ATHENS, Ga. — Georgia’s dry May has
intensified drought conditions
statewide.
Many places in middle and south Georgia had less than an inch
of rain in May. Across
north Georgia, May rainfall totals were generally less than 2.5
inches. Normal rain totals
for May should be between 3.5 inches along the coast to almost 5
inches in the mountains.
In middle and south Georgia, rainfall totals for May include
0.04 inches at Tifton,
0.21 at Newton and Vidalia, 0.30 at Macon, 0.34 at Camilla, 0.36
at Augusta, 0.41 at
Dublin, 0.57 at Fort Valley, 0.66 at Alma, 0.78 at Columbus, 0.96
at Savannah, 1.08 at
Valdosta, and 1.18 at Midville.
Rainfall was greater in north Georgia but still well below
normal. May totals were 1.07
inches at Rome, 1.14 at Watkinsville, 1.51 at Griffin, 1.62 at
Blairsville, 1.85 at
Atlanta, 2.02 at Duluth, 2.17 at Athens, 2.52 at Jonesboro, and
2.77 at Gainesville.
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Soil Moisture Low
…
A bigger concern than the lack of rain is the lack of soil
moisture. Soil-moisture
models from the National Oceanic
and Atmospheric
Administration‘s Climate Prediction
Center
indicate that soil moisture across the state is between the first
and 10th percentiles for
the last day of May.
At the first percentile, we would expect soils to have more
moisture in 99 of 100
years. At the 10th, we would expect the soils to have more
moisture in nine out of 10
years.
With little soil-moisture recharge last winter, reserves are
quickly being depleted.
One measure of the rate at which soil moisture is changing is the
balance, a simple moisture accounting system.
… And Getting
Lower
To calculate the water balance, take the rainfall during a
given period and subtract
the soil-moisture loss due to evaporation and plants’ water use
during that period. A
negative water balance means that the soils lost moisture during
the period. A positive
value means the soils gained moisture.
Between April 1 and May 30, all Georgia locations lost soil
moisture. Some
water-balance values include -10.74 inches at Dublin, -10.50 at
Tifton, -10.48 at Newton,
-9.65 at Midville, -9.51 at Fort Valley, -9.09 at Vidalia, -7.98
at Griffin, -6.96 at
Camilla, -6.93 at Watkinsville, -6.66 at Alma, -5.54 at Valdosta,
-4.86 at Jonesboro,
-4.39 at Duluth, -3.44 at Gainesville, -2.48 at Rome and -0.75 at
Blairsville.
Stream
flows statewide remain at record- to near-record-low flows
for the end of May. The
Altamaha, Flint, Little, Ocmulgee, Oconee, Ohoopee and St. Mary’s
rivers set daily
low-flow records for May 31.
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Keetch-Byram Drought
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The higher the KBDI numbers,
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Wildfire Dangers
Rising
Wildfire dangers are increasing. A measure of wildfire drought
is the
Drought Index from the
scale runs from zero to
800.
As of May 30, KBDI values were greater than 600 across the
southern quarter of Georgia.
KBDI values greater than 500 were south of the fall line
(Columbus to Macon to Augusta).
With KBDI values greater than 500, expect excessive site
damage when fires break out.
With values greater than 600, just suppressing fires becomes a
major problem.
Drought Likely to
Continue
I expect the drought to continue through the summer, barring a
tropical weather system.
This outlook is based on two factors.
The first is that with normal weather, soils in Georgia lose
moisture during the
summer. Thus, even if Georgia returns to normal rainfall
patterns, the soils will keep
getting drier.
The second factor is the lack of soil moisture for
thunderstorms. During the summer,
most of Georgia’s rain is the result of scattered afternoon and
evening storms. Without a
readily available local supply of moisture, these storms will be
diminished.
