The Christmas Day Snowstorm of 2002

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The Christmas Day Snowstorm of 2002

• Meteorology 361 presentation

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Highlights
Oneonta measured 24 snowfall Many
reports of 30 Classic Noreaster
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Surface Map animation
Watch for
Low on stationary front near Gulf Low
develops and moves up Ohio valley Secondary low
forms off East coast Cold air damming
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Features to notice in Satellite Loop
Large Cloud shield in south on Dec 23
Clouds in Canada move independently Cloud
shield splits on Dec 24 High cloud tops in
southeast on Dec 24 Coastal redevelopment on
Dec 25 Dry tongue becomes pronounced Dec 25
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850 mb loop
Strong temperature gradient Warm air wedge
gets as far north as LI Redevelopment of Low
12-18Z on Dec 25 Strong deepening drives cold
air south behind Low after 18Z on Dec 25
Heaviest snow occurs just on cold side of
temperature gradient
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500 mb Vorticity
Increases and splits as it crosses mountains and
goes offshore Max of 38 x 10E-5 per second PVA
offshore supports surface Low, not the heavy snow
inland (Note some Eta forecasts were used to
fill in times between 00Z and 12Z)
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Jet Streams
Split flow Ridge in Polar westerlies
supports cold air Trough in Subtropical
westerlies for Low Powerful Subtropical Jets
mean abundant humidity available First
Subtropical Jet supports initial Low in right
rear quadrant Second Subtropical jet supports
redeveloped Low in left front gradrant
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U.S. Radar Loop
Features to notice Severe squall line in
southeast Initial Low dies in midwest New
echoes form east of Appalachians Echo intensity
in snow up to 50 dbz
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Northeast Radar Loop
Features to notice Largest area of strong
echoes along coast Mesoscale snowbands around
40 dbz in upstate NY
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Verification 00Z Dec 26
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12 hour fcst map
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24 hour forecast
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36 hour forecast
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48 hour forecast
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• Eta Surface Initialization 00Z Dec 26, 2002

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Eta Surface initialization
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• Eta 24 hour Forecast
• 00Z Dec 26, 2002

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Eta 24 hour fcst for 00Z Dec 26
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• Eta 48 hour Forecast
• 00Z Dec 26, 2002

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Eta 48 hr fcst
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• Eta 72 hour Forecast
• 00Z Dec 26, 2002

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Eta 72 hr fcst
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• GFS 120 hour Forecast
• 00Z Dec 26, 2002

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GFS 120 hr (5 day) fcst
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• GFS 144 hour Forecast
• 00Z Dec 26, 2002

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GFS 144 hr (6 day) fcst
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• GFS 168 hour Forecast
• 00Z Dec 26, 2002

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GFS 168 hr (7 day) fcst
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Conclusions
Low began near Gulf coast redeveloped off coast
of N. Carolina Classic Noreaster north of
Hatteras With cold air in place, snow even at
coast Strong subtropical Jet and ageostrophic
flow Severe thunderstorms in warm sector
Mesoscale snowbands produce record amounts for
interior New York Eta forecasts out to 48 hours
were excellent. GFS had an accurate forecast at
144 hours, but 168 hour forecast was poor.