Smoke/Fire
Weather - Frequently Asked Questions
Over the past few weeks, there may have been a few days that you
have seen or smelled smoke in the air over north Alabama and southern
middle Tennessee. In addition, you may have noticed Red Flag Warnings
on the watch/warning/advisory map on our homepage. The purpose of
this web page is to provide some answers to questions that are frequently asked
regarding the smoke and wildfire risk.
Where has the smoke affecting
the Tennessee Valley been coming from?
Believe it or not, much of the smoke that you have been seeing and
smelling over the past couple weeks has been coming from wildfires
in southeastern Georgia and northeastern Florida. The most significant
contributors to this smoke have been the 'Big Turnaround' and 'Bugaboo'
wildfires, which have burned over 430,000 acres of land in Ware
and Charlton counties in Georgia and Baker County in Florida. The
first "bout" of smoke across our area occurred on Monday,
May 14th and Tuesday, May 15th, with smoke reducing visibilities
as low as 3 miles on the 15th. There was another significant plume
of smoke that moved across the area on Tuesday, May 22nd and Wednesday,
May 23rd, with visibilities going as low as 1 mile in the Shoals
area and many other areas seeing significant visibility reductions
on the 23rd. In both cases, the plumes of smoke were steered across
the area around high pressure that has been positioned to our northeast.
The above visible satellite image from 8:15
AM on May 23rd shows smoke streaming from the wildfires over Southeast
Georgia and Northeast Florida around high pressure centered off
the East coast. The most dense plume of smoke extends from near
Valdosta, Georgia, through Montgomery, AL and the Shoals area. 1000-850mb
streamlines are overlayed on the satellite image showing the mean
wind flow in the lower layer of the atmosphere. Click on the image
to enlarge it.
Is it uncommon for this
area to be affected by smoke from fires as far away as the ones
in SE Georgia and NE Florida?
It actually isn't that uncommon for smoke from wildfires to travel
that far of a distance. There have been many occasions in the past
when smoke from fires as far away as Canada or Mexico have caused
hazy conditions in the Southeast. In a majority of these cases,
the smoke was not dense enough to be smelled this far away. More
prolific wildfires are more common west of the Rocky Mountains in
the United States than they are in the Eastern United States, so
the Tennessee Valley doesn't see denser smoke (similar to what we
have seen on recent occasions) as often as other areas of the country.
What is fire weather?
Fire weather is the use of meteorological parameters such as relative
humidity, wind speed and direction, cloud cover, mixing heights,
and soil moisture to determine whether conditions are favorable
for fire growth and smoke dispersion. The fire weather products
we issue such as the Fire
Weather Planning Forecast, Fire Weather Watches, Fire Weather
Warnings, and Spot Forecasts are generally intended for land management
agencies in our area such as the Alabama Forestry Commission (AFC)
and the United States Forest Service (USFS). These products provide
meteorological data which help these agencies make decisions relating
to fire weather, such as when to execute controlled burns and when
to expect a higher probability of wildfires.
What is a Red Flag Warning?
Should I be concerned about it?
The criteria for the issuance of a Red Flag Warning varies from
state to state. The National Weather Service in Huntsville only
provides fire weather services for our counties in North Alabama.
For more information about the fire weather program for counties
in the Tennessee portion of our forecast area, please consult the
National Weather
Service in Nashville for Lincoln County and the National
Weather Service in Morristown for Moore and Franklin counties.
In Alabama during the months of May through October, there must
be a combination low relative humidities (at or below 30%), gusty
winds (sustained 20 foot winds of 10 mph or greater), and dry conditions
(KBDI indices
equal to or exceeding 500, except this criteria is suspended for
counties under a Fire Alert) for a Red Flag Warning to be issued.
When a Red Flag Warning is issued by the National Weather Service,
outdoor burning is strongly discouraged. The state of Alabama may
issue a "Fire Alert", which means the number of burning
permits issued will be restricted to persons who have burning experience
and exceptional control equipment. A Fire Alert has been in effect
for the entire state of Alabama since May 18th. If conditions worsen,
the state could issue a "Drought Emergency", which is
a complete burn ban.
Satellite Imagery From
Recent Smoke Plumes
Below are some recent satellite images of smoke affecting our area.
MODIS images are courtesy of NASA and the University of Wisconsin.
Click on any image to see a larger version of it.
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