85 1 2 3 4 5 6 7 7 8 9 10 11 11 12 13 14 16 17 19 22 29 90 1 2 3 4 5 6 6 7 8 9 9 10 11 12 13 14 15 17 19 22 28 95 1 2 3 4 5 5 6 7 8 8 9 10 11 12 13 14 15 16 18 21 28 100 1 2 3 4 4 5 6 7 7 8 9 9 10 11 12 13 14 16 18 21 27 105 1 2 3 3 4 5 6 6 7 8 8 9 10 11 12 13 14 15 17 20 26 110 1 2 2 3 4 5 5 6 7 7 8 9 9 10 11 12 13 15 17 20 26 115 1 1 2 3 4 4 5 6 6 7 8 8 9 10 11 12 13 14 16 19 25 120 1 1 2 3 4 4 5 5 6 7 7 8 9 10 10 11 13 14 16 19 25 125 1 1 2 3 3 4 5 5 6 6 7 8 8 9 10 11 12 13 15 18 24 Table 6 – Rainfall moisture factor (RMF) as a function of hourly rainfall Figure 6 – Rainfall Moisture Factor (RMF) as a function of hourly measured rainfall.
Table 7 – Evaporation correction factor as a function of fuel surface temperature. Figure 7 – Relationship between Evaporation Moisture Factor (EMF) and fuel surface temperature. Figure 8 – Flow diagram of the table-based fine dead fuel moisture calculations. Table 8 – Example Moisture Correction Factor (MCF) table for fuels that are absorbing water. Relative Humidity (%) 7% <5 5 to 9 10 to 14 15 to 19 20 to 24 25 to 29 30 to 24 35 to 39 40 to 44 45 to 49 50 to 54 55 to 59 60 to 64 65 to 69 70 to 74 75 to 79 80 to 84 85 to 89 90 to 94 95+ <30 -4 -2 0 1 2 2 3 4 5 6 6 7 8 9 10 11 12 13 15 18 30-49 -3 -2 -1 0 0 1 2 2 3 3 4 4 5 6 6 7 8 9 11 13 50-69 -3 -2 -1 -1 0 0 0 1 1 2 2 2 3 3 4 4 5 5 6 8 70-89 -2 -1 -1 -1 -1 0 0 0 0 0 1 1 1 1 2 2 2 3 3 4 90-99 -1 -1 -1 -1 -1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 2 100-104 -1 -1 -1 -1 -1 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 105-110 -1 -1 -1 -1 -1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 110-115 -1 -1 -1 -1 -1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 > 115 -1 -1 -1 -1 -1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Figure 9 – Comparison of Nelson-calculated fine dead fuel moistures (blue) to SimpleFMMC (red) calculated values calculated from hourly weather data at the Sanborn RAWS . Despite the huge simplifications in model logic, correlations between the complex and simple models are 0.94.
Table 9 – Example measurement and computation worksheet for fuel moisture calculations. Full computation sheet included in printable PDF of tables. SimpleFFMC Fine Fuel Moisture calculation worksheet A B C D E F G H I J K L Weather Observations Previous MC (t-1) Rainfall Factor (RMF) Evaporation Correction Factor (ECF) Moisture Correction Factor (MCF) FMC Temp RH Rainfall Solar Radiation Surface Temp Units (F) (%) (in) (W/m2) (F) (%) (%) (%) (%) (%) (%) Table Reference Estimated from local table Ref Table 1 Ref Table 2 Ref Table 3 Ref Table 4 Ref Tables 5 and 6 Notes If no local table, use 800 for clear days, 400 for overcast days and 0 at night Moisture content from previous hour or EQMC if first observation 0 if no rainfall over last observation period 0 if FMC (t-1) < 30% If FMC (t-1) > EQMC use Table 5, otherwise use Table 6 FMC (t -1) + RMF + ECF + MCF Calculation Ref If D = 0, record 0 If H < 30, record 0 If H > G, use Table 5 else use Table 6 H+I+J+K Date/Time
SimpleFFMC Fine Fuel Moisture calculation worksheet A B C D E F G H I J K L Weather Observations Equilibrium Moisture Content (EQMC) Previous MC (t-1) Rainfall Factor (RMF) Evaporation Correction Factor (ECF) Moisture Correction Factor (MCF) FMC Temp RH Rainfall Solar Radiation Surface Temp Units (F) (%) (in) (W/m2) (F) (%) (%) (%) (%) (%) (%) Table Reference Estimated from local table Ref Table 1 Ref Table 2 Ref Table 3 Ref Table 4 Ref Tables 5 and 6 Notes If no local table, use 800 for clear days, 400 for overcast days and 0 at night Moisture content from previous hour or EQMC if first observation 0 if no rainfall over last observation period 0 if FMC (t-1) < 30% If FMC (t-1) > EQMC use Table 5, otherwise use Table 6 FMC (t -1) + RMF + ECF + MCF 25-Jul-16 7:00 AM 77 94 0 23.26 90 19 19 0 0 -1 18 8:00 AM 84 76 0 161.657 96 14 18 0 0 -1 17 9:00 AM 82 86 0 123.278 94 16 17 0 0 -1 16 10:00 AM 83 72 0 324.477 103 12 16 0 0 -1 15 11:00 AM 80 79 0 196.547 96 15 15 0 0 -1 14 12:00 PM 80 87 0.09 293.076 98 14 14 21 0 0 35 1:00 PM 77 84 0.02 238.415 92 17 35 7 0 0 42 2:00 PM 87 74 0.01 702.452 111 12 42 4 0 0 46 3:00 PM 88 69 0 846.664 117 11 46 0 -8 0 38 4:00 PM 88 62 0 748.972 115 9 38 0 -8 0 30 5:00 PM 88 67 0 0 111 10 30 0 -7 0 23 Table 10 – Worked example fuel moisture calculation from the St. Mark (West) RAWS station on 25 July 2016.