2010/2011 Forecast Verification

Data Verification

For Philadelpia/South Jersey: Philadelphia International Airport.

For the Washington D.C and surrounding suburbs: Dulles and Regan International Airport

Summary

Overall, this was a very cold winter. December ended up being the coldest, but it remained cold and below average for all of January and the first 10 days of February. February overall was the warmest. The amazing thing about this winter was the contrast in snowfall. Philadelphia and Southern NJ had another harsh winter with 40+ inches of snow and big snow events. However, it was a whole different story for the Washington, D.C. area, which saw much less with only 10-18 inches in general. As mentioned in the forecast, there were some things that compared to the winter of 1917-1918. That season ended up being a very good match for what we saw this winter, especially with temperatures(see maps below). The equatorial pacific ocean experienced La Nina conditions of moderate to strong intensity. When this is the case, research has shown that the mid-atlantic area and south of New York City does not see a lot of snow, nor big snowstorms, and has warm temperatures.

Another phenomenon that may have offset the La Nina was the Arctic Oscillation. Like last winter, it was in the negative phase all of December and January and when this is the case, the Eastern U.S. experiences much colder and snowier conditions. Please see the links below for more information on the Arctic Oscillation.

Total Seasonal Snowfall

Philadelphia/South Jersey - 44.0 inches

Washington, D.C. - 9.9 inches

D.C. suburbs(North and West) - While Dulles Airport reported 12.5", on average, most areas(20-40 miles from the city)received around 15-20"

Monthly Analysis

Washington, D.C. and Surrounding Suburbs

December

• Temperatures: Dulles: -5.1 degrees Below Normal, Regan: -4.9 degrees Below Normal
• One day of 60+ Temps(Dec. 1st)
• Total Snowfall: Dulles: 1.5" inches, Regan: 2.1" inches
• One snow event of 1-3" on the 16th
• Precipitation: Dulles: 1.47"(-1.60" Below Normal), Regan: 1.78"(-1.27 Below Normal)

January

• Temperatures: Dulles: -1.7 degrees Below Normal, Regan: -1.3 degrees Below Normal
• Total Snowfall: Dulles: 10.3", Regan: 7.3"
• One Ice Event on the 17th/18th; One Snow Event on the 25th: 4-6" around the city, 8-14" NW Suburbs
• Precipitation- Dulles: 1.87"(-1.18" Below Normal), Regan: 2.25"(-0.96" Below Normal)

February

• Temperatures: Dulles: +3.3 degrees Above Normal, Regan +3.6 degrees Above Normal
• Total Snowfall: Dulles: 0.7", Regan: 0.5"
• 4 days of 60+ degree temperatures; 2 days of 70+ degrees
• Precipitation: Dulles: 2.21"(-0.56" Below Normal), Regan: 2.12"(-0.51" Below Normal)

Philadelphia/South Jersey

December

• Temperatures: -4.7 degrees Below Normal
• Total Snowfall: 12.7"
• Major Snow Event(Historic for NJ) on the 26th; General 10-20". Amounts depended on your location, with Philadelphia having 12.4" and Atlantic City 20.3"
• Precipitation: 3.24"(Very close to normal, -0.07")

January

• Temperatures: -3.0 degrees Below Normal
• Total Snowfall: 25.2" inches
• Two Snow Events: 5.2" on the 11th/12th, and 15.1" on the 26th/27th; One Ice Event on the 17th/18th
• Precipitation: 3.39"(Very close to normal, -0.13")

February

• Temperatures: +2.4 degrees Above Normal
• Total Snowfall: 6.1" inches
• One Snow Event: 6.0" on the 21st/22nd
• 5 days of 60+ degree temperatures
• Precipitation: 2.65"(Very close to normal; -0.09")

Maps(Comparison this season with 1917/1918)