SEV HI TURB Cntrl CA - National Weather Service

MOD HI TURB Central CA Noel Keene ZOA CWSU 12 Oct 2008 Water Vapor Imagery

04Z 12 Oct 1630Z 12 Oct 1630Z 12 Oct

Some Speed Confluence and Dir Diffluence near FL300 PIREPS 15Z-18Z 12 Oct

12Z Sounding 12 Oct 08 L/L flow not strong enough or ELY enough to cause WDSPR SEV Lo Turb over Bay Area hills

Gradients 17Z 12 Oct Current ELY SFO-WMC gradient(green -0.9) not strong enough for SEV TURB(usually is -10+) and model(blue) overestimating offshore flow GTG Model Generally Correct But

Overdone Lessons Learned/Notes WDSPR Mod Hi Turb Event Several Days After Anomalously Strong Trof Passage

Valley Highs Dropped 10F after Trof Psg 24hr H5 Hgt Change 180M 12Z 10/9-10/10 48hr H5 Hgt Change 330M 12Z 10/9-10/11 No WDSPR Mod-Sev Lo Turb Event

SFC Pressure Gradients/Low-Level Flow Not Sufficient Dir(too much parallel to hills) or Speed to Cause Multiple Sev Lo Turb Rprts(1 Sev Lo Turb LVK)