Overview of the 2009-2010 Snow season in the southern Appalachian mountains Baker Perry1, David Hotz2a, Stephen Keighton2b, Charles Konrad3, Laurence Lee2c, Greg Dobson4, Dorothy Hall5 1Department of Geography and Planning, Appalachian State University 2National Weather Service (aMRX, TN; bRNK, VA; cGSP, SC) 3Department of Geography & SERCC, University of North Carolina 4NEMAC, University of North Carolina at Asheville 5NASA Goddard Space Flight Center Eastern Snow Conference Jiminy Peak, MA June 10, 2010

Location of Study Area and Topography

Highlights of 2009-2010 Snow Season Near-record to record snowfall occurred across much of the region (McRoss, WV: 496 cm). 25 separate snow events (including 10 major snowstorms > 15 cm) affected the region. Many stations set records for days of measurable new snowfall (Beech Mtn, NC: 66) and snow cover (Boone, NC: 71). Snow water equivalent (SWE) exceeded 250 mm at highest elevations in NC/TN and in portions of SE West Virginia. Snow depth approached record values (McCross, WV: 160 cm). Snow drifts buried roads and driveways at times, making travel difficult to impossible and closing schools for over 5 weeks in some areas.

Warm-Phase ENSO (El Niño) 18 Dec 2009 Warm-Phase ENSO (El Niño) and Negative Arctic Oscillation (AO) = Moist and Cold NCDC 2010

850 hPa Temperature Anomaly Dec 2009 to Feb 2010 temperature ranked much below normal and precipitation above to much above normal across the southern Appalachian Mountains.

Two highly anomalous periods from 1-13 Jan 2010 and 11-19 Feb 2010 were particularly important in producing upslope snowfall in the higher elevations and allowing existing snow cover to persist at lower elevations. 1-13 Jan 2010 11-19 Feb 2010

Numerous stations set new records for days of snow cover. Boone NC: 71 days (mean: 26 days) Mt. LeConte, TN: 115 days (mean: 64 days)

MODIS Fractional Snow Cover Data TN NC Boone Asheville Nearly continuous snow cover persisted across much of the NC Mountains from mid-December to early March (early December to early April at highest elevations) 24 Dec 2009 TN NC Boone Asheville 19 Feb 2010 Boone TN NC 20 40 50 60 70 80 90 100 1 FRACTIONAL SNOW COVER (%) Cloud Water Land Asheville 4 Mar 2010

AMSR-E Snow Water Equivalent (SWE) Data 8 Feb 2010 NC SC TN AMSR-E Snow Water Equivalent (SWE) Data Maximum SWE values exceeded 100 mm across much of NW NC and SW VA, with snow surveys indicating over 250 mm at the highest elevations in late February and early March 14 Feb 2010 NC SC TN 19 Feb 2010 NC SC TN

Collaborative Efforts with Dr. Sandra Yuter

Poga Mountain, NC Met Station (1137 m) 12-hr New Snowfall and SWE Met Station (1137 m) Pluvio Weighing Precip Gauge Parsivel Present Weather Sensor Flat Springs COOP Station (1018 m)

Synoptic Classification Scheme NE – Northeastward tracking low passes north of area SE – Southeastward tracking low passes across or south of area MBN – Miller B cyclogenesis to north of Cape Hatteras, NC MAB – Lows that display both Miller A and B characteristics MA – Miller A low tracks south and east of area U – Northwest upslope flow in absence of synoptic-scale surface features X – Unclassified Perry et al. (2010), Phys. Geo.

Sea Level Pressure Pattern by Synoptic Class Northeast Tracking (NE) Southeast Tracking (SE) Miller B North (MBN)* Miller A/B (MAB) Miller A (MA)* Upslope (U)*

Miller A cyclones contributed 34% of annual snowfall and 55% of SWE

Highest new snowfall density was associated with Miller A cyclones (heavily rimed needles and periods of graupel) and upslope events were much lower density (and primarily dendrites). Most snow events associated with westerly or northwesterly upslope flow.

Societal and Economic Impacts Some school districts missed over 5 weeks of school! Many were forced to attend school on Saturdays, which can be a burden to staff and budgets, in addition to parents and students. In Virginia, the total state cost was triple the annual snow removal budget, causing strain on the state budget. Local businesses lost much revenue on one of the busiest shopping weekends just prior to Christmas. Timing of snow storms can play a critical role in the impacts experienced. Many storms during this past season were on weekends, significantly impacting Friday travel. These numbers do not reflect delayed starts and early releases, all which add up to total missed hours, which is how districts are graded by state officials.

Would have missed another 5-10 days if the timing of the storms had been different (i.e., not over holidays or on weekends)

Summary and Conclusions Winter of 2009-10 was characterized by highly anomalous atmospheric circulation: Warm-phase ENSO and highly negative AO. Resulted in record snowfall across portions of SE West Virginia and record number of days of snow cover across SW Virginia and NW North Carolina. Miller A cyclones contributed the bulk of the snowfall and SWE across the region, with west and northwest upslope flow making significant contributions on windward slopes and at higher elevations. Most severe winter since the late 1970s and rivaled or surpassed many of the historic winters from the 1960s.

Acknowledgments Grants Individuals UNC GA (Perry, Yuter, & Miller) RENCI (Miller & Perry) Appalachian State URA (Perry & L’Heureux) Appalachian State GRAM (Perry & Kelly) Individuals Chris Fuhrmann Ryan Boyles Ashley Frazier Douglas Miller John L’Heureux UNCA/ASU Students