early and late northeast snow storms

EARLY AND LATE NORTHEAST SNOW

STORMSHali Castleman, Chris Kasprak, VJ Vesnaver, John Kerr

October 3-4 1987

•Record setting snowfall in Virginia, Maryland, Delaware, Pennsylvania, and Western New York

•The greatest snow total occurred in central Pennsylvania where 29.8 inches fell at Lock Haven

November 6-7 1953

April 18-19 1983•Stalled vehicles and hazardous driving conditions resulted in the closure of many major highways

•Heaviest snowfall in Pennsylvania and New York up to 19.6 inches reported

May 9-10 1977

Latest Recorded Snow in Boston

500,000 People Without Power in MA

12.7 Inches in Worcester

10-20 Inches in the Berkshires

Winchester CT 1977

Start With What We Know…

These early/late season snow storms are all familiar in some ways Strong Low Pressure Systems Combination of Lows

Characteristic Differences They occur outside of the typical

snowstorm season (December-March) Nature of the low pressure systems Where’s the High? How does it get so cold?

500-hPa map

250-hPa map

Cutoff Low

Cutoff Low

Cut Off Lows

Meeting of the low pressure system and the

anticyclone

Where is the High Pressure?

With no anticyclones to the north bringing in the cold air, these early and late storms need to make their own.

Cooling by Melting- The Bergeron Process

Cooling by Melting

Cut Off Low

No sourceOf Canadian Arctic air

April 9-10 1996 The significant

snowstorm of the long winter of 1995\1996

A few locations in Massachusetts, northern Rhode Island, and southern New Hampshire reported over 20 inches of snow

500-hPamaps

250-hPa maps

Cut off low

Surface maps

850-hPamaps

Valid only: September and May