Title: Downscaling for Fire Weather Forecasting in Complex Topography
1Downscaling for Fire Weather Forecasting in
Complex Topography
Heath HockenberryNational Weather Service Fire
Weather Program Manager
2Fire 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 ?
3Fire 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
4S-190 Introduction to Wildland Fire Behavior
- Basic Concepts and Terminology of Wildland Fire
5Introduction to Fire Behavior TermsThis
exampleSpotting
- Fire producing sparks or embers that are carried
by the wind or convection that start new fires
beyond the main fire
6S-290 Introduction to Wildland Fire Behavior
- The heart of fire weather is taught in this
course
Stability
Winds
7S-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.
8S-290 Techniques
The thermal belt
Inversion Depth
9S-390 and S-490 Advanced Wildland Fire Behavior
Wind Downscaling
- General Winds
- Local Winds
10Examples of Local Wind circulationsslope winds
and sea breezes
1120 FT WINDS RELATIONSHIP 20 ft winds General
Winds Local WindsWhich dominates?General?
Local? Both?
12Terrain 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!
13Terrain 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
14Terrain Correction Factors Example
6 mph
6 mph
6 mph
0-1 mph
Local slope winds
15Terrain Correction Factors Example
20 mph
10 mph
7 mph
5 mph
0-1 mph
General Winds
16Terrain Correction Factors Example
20 mph
16 mph
13 mph
11 mph
2 mph
20 ft WindsGeneral Winds Local Winds
17Terrain Correction Factors Example
20 mph
16 mph
2 mph
2 mph
0 mph
20 ft WindsGeneral Winds Local Winds
18High Elevation Gaps
Strong pass winds can also result from
upper winds combined with a low level pressure
gradient.
19Advanced Incident Meteorology Forecasting
Forecasting on an Incident Management Team
20Satellite Dish allows ingest and dissemination
of forecast products
21IMET Forecasting
- Why Pibals?
- Diurnal Wind Patterns.
- Complex Terrain.
- Smoke/Public Health Concerns
- Model problems!!!!
22Incident Management Team Worried about the
forecasted Gap wind Event
? East
East Flank of Fire Left Alone ?
South ?
? West
July 7th 2003 Brent Wachter
23Protect Taos Pueblo and Taos to the West
? Air Tanker Drop
24IMET Forecasting
25Sanford Fire
Data Rick Stratton, SEM, Missoula Fire Lab
26Sanford Fire Fuel
27WTR 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(No Transcript)
29IMET Forecasting
30Regression 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.
31DGEX vs. GFS (Model Downscaling)http//wwwt.emc.n
cep.noaa.gov/mmb/mmbpll/dgexhome.ops/
500 mb ht/Vort
850 mb wind
32Acknowledgements
- 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. - NCEPs Geoff DiMego.
- The National Interagency Fire Center Training
Branch.