1. By Matt Masek March 22, 2012

2. Outline Review of 2011 – 2012 Winter Role of La Niña and Arctic Oscillation Spring Outlook One month (April) outlook Three month (April, May, June) outlook Current Drought Conditions Developing??? Quick look at the end of March Forecast

3. La Niña 2011-2012 For southwestern Nebraska, closer proximity to cool temperatures and drier conditions. La Niña - Typical Wintertime Pattern

4. What was 2011-2012 Winter? Temperatures were above normal Precipitation (rain/snow) was above normal Why - last year and this year both were La Niña years La Niña was NOT the dominate player

5. So what was the dominate player ? Arctic Oscillation Based on 1000 mb height anomalies pole ward of 20° N 2011-2012 Positive Phase Only major snowstorm for southwest Nebraska

6. 2011-2012 Winter North Platte, NE Facts for the 3 month period of December, January, & February (and the last 5 years).

7. 2011-2012 Winter North Platte, NE

8. Temperature Summary for North Platte Dec 1, 2011 to Feb 29, 2012 Smooth tan line is normal Red and blue lines are records Precipitation Summary for North Platte Dec 1, 2011 to Feb 29, 2012 (dark blue) Dec 1 2010 to Feb 28, 2011 (magenta) Smooth red line is normal

9. 2011-2012 Winter Imperial, NE Temperature Summary for Imperial Dec 1, 2011 to Feb 29, 2012 Smooth tan line is normal Red and blue lines are records Precipitation Summary for Imperial Dec 1, 2011 to Feb 29, 2012 (dark blue) Dec 1 2010 to Feb 28, 2011 (magenta) Smooth red line is normal

10. 2011-2012 Winter Haigler, NE Temperature Summary for Haigler Dec 1, 2011 to Feb 29, 2012 Smooth tan line is normal Red and blue lines are records Precipitation Summary for Haigler Dec 1, 2011 to Feb 29, 2012 (dark blue) Dec 1 2010 to Feb 28, 2011 (magenta) Smooth red line is normal

11. Spring Outlook Still have a La Niña pattern (although it is weakening) Lingering effects from wintertime pattern and the positive AO Polar Jet Stream – promotes more clipper systems or fast moving cold fronts Fast moving fronts have limited time to produce significant moisture over the high plains Drier overall atmospheric conditions favor a wide swing of temperatures from day to day Due to warm winter over the Northern Plains there is a lack of snow cover – this will help to modify (warm) cold arctic outbreaks

12. Climate Prediction Center Forecast - April Higher confidence in southwest Nebraska to experience below normal precipitation while equal chances for above, below or near normal precipitation for the rest of Nebraska. Higher confidence for above normal temperatures to continue over Nebraska and much of the lower 4 8 states.

13. Climate Prediction Center Forecast - April, May, June The forecast for April, May and June are higher chance for below normal precipitation over Western Nebraska, with equal chances for above, below or near normal precipitation over central and eastern Nebraska. There is higher confidence the desert southwest and much of the south and eastern U.S. will see above normal temperatures. However over Nebraska no strong signals results in equal chances for above, below or near normal temperatures.

14. Climate Prediction Center Summer Forecast – June, July, August The ENSO (El Niño Southern Oscillation) phase is expected to trend toward neutral this summer. This pushes the long range forecast to have more uncertainty for the summer across the central plains. Thus western and north central Nebraska see a forecast of equal chances for above, below or near normal precipitation and temperatures. Although recent trends for warm conditions over the desert southwest have a chance of expanding over the high plains.

15. Current Drought State

17. Drought Developing??

18. Areas to the southwest of Nebraska are being monitored for developing drought conditions over the next several months. Due to the uncertainty of precipitation for May and June, southwest Nebraska is not expected to see the development of the drought yet. Below normal precipitation is expected over the next month or so. April is when this area begins to receive more significant rainfall from thunderstorms. May and June are the wettest months of the year.

19. Climate Prediction Center 8 to 14 Day Outlook (Mar 29-Apr 4) March to end and April begins with continued warm conditions. Low pressure system tracks across the southern plains. Western Nebraska likely to miss out on the moisture with this system.

20. National Weather Service Online

21. Weakening La Niña to create tricky forecast for Nebraska Higher confidence April will be warm Higher confidence areas to the southwest – dry Drought conditions may expand into southwest Nebraska, (May and June?) however uncertainty exists at this time. Questions – Matthew.Masek@noaa.gov The End – Questions???