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Understanding the Vermont Fire Danger Report

 


Below is a sample the the Vermont Fire Danger Report issued daily through spring fire season in Vermont, typically from the end of March when snow melts to early to mid May when Vermont greens up.  The report is issued periodically through the summer and fall until snowfall ends fire season for the year.   Scroll down to find column definitions.

 
Vermont Fire Danger Report Sample
Vermont Fire Danger Report sample.

 

Vermont calculates fire danger based on the 1988 version of the National Fire Danger Rating System (NFDRS).  Input into the NFDRS model comes from weather observations at 5 remote automated weather stations (RAWS) located as follows:
     
Location Abbreviation WIMS ID Number
Essex ESS 430501
Elmore ELM 430601
Sweezy (Danby) DAN 431301
Marlboro MARL 431401
Nulhegan (Brighton) NUL 430402

 

Column Definitions for Daily Weather Observations (green section)

Column Heading Definitions

Station (Sta):

ELM; ESS; DAN; MAR; NUL

Date:

Date of observation

Time (Tm):

Observation time is 1:00 pm (LST) or 1300 hours

SOW (WX):

State of the weather – description of the weather at the time of observation.

 

   0 – clear, less than 10% cloud cover

   1 – scattered clouds, 10-50% cloud cover

   2 – broken clouds, 60-90% cloud cover

   3 – overcast, 100% cloud cover

   4 – fog

5 – drizzle or misting

6 – rain

7 – snow or sleet

8 – showers

9 – thunderstorms
Dry Temp (Tmp): Observed dry bulb air temperature (Fahrenheit)
RH: Relative humidity
Wind Dir (Dir): Wind direction displayed in degrees. Degrees for cardinal wind directions listed below (readings can be between cardinal directions, i.e. North-northwest – 338, etc.)
 

North – 360 or 0

Northeast – 45

East – 90

Southeast – 135

South – 180

Southwest – 225

West – 270

Northwest – 315

Wind Sp (WS):

Wind speed – observed average ten-minute wind speed (calm is 0 for both speed and direction).

Temp Max (Tmx):

Observed maximum temperature in the last 24 hours (Fahrenheit)

Temp Min (Tmn):

Observed minimum temperature in the last 24 hours (Fahrenheit)

%RH Max (RhMx):

Observed maximum relative humidity in the past 24 hours.

%RH Min (RhMn):

Observed minimum relative humidity in the past 24 hours.

Duration (Dur)

Actual number of hours of precipitation observed in the last 24 hours, cumulative total of all occurrences.

Amount (Amt)

Amount of precipitation observed in the last 24 hours.

 

Column Definitions for National Fire Danger Rating (NFDR) Index (blue section)

Column Heading Definitions

Station Id (Sta):

Elmore; Essex; Danby; Marlboro; Nulhegan

Obs Date (Tm):

Date of observation

Ob Tm:

Observation time is 1:00 p.m. (LST) or 1300 hours

Wind Speed (WS):

Wind speed – observed average ten-minute wind speed (calm is 0 for both speed and direction0.

Woody Fuel Moisture (Wdy):

Calculated field that represents the water content of live woody plants expressed as a percent of the oven-dry weight of the plants.

Herbaceous Fuel Moisture (Hrb):

Calculated field that represents the water content of live herbaceous plants expressed as a percent of the oven-dry weight of the plants.

1-Hour (1hr):

Calculated one-hour timelag fuel moisture content, in percent, of dead herbaceous plants and roundwood less than one-forth inch in diameter, also includes the uppermost layer of the forest floor.

10-Hour (10hr):

Calculated ten-hour timelag fuel moisture content, in percent, of the dead fuels consisting of roundwood one-fourth to one inch in diameter, and roughly, the layer of litter extending from just below the surface to three-fourths inch below the surface.

100-Hour (100hr):

Calculated 100-hour timelag fuel moisture content, in percent, of dead fuels in the 1-3 inch diameter class.

1000-Hour (1000h):

Calculated 1000-hour timelag fuel moisture content, in percent, of dead fuels in the 3-8 inch diameter class.

Ignition Component (IC):

A calculated field which provides an index indicating the probability that a heat source, natural or man-made, will cause a fire requiring suppression action. IC values range between 0 and 100.

Spread Component (SC):

A calculated field which provides a relative index of the forward rate of fire spread. The scale for SC values is open ended.

Energy Release Component (ERC):

A calculated field which provides a relative index of the available energy (heat) (Btu) per square foot within the flaming front at the head of a fire. The scale for ERC values is open ended.

Burning Index (BI):

A calculated field which provides an index indicating the difficulty of containing a single fire. The BI has a linear relationship to flame length at the head of the fire (10 times the predicted flame length) and is derived from the SC and the ERC. The scale for BI values is open ended.

Adjective Fire Danger Rating (R):

The fire Danger Rating is used to communicate fire danger to the public (Smokey’s arm).   L=low; M=moderate; H=high; V=very high; E=extreme.

Keetch-Byram Drought Index:

KBDI is a calculated field which is used to estimate deep drying of litter and duff. The value is calculated based on observations – 0 represents saturated, 800 represents maximum drought.

 

Forecast Data and Forecast NFDR Index (yellow section)

Calculated values based on the current days fire weather observations and the forecasted weather observations from the National Weather Service.  These observations are then used to calculate the NFDR outputs.

Notes (orange section)

Section used to describe how current weather observations are affecting fire danger indices, what these indices mean for firefighters and for wardens issuing permits and what the expected conditions are likely to be tomorrow.


Print version of this document - .doc format

 

VT Department of Forests, Parks & Recreation, March 2009

 
 



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