All 4 major global models at 0Z (7 pm EST data inputs to the models) are now showing a pretty significant to major coastal storm this weekend (mostly Saturday late morning through the evening for the Philly-NYC region), but only one of them is showing significant snowfall. The GFS shows a snow to rain storm with significant snowfall along and NW of 95 (and rain SE of 95), while the UK shows a monsoon of a rainstorm with 1-3" of rain (close to 1" well NW to almost 3" near the coast), and the Euro and CMC show a major storm a couple hundred miles off the coast, with just some modest rains near the coast, but huge rains offshore (1-3"), so the precip is certainly there with all 4 models.
But we're about 5 days out and obviously much can change between now and the event, especially with the main players being well offshore of the North American continent, meaning they're not being sampled well for initial conditions, meaning much greater forecast uncertainty. Probably the biggest issue with getting major snows, even if we end up with a great snowstorm track to the 40N/70W "benchmark," is that the antecedent temps leading up to the storm look borderline for snow. Of course, the track is clearly in question also, with 2 of the 4 models basically showing an offshore solution with light to modest rain for just the coast.
This is a serious "thread the needle" scenario, meaning a major snowstorm is unlikely, but if we get a storm as powerful as all of the models are now showing and it takes a perfect track for snow (only 1 is showing that and only partly), it's possible a storm like that could essentially "generate" its own cold air via dynamic cooling with heavy precip rates which can sometimes turn a rainstorm into a pastebomb of a snowstorm (especially NW of 95, but even along 95 and SE of there, too). So, nobody needs to buy milk and bread yet (or a canoe), but this one is worth tracking - I think we should know by Wednesday whether there is going to be any significant snow threat. The one thing that's starting to look likely is the potential for heavy surf and possibly minor tidal flooding (fortunately it won't be a full moon).
https://forecast.weather.gov/produc...&format=CI&version=1&glossary=1&highlight=off
But we're about 5 days out and obviously much can change between now and the event, especially with the main players being well offshore of the North American continent, meaning they're not being sampled well for initial conditions, meaning much greater forecast uncertainty. Probably the biggest issue with getting major snows, even if we end up with a great snowstorm track to the 40N/70W "benchmark," is that the antecedent temps leading up to the storm look borderline for snow. Of course, the track is clearly in question also, with 2 of the 4 models basically showing an offshore solution with light to modest rain for just the coast.
This is a serious "thread the needle" scenario, meaning a major snowstorm is unlikely, but if we get a storm as powerful as all of the models are now showing and it takes a perfect track for snow (only 1 is showing that and only partly), it's possible a storm like that could essentially "generate" its own cold air via dynamic cooling with heavy precip rates which can sometimes turn a rainstorm into a pastebomb of a snowstorm (especially NW of 95, but even along 95 and SE of there, too). So, nobody needs to buy milk and bread yet (or a canoe), but this one is worth tracking - I think we should know by Wednesday whether there is going to be any significant snow threat. The one thing that's starting to look likely is the potential for heavy surf and possibly minor tidal flooding (fortunately it won't be a full moon).
https://forecast.weather.gov/produc...&format=CI&version=1&glossary=1&highlight=off
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