Jan 19, 2012: Saturday Snow Forecast

Cloud cover increased across the area today as a weak clipper approached the region from the west, with temperatures reaching the lower 30s inland and the mid 30s across the rest of the area. Light ocean/sound effect snow developed late this afternoon across parts of Long Island and southern Connecticut, with these areas reporting light snow with very light accumulations through the evening. The clipper will quickly pass through the area with only isolated flurries at most, although the focus of the latest forecast is for Saturday, when there are increasing indications that the first significant snowstorm of the winter months will affect the area.

Tomorrow’s Outlook:

With the clipper clearing the area tonight, leaving behind a dusting to an inch in Long Island and southern Connecticut, mostly sunny skies are expected across the area tomorrow with temperatures reaching the lower 30s inland and the lower to mid 30s across the area, making tomorrow the second day in a row to feature below average temperatures.

Friday Night – Saturday: First Snowstorm Of The Winter Months

With yesterday’s update, I mentioned how a storm was expected to affect the area, with snow likely to start out across the area but changing over to rain, sleet and perhaps freezing rain. Right after my update last night, however, the entire model guidance, even the northernmost models which were consistent with a mostly wet outcome, significantly shifted to the south, favoring a snowstorm across the area. My initial thinking did not turn out to be correct with this storm, complicated by the models’ difficulty with handling the storm correctly, although after reviewing the latest models, there is a high confidence level that the area will in fact see its first significant snowstorm of the winter months.

**The scenario map below was made before the latest data came in, so the storm will likely be further south than this map. The snow map in the bottom was adjusted with the latest data.**

The latest models continue to shift south, and as a result, I went with a southern storm scenario map, although the map to the left was made before the latest data came in, so my expectation is for a further south scenario. There is plenty of cold air ahead of this storm, which will lead to the entire area starting out with snow along with temperatures still in the lower to mid 20s north and west of NYC, and in the mid to possibly upper 20s for NYC and Long Island.

Snow is expected to develop across the area between 3-4 AM, with a moderate snow for most places by 7 AM. The storm will quickly move through the region, however it is still expected to produce moderate snow from about 7 AM to 12 PM. Temperatures during the peak of the storm are likely to be in the mid 20s north and west of NYC, and in the mid to upper 20s for NYC and closer to the coast, resulting in slightly higher snow ratios for this storm. The storm will also quickly move out of the area, ending by 1-3 PM across the entire area. Temperatures aloft may warm up enough that sleet could fall at the very end in parts of NYC and Long Island, although the further south the storm tracks, the less likely this would be.

I also went with a further south scenario than most models with my snow map, accounting for any additional slight south trend on the models. Most models suggest at least 0.4″ QPF in the form of snow, ranging from 0.3″ on the drier models to 0.5″ on the wetter models, such as the NAM. Combined with higher ratios, snow amounts may end up in the 4 to 6 inch range across most of the area. The lowest totals are expected to be in NYC and Long Island, where 2 to 5 inches of snow are likely, with higher amounts across northern NJ, SE NY and southern CT, with at least 3 to 7 inches of snow expected.

There is still some slight uncertainty with the storm, and the forecast could slightly change. If any change is made to the forecast, it would be more likely to shift the snow zones slightly further south while keeping the area in the 3 to 6 inch range for snowfall. Stay tuned for more updates on this storm tomorrow afternoon and evening.

Longer Range Update: After cold temperatures on Saturday night, much warmer temperatures will return by Monday as a low pressure tracks well to the northwest of the area, with high temperatures expected to reach the 50s, likely to melt any leftover snow from Saturday’s snowstorm. Temperatures will cool back down into the 40s after Monday, with another storm possible towards the second half of next week.

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