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Cold air sticks around, light snow likely on Saturday

Bitter cold has settled into the Northeast states over the past several days, and is here to stay for the next 7 days at least. Arctic air will continue to funnel into the Northern 1/3 of the United States, thanks mostly to a large ridge in the Pacific Ocean and enhanced blocking in the high latitudes near the Arctic areas. This blocking (or these “blocking ridges”) in the higher latitudes act to disrupt arctic circulations from their typical state and, often times, send cold air southward into the USA. So here we are.

The flow of arctic air will continue through the weekend, and a weak disturbance will swing through the Northeast states during this time as well. Forecast models had jumped around quite a bit with the potential evolution of this event, including the almighty European model, which at one time persistently suggested the storm would be something of greater significance. It will be wrong – as the storm system will remain very progressive and swing through the Northeast states without much fanfare.

Forecast models suggest the potential for light snowfall on Saturday as a weak storm system passes by.

Forecast models suggest the potential for light snowfall on Saturday as a weak storm system passes by.

Well, that depends on what your definition of “fanfare” is. The storm will, in the end, produce an area of light snow across the Northeast states. This swath of very light snowfall accumulations is likely to reside from Pennsylvania through New Jersey, including parts of Long Island. Snow will accumulate quickly on roads (you can thank very cold air, ground, and pavement temperatures for that), so things may get slippery for a time on Saturday. But precipitation amounts will be very low and the storm system itself won’t have much of an impact.

Why is that, exactly? Simple: The progressive nature of the weather pattern doesn’t allow for enough amplification of the jet stream. Without amplification, you don’t have sufficient lift to produce precipitation in the atmosphere. With low moisture content in the airmass to begin with, it’s going to be very hard to squeeze out snow of significance. So the forecast moving forward accounts for light snowfall of T-2″ in most areas, probably less than that in NYC and points west. Areas on Long Island have the best chance of seeing amounts closer to 2″ as the storm “strengthens” a bit off the coast.

This system will gradually shift away from the area during the weekend, and all eyes will turn to the potential for a larger system next week. There has been plenty of chatter on social media (when is there not?) about the potential for a huge storm system next week. We’re here to tell you that…well, that’s not exactly incorrect. The potential for something significant does exist. But the probability of the event occurring remains quite low.

These two disturbances may interact over the USA next week, with the potential for a large storm system. But their interaction remains extremely uncertain.

These two disturbances may interact over the USA next week, with the potential for a large storm system. But their interaction remains extremely uncertain.

Here’s the setup: A large ridge is forecast to build in the Western part of North America. This ridge will disrupt the circulations in those areas, sending atmospheric disturbances on a roller coaster ride – way north into British Columbia, and then way south down the east side of the ridge. As these disturbances come southward, they will pick up speed, and amplify into the United States. Forecast models also suggest that, at the same time, a lingering disturbance will be meandering in the Southern United States, precariously close to southern jet stream moisture and lift.

The key interaction will occur when the Pacific disturbance drops southward into the United States. How fast will it dive southward? Will it interact quickly with the Southern disturbance, or will it remain slightly slower and interact later (or not at all?) This is the struggle we will continue to have over the next few days – and forecast models are already jumping around with their potential solutions. The afternoon European run yesterday indicated a record-breaking snowstorm, while the evening run last night showed the storm 1500 miles off the US East Coast with limited impacts.

So what are we watching for exactly? We’re carefully watching that disturbance we discussed, emanating from the Pacific Ocean, and the amplitude of the ridge out in the Western part of North America. The disturbance itself is still currently situated in a  huge gyre in the North Pacific Ocean, spinning around with many other disturbances in a circle. As you may imagine, its emergence, track, and intensity is extremely uncertain right now. And even when it does emerge, we want to look carefully at how the Western North America ridge is positioned. That will dictate where the disturbance tracks  and how it enters the USA.

The disturbance which is responsible for a potential storm is currently spinning in this huge gyre in the Northern Pacific Ocean.

The disturbance which is responsible for a potential storm is currently spinning in this huge gyre in the Northern Pacific Ocean.

If these two disturbances do phase, the potential will exist for a powerful storm system. But currently, we aren’t comfortable forecasting that. The potential for the two to phase certainly exists, but is extremely low at this time. Current indications are that their interaction will occur much too far east for the US East Coast to be impacted. But you better believe we’ll be watching it very carefully – with new data coming in over the next few days, we will begin to hone in on our thoughts on the evolution of the storm system.

So, as we say quite often, stay tuned! And have a wonderful Friday!

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