Tuesday, August 26, 2014
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Bolaris: Will Monday storm be the biggest March snowfall ever in Philly?

A PennDot plow train heads south on Route 202 between Dilworthtown Road and Route 1 in Birmingham Township on Feb. 13, 2014. John Bolaris thinks expected snow totals on Monday could be the largest ever to hit Philly in March.
A PennDot plow train heads south on Route 202 between Dilworthtown Road and Route 1 in Birmingham Township on Feb. 13, 2014. John Bolaris thinks expected snow totals on Monday could be the largest ever to hit Philly in March. CLEM MURRAY / Staff Photographer, file
A PennDot plow train heads south on Route 202 between Dilworthtown Road and Route 1 in Birmingham Township on Feb. 13, 2014. John Bolaris thinks expected snow totals on Monday could be the largest ever to hit Philly in March. Gallery: Cold, hard facts: Philly's wild winter records

Could Monday's snowstorm be the biggest ever to hit Philly in March?

Yes, the possibility does exist as I analyze the very latest computer guidance. The No. 1 snowstorm for March was 11.7 inches in 1993, followed by the infamous blizzard of 1888, which dropped 10.5 inches. The 1958 snowstorm of 9.6 inches is the third biggest.

As of now I'm forecasting the possibility of 8-12 inches of snow by the time the storm pulls away late Monday afternoon or early evening.

The set-up

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  • A storm that is relieving the drought in Southern California will rapidly move east and generate a series of storms spreading across the Southern Plains, Gulf states, Tennessee Valley, the Southeast, the Mid-Atlantic, and arriving here in the Northeast by Sunday evening.

    At the same time a polar front with bitterly cold air will approach the Northeast and Mid-Atlantic from the Great Lakes.

    This polar front will act as a track for two waves of low pressure (2 distinct storm systems) to ride up along a spread a huge path of snow, sleet, freezing rain and severe thunderstorms.

    The first wave will approach the Delaware Valley on Sunday evening with a mix of rain, sleet and snow and take us through most of Sunday night. Not looking at anything heavy for Sunday night.

    As we move into the Monday morning rush, however, the second storm system will take over at the same time polar air comes funneling down from the north and west.

    The second storm is loaded with Pacific and Gulf of Mexico moisture. The combination of rapidly falling temperatures with this moisture supply spells HIGH IMPACT trouble for just about the entire Delaware Valley.

    The heaviest snow belt seems to be setting up right along the I-95 corridor, as it has most of this winter, but this time the highest snow amounts appears to be setting up east of the Delaware River across southern New Jersey and central and northern Delaware. This area stands the best chance of exceeding 12 inches of snow.

    Computer models have been trending colder and consistently more eastward with the heaviest amounts of snow.

    What I will be watching closely is to see if this eastward shift continues, keeping the highest snow amounts east of the city across southern New Jersey.

    For now I'm keeping the city in the heavy snow belt.

    General timing

    Sunday evening: Mix of rain and sleet arrives with wet snow north and west of city.

    After midnight: Mix could change over to freezing rain and sleet for a time. My biggest concern with this is that it could produce a very dangerous glaze of ice.

    Monday morning commute: Ice to all snow, becoming steady and heavy at times. Rapid accumulations will likely start to take place. Exact timing will be refined.

    Monday, 9 a.m.-3 p.m.: Rapidly accumulating snow. Extremely hazardous conditions likely.

    After 3 p.m.: Snow tapers off and ends by late afternoon or early evening.

    Temperatures by day will fall into the teens, making for high snow ratios. 15-1 or even higher - meaning one inch of liquid equals 15 inches of snow.

    In summary

    This will be a a HIGH IMPACT STORM, meaning major disruption of travel, widespread school closings, and at least 6 inches of snow in the city of Philadelphia.

    Currently calling for 8-12 inches, with the best chance of seeing the 12-inch amounts across southern New Jersey and parts of Delaware.

    Also watching a possible sharp cut-off in the heavy snow amounts as you head north into Upper Bucks and into the Lehigh Valley as the heavy snow banding projection has been steadily shifting south and east.

    One note: the storm will likely NOT make a high impact in New York City or Long Island as the heaviest snow should remain south.

    Keep ya posted.

    John Bolaris

    John Bolaris For Philly.com
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