New Year, New Pattern.

Before I get into the long range, some of us in the coverage area will have to deal with a Wintry Mix Monday Night, before a change over to rain. 48 hours ago, models were trending colder, suggesting that many of us, even York/Lancaster counties, would see at least a moderate impact from snow, sleet, and freezing rain. Reason being was the location of the High Pressure system sitting in Canada, was originally modeled to be a few hundred miles southwest, and much slower to leave the Northeast. With a clock-wise motion, this helps funnel in the cold air into our area from Canada.

I drew up a quick image to represent what I am talking about. "X" marks the spot. The "X" is where the high pressure was originally modeled to be. The "H" you see stands for High Pressure, which is where the HP is now modeled to be.

Pretty substantial difference as you can see. This leads to a more wet scenario than white. To be honest, as a snow lover myself, this is a great thing. Because let me tell you, this would NOT of been a snowstorm for the Lower Susquehanna Valley even if the HP was located where it was originally modeled. Instead, it would of been a significant sleet and freezing rain storm..two types of precipitation you do not want to mess with.

Here is a zoomed in look over our region during the onset of the storm.

Notice the oranges and pinks...our area might not escape all of the sleet/freezing rain. But look how quick the transition is from pinks/oranges to green. Green being rain obviously. It still is possible that as far south as Northern York, may start off as a period of Sleet... AT THE ONSET. But, within a half hour it will turn into a cold rain for everyone south of I-80.

Areas north of I-80, may hang onto the sleet/freezing rain a little longer. Enough that Winter Weather Advisories may be posted for those areas. But, even these areas will transition to a cold rain.

LONG TERM UPDATE:

As the New Year approaches, our weather pattern will be changing. Take a look at the current temperature anomalies.

Hard to miss the warm pool of temperatures across the Eastern half of the US. This storm that will impact us Monday Night into Tuesday Morning will take a track right along the temperature gradient, or where the above normal temps, meet the below normal temps. I guess you can call that your lesson for the day. Many storms follow where the temperature gradient sets up. Alright back on track. Take a look at Western Canada. Notice the below average temps located there where I have the "X". This would indicate a trough over the western half of the US, and a ridge in the East. Typically, whatever happens in regards to temperatures in Western Canada, the opposite occurs over the Eastern US. This whole month of December we have been under that Southeast Ridge. This is why our temps are record breaking warm.

But...looking ahead after the New Year, we have a whole different pattern setting up.

Notice the warm pool of air in Western Canada. This is a huge difference than what we saw for the entire month of December. This leads to a more seasonal/colder look for the Eastern US.

Not only does that pool indicate warm temps in Western Canada, it also promotes ridging in the West and a trough in the East. Although, I would like to see that warm pool of air slide further south into the Western US, to receive our bigger storms, this pattern would still support clippers that burst out of Canada and impact our region with light to moderate snowfall events. Now do not worry snow lovers. The chance for big storms will increase as we head later into January. But, for the first week of January. we are looking at a "clipper pattern" with colder temperatures in the East.

-Chris

Looking Ahead Through The Rest Of December

Many of you may be wondering where the season we call Winter is. I am beginning to wonder the same thing. However, as many forecasters expected, this month of December has been predicted fairly accurately, but not perfect. I will be the first to admit, that I did not expect it to be this warm, nor did I expect us to struggle to see a single snowflake throughout the entire month of December. Granted, we are only half way through the month, but the signals are pointing to a snow-less month.

First off, here is a look of how December has started off in the temperature department:

Nearly the entire Lower 48 is above average temperature-wise for the month! It truly is incredible. Right now all of Pennsylvania is averaging between 4 and 6 degrees Celsius above normal which is an outstanding number, that will continue to climb as we head into the rest of the month.

Tuesday through Thursday will remain above average, until a low pressure system slides to our south on Thursday, delivering with it rainfall. This system will bring with it a minor to low-end moderate rainfall event. Meaning, the area can expect between a quarter of an inch to an inch of rainfall before the night's end on Thursday.

Shockingly, on the backside of this system, it will bring with it much colder air to the region for Friday, Saturday, and Sunday. Lake-Effect Snow will be cranking this weekend. Areas near Lake Erie may receive several inches of snow, while areas near Lake Ontario could see double digit snow totals is localized locations. As for the Lower Susquehanna Valley, the chance for some of those Lake-Effect Snow Showers to survive the mountains is slim, but there is a chance for some flurry activity during the day Saturday.

Above is valid Saturday Morning. Nearly all of PA is in the lighter blues, which means temperatures between 1 and 4 degrees below normal for this time of year. But, would you look at what is occurring in the picture that we have not seen for quite sometime... a RIDGE OUT WEST AND A TROUGH IN THE EAST..WOW.  Okay, I'm exaggerating a bit and kind of making fun of our weather pattern that we have been stuck in for practically the last month. Anybody who has an understanding of the weather knows what I am talking about.

Here is look of the Lake-Effect Snow Showers I was talking about valid Saturday Morning. A stiff North West off the lakes will deliver a rather brutal cold shot to the mid-state regardless if we do see the flakes fly. Temperatures Saturday may not even make its way out of the thirties! At least it will put us in a the holiday spirit for a little bit. Best chance for any snowfall, is State College, North and West.

This cold shot is short lived however, by the time next Monday (12/21) rolls around, temperatures will be back to warmer than average.

Here is a sneak peak of temperatures Christmas Eve compared to normal:

Ouch...20+ degrees above normal for Christmas Eve into Christmas?? That would put our temperatures into the 60s! With areas near the Mason/Dixon line approaching the 70 degree mark....

Forecast breakdown for the rest of the month:

Tuesday 12/15 - Thursday 12/17: Temperatures averaging above normal. Thursday features a rain event for our area.

Friday 12/18 - Sunday 12/20: Slightly below average temperatures. Lake-Effect Snow gets cranking, possible flurries flying around on Saturday for the Lower Susquehanna Valley.

Monday 12/21 - Wednesday 12/23: Above normal Temperatures as the Southeast ridge emerges once again.

Thursday 12/24 - Saturday 12/27: Well above normal Temperatures, approaching record high's with many of us reaching the 60s.

Sunday 12/28 - Tuesday 12/31: Temperatures beginning to decline, however still above normal.

-Chris