Team White Sands Mountain-Wave Down- slope Wind Event Reviewed Meteorology Branch Forecast Section RO-DA-F 505-678-2488/2462 Eric Hatfield Meteorology.

Team White SandsTeam White Sands

Mountain-Wave Down-slope Wind Event

Reviewed

Mountain-Wave Down-slope Wind Event

ReviewedMeteorology Branch Forecast Section

RO-DA-F505-678-2488/2462

Eric Hatfield

Meteorology Branch Forecast SectionRO-DA-F

505-678-2488/2462Eric Hatfield

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. OPSEC REVIEW CONDUCTED ON 9 AUG 05

2Team White SandsTeam White Sands

Presentation Highlights

•What happened 12-13 Mar 05?

•Explainable by usual spring storms?

•Down-slope wind event

•Summary



What Happened?

•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

•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

•Weak Flow

•Jet is well North

•Weak trof SRNCA way too weak

**Not Here**



Explainable by usual Spring Storms?RT-FDDA 700mb Hgt, Temp & Winds valid 06Z, 13 Mar 05

•Gradient is tightenough

•Note 30-40 kts Main Post areatowards El Paso



Explainable by usual Spring Storms?RT-FDDA 850mb Hgt, Temp & Winds valid 06Z, 13 Mar 05

•Gradient is tightenough

•Trof is way east over Texas



Explainable by usual Spring Storms?

Conclusion: NO

Begs the question,What did cause it?



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!



Upper Air SoundingRT-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**



Mountain-Wave Cross SectionRT-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**



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.


Team White SandsTeam White Sands

The EndThe End

Team White Sands Mountain-Wave Down- slope Wind Event Reviewed Meteorology Branch Forecast Section RO-DA-F 505-678-2488/2462 Eric Hatfield Meteorology.

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