Northern Hemisphere Snow Cover Above Normal

Latest indications from Florida State University (of all places to track snow) are showing the first above-normal marking of North Hemisphere snow cover in months.

The top graphic is the 7 day snow cover change over the northern Hemisphere, with the bottom image depicting a graph of snow cover anomalies over the same region. It appears a recent burst of snow over Canada and Russia is contributing to this above normal marking.

I expect the Canadian snowfall to diminish over the next week or two, as a massive ridge covers most of the nation, thereby reducing chances for sustained snow cover in the region. However, the continuous building of the Siberian snowpack tells me that snow will likely return for Canada this winter, as well as much of the Eastern US.

Expect my new thoughts on this winter to come out late October-early November.

Andrew

Long Range Lookout: Pattern About To Get Dicey

This is the October 17, 2012 edition of Long Range Lookout.

This weather pattern is about to get a whole lot... warmer. Yes, warmer. Above, you can see the 500mb height anomalies on the left, and the GFS Ensemble 'spaghetti' forecast on the right for approximately 6 days away.

The right image is composed of 500mb height forecasts from each member of the GFS Ensembles. When you combine them into one image like the one seen above, the result is a very messy picture (especially in the long range). These twisting, turning lines are what gives the right image the nickname 'spaghetti model' forecast. On the left is the 500mb height anomalies from the ensembles on the right. The 500mb layer is considered the best to look for high and low pressure systems. Blue areas are stormy areas, and red spots are composed of high pressure anomalies. The darker each color is, the stronger its respective apparatus is.

This forecast is showing a strong high pressure stretching across the heavy majority of Canada, including near Greenland, the focus point of the North Atlantic Oscillation (NAO). When you get a ridge like this near Greenland, a negative NAO develops, which can bring cold and snow to the East US in the wintertime. However, check out that deep blue area over the northeast Pacific and western US. That is a very strong negative PNA pattern. In a negative PNA, a deep disturbance locks up the West Coast, and a ridge of high pressure develops in the East US in response. This, in turn, hampers cold and snow efforts to reach the US.

So, over the next week or two, expect a warm up to enter the playing field. This warm up looks to be short-lived before a big cool down enters the States, but that will be on a separate post.

Remember, you can catch Long Range Lookout every Wednesday, here on The Weather Centre.

Andrew

Updated Snowfall Forecast for 2012-2013 Winter

THIS IS NOT AN OFFICIAL FORECAST. The Final 2012-2013 Winter Forecast still stands- this is an update on my thoughts but is NOT composed of my official thoughts... yet.

This is an updated forecast of what I am expecting in terms of snowfall this winter. Please note that this forecast does not have as much research behind it as our Final Winter Forecast, so use at your own risk.

I am forecasting above normal snowfall for much of the Plains, Great Lakes, Midwest, Ohio Valley and parts of the Northeast, with the core of the snow hitting the Midwest and Plains. Here's the lowdown on why:

1) Lezak Recurring Cycle. As I posted in this recent post, there has been a favoring of precipitation over the northern Plains, Great Lakes and Midwest. This means that there should be quite an active period for those regions at least twice this winter, possibly bringing some very heavy snows with them. Additionally, the presence of cold air that may be tied into the LRC would enhance snowfall potential over these regions.

2) Possible Rebounding La Nina. As I posted today at this link, there is a new trend of cool water anomalies just off the coast of South America and likely associated with the ENSO pattern. A La Nina favors the Midwest and Ohio Valley for snowfall. Based on how global wind patterns have been characteristic of a La Nina recently, it is possible we could see La Nina effects in the USA as well, hence the 'core of snow' region lodged in the mentioned areas.

3) No More El Nino. The El Nino is gone, and there are very little effects of an El Nino worldwide. Because an El Nino favors the East Coast for snowfall, this reduces the chances for above normal snow.

I would like to remind everyone that THIS IS AN UPDATE and DOES NOT RESEMBLE my OFFICIAL THOUGHTS. My official thoughts remain in the Final 2012-2013 Winter Forecast. I will have my latest official thoughts out by the end of this month.

Andrew

La Nina Coming Back For 2012-2013?

Latest indications from the Equatorial Pacific are that something significant is happening. Let's get right to it.

This image is from the Climate Prediction Center, showing the latest Observed Sea Surface Temperature on top and sea surface temperature anomalies on the bottom. I outlined a region on the bottom image showing what I am so concerned about.

Do you see that blue area off of the South American coast circled in black? That is what very well could be a La Nina. This is the same phenomenon that was observed in the winters of 2010-2011 and 2011-2012. Now, this could indeed just be a quick cool down of a specific part of the ocean. However, I have reason to disprove this.

1) The water anomalies look wavy. The wavy look of this water anomaly suggests that this is an oscillation and not just an anomaly of cool water spontaneously bubbling up. Considering the ENSO phenomenon is an oscillation and oscillations tend to move in certain ways, this wavy pattern is no different.

2) This has been a sustained cooling. This appearance of cool water was not sudden. It has been developing in the last few weeks, more significantly this week and last week than in the past while. Given that this was not a sudden appearance-disappearance case, I find the case of a possible La Nina strengthened.

3) Global wind anomalies favor a La Nina. In this post published not too long ago, I highlighted regions that are showing typical La Nina characteristics. The observation of La Nina signals worldwide and this new development give me a stronger indication that this may be an emerging La Nina.

BUT WAIT!

Underwater anomalies are still suggesting that El Nino-status waters remain present. It will take another few weeks to determine if these warm waters take down the new cold pool or are beaten by what could be a newborn La Nina.

Andrew

LRC Showing Snowiest Regions This Winter

The LRC pattern is giving up hints on who could get crushed this winter. But before we get into any of that, what exactly is the LRC?

The LRC, or Lezak Recurring Cycle, is an annual pattern that sets up during the fall and is present into the following spring. This pattern cycles, or repeats, every 40-60 days. Each repetition is referred to as a 'cycle'. The length of each cycle varies each year, and NO PATTERN IS THE SAME from year to year. The LRC tracks storm systems and high pressure systems, repeating them through each cycle. However, these apparati will change location slightly and change strength with each cycle of the LRC.

Let's start out this investigation by taking a look at what has happened in the nation throughout the past several weeks.

500 millibar map from September 22

500 millibar map from October 9

500 millibar map from October 14

The 500 millibar map is the best place to look for low pressure systems and high pressure systems. Low pressure systems are characterized by depressions in the lines on the map. The deeper the depression, the stronger the storm. High pressure systems are shown as an upward arcing feature. Like the previous rule, the stronger the arc, the stronger the high pressure system.

In all three pictures above, you can clearly see several storm systems on the map. However, there were strong storm systems in the Midwest and Northeast for these periods, with a few cut off lows just off the Southwest coast. During these three images' timeframes, the northern half of the country (as well as the Plains) got smashed with several inches of precipitation, with over 2 inches in some areas over the Midwest.

The new Lezak Recurring Cycle for 2012-2013 appears to be setting up, and people in the Accuweather Forums, as well as the inventor of the LRC, Gary Lezak himself, are buzzing about it. This latest blog entry by Mr. Lezak indicates that the LRC is indeed showing itself, as this quote from his blog demonstrates:

Energy coming over the Pacific Northwest coast this morning will begin diving south over the plains states tonight.  This is not necessarily the greatest sign for this year’s weather pattern, as this is the third storm to dig into this position, which strongly implies that we have a pattern setting up with a long-term long-wave trough northeast of Kansas City. I would love to see some energy digging into the western states or Rocky Mountains, but recently this has not been happening. 

You're probably thinking "So what? Why should I care about just a pattern?"

Well, the Lezak Recurring Cycle has historically helped predict who could get the most snow during the winter, as the storms typically follow their paths in past cycles. For example, if a storm were to go through the East Coast and it was in the LRC, 40-60 days later would see the same piece of energy hit the generally same area.

The presence of so many strong storms in the northern half of the nation suggests to me that the Plains, Midwest, Great Lakes and Northeast are in for a quick start to winter. Keep a close eye on early December for these same pieces of energy to hit the mentioned regions...possibly with snow this time.

Andrew