Terpeast

All ens models show the PNA flipping from - to + around the 7th, and it looks to have some staying power. Atlantic not quite where we want it to be, though.

Thank you. And did you use ChatGPT by any chance?

Remember that the wind controls the flow and track of a storm system. To understand blocking, let’s think of the opposite scenario: Cold airmass (low geopotential height) over Greenland and a warm airmass (high geopotential height) over the west Atlantic. This is a +NAO. The temp gradient in between the two air masses are going to be pretty damn steep. So we should expect very strong winds going between the two air masses. An incoming storm is going to follow the wind and traverse between the two air masses. Since the wind is moving fast, the storm will race through there. Now, lets flip the air masses around and get a -NAO. 50/50 low in the western atlantic with a greenland high. Now the temp gradient will be much flatter. Wind will be moving very slowly, and may even reverse. An incoming storm approaches, and then because of weaker winds, it has nowhere to go. It gets “blocked”, hence the term. Sometimes it goes under the block, which means further south bringing more cold air south, which means snow for our location.

Couple of things. First, for the models to work well, they use pressure as a vertical coordinate system instead of height. Instead of 2,000 feet 4,000 ft 10,000 ft and so on, you have 900mb 800mb 700mb all the way up to 10 mb. It’ll be too complicated for the models/equations otherwise. Second, geopotential height patterns tells you where the warm air masses and cold air masses are. The higher the geopotential height at the 500mb pressure surface (think coordinate system), the warmer the airmass. The lower the geopotential height is, the colder the air mass. Now, when you have a cold and warm airmass butting up against each other, there is wind… and the stronger the temperature gradient between the air masses, the stronger the wind is. And it is that wind that controls the flow and track of storm systems. Took me three paragraphs to explain it. Maybe someone else can do it in one.

Can you post the Jan 1985 map? I am sure it looks totally different from the rest.

If we’re talking the difference between T/0.1” and 1-2”, remember that if it had been a smidge colder on the front end of the cutter, we might be dancing instead of whatever we’re doing now. Or if the anafront produced just another hour of snow in the right places. A lot of it is pure luck.

“La Niña tends to limit hurricane development in the Atlantic” Uh, no it doesn’t…

@Maestrobjwa that’s actually good advice. You have many ways to get it out of your system: 1. Chase a LES event in Buffalo 2. Move to NNE where snow is guaranteed (but so are months of 50s gray windy days) 3. Move to Denver where seasonal snowfall is similar to northern midatlantic, but even when it doesn’t snow, you can always drive 1-2 hours west to hit the slopes. 4. Move to a warm tropical climate and forget about snow altogether. I have done all 4 of the above. Trust me, when you move to a snowy area, it’s just not the same where we go nuts whenever it snows precisely because it’s not the norm. It gets boring and tedious after a while. Imagine having to shovel your car out every 2 days and scrape the ice off it. I got sick of it. I’ve lived abroad in a tropical climate (southeast Asia) and there’s a ton more to life than tracking snowstorms, most of which usually fail.

Low of 15

Topped 31 for the high. Sunny but still cold. Had a great Christmas today with the fam. Happy holidays all!

Pretty spot on. The MA has never done “complicated” well as far as I can remember. In fact, anytime a forecaster referred to an incoming system as “complex” - that’s an automatic red flag imo.

Everything is covered with a layer of thick sparkly frost. Almost looks like a dusting and white christmas. Merry Christmas all!

What do the extended ens look like? We’ve had thaws before like this even in big winters. I think we get a total of 3 maybe 4 chances. We already whiffed at one, so 2-3 more periods of cold in mid-late Jan, then a thaw last week of Jan, then another shot sometime in Feb, and maybe one last brief window in March. I think we get something in Feb, maybe Jan, too. Always a chance we could whiff on all chances, but I don’t think so.

Low 9, now 11. Merry Christmas from Ashburn!

Great story, glad you enjoyed it.. though I’m not sure the dog did.

Topped out at 20. It was cold enough to get a low tire pressure warning, so I reinflated my tires. Now I’m wondering if I should deflate them a bit when it warms back up?

Thanks! Learned something new today.

I'm terrible at reading those MJO projections... so please correct me if I'm wrong. The black line is what has already happened, and the red part is what is happening right now, and the blue/purple is the forecast? And it seems to get stuck in 7, barely outside of COD? So if it's not going to phase 8, we would rather it go into COD and rely on another pattern like PNA or NAO, right?

Yeah, it’s good to see that there’s an end to the temporary warmth. We can snow on this look in January.

At the moment, it looks like we go well AN between 12/28 and 1/9 then trend to near normal temps by 1/10. For now at least.

Think I’m bottoming out at 5 degrees. DCA went down to 9?! Wow

9 degrees now. Heading down to 6, maybe 5.

And is there a sign of a STJ about to develop (negative h5 anomalies east of hawaii)?

Not saying we'll get anything out of it, but isn't that a clipper that was deemed extinct since 2015?

Just picked up my kid from daycare an hour and half earlier than usual. My car door was frozen shut. Had to pour hot water through the door crack. Took 3 tries until it finally opened. Car thermometer (which has a slight warm bias) read 16 degrees. Ashburn VA. So, yeah. It's cold.