Southern Area Fall 2010 Wildfire Assessment

8/8/2019 Southern Area Fall 2010 Wildfire Assessment

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Southern Area Fire Risk Assessment

October-December

2010


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Contents

Section Page

Executive Summary 3

Introduction & Background 4

Weather 5

Fuels 6

Fire Behavior 7

Summary 8

Recommendations 9


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Executive Summary

In response to a deepening drought over a large portion of the Southern Area, a Fire Risk Analysis was

conducted to assess the potential and expected fire situation for a fall fire season. The assessment period

extends from October 9, 2010December 31, 2010. The analysis included a look at the current weathersituation and extended forecast, fuels compared to normal for the time of year, National Fire Danger Rating

Systems energy release component for each Southern Area Predictive Service Area, and fire occurrence.Recommendations are provided based on the findings and conclusions of the analysis.

The outlook for the fall is for below average rainfall during October, November and December. Below

average temperatures in October will give way to above average temperatures in November. Warm and

dry conditions will add to the fire potential and the monthly outlook calls for increasing potential acrossnearly all of the Central and Lower Mississippi River Valley. Fuels analysis indicates that energy releasecomponent, 1000 hour fuel moistures, are running at or above critical levels in several Predictive Service

Areas covering portions of Texas, Louisiana, Arkansas, Mississippi, Alabama, Florida, Georgia, Tennessee,

and Kentucky.

Fire activity has been increasing across the region with extended attack fires occurring on USFS andstate/private lands. The level of activity for this time of the year is above normal.

The analysis and findings indicate the following probabilities for the fall fire season in the Southern Area.

Scenario Description for the

October-December 2010 fire season Southern Area Probability

Most Likely Case

Periodic rains do not develop and above normal fire activity

intensifies at a rapid rate beginning in mid to late October. Drought

escalates across the region into winter.

High Confidence

Best Case

Dry pattern continues but with periodic rains

Fire activity is average for the upcoming period. Low Confidence

Worst CaseExtreme drought takes hold across the entire region through

December. Extreme fire behavior and fire activity takes hold across

the vast majority of states

Low Confidence

Activate Decision Support Team at SACC at PL3Supplement local & state initial attack resources earlier than normalAdditional aviation assets will likely be neededTimely fire information flow to SACC is critical for acquiring & keeping national resources


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Introduction & Background

The deepening drought over a large portion of the Southern Area presents a serious concern for the

potential impact it could hold for a fall fire season. Drought has been increasing for most of the summer

across many areas of the region and has increased over the last month. A few tropical systems have

provided some relief over the last few months in Texas and the Atlantic coast. However, besides these

systems, very little rain has fallen over the region.

The current drought monitor map

indicates the most significant drought is

in the southern coastal plains of the

region. However, increase drought is

taken place over every state in the

region and on all ownership patterns.

The impacts of drought as severe as the one in the Southern Area are significant. Of chief importance to

fire managers is the impact it can have on the live vegetation and dead woody material, collectively called

fuels. Drought places stress on vegetation through reduced moisture availability. The result is a

corresponding reduction in the moisture content of the foliage, as well as reduced moisture content in both

the duff layers and down material on the forest floor. There is an inverse relationship between fuelmoisture content and the availability of a fuel to ignite and burn. As fuel moisture content decreases, fuel

availability for ignition and burning increases. With drought, this process has taken place over an

extended period of time, resulting in an increased amount of available fuels for combustion in a wildland

fire. Along with increased fuel availability come the potential for increased fire intensities and difficulties

of control. The net result of all this is an increase in the fire risk potential and the amount and type of fire

fighting resources needed to respond to the situation.

CURRENT CONDITIONS

Fourteen day rainfall shortages of one to two inches are common across a broad area extending from

northern Kentucky southward to Mississippi, Louisiana, Arkansas, Oklahoma, and eastern Texas. Areas of

western Tennessee and western Alabama are included in this region as well. Thirty day shortages increase

in this area to three to four inches and are locally higher along the immediate Gulf Coast where shortages

of five inches can be found. The rainfall deficits are still present when one considers a sixty day timeframe.

These values equate to less than 5% of normal rainfall at fourteen days and five to ten percent of normal at

thirty days. Similar depictions can be seen on Soil Moisture Anomaly maps and Palmer Drought Index

maps.


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This map highlights the area of concern as a

condition that has been building over a long period

of time.

Soil moistures will continue to be depleted with the

expected below average rainfall. The antecedentcondition of low soil moistures leading into the fall

fire season will elevate the potential for large fires.

If the winter also experiences below normal

precipitation as expected, the spring fire seasoncould be problematic.

The days since significant rain for southeastern

Arkansas, Louisiana, and central Tennessee are

near, at, or above historical maximums. Those that

are near historical maximums will likely climb to record setting levels based on a data set that extends

from the 1890s in some cases to present. Eastern Arkansas has not seen significant precipitation (0.25 inch

or greater) in over seventy days.

WEATHER OUTLOOK

The outlook for the fall is for below average rainfall during October, November and December. Below

average temperatures in October will give way to above average temperatures in November. Warm and dryconditions will add to the fire potential and the monthly outlook calls for increasing potential across nearly

all of the Central and Lower Mississippi River Valley. Fire potential may increase in Texas and Oklahoma

in December and January. The monthly and seasonal assessment maps are provided below. These maps are

a collaborative effort of the Predictive Services Units in all Geographic Areas and are generally updated

around the first or second day of each month.
http://www.predictiveservices.nifc.gov/outlooks/monthly_outlook.jpghttp://www.predictiveservices.nifc.gov/outlooks/seasonal_outlook.jpg


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The seasonal drought outlook maps

indicate increasing drought for much of

the region to extend into December.There will likely be no break between the

fall fire season and the traditional spring

season across much of the region.

Fuel and Fire Danger conditions

Long-term drying conditions have been in place for much of the region for the past several months.

The effect of this long-term moisture deficit has produced historically low fuel dryness levels over

much of the south during the late summer and early fall of 2010.

Generally, extreme fire behavior can exist when two conditions are present. One of those conditions

is the long term drying of fuels. This condition now exists across the majority of the southern GACC.

The second is daily fire weather conditions (low humidity, high temperatures, and high winds), which

can lead to large fire growth. This second condition is likely to develop on a regular basis based on

the forecasted weather for the next several months. Also, due to the long term drying of fuels, critical

fire weather thresholds which are normally used may be reached at more benign weather conditions.

In other words, under normal fuel moisture conditions, firefighters might see elements of extreme firebehavior when humidity values drop below 30%. However, due to the long term drying of fuels

extreme fire behavior may begin at humidity values of 35 to 40%. Energy Release Component

(ERC) provides an index that is correlated with flammability of fuel and difficulty of suppression.

ERC is often referred to as an indicator of fuel dryness. This index seems to be most useful for

characterizing the seasonal severity of this fire season across the Southern Area. ERC for each

Southern Area Predictive Service Area (PSA) can be calculated based on weather measurements taken

at Remote Automatic Weather Stations (RAWS).

The ERC maps shown below illustrate the current and future dryness of fuels for the region. The first

map shows a large area above the 97th percentile. The second map shows the forecasted ERC values

in 7 days. Notice a very large portion of the region will be creating new historic high ERC values.

Also, critical ERC values will also be reached by the mountain states by the traditional start of the fallfire season.


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Predicted Fire Behavior

The combination of long term drying of fuels and the expected weather over the next several months

indicates a significant probability of extreme fire behavior and long duration burning for much of the

of the southern and western portions of the region. Without a significant change in weather

conditions, firefighters could see unprecedented fire behavior as leaf fall occurs and grasses continue

to cure.

Many fires will likely exhibit extreme rates of spread along with short and long range spotting.

Active burning during the night will decline as humidity recovers with nocturnal cooling. Due to

deep burning conditions, mop up times will likely be longer and fires will need to be checked for

multiple days before being declared out. All these conditions lead to more resources being needed for

fire suppression for both initial and extended attack.

It is also worthwhile to keep in mind the human triggers during the period of interest. Hunting season,

fall agricultural burning, and the traditional Halloween fire period will add additional risks to the fire

potential. The potential for early wintery weather, across the northern tier of the region, will reduce

fire potential and provide a reprieve to fire managers in what is otherwise expected to be a busy

season.

Fire behavior recommendations

Activate the Decision Support Team at SACC when at regional PL 3 or as conditions

warrant.

Support will be needed to update and maintain predictive services and decision support

products.

Produce a fuels/fire behavior advisory when conditions warrant.

Develop a product which integrates with the 7-day outlook product currently produced by

predictive services, to predict fire potential for the upcoming 7 day period.


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Summary and Recommendations

Findings

It will take an increase in precipitation over an extended period to erase fuel and soil

moisture deficits in above referenced PSAs as well as other locations currently seeing ashort term recovery.

Following short duration precipitation events the potential to return to a period of high fire

danger resulting in more Initial Attack and larger fires could occur fairly quickly (within 3

days).

Daily low RH values in the drier areas will result in continued high fire danger even with

some precipitation unless rainfall returns to normal or above normal levels. This scenario

should be expected as cold front passages become more frequent.

Live fuels are currently entering their dormant phase in most of the Southern Area. Leaf

drop will add fuel to the fuel bed and wind reduction will decrease inside of timbered

areas. This will add to intensity and spread of fires, especially on slopes.

Conclusions

Most Likely Scenario High Confidence

The dryer weather pattern continues with infrequent significant precipitation observed and time

between rain/precipitation events exceeds 10 days. Moderately windy conditions along with post cold

front low humidity (10-25%) reaching critical levels will escalate fire behavior. The drought deepens

with the fall fire season potentially extending into the winter months. Fire danger indicators stay highto extreme, perhaps setting records for the winter months. A high level of localized wildland fire

activity occurs, as does the expected number of incidents needing Incident Management Teams.

Outside assistance is required for teams and other suppression resources, high need to support Type I

and Type II incidents. Implementation of prescribed fires may be negatively affected.

Best Case Scenario Low Confidence

Periodic significant rainfall and widespread cooler temperature during the fall months will keep

fire activity to normal or below normal for this time of the year. Precipitation events frequency isin the 7-10 day range. Drought severity waxes and wanes with the drier, highest threat areas

moving throughout the southern area.

Worst Case Scenario Low Confidence

Extreme drought takes hold across the entire region through December. Little if any rainfall takes

place for an extended amount of time. NFDRS indices continually break records creating new historic

highs. Extreme fire behavior and fire activity takes hold across the vast majority of states. Extended

attack incidents are common. Area command teams will be needed.


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Recommendations

When the regional preparedness level reaches PL3 the Decision Support Team should be

activated at the Southern Area Coordination Center to provide Fire Behavior, Fire Danger,

GIS Analyst, and WFDSS specialists to support incidents and fire managers to assist in

making decisions.

Supplement local and state initial attack resources earlier than normal.

Additional aviation assets may be needed in areas which air tankers have not traditionally

been utilized.

Start up the regular suite of Decision support products.

Obtain and provide for detailed ongoing updates of current and forecasted fuels

conditions. This can be accomplished by utilizing the Decision support team.

Issue fuels and fire behavior advisories as needed to communicate to fire managers theareas where extreme fire behavior is possible. Fireline tactics should be altered to provide

for firefighter and public safety.

Alert fire managers in areas with critical fire danger to consider logistical needs for

extended attack fires.

If conditions persist this product should be updated within a 45 day period.

Assessment Team:

Clint Cross, USDA Forest Service, Regional Office

Denver Ingram, National Park Service, SACC

Kevin Scasny, U.S. Fish and Wildlife Service, SACC

Jon Wallace, U.S. Fish and Wildlife Service, A.R.M. Loxahatchee NWR

Documents

Southern Area Fall 2010 Wildfire Assessment