The High Wind Event of 7 March 2004 in the Piedmont of the Western Carolinas Harry Gerapetritis National Weather Service Greer, SC

High Impact Event Steeple blown off church in Hickory, NC Widespread grass fires Barns and mobile homes blown over in Gastonia, NC and an historic church moved off its foundation Large limbs crashing through roofs in Salisbury, NC Over 30,000 people without power in Charlotte metro area Control tower evacuated at Charlotte-Douglas International Airport due to wind gusts of 55 mph Huntersville, NC man killed by a falling tree limb, and a thirteen year-old boy drowned on Lake Greenwood, SC

Magnitude of Event Largely Unanticipated Foothills: –.TONIGHT…PARTLY CLOUDY WITH A CHANCE OF RAIN SHOWERS THIS EVENING. VERY WINDY WITH LOWS IN THE MID 30S. NORTHWEST WINDS 20 TO 30 MPH…WITH GUSTS NEAR 50 MPH AT THE HIGHER ELEVATIONS. CHANCE OF PRECIPITATION 40 PERCENT. Piedmont: –.TONIGHT…PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF RAIN SHOWERS THIS EVENING. WINDY WITH LOWS IN THE MID 30S. WEST WINDS 15 TO 25 MPH. FOUS22 KHKY KHKY GFS MOS GUIDANCE 3/07/ UTC DT /MAR 7/MAR 8 /MAR 9 /MAR 10 HR N/X TMP DPT CLD SC SC OV CL CL CL CL CL SC SC CL CL SC SC OV OV OV OV OV OV SC WDR WSP P P

500 hPa Eta Forecast at 00 UTC March 8, hPa heights, wind barbs, isotachs

850 hPa Eta Forecast for 12 UTC March 8, hPa heights, winds, isotachs

Visible Imagery and Surface Observations 20 UTC

00 UTC March 8, 2004 Greensboro, NC Sounding (GSO)

KGSP Composite Reflectivity 0100 UTC 8 March 2004

Eta Frontogenesis Forecast at 00 UTC 8 March, hPa 2-D F n, MSLP, thickness

Eta Cross Section Valid at 00 UTC 8 March 2004 Potential temperature, omega, wind barbs

00 UTC 5 February 2002 Blacksburg, VA Sounding (RNK)

500 hPa Eta Forecast valid at 00 UTC 5 February hPa heights, wind barbs, isotachs

Eta Cross Section valid at 00 UTC 5 February 2002 Potential temperature, omega, wind barbs

00 UTC 29 March 2000 Greensboro, NC Sounding (GSO)

Eta 500 hPa Forecast valid at 00 UTC 29 March hPa heights, wind barbs, isotachs

Eta Cross Section valid at 00 UTC 29 March 2000 Potential temperature, omega, wind barbs

Summary Consider high wind potential if you have: A.A deep, surface-based, mixed layer Dry-adiabatic into the hPa layer, or higher Usually capped by a narrow moist zone with dewpoint depressions 5 degrees C or less B.A strong, mid-tropospheric speed maximum Winds 50 knots or greater at 700 hPa, or top of mixed layer Winds 100 knots or greater at 500 hPa C.Strong downward omega in the lower troposphere 6 to 9 microbars/second or stronger Subsidence is often due to cold advection, but frontogenesis or other sources can also contribute