Reality check: Extreme cold incoming for the entire Northeast

Good evening.

Winter has become much more active lately, although we haven’t seen anything close to the impact we saw for many in the late January blizzard. However, the coldest weather of the winter so far – reminiscent of the extreme cold we saw the last couple years – is incoming for the entire Northeast. Temperatures will likely plummet to near record levels, possibly the coldest in over 20 years for some.

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500mb geopotential heights for Saturday afternoon (GFS model). Notice heights as low as about 4,950m over the north country. That is a piece of the polar vortex digging south – and usually means VERY cold weather!

Models are unanimous in the polar vortex digging southward and allowing extremely cold air in the upper levels to reach the Northeast this weekend. Temperatures at the 850mb level (about 4,000 feet aloft) could drop as low as -40 for some this weekend, particularly from late Saturday to late Sunday. Although the air mass tends to modify near the surface, due to bodies of water, topography, urban uses and other factors, it will still be dangerously cold. Add strong winds and it will feel much, much colder still. You certainly don’t want to be outdoors this weekend for any extended period!

18Z GFS temperature forecast at 850mb (about 4,000 feet aloft) on Saturday afternoon. Notice the polar air core.

18Z GFS temperature forecast at 850mb (about 4,000 feet aloft) on Saturday afternoon. Notice the polar air core.

18Z NAM forecast temperatures for Sunday morning. Most models agree overall. This does not take into account the wind.

18Z NAM forecast temperatures for Sunday morning. Most models agree overall. This does not take into account the wind.

So how cold will it get?

Although models tend to deviate on the forecast, this is what I am thinking. Temperatures may vary over short distances due to local factors. Notice the chart below shows the estimated times until the human body sustains frostbite. Hypothermia is also possible if not properly dressed. For all areas, Sunday morning should be the coldest, but Saturday and Monday will also be very cold.

Frostbite times and wind chill impacts and calculator (NWS).

Frostbite times and wind chill impacts and calculator (NWS).

  • Northern Maine and adjacent parts of Canada: 15 to 30 below zero (wind chill 35 to 55 below zero)
  • Interior northern New England and Adirondacks: 15 to 30 below zero (wind chill 35 to 55 below zero)
  • Northern valleys (St. Lawrence, Champlain, Ottawa, upper Hudson, etc.): 15 to 25 below zero (wind chill 30 to 45 below zero)
  • Coastal northern New England: 5 to 20 below zero (wind chill 20 to 35 below zero)
  • Coastal southern New England: Near zero to 15 below zero (wind chill 15 to 30 below zero)
  • Interior southern New England and Catskills: 10 to 20 below zero (wind chill 25 to 40 below zero)
  • Central valleys (Mohawk, lower Hudson, Susquehanna, Lake Ontario shore, etc.): 5 to 15 below zero (wind chill 20 to 35 below zero)
  • New York City region: 5 above to 15 below zero (wind chill 15 to 25 below zero)
  • Northern Mid-Atlantic coast (NJ, DE, Philadelphia area): 10 above to 5 below zero (wind chill 10 to 20 below zero)
  • Central New York and northern Pennsylvania highlands: 5 to 15 below zero (wind chill 20 to 30 below zero)
  • Interior southern Pennsylvania: 5 above to 5 below zero (wind chill 10 to 20 below zero)
  • Chesapeake and Potomac region (DC, Baltimore): Near zero to 10 (wind chill near zero to 15 below zero)
  • Central Appalachians/Blue Ridge: Near zero to 10 (wind chill near zero to 15 below zero)
  • Southern Piedmont/valleys (Shenandoah, James, upper Potomac, etc.): 5 to 15 (wind chill near zero to 10 below zero)
  • Southern Mid-Atlantic coast (MD, VA): 10 to 15 (wind chill near zero to 10 below zero)

No matter how you slice it, these temperatures are very cold and quite dangerous. Even the warmer southern areas are much, much colder than normal and northern areas are quite inhospitable. The wind chills are not exact temperatures but indices that determine the heat loss to the human body, in other words, what it “feels like”. Given that winds could be 10 to 20 mph, it will make the air feel even colder than the already low temperatures. For what it is worth, the last time New York City had a sub-zero low was in January 1994!

I won’t recreate this brochure, but here is a good publication on the wind chill and impacts published by the NWS: http://www.nws.noaa.gov/om/winter/resources/wind-chill-brochure.pdf

On the bright side, more moderate weather will move in for next week starting Monday and Tuesday, so we just have to get through the weekend! Even though there are hints the polar vortex may try to push down late in the week – we just have to wait and see.

Forecaster Craig Ceecee

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