Red Flag Watch Warning Program for Hawaii

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Red Flag Watch / Warning Program for Hawaii

• Derek Wroe
• National Weather Service Honolulu

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Red Flag Program

• Purpose 1. A combination of dry fuels and
  weather
• conditions supports extreme fire danger and/or
  extreme fire behavior.
• 2. Alert land managers for the potential of
• widespread ignitions or control problems with
• existing fires, both of which could pose
  threat to
• life and property.
• NWS cannot keep Red Flag event confidential

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Red Flag Program

• Products 1. Fire Weather Watch - Issued when
  there is a high potential for the
  development of a Red Flag event. Issued 12 to
  72 hrs prior to expected onset of criteria.
• 2. Red Flag Warning - Issued for impending or
  occurring Red Flag event. Denotes a high
  degree of confidence that weather and fuel
  criteria of a Red Flag event will occur in 24
  hrs or less.
• Forecasters can coordinate issuance of Red Flag
  products with local land and fire managers
• All NWS watches and warnings must be available to
  public

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Tropical Location Criteria
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Proposed Criteria

• All three criteria met at Honolulu International
  Airport (HNL)
• - KBDI 600
• - Minimum RH (1 hr or more) 45
• - Wind Speed (1 hr or more) 20 mph
• For mainly leeward only?
• - Chu (2003) confirmed
• highest fire danger over
• leeward areas
• Criteria met an average
• of 4 days/yr from 1980-2005
• - Target less than 10 days

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What is KBDI?

• Chosen to reflect fuel conditions by describing
  soil moisture deficit
• Designed for the warm and humid southeastern U.S.
  that is somewhat similar to the climate of Hawaii
• Developed to determine availability of drought
  fuel load
• Ranges from 0 to 800
• - 800 extreme drought
• - 0 saturated soil
• Changes daily based on observed maximum
  temperature and rainfall

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KBDI

• 0 200 Nearly all soil organic matter, duff
  and litter are left intact after a burn. Within
  minutes after fire area is smoke free.
• 200 400 Litter and duff begin to contribute to
  fire intensity. Soil exposure is minimal.
  Smoldering with resulting smoke can carry into
  night.
• 400 600 Upper range at which most understory
  type burning should be conducted. Most of the
  duff and organic layers will ignite and actively
  burn. Considerable soil exposure occurs.
  Complete consumption of all but largest dead
  fuels. Fuels may smolder for days with possible
  fire control problems.
• 600 800 Most severe drought conditions. Many
  states issue burning bans. Fires will be intense
  and deep-burning. Most subsurface soil organic
  material will be consumed with great soil
  exposure. Live understory is part of fuel
  complex. Smoldering may occur for many days with
  fire control problems.

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Why KBDI and Why HNL?

• Dolling et al (2005) found a strong statistical
  relationship between KBDI and fire activity, both
  in the number of fires and total acres burned
• Dolling et al (2005) found that the driest
  leeward stations on each island can serve as
  reference stations to diagnose fire activity
• - Kekaha, Kauai
• - HNL, Oahu
• - Lahaina, Maui
• - Naalehu, Hawaii
• Only HNL can provide high quality, real-time data
• In tropics small fluctuations in weather
  variables are crucial
• - Departures of 5 15 from average can be
  considered large!
• Using HNL to assess Red Flag potential simplifies
  the forecast process and can be effective

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Mean Annual Precipitation
7000 mm 275 inches 1200 mm 47 inches 600
mm 24 inches
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Mean Annual Precipitation
9000 mm 354 in 7000 mm 275 in 1000 mm 39
in 400 mm 16 in
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Mean Annual Precipitation
9000 mm 354 in 7000 mm 275 in 1000 mm 39
in 400 mm 16 in
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Mean Annual Precipitation
7000 mm 275 inches 1200 mm 47 inches 600
mm 24 inches
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Mean HNL Conditions

• Criteria most likely met during fire season peak
• Only small departures (5-15 ) from mean wx
  conditions will satisfy Red Flag criteria
• Proposed criteria
• - KBDI 600
• - RH 45
• - Wind 20 mph

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HNL Mean RH 1980-2005

• RH 45 on 23 of the days from 1980 to 2005

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HNL Mean Max Wind 1980-2005

• Wind 20 mph on 22 of the days from 1980 to
  2005

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Weather Criteria

• Both weather criteria (RH 45 and wind 20
  mph) satisfied on only 5 of days from 1980 to
  2005
• - On average, these conditions met only 17 days
  per year
• - Coupled with KBDI information about fuels, all
  three criteria designed to underscore potential
  for extreme fire behavior and/or extreme fire
  danger

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HNL Mean KBDI

• KBDI 600 typical late summer and early fall
  peak fire season
• KBDI 600 on 34 of the days from 1980 to 2005

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HNL KBDI 1980-2005

• Varies greatly during each year and from
  year-to-year
• KBDI 600 represents the highest 34 of database
• KBDI 500 typical nearly 50 of the year

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Red Flag Criteria

• Requested to keep Red Flag days to less than 10
• Only 1 of days meet criteria, yielding an
  average of 4 Red Flag days per year
• Events distributed unevenly with nearly half of
  the years from 1980 to 2005 having no events
• Proposed criteria
• - KBDI 600
• - RH 45
• - Wind 20 mph

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Performance

• Fire experts identified 6 past events exhibiting
  extreme fire behavior
• Of the 5 events from 1980 2005, 3 out of 5
  events occurred on or near a Red Flag day
• - 1 of the 2 missed events occurred on a
  borderline day
• Another identified event (Aug 5, 1970) occurred
  in the middle of a five day stretch of Red Flag
  days
• Remember, on average only 4 Red Flag days happen
  each year

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2007 Performance

• Most of 2007 was very dry (KBDI 750 for only
  4th time since 1980)
• - KBDI exceeded 600 in mid April (normally
  reached in late July)
• 29 Red Flag days
• - highest number of Red Flag days of any year
  1980 2007
• - first Red Flag day of the year (Apr 23) had 60
  acre fire near Village Park
• Two very large fires exhibiting extreme fire
  behavior occurred during the years two extended
  Red Flag events
• - Olowalu Fire on Maui
• - Waialua Fire on Oahu
• Through newspaper reports, over 20,000 acres
  burned in 85 events
• - 16 of these events occurred on Red Flag days,
  burning over 10,000 acres
• - Red Flag days cover 19 of the events but
  burned 52 of the acreage in 2007

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2007 Extreme Events

• Olowalu Fire 2600 acres, Jun 28-30
• - Red Flag days
• Jun 22-30 (except 27th)
• Waialua Fire 6700 acres, Aug 12-18
• - Red Flag days
• Aug 13-21
• (except 17th 19th)

Waialua Fire
Olowalu Fire Wailua Kauai Fire
Maili Fire
Ukumehame Fire
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Red Flag Predictability

• In tropics small fluctuations in weather
  variables are crucial
• - Departures of 5 15 from average can be
  considered large!
• Forecasters can detect these trends (from
  Forecast Discussions)
• - Waialua Fire (Sun, Aug 12 Aug 18, 2007)
• Fri, Aug 10 A tightening of the pressure
  gradient will increase trade winds
  on Sunday.
• Thu, Aug 16 A much drier and more stable air
  mass is moving in from the east
• subsidence inversions are lower and
  stronger than 24 hours ago.

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Red Flag Predictability (cont)

• - Olowalu Fire (Thu, Jun 28 30, 2007)
• Thu, Jun 21 inversion height near 6000 ft is
  not expected to change muchand
  upstream moisture is rather meager.
• expect locally breezy trades to blow
  through at least day 5
• Wed, Jun 27 Expect winds to max out today
  through Thursday.
• Air mass over our region is expected
  to become more stablehence expect
  showers in the coming days to be on
  the lighter side.
• brisk trades and dry weather through
  Friday.

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Red Flag Predictability (cont)

• - West Big Island Extreme Event (Mon, Aug 1,
  2005)
• Wed, Aug 1 feature seems to be kicking up
  winds
• remains stable therefore have below
  normal probability of precipitation
• a breezy pattern can be expected

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Summary

• Purpose of Red Flag
• - Combination of dry fuels and weather
  conditions supports extreme fire danger and/or
  extreme fire behavior.
• - Alert land managers for potential of
  widespread ignitions or control problems with
  existing fires
• All three criteria met at Honolulu International
  Airport (HNL)
• - KBDI 600
• - Minimum RH (1 hr or more) 45
• - Wind Speed (1 hr or more) 20 mph
• To be issued for leeward areas only?
• Criteria met an average of 4 days/yr from
  1980-2005
• Criteria can capture extreme fire behavior
  events
• - 4 out of 6 identified events prior to 2005
  captured
• - 2 out of 2 known events during 2007 captured
• 2007 fires on Red Flag days accounted for 52 of
  acreage burned

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Questions?

• derek.wroe_at_noaa.gov
• 973-5280

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Alternative Criteria?

• Alternative criteria
• - KBDI 500
• - RH 45
• - Wind 20 mph
• Increase in Red Flag days would be minimal
• - 5 days per year on average
• - 1.5 of the days from 1980 to 2005
• Of the identified extreme fire days, these
  criteria perform with same accuracy as proposed
  criteria
• 2007 performance unchanged from proposed criteria

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HFDRS
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RH Table
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RAWS Main Airports
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Extreme Events

• Identified informally
• - Aug 5, 1970 West Oahu RFW
• - May 16, 1984 West Oahu No, borderline!
• - Jul 24, 1994 West Big Island No
• - Aug 4, 1999 West Big Island RFW
• - Jul 3, 2003 West Oahu RFW
• - Aug 1, 2005 West Big Island RFW
• 2007 Extreme Fires
• - Jun 28 30 Olowalu RFW
• - Aug 12 18 Waialua RFW