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E PA/NJ/DE Winter 2022-2023 OBS Thread


Ralph Wiggum
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17 minutes ago, wkd said:

I don't necessarily agree.  If there had been colder air, why would we have been toast? There have been numerous times where the primary low tracks to the lakes but there is enough cold air (often due to CAD) that the secondary low offshore produces a lot of snow in our area.  By the way, thanks for responding.  I wish we had more discussion (including Mets) in our subforum.  Ralph seems to be the only one attempting to do any  forecast analysis.   Thanks Ralph!

Someone smarter than me (which is 99.9% of this board) can give you a better answer, but here's my uneducated understanding. In order for CAD, we need a cold high anchored to our north (say Quebec) drilling low-level cold air down the east side of the Apps. So when WAA attacks from the south/southwest, it "rides up and over" the cold dome of air.

But we haven't had any cold highs anchored to our north this year because we haven't had a 50/50 low or -NAO to lock it in place -- probably because of the uber SER/WAR. Lows coming from the south quickly erode any cold air at the surface and whatever high that exists to our north scoots out to sea. 

 

Virga here, 36F/DP28F

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9 minutes ago, JTA66 said:

Someone smarter than me (which is 99.9% of this board) can give you a better answer, but here's my uneducated understanding. In order for CAD, we need a cold high anchored to our north (say Quebec) drilling low-level cold air down the east side of the Apps. So when WAA attacks from the south/southwest, it "rides up and over" the cold dome of air.

But we haven't had any cold highs anchored to our north this year because we haven't had a 50/50 low or -NAO to lock it in place -- probably because of the uber SER/WAR. Lows coming from the south quickly erode any cold air at the surface and whatever high that exists to our north scoots out to sea. 

 

Virga here, 36F/DP28F

It's all about the depth of the cold air....if the primary tracks to the Northwest and pulls above 0c air in at the 850mb (5k feet) level it is unlikely unless you have a bombing low off the coast to drag the freezing level back to the 850 level. Plus there is really nothing preventing warm buoyant air from surging above the surface with the absence of the deepening pressure off the coast. So normally once you turn to non-snow you stay there. That said if enough low level cold air you could certainly see a transition back to some ZR etc.

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