Written By: Scott Hetsko
Freezing drizzle falling tonight has resulted in numerous car accidents and we've had reports of a few exits on 490 closed due to the accidents around 11 p.m. tonight. Please take your time on the roads, if it is drizzling with temperatures below 32 degrees...it is likely freezing on contact!
The icy conditions will improve toward early morning hours but the early commute may be slick in spots.
I have a question about the indices (NAO, AO, PNA):
ReplyDeleteIf the PNA goes strongly positive, and the NAO goes negative as a result, I know that typically means a good western ridge, eastern trough setup, and cold conditions for our region. BUT, what if the AO goes slightly positive at the same time - would that cutoff the supply of arctic air to our region, even though the NAO is negative due to the positive AO keeping it locked well to the north? Or would a good, solid negative NAO be able to tap into the cold air regardless, overriding the positive AO?
Thanks in advance!
Dan
DK - are you asking about the potential pattern coming up where a trough continues in the east but it doesn't get that cold around her?
ReplyDeleteHa, yes Brian. I see remarkably good agreement that the PNA is going to go at least neutral and likely positive by January. I also see the NAO showing hints of trending farther into negative territory during that same time, which would make sense. But at that same time, I also see the AO trending toward neutral, which would seem to "water down" the cooling effects of a positive PNA and negative NAO.
ReplyDeleteOn the other hand, I wonder if that pattern might be more conducive to synoptic systems taking a more favorable path for WNY. It seems that a big part of the reason that we've been free of synoptic storms is because of this very negative AO, similar to last year. It would seem that with a negative NAO and a positive PNA, we will be cold enough for mostly snow events...BUT what will be different this time around is that the storms will track closer to us because the AO isn't shoving the cold sooo far south and thus steering the storms well south time after time. So maybe we will be looking at a more classic winter pattern come January, with cold remaining in place, and clipper systems streaking across our area every 3 or 4 days giving us renewed synoptic snowfall with some lake enhancement / effect on the back side. Then again, I might not know what i'm talking about, either lol. Just speculating on my part.
ReplyDeleteNot sure how air temps increasing will lead to more oppotunities for synoptic snow.
ReplyDeleteWell, warmer air can hold more water for one thing. Also, warmer air can hold more energy which can breed storms. But it's all relative. Some of our biggest synoptic snow storms happen with temps within just a few degrees of freezing - not when we're bitterly cold. Just look at the D.C blizzards last year. They weren't exceptionally cold by Rochester standards. Mostly upper 20's to low 30's much of the time. We're better off being just on the edge of the warmer air than being so deep into the cold air mass that all the storms steer well away from us. That's part of the reason why the Arctic is so dry. Remember, storms like to ride along boundaries between warm and cold air, so if you're too deep into the cold air, the atmosphere holds much less energy, is much drier, and just isn't conducive to major synoptic storms.
ReplyDeleteOk see what you are saying but I believe they are predicting us to be close to 40 at the end of next week.
ReplyDeleteyep, maybe a brief thaw. But i'm talking about the pattern shift more like two weeks from now. More of a fundamental pattern shift to more active weather. I have a feeling that the rest of December into the first several days of January will continue to be inactive and seasonably mild, but I think snowy weather might ramp right back up again in earnest by 5th or 6th of January. Just my unprofessonal opinion. Scott January or February could be a 40" snowfall month. I think he's right!
ReplyDeleteIt looks like this storm is not going to big for anyone/ Too far out to sea.
ReplyDeleteLooks like News 8 has taken a holiday break for a while and that is good because we have quiet weather for the next two weeks. Then hopefully DK is right the pattern will change and things pick up from January 9th and on. Happy Holidays to all.
ReplyDeleteI'm NOT a meteorologist, so take my thoughts on here with a grain of salt.
ReplyDeleteWell DK it is the only grain of salt we have since News 8 is MIA and did not ask answer your question about AO, NAO and PNA. So what youy say sounds good to me! Different pattern starting mid January leads us to a more favorable storm position and more synoptic snow.
ReplyDelete