Posts

John Homenuk

Increasing potential for significant snow next week

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Four months have gone by since we first began tracking the potential for snow and cold in November. The best atmospheric weather pattern for significant snow chose not to arrive until the middle part of March. Yet, here we are, tracking the potential for a tremendous storm system to impact the Northeast United States early next week. Forecast models have begun to hone in on the development of a strong low pressure system off the coast, with tons of moisture and cold air available.

A few weeks ago, our forecasters were tipped off to this potential by the development of high latitude blocking. This is a critical component to any forecast, especially for cold and snow, and especially in the Northeast United States. See, these high latitude blocks are extremely disruptive to the atmospheric flow. Essentially, ridges of high pressure develop way up in the polar and arctic regions and “Block” the progression of systems through the region. They also dislodge cold air, which normally would be bottled up in the higher latitudes, further south into Canada and sometimes New England.

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Doug Simonian

Technical Analysis: Northeast US Severe Weather Wednesday

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Yet again, the weather is completely divergent from the calendar, as we are tracking a severe weather event in the Northeast on Wednesday. This is following a moderate risk of severe weather in the Ohio and Tennessee Valleys today. It all starts with a warm front moving through the region tonight and early Wednesday morning, which will help make the already warm airmass even warmer, and also more moist. This will trigger some showers and possibly a rumble of thunder during the overnight and on Wednesday morning. Afterward, mid-level winds look to dramatically increase in strength as dynamics become extremely impressive ahead of a strong cold frontal boundary.

There will also be an elevated mixed layer (EML) moving into the region, which further helps promote high amounts of mid-level instability — perhaps more than we had on Saturday. We also have more deep-layered wind shear thanks to extremely fast westerly winds aloft, which could lead to multicellular clusters and even some supercells forming on Wednesday afternoon. The EML and westerly mid-level winds also lead to more dry air aloft, which is favorable for hail formation as well as being able to efficiently transfer strong winds down to the surface via density momentum. Saturday’s soundings were more moist aloft, and also had a marine layer closer to the coast — so in a lot of ways, this setup has a higher potential than Saturday’s storms, which is saying a lot.

But the devil lies in the details, and there are a few factors that make this setup have a much higher bust potential than there was for Saturday’s storms. Saturday was pretty much a guaranteed setup to get a solid line of thunderstorms, but not truly good severe potential from I-95 and east. Wednesday will have much higher potential but also have a few more things that could go wrong and prevent widespread severe convection.

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John Homenuk

Multiple chances for wintry weather this weekend

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A period long discussed as a potential “window” for wintry weather is now within the short to medium range, and forecast models continue to hone in on the development of wintry weather for parts of the Eastern Untied States, particularly the Northeast US as early as Friday and Saturday. A large ridge in the Pacific Ocean will dislodge cold air into Canada and the Northern 1/3 of the US, while an active jet stream pattern continues.

The first disturbance approaches the area during the middle part of this week, with an additional disturbance from the polar jet driving southwards through Central Canada and potentially phasing with a trough over the Ohio Valley. This phase could allow a storm system to form quickly off the Mid Atlantic coast, with precipitation spreading northwards into the Northeast US.

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John Homenuk

Premium: Warming trend in the East will be short lived

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Weather news this week has been centered around the presence of a large ridge, building into the Central United States. This ridge will reach eastward to the Ohio Valley, with tremendously warm temperatures surging from the desert southwest into the heart of the country. In the East, however — especially the Northeast — this warm air will be short lived. An active pattern throughout the Northern jet stream will keep the upper air pattern very active, and the amplification of the pattern will allow colder air to surge into Southeast Canada and the Northeast.

Much of this will be centered around a cold front, which will move through the Northeast US on Thursday afternoon and evening. Temperatures will warm up throughout the East on Wednesday and Thursday. Thereafter, on Thursday afternoon and evening, an  impressively strong system in the mid and upper levels of the atmosphere will drop southward into Southeast Canada and eventually the Northeast, interacting with moisture and providing sufficient lift for heavy rain.

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