a look back at 2011/ a look ahead at 2012 john lewis, senior forecaster national weather service...
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A Look Back at 2011/A Look Ahead at 2012
John Lewis, Senior Forecaster
National Weather ServiceLittle Rock, Arkansas
The Year So Far
2011 started with widespread drought conditions following a winter with below normal precipitation.
Most of Arkansas was hammered with heavy rain in April and May, with a hot and dry summer to follow.
Most recently, there was one deluge after another in November and early December.
The Year So Far
It has been a year of extremes (feast or famine)!
Breaking It Down2011 (Thru Oct)
Breaking It DownJune – Oct, 2011
Drought StatusOctober 25,
2011
An extreme to exceptional drought was noted in much of southwest Arkansas.
Fronts (boundaries) moved into Arkansas from the northwest and stalled. Heavy rain focused along and north of the fronts.
Wet PatternNovember/Early December, 2011
A Lot of of RainNov 12 – Dec 11, 2011
Rainfall
A Lot of of RainNov 12 – Dec 11, 2011
Departure (+/-)
Drought Status
An extreme to exceptional drought remained in the far southwest.
December 6, 2011
Drought StatusDecember 6, 2011
An extreme to exceptional drought remained in the far southwest.
+11.76”
-18.53”
Arctic Oscillation (AO)
Arctic Oscillation (AO)
Arctic Oscillation (AO)
Arctic Oscillation (AO)
Arctic Oscillation (AO)
La Niña Conditions
Below normal sea surface temperatures (SST) were noted in the equatorial Pacific.
La Niña Setup
West East
Stronger Westward Trade WindsStronger Westward Trade Winds
La Niña Setup
West East
Warm Surface WaterWarm Surface Water
Cool Water/UpwellingCool Water/Upwelling
La Niña Pattern
La Niña Pattern
Winter ForecastTemperature
Below NormalBelow Normal
Above NormalAbove Normal
Winter ForecastPrecipitation
Below NormalBelow Normal
Above NormalAbove Normal
Drought StatusDecember 6, 2011
Drought OutlookThrough February, 2011
Arkansas should mostly stay out of the drought business, with improvement possible in the southwest.
January – March PrecipitationTypical La Niña
There is usually a wet signal from Arkansas to the Ohio Valley by late winter/early spring.
The Forecast
Significant precipitation this winter will be most likely in northern/eastern Arkansas, with lesser amounts expected in the southwest (where departures from normal are already extreme).
Be prepared for an active late winter/early spring, with severe storms and at or above normal precipitation.
Flooding could become a problem, especially in the White River basin.
Drought FrequencyLittle Rock
Norm Precip = 50” <45” <40”1920s 6 3 1930s 3 11940s 3 21950s 4 11960s 3 21970s 2 0 1980s 1 11990s 5 12000s 4 2
Since the 1870s…
Three Consecutive Years < 45”
5 times (last 1998-2000)
Three Consecutive Years < 40”
Never
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
The End
Thanks for coming!