Tuesday Nov 29th: Big Flip to Winter in 10 Days

 Good morning. What has seemed like a tame weather pattern in recent days will made a pretty big flip by the time we get from the Dec 10th to 20th time period. I expect winter to arrive pretty abruptly with a step down to cold and yes possibly snowy conditions. There are many factors in the atmosphere evolving right now to support this that I have been watching evolve carefully over the last two weeks. Today I will discuss some of these.

Starting off, my going forecast idea is that by Dec 10th the northeast enters a a wintery period of weather. This means colder than normal conditions with the chance of a snow event between the 10th and 20th timeframe. Prior to this occurring, things should stay seasonable with the chance of a few light rain events. Do not be fooled however, there are things evolving right now that we have not seen in recent Decembers.

Starting off, going way up into the atmosphere at the stratosphere, the polar vortex has been weakened in recent weeks. What does this mean? Normally when you have a tight wound up PV, it locks all the cold air up in the pole and its mild across our area. When the PV becomes stressed and is not able to strengthen, you start to see some of that cold air pour south. 

The image below shows the current PV. Notice how it is off its center axis and pushed south closer to our side of the globe in blue...

As we move further down in the atmosphere, we are seeing other factors emerge that are also putting stress on this vortex while setting up a pattern for stormy weather by week 2 of December...

Looking at the image above sums up what is projected to occur. Red areas are high pressure and warm air, blue are lower pressures and colder air. What is happening over Greenland is quite signifigant. That big red blob is called a blocking pattern. This means it causes the jet stream to buckle over our area allowing storm energy to consolidate near the east coast. We have not seen a projected pattern like this since December 2009. If this verifies, it will mean the chances for winter winter significantly increase by week 2 of Dec. 

In my opinion what is occurring is all connected to the stratosphere in the first image.  There are many theories as to why we may continue to see a weakened stratosphere/Polar Vortex this winter, one of them being the Tonga underwater volcano earlier this year. It injected an unprecedented amount of water vapor into the atmosphere which one can speculate has had an impact on the stratosphere. 

In any event, when I put together my Winter Forecast in Oct I saw evidence this could happen in December. Now its a waiting game. Remember these are still projections, but do not be surprised if there is snow in your back yard by mid Dec. 

More to come. I post daily update on my twitter handle @weatherwilly. 

Tuesday: No Changes to Tonight's Forecast

Here is my projected snowfall for tonight. I kept things the same from yesterday am..

Most snow will be in the mountains of New England in pink zone, cant rule out a few flakes to start but no accumulation.

Initially some snow is futher south this evening...

It quickly changes over as warm air aloft works in...

Stay tuned, more on the upcoming pattern this week. 

Monday the 14th: Pattern Change has Arrived, Winter Knocking

Good morning. In the last 24 hours there has been a noticeable change in the weather pattern. We went from very mild conditions to what now feels like winter has arrived. For the most part, I expect this pattern to hold through at least the first half of December. A storm system is even scheduled to arrive tomorrow night which will drop accumulating snow in the mountains of the Northeast with the chance of first flakes for many areas 50 miles off the coasts.

Lets take a look...

As of 7am this morning winter temps are over the region...

This is due to air now funneling in directly from Canada seen in blue...

This cold air will hold through the week with temperatures in the low to mid 40's for highs and lows in upper 20's to low 30's (depending where you live).

On Tuesday a storm system approaces from the southeast and tries to run into this cold air...

Initially some of the cold air can hold in areas like NW NJ, NW CT, Mass ect to cause our first flakes of the season to fall Tuesday night! This however should quickly change over to rain as warm air aloft works into the storm. The focus for any accumulating snow will be the mountains of New England...

I have put together a map to explain my thoughts on this...

As you can see the focus is mostly on the mountains. Regardless, anyone in pink can see some initial flakes before this changes over tomorrow night.

Looking ahead I expect this colder than normal pattern to hold into December. This is due to a variety of factors I am watching evolve. I will discuss this more as the days go on. 

Stay tuned. 

Tuesday Nov 8th: Pattern Change Coming, Cold Air Arrives by This Weekend

 Good morning. Winter is knocking on our door and a big pattern change is on the horizon. This is something I have been talking about on twitter the last two weeks and now all indications are it will occur. What does this mean? It means compared to the warm temps we have seen in recent days, temps will step down into the 40's for high and 30s for lows over the next few weeks. This process starts by end of next weekend in the wake of a big tropical rainmaker that will impact the area on Friday night.

Lets take a look...

Seasonable to mild conditions this week give way to a tropical storm/hurricane that will hit eastern Florida and move up the coast as a sub tropical system on Friday night...

This tropical system is interacting with a cold front and will produce heavy rains over the area through Saturday morning...

In the wake of this a big cold front arrives Saturday night with temps dropping into the 30s by Sunday morning...

This is the arrival of the pattern change I have been discussing. What is happening is the configuration of the jet stream is changing. This is due to a variety of factors which include, the stratosphere, convection in the tropics, ocean temperate patterns etc. The image below shows why colder air will come into our region the 2nd half of November...

The question then becomes will it stick around for December? My winter forecast indicates it does but of course we will have to monitor. If we see a flip to warm by 1st week of December that is a red flag for my winter forecast. 

In terms of snowfall, I would expect flakes to start flying in interior New England by next week with the chance of some accumulating snowfall by end of next week especially in ski areas. For areas closer to the coast, we can not rule out seeing your first flakes flying in the air by the end of next week, but overall I do not expect any snow yet. It is still early.

So enjoy those last few days of warmer temps middle of this week. Winter is knocking.

More to come. 

Saturday Note: Big Pattern Change Coming Mid November

 Winter is knocking...stay tuned for more details Monday.