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Downscaling for Fire Weather – Forecasting in Complex Topography

Downscaling for Fire Weather – Forecasting in Complex Topography. Heath Hockenberry National Weather Service Fire Weather Program Manager. Fire Weather – How are forecasts made?. Like everything else, start with the broad model output.

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Downscaling for Fire Weather – Forecasting in Complex Topography

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  1. Downscaling for Fire Weather – Forecasting in Complex Topography Heath HockenberryNational Weather Service Fire Weather Program Manager

  2. Fire Weather – How are forecasts made? • Like everything else, start with the broad model output. • Unlike everything else, apply basic conceptual knowledge of terrain and fuels. So how do we get from this…. To this ?

  3. Fire Weather – “Old School” Meteorology • Operational Fire weather is far from a complex, fine scale model with fire feedbacks and parameterizations. • Conceptual models are still the basis of forecasting in complex terrain. Essential reading Essential Training

  4. S-190 Introduction to Wildland Fire Behavior Basic Concepts and Terminology of Wildland Fire

  5. Introduction to Fire Behavior TermsThis example…Spotting • Fire producing sparks or embers that are carried by the wind or convection that start new fires beyond the main fire

  6. S-290 Introduction to Wildland Fire Behavior Stability Winds The “heart” of fire weather is taught in this course…

  7. S-290 Techniques Adjustment to Temperature using Average Lapse Rate Known: Elevations and the temperature at the lowest elevation Elevation Change: 2000 feet Average Lapse Rate -3.5F/1000 feet Simple calculations like this are done all the time in fire weather, for temperature adjustments.

  8. S-290 Techniques The thermal belt Inversion Depth

  9. Wind Downscaling… S-390 and S-490 Advanced Wildland Fire Behavior • General Winds • Local Winds

  10. Examples of Local Wind circulations:slope winds and sea breezes

  11. 20 FT WINDS RELATIONSHIP 20 ft winds = General Winds + Local WindsWhich dominates?General? Local? Both?

  12. Terrain Forced Flows The effects of terrain on General Winds: • Dissipation of wind by terrain features • Acceleration of wind by terrain features • Diversion of wind around terrain features Due to the complexity of terrain and atmospheric interaction these are… DIFFICULT TO PREDICT!

  13. Terrain Correction Factors Suggested General Wind correction factors: • Assuming: • Gently sloped terrain. • Neutral or unstable (or above inversion). • Windward slope exposed to general winds. Upper 1/3 of slope: 0.4 to 0.6 of General Wind Middle 1/3 of slope: 0.3 to 0.4 of General Wind Lower 1/3 of slope: 0.2 to 0.3 of General Wind Sheltered Areas: near zero

  14. Terrain Correction Factors Example 6 mph 6 mph 6 mph 0-1 mph Local slope winds

  15. Terrain Correction Factors Example 20 mph 10 mph 7 mph 5 mph 0-1 mph General Winds

  16. Terrain Correction Factors Example 20 mph 16 mph 13 mph 11 mph 2 mph 20 ft Winds=General Winds + Local Winds

  17. Terrain Correction Factors Example 20 mph 16 mph 2 mph 2 mph 0 mph 20 ft Winds=General Winds + Local Winds

  18. High Elevation Gaps Strong pass winds can also result from upper winds combined with a low level pressure gradient.

  19. Forecasting on an Incident Management Team… Advanced Incident Meteorology Forecasting

  20. Satellite Dish allows ingest and dissemination of forecast products

  21. IMET Forecasting • Why Pibals? • Diurnal Wind Patterns. • Complex Terrain. • Smoke/Public Health Concerns • Model problems!!!!

  22. Incident Management Team Worried about the forecasted Gap wind Event ↑ East East Flank of Fire Left Alone → South → ↓ West July 7th 2003 Brent Wachter

  23. Protect Taos Pueblo and Taos to the West ← Air Tanker Drop

  24. IMET Forecasting

  25. Sanford Fire Data: Rick Stratton, SEM, Missoula Fire Lab

  26. Sanford Fire Fuel

  27. WTR Weather Stream File for FARSITE ENGLISH 8 12 0 600 1700 54 87 50 20 7500 8 13 0 600 1700 52 88 50 20 7500 8 14 0 600 1700 52 88 50 25 7500 8 15 0 600 1700 57 87 50 27 7500 8 16 0 600 1700 56 81 50 23 7500 8 17 0 600 1700 57 81 50 20 7500 8 18 0 600 1700 53 81 50 21 7500

  28. IMET Forecasting

  29. Regression Equations Techniques • National Fire Danger Rating Forecasts from local NWS Offices. • Fire-business driven fuel dryness prediction, tailoring broad scale models to predict fuels’ receptiveness to fire.

  30. DGEX vs. GFS (Model Downscaling)http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/dgexhome.ops/ 500 mb ht/Vort 850 mb wind

  31. Acknowledgements • NWS Mets and IMETs Chuck Redman, Coleen Decker, Chris Gibson, Brent Wachter, Jim Prange, Bob Servick, Julia Rutherford, Bernard Meier, Larry VanBussum, and Chuck Baker. • Predictive Services GACC Mets Terry Marsha, John Saltenberger and Tim Mathewson. • NCEP’s Geoff DiMego. • The National Interagency Fire Center Training Branch.

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