra crest by Friday night.  The NWS is not issuing a winter storm warning as snowfall is expected in the 3 to 6 inch range in town with 1 to 4 inches along the 395 corridor. High temps will be falling through Saturday with highs in the upper 20s by then….Lows in the teens….

 

WX Discussion:

This weather system is highlighted by a split in the flow in the long wave pattern along about 40 north with main precip band to the north, then weakening to the south. Main energy will dive south into Northern Baja. This sort of storm is reminiscent of many during drought years….  Additionally, the behavior of the systems in the models from 5 to 7 days out vs within a few days of the event suggests that the global models do not have a handle on the overall pattern, over the eastern and central pacific. Thus there is little confidence beyond 3 to 4 days.   Case in point; there is another very significant storm showing up, from the WNW in the 18Z GFS model run today 1/18/18,  This is for the period next Wednesday the 24th through Thursday night.  The EC has it as a very cold NW or inside slider.  In my opinion neither model has a handel on the final outcome for that period. The Dweebs can not wait until the QBO switches from Negative to Positive later this Summer or Fall of 2018. In my opinion, this teleconnection along with others is partially responsible for the extreme dryness so far this Winter.

 

The Dweeber……………….:-)

 

 

Big Weather Changes Coming to the US as the Large Scale Ridge-Trough Pattern Comes to an end….1st in Series of Snowstorms headed for Mammoth later Thursday with main snowfall expected after Midnight Thursday Night…..

Tuesday the 16th:

There were a few snow showers around overnight but nothing measurable. Main effect of this short wave will be the beginnings of a pattern change that will bring cooling, gusty winds over the crest and the flattening and displacement of the upper west coast ridge. Today’s highs will be in the mid 40s, more typical of what January should be like.

The mean ridge position now over the inter mountain west will shift even further east to the Central US by Friday.  This get’s accomplished by a strong upper jet with upstream amplification behind it, diving south through California by Friday.  It will be this upper jet with cold Gulf of AK air that pushes though Central CA Thursday night into Friday. The Air Mass is too modified for Platinum Powder,  but will bring over all, higher than normal Snow to Water ratios by Friday Morning. This storm has a down slope signature, so expect a very windy Thursday afternoon and night. There may be travel restriction’s for high-profile travel trailers during this time. Main Snowfall will occur Thursday night into Friday AM with snow showers Friday afternoon. Daytime highs in Mammoth will cool to the upper 20s by Friday and remain through Saturday. Night time lows are expected in the teens.  The upper jet remains over the Eastern Pacific into CA from this Thursday though the following Thursday. This means that Mammoth will be in for a windy period, more often on than off.  The folowing storm will be Sunday night. However, at this time, the models differ on where to place the axis of the upper jet. That location will influence how much snow will fall.

 

More Later……………..

 

Dr Howard and the Dweebs………………………:-)

 

 

8:30AM Monday…MLK DAY

Forecast models came in a little dryer this morning with the Thursday Night- Friday system, as the “AR” is trending more on the weak side than moderate. Nevertheless, this system still has the capability to bring 12 to 18 inches of snow, over the upper elevations and 6 to 9 inches in town by Friday night.  This system will finish cold with freezing levels down to around 3500 feet Friday afternoon, then lowering to 2200 feet by Saturday AM  Highs on Friday will be in the upper 20s with lows in the teens.  There will be gusty winds Thursday into Friday afternoon.  It will be a chilly weekend with gusty winds over the upper elevations with another weather system expected Sunday night into the following Monday.

 

_____________________________________________________________________________________________________________________________________________________________________________

 

Confidence continues to increase for a significant snowstorm to reach Mammoth by Thursday morning with strongest portion Thursday night into Friday AM. This system has an AR connection that is regarded as light to moderate and coincides with a jet stream that supports the system dynamically.  Although this system has some very cold air with it, the storm will not meet the platinum powder criteria of a foot of snow at a snow to water ration of 15:1.  The snow level will begin at an elevation of about 7000 feet but will crash to the Mono County valley floor Friday. the Freezing Level Friday afternoon will be 2300 feet!  However, by then, only snow showers will be occurring… Looks like a storm capable of 18+ inches by Friday night on Mammoth Mountain. Amounts should be between 6  to 10 inches in town.

 

The next following weekend looks unsettled with a chance of snow showers. The following storm for the Monday and Tuesday the 22nd and 23rd  the following week is dubious at this time due to model difference….

 

The Dweeber…………………..:-)

 

 

Storm System Exits Southern California with death and distruction in its wake…High pressure to build over the state in the coming days leading to a fair weekend….Surface cyclogenesis off the coast of Japan next Wednesday suggests a wet following weekend….

I will begin this morning with the end of my last post with this;

 

Outlook: From January 9th.

Although the Dweebs have not seen the latest ECMWF model, the latest 12Z Tuesday GFS has the upper jet moving back into Northern California early next week where it keeps it there for several days. The Upper Jet sags south towards us, during the second half of next week. (Using the Japanese surface cyclogenesis method), as a timing tool used by Hovmuller, it shows a rapidly deepening surface low that is “bombing” off the coast of Japan the next Wednesday. That energy is expected to come through our area about Sunday the 21st. So, based upon this theory, the following weekend should be wet. (Again, I have not seen the latest EURO as it has not run yet) I will update later today….

Wednesday 10th 4:55AM

We have now become familiar with the term bombing. In meteorology, the term does not refer to some terrorists act. It refers to a rapidly deepening surface system over the ocean. It can happen geographically in the high to mid latitudes, over many areas of the globe in both hemispheres.

There are two terms that represent rapidly falling surface pressure and cyclogenesis over a period of time.

  1. Bombing or Bombing Out or bombogenesis is a term used when surface pressure at 60 degrees north latitude falls at a rate of at least 24 Millibars in 24 hours. This causes explosive development or rapid cyclogenesis.
  2. On November 10th, 2014, remnants of Super Typhoon Nuri caused surface pressures to fall 50 Millibars in 24 hours. The depth of that Bomb Cyclone reached an estimated 924 Millabars. I believe that this was more then enough for a case of “Super Bombing”?
  3. On another note, the Cyclone Bombing that traditionally occurs off the coast of Japan, occurs when cold Siberian air clashes with a disturbance in the westerlies over the warm waters of the western pacific. Rapid Bombogenesis occurs several times a year in this region.
  4. The late Meteorologist Ernest Hovmöller (1912–2008) discovered many useful tools that involved timing.  As an example, the Hovmöller diagram is a very useful tool for determining the speed of various atmospheric disturbances, as it contours a variable in both time and space.
  5. The Dweebs use Hovmoller’s western pacific Bombogenesis tool to help predict the propagation of energy across the pacific for the timing of short wave energy, that transits across the west coast. It is not 100% but is quite useful in determining whether the global models are being accurate in their timing.

Last nights ECMWF has the timing of the surface cyclogenesis like yesterday’s GFS, next Wednesday as well. So the propagated energy should come though sometime about Sunday the 22nd.  Moisture and precipitation will precede the energy, several days ahead. So expect precipitation to begin about Thursday or Friday next week (will fine tune timing later) into the weekend of the 20th. Note: Although this particular cyclone development may not be a “Bombing Cyclone”, the energy non the less will propagate across the pacific.

 

Dr Howard and the Dweebs…………………:-)