Matt Masek NWS Meteorologist, WFO North Platte, NE May 25, 2011

Revisit last year (2010) Revisit last year (2010) What has happened this spring (2011) What has happened this spring (2011) Summer Outlook (2011) Summer Outlook (2011)

North Platte Spring (March, April, May) North Platte Summer (June, July, August)

MAY MAY

Valentine Spring (March, April, May) Valentine Summer (June, July, August)

MAYMAY

El Niño Southern Oscillation (ENSO) El Niño Southern Oscillation (ENSO) 3 Phases – Based on a section of the southern Pacific Ocean (region Niño 3.4) temperature, departure from normal. 3 Phases – Based on a section of the southern Pacific Ocean (region Niño 3.4) temperature, departure from normal. ENSO Warm (3 months +0.5°C) - El Niño ENSO Warm (3 months +0.5°C) - El Niño ENSO Neutral ENSO Neutral ENSO Cool (3 months -0.5°C) - La Niña ENSO Cool (3 months -0.5°C) - La Niña Effects on the United States Effects on the United States Most prevalent in Winter Months Most prevalent in Winter Months Hurricane Season Hurricane Season

Summer 2010 Phase Summer 2010 Phase Weakening El Niño Weakening El Niño Winter Phase Winter Phase Moderate-strong La Niña Moderate-strong La Niña Summer 2011 Phase Summer 2011 Phase Weakening La Niña Weakening La Niña 2010 to 2011 Opposites 2010 to 2011 Opposites

After an El Nino Winter After an La Niña Winter

CPC – Climate Prediction Center CPC – Climate Prediction Center 6 to 10 day outlook & 8 to 14 day outlooks are produced daily (Above Normal, Normal, Below Normal) 6 to 10 day outlook & 8 to 14 day outlooks are produced daily (Above Normal, Normal, Below Normal) One month outlook and 3 month outlooks issued on the third Thursday of the month (Tercile Forecast) One month outlook and 3 month outlooks issued on the third Thursday of the month (Tercile Forecast) One month outlook updated on the last day of the month (Tercile Forecast) One month outlook updated on the last day of the month (Tercile Forecast)

Tercile Forecast (What?) Tercile Forecast (What?) 3 Categories (both Temperature & Precipitation) 3 Categories (both Temperature & Precipitation) Above Normal (33.3%) Above Normal (33.3%) Normal (33.4%) Normal (33.4%) Below Normal (33.3%) Below Normal (33.3%) No shading is NOT normal expected No shading is NOT normal expected No shading is not enough skill to predict one way or the other (Labeled EC or Equal Chance for any of the three categories to happen) No shading is not enough skill to predict one way or the other (Labeled EC or Equal Chance for any of the three categories to happen)

June – Weakening La Niña, Atmosphere still acting like La Niña - more active northern storm track June – Weakening La Niña, Atmosphere still acting like La Niña - more active northern storm track JJA – ENSO becoming neutral, transition period difficult to predict, when La Niña pattern disappears JJA – ENSO becoming neutral, transition period difficult to predict, when La Niña pattern disappears

Heat “bubble” across southwestern U.S. and southern plains could develop and become dominating weather pattern for western and central Nebraska Heat “bubble” across southwestern U.S. and southern plains could develop and become dominating weather pattern for western and central Nebraska More likely over southwest Nebraska More likely over southwest Nebraska If “heat ridge” does develop, above normal temperatures and dry will become more widespread, possible drought? If “heat ridge” does develop, above normal temperatures and dry will become more widespread, possible drought?

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