Saturday, December 22, 2012

Saturday Morning Update: Get Ready for Winter

We are in for a very exciting 10 day stretch from Xmas though the New Year. Three storms will threaten our area and it looks like we are setting up to have a classic stretch of winter. I want to break down each storm in this post and what the possibilities are for snow/rain/ice for our area.

So starting with the snow event that is coming for late Xmas eve lasting until Xmas morning this is pretty locked in. Snow will spread into north Jersey by 8 pm and last until about 7 am Xmas morning. This is not a major storm and will be a light to moderate event. I am calling for 4-5 inches over the high elevations of North Jersey (1000ft+), 3 inches for the central part of the state, and 1-2 inches on grassy surfaces south east of Trenton. Travel should not be too much of an issue considering the heaviest snow will occur after midnight. It will be a nice scene to wake up to. My confidence for this storm is very high and I see no reason why this event will not materialize.

Now after Xmas is where things get more interesting. All eyes are on the 27th of December for a potential powerful coastal storm. Now anytime a complex storm system like this is 5 days out there are always a range of possibilities for where the exact track will be. Here is what we do know...A storm is coming that's a given. This storm will have more cold air to work with than the last few rain storms that hit our area. Because of more cold air in place the surface storm which will originate in the south central part of the country will be more likely to want to transfer its energy where there is a contrast between cold and warm air. That region is over the Atlantic ocean. The question becomes how late or early will this transition take place. If the parent storm stays stronger and waits to transfer its energy then we will more likely be in for a mixed precipitation event (snow to ice to rain to snow) If the source of the cold air up in Canada holds strong then this transition will take place faster, allowing the storm to form in an ideal spot for snow for everyone to the west of I-95. Let's take a look at the model output (from pro site) then I will make an initial prediction. Clicking on all images makes them bigger.

The first panel directly to the right is showing both  lows. Notice the one on the left (black circle) is weakening and the one on the right is taking over. By the time we get to the 2nd panel the storm has fully transitioned into one coastal low. Under this scenario the transition is taking place too late. This would result in more mixed precip and rain for our area.I am showing this first bc this is the latest run of the GFS model as of 10 min ago. Last night it had a colder solution with more snow but it has backed off a bit. I am not a flip floper with models so like I said once I illustrate all the info I look at I will give you my prediction. 

So now lets go to a model that is more bullish for snow- the European (3rd panel down on the right side). Notice compared to the first panel from the GFS this model is showing the coastal low taking over quicker, which allows the cold air to flow in 
from Canada. This scenario would give everyone to the west of I-95
 6+ inches of snow with the 
higher elevations getting 8-10. 
The panel directly below shows
 snow cover by next Friday from
 this model. 
Click the image to get a bigger view.

So based on all of this info along with other outputs I look at what is my initial prediction for the 27th storm? Lets break it down by region. South East of I-95: mostly rain changing to snow at the end with a few inches of accumulation possible. North West of I-95 below 600ft: light snow changing to moderate to heavy mixed precipitation changing back to snow accumulating 4-5 inches. Northwest of I-95 above 600ft (western morris county, warren county, sussex county): Snow possibly mixed with sleet and rain initially becoming all snow accumulating 5-8 inches. 

So there it is, my initial prediction. As the days pass I will keep updating these projections but that is my best first guess based on everything I am looking at. Of course there is the possibility that these amounts can be more (high range of 12 inches) or less (a few inches) based on how the dynamics set up as explained above with the graphics.

So after the 27th event whats next? Well I am tracking two more potential snow threats one on the 30th (could be big) and another one on January 3rd. I will post more on these once I can iron out more details with the 27th storm. In any event not counting the Xmas eve snow, if we dnt see some other big event from now until January 3rd with this pattern, then we can pack it in because I don't know any other set up that could. Keep checking in daily for updates.

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