Good morning Weather2020 bloggers,

A strong storm system is blasting into the west coast this morning.  The Lake Tahoe area is a target this morning with 125 mph wind gusts forecast to occur today over the higher ridges.  Can you imagine that? Take a look at this forecast alert:

Lake Tahoe Area Forecast:

 

  • Timing:  Snow and rain will spread quickly across the Sierra and Lake Tahoe basin this morning and become heavy. Snow will decrease briefly this afternoon…with bands of snow and snow showers developing again tonight through early Friday morning
  • Total snow accumulations through Friday morning: Above 7,000 feet….1 to 2 feet with locally up to 3 feet near the Sierra crest. Below 7000 feet…7 to 14 inches with 18 inches possible west of Highway 89
  • Winds: Southwest 30 to 45 mph with gusts up to 65 mph. Ridge gusts up to 125 mph. The strongest winds are expected through 8 AM this morning. Damage to trees is possible
  • Snow levels will start out high near 8,500 feet early this morning, then falling quickly to below 5,500 feet by midday. Lake level is 6,200 feet

The weather pattern is about to buckle. What I mean is it is about to go from zonal flow, west to east, to more wavy and meridional flow, north and south.  A powerful jet stream is now heading towards the west coast. Take a look:

Powerful Jet Coming In

As this jet stream blasts in the morning, the Lake Tahoe area and the higher ridges are in the right position to have these high winds reach the surface. Look at what happens to the flow aloft by noon Friday:

1

This storm will move into the southwestern part of the nation by Friday.

2This next map shows what the weather pattern is forecast to look like by Sunday morning, December 13th. This storm is moving through one of the LRC long term long-wave trough positions. It is actually taking a great track to bring Kansas City snow, but guess what….it’s likely going to be too warm.  We forecasted this storm, and this developing series of storm systems to arrive during the next ten days to two weeks. Take a look at the last cycle, or 50 days ago:

LRC Cycle 1 October 23

The weather pattern sets up every fall between around October 1st and November 10th, cycles, and then repeats. We have identified the likely cycle length and if you go back 50 days you can see a similar storm system on October 23rd. The December version is a bit stronger and farther south, but even the shape of the storm is the same.  Look at the dip in the flow over Nebraska and the Dakota’s. A similar dip is approaching the plains states this weekend.

I don’t know how to say this any other way, “the lightbulb” went off!  In the past seven to ten days the LRC finally came into focus. It is really one of the more incredible moments every year and it’s hard to describe. And, those of you who have been following the LRC with us for the past decade will likely understand the best. This is the first example of the year. You can not make these comparisons before, roughly the end of November. The old pattern fell apart in September and early October and we now have a pattern cycling that has never happened before.  This is just one snap shot in time. It isn’t just this one day, but the entire pattern that is cycling.

This storm is likely taking a great track for heavy precipitation in the KC metro area and surrounding areas. It is also taking a track that would usually produce heavy snow, but it appears it will be just a bit too warm. We will continue to monitor this closely.

Here is a rainfall forecast from the 06z (midnight) run of the GFS model:

Screen Shot 2015-12-10 at 7.25.31 AM

Let’s see how the models look today. The models will narrow in on a more consistent solution after this energy blasts over the west coast today.  Most of the energy has been located over data sparse regions across the eastern Pacific Ocean.

Take a look at what is happening and forecast to happen with the Arctic Oscillation:

AO December10

The AO has been staying, “living”, mostly in positive territory this season. It did dip into negative territory one time around the second week of October, and it is forecast to do about the same type of dip in the next week. Let’s continue to monitor this closely. When the AO and NAO dip into negative territory there is an increased chance of blocking and the potential for the Arctic air to build and blast south. So, we must pay close attention to these developments. Some of the models have it getting pretty cold in ten days or so.

Have a great day and thank you for participating in the LRC Forecast Experience Blog. Let us know if you have any questions or comments.

Gary