Team White Sands Mountain-Wave Down- slope Wind Event Reviewed Meteorology Branch Forecast Section RO-DA-F /2462 Eric Hatfield Meteorology Branch Forecast Section RO-DA-F /2462 Eric Hatfield APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 2 Presentation Highlights What happened Mar 05? Explainable by usual spring storms? Down-slope wind event Summary APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 3 What Happened? Mar 05: --Winds gusted 30-50kts 16-03L on Main Post. --’Howled’ all night at forecaster’s house in El Paso blowing garbage can east about 15ft. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 4 Explainable by usual Spring Storms? RT-FDDA 500mb Hgt, Rel Vort & Winds valid 06Z, 13 Mar 05 Weak Flow No Vort max over AZ/SRN CA or Upstream Pattern over CNTRL Rockies more similar to Spring Storms **Not Here** APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 5 Explainable by usual Spring Storms? RT-FDDA 300mb Hgt & Winds valid 06Z, 13 Mar 05 Weak Flow Jet is well North Weak trof SRN CA way too weak **Not Here** APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 6 Explainable by usual Spring Storms? RT-FDDA 700mb Hgt, Temp & Winds valid 06Z, 13 Mar 05 Gradient is tight enough Note kts Main Post area towards El Paso APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 7 Explainable by usual Spring Storms? RT-FDDA 850mb Hgt, Temp & Winds valid 06Z, 13 Mar 05 Gradient is tight enough Trof is way east over Texas APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 8 Explainable by usual Spring Storms? Conclusion: NO Begs the question, What did cause it? APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 9 Enter the Mountain-Wave Down- Slope Classic Characteristics---- At Night (It did) Flow nearly perpendicular to mountains (It was) Negative Wind Shear within 2 km of ridge top Stable Layer within 2 km of ridge top Can double-triple wind speeds if all are in place! APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 10 Upper Air Sounding RT-FDDA Skew-T for Main Post valid 06Z, 13 Mar 05 Ridge top is about 750mb Lowering wind speed up to 600mb No Stable Layer **Not Classic** APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 11 Mountain-Wave Cross Section RT-FDDA valid 06Z, 13 Mar 05 Long arrows cascading down the hill Wave is above the ridge Critical Point is a little high **Not Classic** APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands 12 In Summary This non-extreme wind event is a Down-Slope Wind –Event variant. Elements were present except the stable layer within 2 km of ridge top. This event also shows you can get warning criteria winds without having very strong winds aloft. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

Team White Sands The End