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Mountain-Wave Down-slope Wind Event Reviewed. Meteorology Branch Forecast Section RO-DA-F 505-678-2488/2462 Eric Hatfield. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05. Presentation Highlights.
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Mountain-Wave Down-slope Wind Event Reviewed Meteorology Branch Forecast Section RO-DA-F 505-678-2488/2462 Eric Hatfield APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05
Presentation Highlights APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • What happened 12-13 Mar 05? • Explainable by usual spring storms? • Down-slope wind event • Summary
What Happened? APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • 12-13 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.
Explainable by usual Spring Storms?RT-FDDA 500mb Hgt, Rel Vort & Winds valid 06Z, 13 Mar 05 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • Weak Flow • No Vort max over AZ/SRN CA or Upstream • Pattern over CNTRL Rockies more similar to Spring Storms **Not Here**
Explainable by usual Spring Storms?RT-FDDA 300mb Hgt & Winds valid 06Z, 13 Mar 05 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • Weak Flow • Jet is well North • Weak trof SRN • CA way too • weak **Not Here**
Explainable by usual Spring Storms?RT-FDDA 700mb Hgt, Temp & Winds valid 06Z, 13 Mar 05 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • Gradient is tight • enough • Note 30-40 kts • Main Post area • towards El Paso
Explainable by usual Spring Storms?RT-FDDA 850mb Hgt, Temp & Winds valid 06Z, 13 Mar 05 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • Gradient is tight • enough • Trof is way east • over Texas
Explainable by usual Spring Storms? APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 Conclusion: NO Begs the question, What did cause it?
Enter the Mountain-Wave Down-Slope APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • 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!
Upper Air SoundingRT-FDDA Skew-T for Main Post valid 06Z, 13 Mar 05 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • Ridge top is about 750mb • Lowering wind speed up to 600mb • No Stable Layer • **Not Classic**
Mountain-Wave Cross SectionRT-FDDA valid 06Z, 13 Mar 05 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • Long arrows cascading down the hill • Wave is above the ridge • Critical Point is a little high • **Not Classic**
In Summary APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05 • 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.