Wildfire Danger Assessment 250219 to 270219

Wildfire Danger Assessment for Tuesday 25th – Thursday 27th February 2019 for Scotland.

Wildfire danger assessments are made on a broad area basis. For more local risk assessments both the seasonal condition of fuels and local weather conditions should be taken into account.

The overall fire danger assessment is HIGH for eastern Scotland for 26/02/19 - 27/02/19.

Ignition Potential - Fine Fuel Moisture Code and potential spread Initial Spread Index: EFFIS Fine Fuel Moisture Code forecast 25/02/19 for 26/02/19

Initial Spread Index Code forecast 25/02/19 for 27/02/19

The EFFIS FFMC forecast for the period 25/02/19 to 26/02/19 indicates a HIGH ignition potential for eastern Scotland. This reduces by 27/02/19. The Initial Spread Index is largely below 2 indicating low/moderate spread potential.

Images courtesy of European Forest Fire Information Service (EFFIS)

EFFIS FFMC Fire Danger class bands: The scientific evidence indicates that significant numbers of wildfires often occur in the UK in the when FFMC is above 80 and ISI above 2. Any yellow area on the map indicates an FFMC of more than 83 and for ISI yellow indicates values between 3.2 - 5.

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At this time of year, the late winter, the seasonal condition of the fuels (vegetation) will be reacting most to the combination of frost and warm dry weather and can reach very low moisture contents.

There has been little rain in the east over the winter and there is a lot of dead grass and dead heather.

EFFIS Duff Moisture Code forecast 25/02/19 for 27/02/19

EFFIS Drought Code forecast 25/02/19 for 27/02/19

The Duff Moisture Code (1.2cm - 7cm) and the Drought Code (7cm – 14cm) give us an indication of the dryness of the deeper organic soil layers. The DMC soil layer is moister due to recent rain. The Drought Code is still indicating dry soils at depth in the east reflecting the 2018 drought and the low levels of rain over the winter in the east. If the drought continues it will become an increasing issue, because at the moment the high duff moisture will constrain smouldering but should this dry out all layers will become available to burn more quickly than normal.

General weather forecast information: Snow has been followed by a very mild settled period, which will continue through Wednesday.

There is some rain forecast for the NW Highlands & Islands over the next couple of days. A band of rain is forecast to cross the country from the west on Thursday. Winds across west Scotland are brisk southerly but in east Scotland are moderate with variable directions. Aboyne in the east had a record temperature of 18.3 degrees centigrade last week and maximum temperature will be around 16-18 degrees this week, very high for the time of year. Humidity levels are moderate in the east, with overnight dew.

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Discussion: The key issue now is the moisture in live fuels, and the moss and litter layer and deeper peat. The high FFMC on the 27th February, but low ISI indicate that all surface fuel layers will ignite readily and burn quite hot but spread rates should be moderate. There is potential for re-ignitions from the upper moss and litter layer.

People conducting Muirburn should be cautious, especially on south-west facing slopes and where there is deep heather and a significant moss layer. Fires could burn hot at the moment, be difficult to extinguish, and water may be needed.

Fire Danger for period: The fire danger for eastern Scotland is HIGH 25th – 27th February. Then from mid-day Thursday 28th February it should reduce to low.

M. Bruce Director Firebreak Services Ltd Date 25/02/19

Tel. 013398 86451 Mob. 07967 681807 Em. info@firebreakservices.co.uk https://firebreakservices.co.uk

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Appendix A: Background information The EFFIS system is based on the Canadian Fire Weather Index system, of which FFMC, DMC, DC & ISI are a sub-indices. FFMC looks at the dead fuel moisture of the litter layer on the soil surface. The Initial Spread Index (ISI) is FFMC plus a wind function. DMC & DC look are deeper soil moisture indices.

Table 1 EFFIS fire danger class bands:

FFMC DMC DC ISI

VERY LOW Green < 82.7 < 15.7 < 256.1 < 3.2

LOW Yellow 82.7 - 86.1 15.7 - 27.9 256.1 - 334.1 3.2 - 5

MOD Brown 86.1 - 89.2 27.9 - 53.1 334.1 - 450.6 5 - 7.5

HIGH Red 89.2 - 93 53.1 - 140.7 450.6 - 749.4 7.5 - 13.4

VERY HIGH Black >= 93 >= 140.7 >= 749.4 >= 13.4

EFFIS fire danger classes were originally created to support decision making in Mediterranean areas.

The equivalent fire danger with typical grass and shrub fuel types in the British Isles is significantly lower. European Forest Fire Information Service (EFFIS) can be viewed at: http://effis.jrc.ec.europa.eu/static/effis_current_situation/index.html The weather data that is used in the EFFIS Fire Weather Index model is from the European Centre for Medium Range Forecasts (ECMWF).

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