Wildlife and Forestry - Jeff Taverner, Arkansas Game & Fish Commission
Forest2012
1. Drought in Arkansas
John Lewis
National Weather Service
Little Rock, Arkansas
john.lewis@noaa.gov
Emilie Nipper
National Weather Service
Little Rock, Arkansas
emilie.nipper@noaa.gov
2. Recent Trends
Since 2010, La Niña conditions (cooler
than normal water in the equatorial
Pacific Ocean) were dominant.
The Arctic Oscillation (AO) played a
significant role in temperature trends
and precipitation amounts.
There have been a lot of extremes,
with either feast (i.e. very active
weather) or famine (i.e. little
rain/heat/drought) and not much in-
14. A Closer Look at AO
1995: 6 th Driest Late 2005: A
Summer at Little Early 2005: Wet Period
Rock (4.84”) Very Dry (Rita)
Late 2001/Early 2002: Early 2008:
Widespread Flooding Tornadoes, Flooding &
Heavy Snow
15. Forecasting With AO
Impacts associated with AO mostly
occur from the fall into the spring
(October through May).
Long range forecasting, at least
beyond a few weeks, is difficult to
impossible with the AO.
Any impacts (due to fluctuation
between positive and negative) are
usually short-lived.
17. La Niña Setup
Warm Surface Water
Cool Water/Upwelling
West East
18. A Closer Look at ENSO
Typical Winter Forecast
Cold
Warm
Wet
Dry
19. Forecasting with ENSO
There is at least some confidence in a
long term forecast when keying on La
Niña/El Niño conditions.
While there may be strengthening or
weakening over several months, the
state (La Niña/El Niño) is fairly
steady.
The forecast can be altered
(sometimes significantly) by the short-
term effects of AO.
25. AO in 2011
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2011 -1.68 +1.58 +1.42 +2.28 -0.04 -0.86 -0.47 -1.06 +0.67 +0.80 +1.46 +2.22
The AO Index was mostly negative,
with a strong positive surge in the
spring of 2011 and again late in the
year.
26. Big Time Rain
April, 2011
Percent
of
normal
rainfall.
34. Deadliest Tornado
In April/May,
67 of the 75
tornadoes in
2011 were
spawned. All
tornado
fatalities (12
of them) and
17 of 18 flood
deaths
occurred
during this
35. Deadliest Tornado
This tornado
(rated EF2)
killed 4 people
just southwest
of Vilonia
(Faulkner
County) on
April 25, 2011.
36. The Dreaded High
A ridge of
high pressure
built over
Arkansas in
June, and
was a
frequent
visitor
through July.
39. Drought Status
October 25,
2011
An extreme
to
exceptional
drought was
noted in
much of
southwest
Arkansas.
40. Wet Pattern
November/Early December,
2011
Fronts
(boundaries)
moved into
Arkansas from
the northwest
and stalled.
Heavy rain
focused along
and north of
the fronts.
41. A Lot of of Rain
Nov 12 – Dec 11, 2011
Rainfall (3.5” to 5.5” is normal)
42. Drought Status
December 27,
2011
A severe to
extreme
drought
remained in the
far southwest,
but was over
elsewhere.
43. Good/Bad Timing
The deluge to end 2011 plus a wet start
in 2012 helped charge the soil with
water at a time when vegetation was
dormant.
The rain stopped coming in April, with
well below normal amounts measured.
44. Arctic Oscillation (AO)
AO+ in
March Flat AO
in A largely
April positive AO
from January
through March
went flat in
April.
45. Precipitation Trends
January through July,
2012
J F M A M J J
10
5 Harrison
Fort Smith
0 Jonesboro
Little Rock
-5 El Dorado
Texarkana
-10
Pine Bluff
-15
Departure From Normal
46. A Lack of Rain
April through July,
2012
Statewide Average: 9.03” (Driest on
Record)
51. Drought Impacts
A University of Arkansas Division of
Agriculture report revealed that 85%
of pastures were in poor or very poor
condition, with the smallest hay
yields since 1954.
According to the Arkansas Forestry
Commission, there were 855 fires that
burned almost 16,000 acres in July
and August.
Record low levels on area tributaries.
53. Playing the Odds
Research showed that odds for a Top
25 warm summer were somewhat low
(42% chance locally) following a
record warm first five months of 2012.
After June/July, we had a Top 5 warm
summer going at several locations,
including Little Rock.
If the research was correct, changes
were coming in August (and possibly
beyond), especially given a developing
El Niño.
55. And Even More Rain…
The first half of September featured
well below normal temperatures at
times and areas of heavy rain.
From July 31st to September 17th,
precipitation departures from normal
went from -7.75 inches to -1.19 inches
at Little Rock (Pulaski County) and
from -10.92 inches to +0.74 inches at
Pine Bluff (Jefferson County).
56. Precipitation Trends
January through September,
2012
J F M A M J J A S
10
Note: September
is
5 Harrison
through the 17th.
Fort Smith
0 Jonesboro
Little Rock
-5 El Dorado
Texarkana
-10
Pine Bluff
-15
Departure From Normal
64. The Forecast
A continued “correction” toward cool
and wet (at/above normal rain and
at/below normal temperatures) is
expected through the end of the year
(El Niño driven).
There may be a return to dry
conditions in the late winter/early
spring (favored in eastern Arkansas).
However, a positive AO could reverse
this.
Drought conditions will likely improve
65. On the Web
Visit the National Weather Service
Little Rock website at this address…
http://www.srh.noaa.gov/lzk
or Google…
National Weather Service Little Rock
