3/16 All Zones Noon Update/Snow Map: More Snow Possible This Weekend

Winter refuses to give up it’s hold on the Northeast United States. Cold and dry weather will continue over the next few days, as the area continues to sit underneath the influence of a large upper-level low centered near New Brunswick, Canada. Another storm system will likely impact the region from early Saturday onward. Precipitation from Saturday evening into Saturday will increase in coverage and intensity, with the possibility of snowfall accumulations throughout the area by Sunday morning.

Backing up to today’s forecast, plenty of sunshine will continue with temperatures rising into the low to mid 30s this afternoon. It will continue to be a little blustery, with wind gusts between 30-35mph. Windchill will remain very cold — only in the upper teens and lower 20’s. Skies remain partly cloudy tonight with lows dropping again into the lower 20’s in the city and upper teens inland and away from the coast. This is very cold for this time of year!

Sunshine is again expected to dominate early on Friday, with clouds regaining control of the sky gradually as the day goes on. Mid level height rises in the atmosphere will allow temperatures to moderate a bit from the past few days, with high temperatures reaching into the middle and upper 30s. The area of denser snowpack will remain colder, in the interior and higher elevations. Again, these temperatures are well below normal for this time of year.

The forecast turns more complicated this weekend as another storm system approaches. Clouds will lower and thicken Friday night, with a warm front approaches in conduction with a low pressure over the Great Lakes. A light wintry mix of snow, sleet and rain will develop throughout the region ahead of this front. This precipitation is expected to remain relatively sporadic, due to stronger confluence from the upper-level over Southeast Canada.

Of more interest is a secondary low pressure area developing off the Virginia coast on Saturday. As a ridge over the Central United States amplifies, the shortwave over the Great Lakes will have room to strengthen and drive southward. This trough digs underneath Long Island on Saturday evening and Sunday morning. While the storm system remains progressive (i.e, no big Nor’Easter), a surface low may still develop south and southeast of the region.

As this surface low develops, and positive vorticity advection in the mid levels strengthens, an inverted trough in the atmosphere’s mid levels may develop. This may cause some enhancement of banding across Long Island, possibly NYC, Connecticut and Southern New England and surrounding areas on Sunday morning. Boundary layer temperatures support a mix of rain and snow initially, but cold air advection and dynamic cooling will allow this precipitation to change to snow.

Exactly when this the changeover occurs, where heavier banding sets up, and when surface temperatures reach near or below freezing will determine snowfall accumulations across the region. At this time, we are forecasting only light accumulations due to warmer boundary layer conditions initially. The highest totals in heavier banding are likely to be away from the NYC Metro Area — thanks to the urban heat environment and warmer surface temperatures. Changes will occur with this forecast as we continue to monitor for the latest trends in placement of the inverted trough and heaviest banding.

Some snow could continue into Sunday morning, if the inverted trough lingers. But as the coastal lows moves further out into the Atlantic any snow should taper off with clearing during Sunday afternoon. Temperatures are likely to remain well below normal through this weekend.

Some moderation may occur by early next week ahead of another frontal system and shortwave trough. But overall a colder, somewhat progressive and active pattern is expected to last through the end of the month. So more storm threats with wintry precipitation can’t be ruled out. Stay tuned more zone forecast updates over next few days, on this weekend’s storm system.