Saturday, August 18, 2018

Winter "Pre" Previews are trickling out.. If you like cold and snow you will LOVE..

Winter outlooks done by mets/ weather hobbyists are more fun than accurate at times but they do make fodder to read and post. I've noted a few notable mets with early previews and others tossing hints.

I have some early thoughts for the areas including Lynchburg, Roanoke,Danville and Blacksburg.

Most guess are predicated upon:

1. We will most likely have a low to moderate Modoki El Nino. This means the Pacific, especially in the mid pacific known as Regions 3/4 will be in an El Nino phase. 

2. The PDO should be positive- Warmer water closer to the north pacific coast from Alaska down towards the US will be warmer. 

3. The Atlantic MAY be more favorable for high lattitude blocking in the NAO and AO regions.

If you have every kept up with my blogs, those are all really good things if you like cold and snow. We always blog from the perspective that snow is a good thing,.

A modoki El nino is the closest winter  to a consistent theme.  Most end up remebered for being fairly cold and rather snowy.  Winters with similiar patterns were 86/87, 02/03 09/10 with other years having lesser levels of commonalities. 

86/87 is remember for have back to back 10-14 inch snowstorms in our area from Jan 22 to 26. Region had 30 to 60 inches of snowfall.

02-03 had MANY storms in the 3 to 6 range and a BIG storm ended up being sleet here (in the 3-6 inch range of sleet). The region had 20-50 inches of snowfall for the winter. 

09/10 had 2 storms over a foot and another get really close. Snowmaggedon dumped close to 15 to 30 inches region wide over a few days but DC north had 40 or more inches in a 10 day stretch.  Seasonal totals were 25 to 50 inches region wide. 

With that,  nothing is every a lock-- especially before we have an offical El Nino and a few other variables. 

If we get to October 15, we know the Modoki El Nino is happening and the other factors are in place, my winter outlook would be:

Temps regions wide-- Seasonal 1-3 below normal for the winter. 

Snowfall, by city. 

Danville region/southside- 10 to 20, but a lot wiggle room for more. 
Lynchburg Area 18 to 28 inches, with higher end potential. 
Roanoke Valley region- 21-31 inches, potential for more. 
Blacksburg, NRV and Highlands Region- 25-35, even more in Lake Effect areas. Also, potential for much higher totals. 

Each city's top 10 snowfall winters has 2-3 modoki winters in those totals. 

Modoki El Nino's are known for having 2 or more LARGE events of over 10 inches.. once snow gets into double digits around here, it's a memorable event. 

There is also a "hot" period from around January 20th until February 10th or so that has a historical precedent these large events with other events being more scattered thoughout the winter season. 

That time period is often easily identifed  in advance by-- Modeling showing strong blocking in the Artic/Greenland region (Negative A0/NAO cuplet) positive PNA(Ridge on the west coast) and the SOI (Southern oscillation index) dropping  7-10 days in advance. (This is tied into the sub tropical jet becoming active)If that happens we could pop 2-3 winter events in a 7-10 day period. 

A couple runs of the seasonal runs from the Canadian Model and European model showed literally perfect 500 mb maps if you wanted a cold and snow winter for December to March. These maps displayed blocking on the west coast and artic/NAO regions with clear evidence of a strong sub tropical jet. Sub tropical jet is very important for our region because we do sit far enough south that we need a pretty unusual pattern to have the northern jet suppressed for snow in our region. 

With that, we are only on August 18th and a lot can and will change.  It is completely possible that we have all the pieces I cited in perfect alignment and we end up with a rather tame winter. This outlook previews where I am likely heading, but will updated my thoughts hopefully by late October.