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National Oceanic and Atmospheric Administration
Climate of 1998
Florida Wild Fires and Climate Extremes National Climatic Data Center, Asheville, NC
June 29, 1998
"The unusually wet mild winter...followed by a severe drought... (has) provided abundant fuel to the wild fires pervasive over Florida." - Alan Basist, NCDC
"So far in June 1998, Melbourne, Florida, has experienced 21 days over 95 deg.F. The probability of this occurring is less than 1 in 1000." - David Easterling, NCDC
Recent abnormal weather in Florida set the stage for the current wild fires.
Local measurements of Lack of Precipitation and High Temperature break Record.
Increases in variability and extremes may be linked to climate change.
Indices show surface moisture values were extremely dry as of June 20th.
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Recent abnormal weather in Florida set the stage for Wild Fires
Over Florida, the unusually wet mild winter promoted abundant growth in the under brush. This weather was immediately followed by a severe drought these last two months (May and June), which rapidly dried out the dense under brush. This combination, wet and mild in the winter, dry and hot in the summer, provided abundant fuel to the wild fires pervasive over Florida.
Additional Satellite Products and Imagery...
The Operational Significant Event Imagery Homepage (NOAA/NESDIS)
NCDC - Images/Movies of Hurricanes and Special Events
National Wildland Fire issues at the National Interagency Fire Center (NIFC) in Boise, Idaho.
- Agencies involved include:
NIFC provides the nation's primary logistical support center for wildland fire suppression. The center is home to federal wildland fire experts in fields as diverse as fire ecology, fire behavior, technology, aviation and weather. Working together and in concert with state and local agencies, NIFC's role is to provide national response to wildfire and other emergencies and to serve as a focal point for wildland fire information and technology.
- US Forest Service,
- US DOI,
- Bureau of Land Management,
- Fish and Wildlife Service,
- U.S. Geological Survey,
- Bureau of Indian Affairs, and
- the DOI's Office of Aircraft Services.
The Joint Fire Science Program
- This NIFC site contains up-to-date national fire news (including Florida), incident management reports, fire weather, geographic coordination centers, and other fire links.
- This NIFC site contains the Wildland Fire Workshop Report and Joint Fire Science Plan for the Nation and also has links to Florida.
Florida Department of Forestry
- This site deals with environmental issues related to wildland fires and contributions that different kinds of plant communities add to the fuel load in national parks and wilderness areas.
Florida Fire Management Information System
FEMA Page (many stories and links)
Local Measurements of Temperature and Lack of Precipitation Break Record
Temperature and lack of precipitation for June 1998, for many long-term stations in Florida, are at record or near-record levels. The warmth of the El Niño continues with a west to northwest flow prevailing over the state. At many locations, the mean temperature through June 25 is either the warmest June or warmest month ever, with the period of record at these locations beginning in the 18th Century.
In addition, many locations have set an extraordinary number of daily maximum temperature records. Locations along the west coast of the state have also set a number of high minimum records as the air flow over the abnormally warm Gulf of Mexico continues. The westerly air circulation at the surface and aloft has precluded development of the normal southeast flow over the state with consequent extreme dryness which began in mid-March 1998.
Sample temperature reports through June 25:
* For these stations, if the mean temperature does not change significantly during the last 5 days of June, the mean temperature will be the warmest month ever at the station. Tampa's record begins in 1825.
** For this station, the current monthly mean will be the warmest June in the period of record.
For June 1998 through the 25th, these sample locations had the listed number of days with maximum temperature>=95 deg.F and>= 100 deg.F. Based on the long-term climate of these locations, the probability of experiencing the listed number of days>=95 deg.F and>= 100 deg.F is less than 1 chance in 1000.
Melbourne, specifically, has only a .3% chance of experiencing 1 day>= 100 degrees.
Sample precipitation reports through June 25:
- November 1997-March 1998 was the wettest Nov-Mar on record (record goes back to 1895).
- April-June 1998 was the driest April-June on record.
- When converted to percent of normal precip & subtracted, the (Apr-Jun) minus (Nov-Mar) difference is unprecedented.
- April-June 1998 was the 3rd warmest Apr-Jun on record. 1948 was warmest, 1991 was 2nd warmest.
The following analyses by NOAA 's Climate Diagnostics Center (CDC), provided by the Western Regional Climate Center, indicate how the surface temperature and relative humidity values for June 1st-25th depart from a 12 year mean.
During June 1998, warm anomalies during the first ten days of June 1998 along the Gulf coast spread northward across portions of the Central Plains and Ohio Valley as upper level high pressure built north and west from the Gulf coast. During the last anomaly period (june 21-30) warmest departures had shifted northward across the Southern Plains into the interior Southeast. Easterly flow across portions of the Gulf coast had brought slightly cooler temperatures and an increase in scattered thunderstorms.
Climate Change, El Niño, and the Florida Drought.
Although the links are not clear, a possible consequence of climate change is more frequent and vigorous El Niño events. The exceptional global warmth for the year to date (January - May, 1998) is clearly El Niño related, however this warmth can also be viewed as being superimposed on top of any climate change being observed.
Another suspected consequence of climate change is enhanced climate variability, possibly bringing on more frequent and severe extreme events, such as flooding and drought. Florida experienced an unusually large amount of El Niño precipitation and mild temperatures during the winter and early spring. However, precipitation in central to northern Florida has been suppressed for the period beginning in late March to the end of June due to an intense ridge of high pressure, with some locations, such as Melbourne, receiving only a few percent of normal precipitation for the period. Temperatures for the same period have been exceptionally warm.
The unusually wet mild winter promoted rapid growth in bushes and grass (i.e. a lush under-story). These climatic conditions were immediately followed by a severe drought during the late spring and early summer, which is normally the beginning of the wet season . The recent period of extended daylight, intense sunshine, and unusually hot dry weather, caused the short rooted under-story to rapidly dry out, and serve as fuel for the pervasive fires throughout Florida.
This is an excellent example of how a combination of extreme events: wet and mild in the winter, dry and hot in the summer, causes severe environmental impacts. Climatic data indicates that the such extreme events are increasing over the United States.
Drought and Crop Moisture Indices
Several indices to describe drought have been developed which respond differently to weather and climate conditions and thus might have different implications concerning soil moisture, vegetation, and water supply. Some processes, such as dryland agriculture (for example the rate at which grasses and brush dry out) are rapidly affected by atmospheric behavior, and the relevant time scale is a month or two. Other processes have longer time scales, typically several months, such as the rate at which shallow wells, small ponds, and smaller rivers become drier or wetter. Some processes have much longer time scales, such as the rate at which major reservoirs, or aquifers, or large natural bodies of water rise and fall, and the time scale of these variations is on the order of several years. Three indices are illustrated below: the Crop Moisture Index, the Palmer Drought Severity Index, and the Keetch-Byram Drought Index.
The Crop Moisture Index for each of Florida Divisions 1 through 3 (the northern half of Florida) has shown a dramatic decrease since the agricultural growing season began on March 1st. From surpluses directly attributed to an exceptionally wet winter due to El Niño, surface moisture values were already dropping as the growing season began and were extremely dry as of June 20th.
March index values were as high as +7.8 for Division 1 (the Panhandle of Florida) which signifies excessive wet conditions and for Divisions 1 and 2 (all of northern Florida), were favorable through the end of April. Zone 3 (north-central Florida) had dried more rapidly and was short of topsoil moisture by the end of April. During May soil moisture continued to decrease and all three zones were excessively dry by the end of the month. Conditions had only worsened through June 20th. Each zone was experiencing extreme dryness with Zone 3 experiencing an index value of -5.41. The current data have been provided by NOAA's Climate Prediction Center.
The Crop Moisture Index is based on weekly mean temperature and precipitation, as an outgrowth of the Palmer Drought Index. It was specifically designed as an agricultural drought index and depends on the drought severity at the beginning of the week and the evapotranspiration deficit or soil moisture recharge during the week. It measures both evapotranspiration deficits (drought) and excessive wetness (precipitation is more than enough to meet evapotranspiration demand and recharge the soil).
The Palmer Drought Severity Index (PDSI) was developed to measure the departure of the moisture supply. The index is based on the supply-and-demand concept of the water balance equation, taking into account more than only the precipitation deficit at specific locations. The objective of the PDSI is to provide a measurement of moisture conditions that are standardized so that comparisons using the index could be made between locations and between months.
The Keetch-Byram Drought Index is computed using maximum daily temperatures, and daily, seasonal and annual precipitation. The index ranges from 0 (no drought) to 800 (extreme drought, often associated with intense, deep burning wildfire occurrence). As of June 25, 1998, extreme drought index values have been computed for northern Florida and other parts of the southeast.
Special Graphics and Images from the USGS
For further information, contact:
- Mike Crowe
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
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