Mar 18, 2013 Storm Summary

This is the first part of tonight's post, which is separated into two parts. The first part is an overview of the March 18 snowstorm, and the second part is a forecast update.

Brief Storm Summary:

A late season snowstorm affected the area on March 18-19, the latest snow event with widespread accumulating snow for the area since March 24, 2011. Widespread accumulations were reported across the area, generally ranging from 1 to 4 inches in most of Long Island and NYC, 2 to 5 inches in the north/west suburbs of NYC, 3 to 6 inches in southern CT, and 4 to 7 inches towards NW NJ and southeastern NY.

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Monday, March 18 Observations:

The third snow event of the month affected the area on Monday, following the March 6-8 snowstorm and the March 16 snow showers. Temperatures were unseasonably chilly leading up to the storm, with highs in the low to mid 30s inland and the mid to upper 30s across the rest of the area. Central Park peaked at 35 degrees, nearly 15 degrees colder than the average high temperature and even colder than the average January highs.

Snow and sleet developed across the area during the mid to late afternoon hours, with heavy precipitation spreading in towards 6-8 PM from west to east as temperatures dropped into the upper 20s to low 30s across most of the area. Initially, this fell as sleet for parts of the area, but later on changed over to heavy snow across most locations except for parts of coastal Long Island and NYC where occasional mixing with sleet continued. Heavy snow continued falling for another few hours, accumulating at rates near and over 1 inch per hour, until about 10 PM-12 AM, when the mixing line began shifting north, with NYC and Long Island, and later on the rest of northern NJ changing over to rain while interior areas changed over to freezing rain and rain. Steady precipitation continued for another few hours before ending towards the mid overnight hours. Based on preliminary storm reports from the National Weather Service, snow totals ranged from 1 to 4 inches in most of Long Island and NYC, 2 to 5 inches in the north/west suburbs of NYC, 3 to 6 inches in southern CT, and 4 to 7 inches towards NW NJ and southeastern NY.

Snow totals were higher than expected with this storm in the area, but were lower than expected in other parts of the region. Additionally, steady moderate rain was forecast to continue falling overnight into the morning hours, when the steadier precipitation in reality ended earlier than expected.The model guidance had several errors with handling this storm, ranging from heavier than expected snow falling in the area to completely missing the lack of precipitation over parts of Pennsylvania, which resulted in less snow than expected for parts of the region north of the area and an earlier than expected ending to the steady precipitation over the area.