Transcription
MICHIGAN FIELD GUIDEFOR CFFDRS FIREWEATHER INDEX (FWI)SYSTEMMarch 2015ABSTRACTBased on the CanadianForest Fire DangerRating System (CFFDRS)and its componentparts, the Fire WeatherIndex (FWI) System andthe Fire BehaviorPrediction (FBP) SystemPermission to reprint given byRobert Ziel AK Div of Forestrywho produced the original guide
Contents12CFFDRS System Overview . 21.1Key References & Training Resources . 31.2Important Conversions . 4Fire Weather Index (FWI) System . 52.1System Overview . 52.2Michigan FWI Interpretation Thresholds . 72.3Monthly Fire Weather Index (FWI) Record . 82.4Tables for the Fire Weather Index (FWI) System . 92.4.1Instructions . 9Visual Surface (10m) Wind Estimate - Modified Beaufort scale . 102.5Michigan DNR Adjective Class Matrix . 13Table 1. Fine Fuel Moisture Code (FFMC); Rain Code Estimation . 14Table 2.a FFMC Drying Tables, Temperature 0º F . 15Table 2.b FFMC Drying Tables, Temperature 10º F . 16Table 2.c FFMC Drying Tables, Temperature 20º F . 17Table 2.d FFMC Drying Tables, Temperature 30º F . 18Table 2.e FFMC Drying Tables, Temperature 40º F . 19Table 2.f FFMC Drying Tables, Temperature 50º F . 20Table 2.g FFMC Drying Tables, Temperature 60º F . 21Table 2.h FFMC Drying Tables, Temperature 70º F . 22Table 2.i FFMC Drying Tables, Temperature 80º F . 23Table 2.j FFMC Drying Tables, Temperature 90º F . 24Table 2.k FFMC Drying Tables, Temperature 100º F . 25Table 3. DUFF MOISTURE CODE (DMC); Rain Code Estimation . 26Table 4. DUFF MOISTURE CODE; Drying Factor . 27Table 5. DROUGHT CODE; Rain Code Estimation . 28Table 6. DROUGHT CODE; Drying Factor . 29Table 7. INITIAL SPREAD INDEX . 30Table 8. BUILDUP INDEX . 31Table 9. FIRE WEATHER INDEX . 32MI CFFDRS Field GuidePage 1 of 32
1 CFFDRS System OverviewThis guide is intended as a reference for US users who may have reason towork with the system in the United States, where English units are primarilyused. Keep in mind that the Canadian Forest Service has produced thedefinitive selection of reference publications and tools.The Canadian Forest Fire Danger Rating System (CFFDRS) was first conceived in1968. The Fire Weather Index (FWI) system was developed and introducedacross Canada in 1970. The Fire Behavior Prediction (FBP) system was releasedin 1984. The Fire Occurrence Prediction (FOP) system and Accessory FuelMoisture system are still in development, with several regional modulesoperational at this time.Though this guide attempts to be faithful to the models embedded in CFFDRS,there are a number of adaptations to the standard depictions found inmaterials produced by the Canadian Forest Service. Most important among these is the use of English units instead of thestandard metric units employed in the system internationally. CFFDRS models and tools do not expressly identify the relationshipbetween standard wind measurements (10 meters sensor height) used andfield measurements at eye level. The relationship between “airport”,“forestry” and winds measured at other heights (e.g. 6 ft for eye level) istaken from Lawson & Armitage (2008). Users are encouraged to interpretthe winds as measured and apply them appropriately for the model used.MI CFFDRS Field GuidePage 2 of 32
1.1Key References & Training ResourcesThe content included in this reference is based largely on these references withseveral graphics and flow charts drawn directly from them.Most of these references, resources, and tools can be found athttp://www.frames.gov/cffdrsLawson, B.D.; Armitage, O.B. 2008. Weather Guide for the Canadian Forest FireDanger Rating System. Nat. Resources Can., Can. For. Serv., North. For. Cent.,Edmonton, AB.Van Wagner, C.E. 1987. Development and Structure of the Canadian Forest FireWeather Index System. Canadian Forest Service, Ottawa, Ont. Forest TechnicalReport 35.Taylor, Steve, Lawson, Bruce, and Sherman, Karen. Introduction to theCanadian Forest Fire Weather Index System, online video. Canadian ForestService. 22 min.Understanding the Fire Weather Index System Interactive Training andReference, CD.Forestry Canada Fire Danger Group. 1992. Development and Structure of theCanadian Forest Fire Behavior Prediction System. Information Report ST-X-3.Ottawa, Ontario, Canada: Forestry Canada, Science and SustainableDevelopment Directorate. 63 p.Hirsch, K.G. 1996. Canadian Forest Fire Behavior Prediction (FBP) System User'sGuide. Natural Resources Canada, Canadian Forest Service, Northern ForestryCentre Special Report 7. Edmonton, Alberta.De Groot, W.J., 1993, Examples of Fuel Types in the Canadian Forest FireBehavior Prediction (FBP) System, Forestry Canada. Poster.Canadian Forest Fire Behavior Prediction System Interactive Training andReference, CD.Tymstra, C.; Bryce, R.W.; Wotton, B.M.; Taylor, S.W.; Armitage, O.B. 2010.Development and Structure of Prometheus: the Canadian Wildland Fire GrowthSimulation Model. Nat. Resour. Can., Can. For. Serv., North. For. Cent.,Edmonton, AB. Inf. Rep. NOR-X-417.Wotton, B.M.; Alexander, M.E.; Taylor, S.W. 2009. Updates and Revisions to the1992 Canadian Forest Fire Behavior Prediction System. Natural ResourcesCanada, Canadian Forest Service, Great Lakes Forestry Centre, Sault Ste. Marie,Ontario, Canada. Information Report GLC-X-10, 45p.MI CFFDRS Field GuidePage 3 of 32
Canadian Forestry Service. 1984. Tables for the Canadian Forest Fire WeatherIndex System. Environment Canada, Canadian Forestry Service, ForestTechnical Report 25.Taylor, S.W., Pike, R.G., Alexander, M.E. 1997. Field Guide to the CanadianForest Fire Behavior Prediction (FBP) System. Fire Management Network,Canadian Forest Service, Northern Forestry Centre. Special Report 11.Kidnie, S.M., Wotton, M.M., Droog, W.N. 2010. Field Guide for Predicting FireBehaviour in Ontario’s Tallgrass Prairie.RunCFFDRS.exe is a stand-alone executable file produced by the CanadianForest Service that includes documentation and references for the entiresystem as well as basic calculators for the FWI and FBP systems.Prometheus, the CFFDRS Geospatial Fire Growth Model, is supported by theCanadian Interagency Forest Fire Center (CIFFC) and its members. It includes aseparate FWI/FBP calculator as part of its installation.1.2Important ConversionsMetric /haKw/mMetersMetersMillimetersKilometersHectaresMI CFFDRS Field GuideMultiply 90.0497090.30480.03937010.621372.4711English secChainsFeetInchesmilesacresMultiply 1173.2808425.41.60930.40469Metric ge 4 of 32
2 Fire Weather Index (FWI) System2.1System OverviewAnalogous in concept to the National Fire Danger Rating System (NFDRS), theFire Weather Index System depends solely on weather readings.CFFDRS calculates FWI codes and indices based on a single “standard” fuel typethat can be described as a generalized pine forest, most nearly jack pine andlodgepole pine.The Fire Weather Index System calls for weather observations to be collectedfrom a standard observation site and time. Location standards can be found inthe “Weather Guide for the Canadian Forest Fire Danger Rating System”(Lawson and Armitage, 2008). The system calls for observations to be taken at“solar” noon, when the sun is at its peak directly overhead.There are three (3) fuel moisture codes calculated from these basic weatherobservations. Unlike the NFDRS fuel moistures, the FWI fuel moisture codesincrease as fuels get drier. Like other accounting systems, the FWI systemcombines knowledge of yesterday’s (or last hour’s) fuel moisture conditionswith the influence of air temperature, atmospheric moisture, wind, andprecipitation since then. The Fine Fuel Moisture Code (FFMC) represents fuel moisture of forestlitter fuels under the shade of a forest canopy. It is intended to representmoisture conditions for shaded litter fuels, the equivalent of 16-hourtimelag. It ranges from 0-101. Subtracting the FFMC value from 100 canprovide an estimate for the equivalent (approximately 10h) fuel moisturecontent, most accurate when FFMC values are roughly above 80.MI CFFDRS Field GuidePage 5 of 32
The Duff Moisture Code (DMC) represents fuel moisture of decomposedorganic material underneath the litter. System designers suggest that it isrepresents moisture conditions for the equivalent of 15-day (or 360 hr)timelag fuels. It is unitless and open ended. It may provide insight to livefuel moisture stress.The Drought Code (DC), much like the Keetch-Byrum Drought Index,represents drying deep into the soil. It approximates moisture conditionsfor the equivalent of 53-day (1272 hour) timelag fuels. It is unitless, with amaximum value of 1000. Extreme drought conditions in the Eastern UpperPeninsula have produced DC values near 650.Similarly, there are three (3) fire behavior indices intended to representspread, fuel consumption/heat release, and fire intensity. The Initial Spread Index (ISI) is analogous to the NFDRS Spread Component(SC). It integrates fuel moisture for fine dead fuels and surface windspeedto estimate a spread potential. ISI is a key input for fire behaviorpredictions in the FBP system. It is unitless and open ended. The Buildup Index (BUI) is analogous to the NFDRS Energy ReleaseComponent (ERC). It combines the current DMC and DC to produce anestimate of potential heat release in heavier fuels. It is unitless and openended. In Alaska and the Lake States, it is the primary indicator of seasonseverity during the growing season. The Fire Weather Index (FWI) integrates current ISI and BUI to produce aunitless index of general fire intensity potential. It is analogous to NFDRSBurning Index. With dry fuel conditions, it is a key indicator of extreme firebehavior potential. Again, unitless and open ended.Diurnal VariationsThere is an hourly implementation for the Fine Fuel Moisture Code that reflectsthe variability in fine fuel moisture as influenced by temperature and humiditychanges. Using the corresponding, locally observed windspeed, updated valuesfor Initial Spread Index and Fire Weather Index may also be produced.Additionally, research in Ontario (Kidnie et.al, 2010) quantified the fuelmoisture trends for grass fuels and established a grass fuel moisture model thatis produced only with hourly data.Seasonal Start-up and Resumption after Interruption in ObservationsDaily records are generally started as soon as there is measurable fire danger inthe spring. Typically, this is defined as the third day after snow has essentiallyleft the area to which the fire danger rating applies.Default seasonal start-up values are 85 for FFMC, 6 for DMC, and 15 for DC.If daily observations are interrupted during the season and missingobservations cannot be estimated, fuel moisture codes must be estimated forthe last day of missing observations and used as “yesterday” fuel moisturecodes for the newly resumed weather observation.MI CFFDRS Field GuidePage 6 of 32
2.2Michigan FWI Interpretation ThresholdsThese thresholds are used by the Michigan Department of Natural Resources toprovide interpretations to FWI observations and forecasts each day. Thoughthey give insight to overall potential across landscapes and areas ofresponsibility, they need to be combined with specific fuels and terrain for thesite to produce fire behavior interpretations when evaluating a specific firesituation.FFMCDMCDCISIBUIFWIMI CFFDRS Field Guide75Surface fire – spreads some80Surface fire – spreads more continuous90High probability of spot fires91Onset of extreme FB20Duff available for ignition3050150Fires moderately intenseExtreme fire behaviorLoss of most available moisture15300500Deep organics near saturationOnset of smouldering combustionSustained deep smoldering010No fire spreadThreshold for crowning20Extreme fire behavior50Rarely exceeds this value30Deeper, heavier fuels start to become involved60Potential for increased mop up, safety concerns90Many fires have potential to escape IA100Bad things can happen3Fire spreads25Onset of potentially extreme fire behavior50 Disaster firesPage 7 of 32
MI CFFDRS Field GuideFire Weather IndexBuildup IndexInitial Spread IndexToday’s DCStation/ZoneDC, Drying FactorDC, RaincodeToday’s DMCDMC, Drying FactorDMC. RaincodeToday’s FFMCFFMC, RaincodePrecipitaton, 24hYearWindspeedWind DirectionMonthRelative HumidityWet Bulb TempDry Bulb TempDay2.3Monthly Fire Weather Index (FWI) RecordElevation ObserverLast Month’s Fuel Moisture 28293031Total Rainfall for MonthPage 8 of 32
2.4Tables for the Fire Weather Index (FWI) System2.4.1InstructionsDaily CFFDRS Weather ObservationsManual observations may be taken with a belt weather kit, as long as the eyelevel windspeed observation is adjusted to 10m Forestry/RAWS windspeedbefore the codes and indices are estimated.Observed 1400 EDT weather elements include: Dry Bulb Temperature Relative Humidity 10m “Forestry” or RAWS windspeed and direction 24 hour accumulated precipitation total.Sudden Weather Changes during the Afternoon may be accounted for bycollecting a new set of observations and calculating a revised set of systemcodes and indices up to 1700 EDT. Do not include any of the rainfall that fellafter the normal collection time of 1400 EDT.The following table, adapted from the metric version in the Field Guide forPredicting Fire Behavior in Ontario’s Tallgrass Prairie (Kidnie et.al.2010), showsthe relationship among wind measurement or forecasts based on both theinstrument height, the size of the opening, the variability of the terrain, andvegetation around the sensor. “Airport” locations are much larger and haveflatter openings than most found in wildland, or “Forestry” 02530354045503610131620232630Airportor 2357810121315172023273033425058677583Height of Wind Measurement/Estimate (in feet)MI CFFDRS Field GuideFire .96.67.27.78.1Page 9 of 32
Visual Surface (10m) Wind Estimate - Modified Beaufort ScaleClassWindspeedTerminologyVisible Effect0Less than 1mphCalmCalm, smoke rises vertically.11 to 3 mphVery LightBreeze24 to 7 mphLight Breeze38 to 12mphGentleBreezeLeaves, small twigs in constantmotion; tops of trees in densestands sway; light flags extended.413 to 18mphModerateBreezeTrees of pole size in the open swayviolently; whole trees in densestands sway noticeably; dust israised in the road.519 to 24mphFresh BreezeBranchlets are broken from trees;inconvenience is felt in walkingagainst wind.625 to 31mphStrongBreezeTree damage increases withoccasional breaking of exposed tops& branches; progress impededwhen walking against wind.732 to 38mphModerateGaleSevere damage to tree tops; verydifficult to walk into wind;significant structural damage occurs.839 to 46mphFresh GaleSurfaced strong Santa Ana; intensestress on all exposed objects,vegetation, buildings; canopy offersvirtually no protection.947 to 54mphStrong GaleSlight structural damage occurs;slate blown from roofs.1055 to 63mphWhole GaleSeldom experienced on land; treesbroken; structural damage occurs.1164 to 72mphStormVery rarely experienced on land;usually with widespread damage.1273 mph ormoreHurricaneForceViolence and destruction.MI CFFDRS Field GuideLeaves of quaking aspen in constantmotion; small branches sway, tallgrasses and weeds sway and bendwith wind, wind vane barely moves.Trees of pole size in the open swaygently, wind felt distinctly on face;leaves rustle; loose scraps of papermove, wind flutters small flag.Page 10 of 32
Seasonal Startup of CalculationsDaily FWI system calculations also require fuel moisture codes (FFMC, DMC,DC) from the previous day. At the start of each fire season, values for thesecodes must be assigned according to procedures established by the systemmanagers. At least one of these three “startup” situations will be encounteredand needs to be addressed properly: At the beginning of the fire season, “begin calculations on the third dayafter snow has essentially left the area to which the fire danger ratingapplies.”(Lawson and Armitage, 2008). In these cases, assign a value of 85for FFMC, a value of 6 for DMC, and a value of 15 for DC except insituations where system managers wish to adjust the DC value forcarryover drought from the previous season and/or precipitation deficitsover the winter.For late-starting stations, the initial values for these three moisture codesmust consider the weather influences that have already accumulated sincethe beginning of the season. Examine fuel moisture code values forseveral nearby stations and assign appropriate startup values for the latestarting station based on interpretation of current conditions at the startuplocation.If, during the season, weather observations are interrupted, either missingweather data will need to be provided or fuel moisture codes must beassigned for the day prior to the next weather observation.Determine Daily Fine Fuel Moisture Code (FFMC) Obtain yesterday’s (or startup) FFMC. Determine if it rained at least 0.03inches in the 24 hours since yesterday’sobservation. If sufficient rainfall is measured, determine FFMC Raincode(Table 1) using the FFMC value from yesterday (or assigned at startup) andthe rainfall amount recorded. This value is called the FFMC Raincode. Use either FFMC Raincode or yesterday's FFMC (if rainfall was insufficient)with DB Temp, RH and Wind recorded for today to determine today’s dailyFFMC (Table 2.a-k).Estimate Duff Moisture Code (DMC) Obtain yesterday’s (or startup) DMC.Determine if it rained at least 0.06 inches in the 24 hours since yesterday’sobservation. If sufficient rainfall is measured, determine DMC Raincode(Table 3) using the DMC value from yesterday (or assigned at startup) andthe rainfall amount recorded. This value is called the DMC Raincode.With the DB Temp and RH recorded for today, use Table 4 to determinethe [DMC] drying factor based on the current month. Add this dryingfactor value to either the DMC Raincode or yesterday's DMC (if rainfall wasinsufficient) to produce today’s daily DMC.MI CFFDRS Field GuidePage 11 of 32
Estimate Drought Code (DC) Obtain yesterday’s (or startup) DC.Determine if it rained at least 0.11 inches in the 24 hours since yesterday’sobservation. If sufficient rainfall is measured, determine DC Raincode(Table 5) using the DC value from yesterday (or assigned at startup) andthe rainfall amount recorded. This value is called the DC Raincode.With the DB Temp recorded for today, use Table 6 to determine the [DC]drying factor based on the current month. Add this drying factor value toeither the DC Raincode or yesterday's DC (if rainfall was insufficient) toproduce today’s daily DC.Determine Daily Initial Spread Index (ISI) Use Table 7Lookup the daily ISI based on the FFMC and 10m windspeed determinedearlier.Estimate Buildup Index (BUI) for site conditions Use Table 8.Lookup the BUI based on the DMC and DC determined earlier.Determine Daily Fire Weather Index (FWI) Use Table 9.Lookup the daily FWI based on the ISI and BUI determined earlier.MI CFFDRS Field GuidePage 12 of 32
2.5Michigan DNR Adjective Class MatrixSPRINGTIME ADJECTIVE RATINGSBegin with Table 1. Using Fine Fuel Moisture Code (FFMC) and Initial SpreadIndex (ISI) calculated for today, find the appropriate adjective class. Ifinstructed to use Table 2, determine the adjective rating using the FireWeather Index (FWI) and Fine Fuel Moisture Code (FFMC).TABLE 1ISI 0.0 - 1.9ISI 2.0 - 3.9ISI 4.0 - 7.9ISI 8.0 FFMC 0.0 to 74.9LOWMODERATEHIGHSEE TABLE 2FFMC 75.0 to 84.9MODERATEMODERATEHIGHSEE TABLE 2HIGHHIGHSEE TABLE 2FFMC 85.0 TABLE 2FFMC 92FFMC 92 FWI less than 30.0VERY HIGHVERY HIGHFWI 30.0 VERY HIGHEXTREMESUMMERTIME ADJECTIVE RATINGSGenerally, begin using the summer criteria on June 1. Begin with Table 3.Using Buildup Index (BUI) and Initial Spread Index (ISI), find the appropriateadjective class. If instructed to use Table 4, determine adjective class using theFire Weather Index (FWI) and Fine Fuel Moisture Code (FFMC).TABLE 3ISI0.0 - 1.9BUI 0.0 to 44.9ISI3 - 3.9LOWISI6.0 - 7.9ISI8.0 - 9.9MODERATELOWBUI 100.0 MODERATEMODERATEHIGHHIGHHIGHISI10.0 VERYHIGHSEE TABLE 4USE SPRING CRITERIATABLE 4FFMC 92FFMC 92 FWI less than 35VERY HIGHVERY HIGHFWI 35.0 VERY HIGHEXTREMEMI CFFDRS Field GuideISI4.0 - 5.9LOWBUI 45.0 to 69.9BUI 70.0-99.9ISI2 - 2.9Page 13 of 32
YESTERDAY'S FINE FUEL MOISTURE CODE, FFMCTable 1. Fine Fuel Moisture Code (FFMC); Rain Code Estimation24 HOUR RAINFALL TOTAL, INCHES (if 24 hour rainfall is less than 0.03 inches, Rain Code Yesterday's FFMC)0.10 0.13 0.18 0.23 0.28 0.33 0.38 0.43 0.48 0.55 0.65 0.75 0.85 0.95 1.25 1.75 2.25 2.750.03 0.04 0.05 0.06 0.07 0.08 0.090.12 0.17 0.22 0.27 0.32 0.37 0.42 0.47 0.54 0.64 0.74 0.84 0.94 1.24 1.74 2.24 2.74 3.242110000000000000000000000010 998877765433221110000000020 19181716151413129765433322111000030 2827252422211918141197655433222100040 383533312927262418151210987765443222150 474441393634323023181513121110987665443355 5148454240373533252017151312111098776544460 56524946434038362722191614131211109887655565 615753504643413829242018161413121110998766570 65615753504744413126221917161413121110109877675 706561575350464433272320181716151312111110987776 716662575450474434282321191716151312111110987777 726762585451484534282421191716151312121110988778 736863595551484535282421191716151413121111988779 736864605652494635292421191816151413121111988880 746965605653494635292522201817161413121111998881 7570656157535047362925222018171614131212111098882 7671666257545047363025222018171614131212111098883 7772676258545148373026222019171615141312111099884 7873686359555148373026232119181615141312121099885 7973686459555249373026232119181715141312121099986 80746964605652493831262321191817151413131210109987 81757065615753503831272421201817151413131210109988 82767166615754503831272421201817161414131211109989 83777166625854513932272422201917161514131211109990 1 2 93 94 95 96 MI CFFDRS Field GuidePage 14 of 32
Table 2.a FFMC Drying Tables, Temperature 0º FRH, %2-8%1218%2228%3241%4456%5968%7278%8288%92% Windmph1-45-910-1415 1-45-910-1415 1-45-910-1415 1-45-910-1415 1-45-910-1415 1-45-910-1415 1-45-910-1415 15-910-1415 1-45-910-1415 2.514.816.317.511.713.614.815.810.211.111.612.0MI CFFDRS Field ain Code or Yesterday's Fine Fuel Moisture Code (FFMC)57-62 63-67 68-72 73-77 777.878.879.9Page 15 of 89.488.387.787.287.686.485.685.1
Table 2.b FFMC Drying Tables, Temperature 10º FRH, %2-8%1218%2228%3241%4456%5968%7278%8288%92% Windmph1-45-910-1415 1-45-910-1415 1-45-910-1415 1-45-910-1415 1-45-910-1415 1-45-910-1415 1-45-910-1415 15-910-1415 1-45-910-1415 0-37-13 17-23 27-3317.828.1 37.7 46.821.431.641 49.823.833.9 43.2 51.825.735.7 44.9 53.317.327.4 36.9 45.820.730.740 48.62332.942 50.424.834.6 43.6 51.916.926.9 36.4 45.220.330.2 39.4 47.922.532.3 41.3 49.724.334 42.9 51.016.626.636 44.72029.8 38.9 47.422.231.9 40.8 49.123.933.5 42.3 50.416.326.2 35.4 44.219.529.3 38.3 46.721.731.3 40.1 48.323.432.9 41.6 49.515.825.7 34.9 43.518.928.6 37.6 45.92130.5 39.3 47.422.632 40.7 48.615.425.1 34.3 42.918.227.8 36.8 45.120.129.6 38.4 46.521.531 39.6 47.514.424.2 33.3 42.016.726.3 35.3 43.618.227.7 36.5 44.719.328.8 37.5 45.612.622.3 31.4 40.113.623.2 32.3 40.814.323.9 32.9 41.314.824.4 33.3 41.7MI CFFDRS Field 7.0Rain Code or Yesterday's Fine Fuel Moisture Code (FFMC)57-62 63-67 68-72 73-77 577.578.479.4Page 16 of .188.888.788.688.187.787.587.387.08
Meters/min 2.982582 Ch/hr 0.33528 Meters/min Meters/min 0.03728 Miles/hr 26.8224 Meters/min Kg/m3 4.460897 Tons/ac 0.22417 Kg/m3 Kg/m3 30. . the "Weather Guide for the anadian Forest Fire Danger Rating System" (Lawson and Armitage, 2008). The system calls for observations to be taken at "solar" noon, when the sun is at its peak .
