The big debate among weather enthusiasts and meteorologists alike is whether NYC (Central Park) will hit zero or below tonight. This has not happened since 1994, and common opinion is that climate change along with the Urban Heat Island Effect would prevent NYC from ever going below zero again. While that thought process is not necessarily without merit, tonight is definitely the best shot NYC has had to go zero or below since 1994 — and perhaps should be even colder than the Arctic outbreaks from the past two seasons.
On February 20th, 2015, NYC got down to +2F, and on January 7th, 2014, NYC got down to +4F. There are certain criteria we look for to see how cold it can get in NYC: 1) 850mb temperatures, as they are a good indicator of the airmass, 2) Timing and degree of cold air advection — NYC due to the Urban Heat Island Effect does not cool off very much from radiational cooling, so they are very reliant on cold air advection, 3) Wind direction — generally a more northerly flow can more efficiently draw trapped colder surface air from the valleys, whereas a more westerly component has the tendency to downslope off the Appalachians and thus moderate somewhat when it hits us, and 4) Degree of mixing — if the surface air “mixes” with the airmass aloft, not as much cold air will be trapped at the surface, making it hard to truly go below zero.
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