Update On Tomorrow’s Storm

**Remember that the 3-day forecasts have now been moved to the new page, the link is in the top right corner of the page, titled “3 Day Area Forecast“.


After my post from this morning, the majority of the models have trended much wetter with this storm, along with the NAM. The GFS now shows 0.5″ QPF, and the NAM would show at least 0.25″ QPF. They are still trending west with the precipitation, which if this trend continues, could put the area under higher precipitation amounts. If this was January and we had a fresh source of cold air, that would fall as snow, with around 4-7 inches. But we are talking about a completely different scenario that will prevent another major snowstorm in the Washington DC to Boston corridor.

First of all, most forecasts for tonight have the low temperatures in the lower to mid 30s for the cities, and in the upper 20s elsewhere. This is not cold enough for a dry, high ratio snowfall, and instead should lead to a wet snow. There should also be rain mixing, as the temperatures are too warm for plain snow. So the total snow that does fall and accumulate will be less than the precipitation amount that falls.

For example, take southern NJ, with near 1″ QPF. They should have rain to start, already taking away some of the precipitation. When it does start to snow, the temperatures should be generally above freezing, limiting accumulations to non-paved surfaces, and the ratios should also be low, also making these amounts even lower. So this way, we went down from what could’ve been 10 inches of snow to just 3-5 inches of wet, heavy snow.

Taking what I said above, with the model trends, I would guess that NYC could get at least 0.4″ QPF if the west trend does verify. Considering that we should also have rain, and temperatures would be warm enough that it falls as mainly wet snow, that takes us down to at least 2 inches of snow. So at this time, my forecast for the New York City area would be 2-4 inches of snow, with the highest accumulations well north and west of New York City.

Below is my snow map for the storm. Remember that the precipitation across most of the area except the far NW areas of the snow zones start out as rain, then change over to mainly snow overnight.

**Slight Correction to the map: Snow amounts should end up being slightly lower in the Washington DC area. There is currently rain falling with temperatures in the 40s, and while snow should fall there later tonight, I do not think that the temperatures will be cold enough for any significant snow accumulation.

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