Matt MasekNWS 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)

MAYMAY MAMAYY

20102010 20112011

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

MAYMAY MAMAYY

20102010 20112011

El Niño Southern Oscillation (ENSO)El Niño Southern Oscillation (ENSO)3 Phases – Based on a section of the southern 3 Phases – Based on a section of the southern

Pacific Ocean (region Niño 3.4) temperature, Pacific Ocean (region Niño 3.4) temperature, departure from normal.departure from normal.ENSO Warm (3 months +0.5°C) - El NiñoENSO Warm (3 months +0.5°C) - El NiñoENSO NeutralENSO NeutralENSO Cool (3 months -0.5°C) - La NiñaENSO Cool (3 months -0.5°C) - La Niña

Effects on the United StatesEffects on the United StatesMost prevalent in Winter MonthsMost prevalent in Winter MonthsHurricane SeasonHurricane Season

Summer 2010 Phase Summer 2010 Phase Weakening Weakening

El NiñoEl Niño Winter 2010-11 Winter 2010-11

Phase Phase Moderate-strong Moderate-strong

La NiñaLa Niña Summer 2011 Phase Summer 2011 Phase

Weakening Weakening La NiñaLa Niña

2010 to 2011 2010 to 2011 OppositesOpposites

After an El Nino Winter

After an La Niña Winter

CPC – Climate Prediction CenterCPC – Climate Prediction Center6 to 10 day outlook & 8 to 14 day outlooks are 6 to 10 day outlook & 8 to 14 day outlooks are

produced daily produced daily (Above Normal, Normal, Below Normal)(Above Normal, Normal, Below Normal)

One month outlook and 3 month outlooks issued One month outlook and 3 month outlooks issued on the third Thursday of the month on the third Thursday of the month (Tercile Forecast)(Tercile Forecast)

One month outlook updated on the last day of One month outlook updated on the last day of the month the month (Tercile Forecast)(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 expectedNo shading is NOT normal expectedNo shading is not enough skill to predict one No shading is not enough skill to predict one

way or the other (Labeled EC or Equal Chance way or the other (Labeled EC or Equal Chance for any of the three categories to happen)for any of the three categories to happen)

June – Weakening La Niña, Atmosphere still June – Weakening La Niña, Atmosphere still acting like La Niña - more active northern storm acting like La Niña - more active northern storm tracktrack

JJA – ENSO becoming neutral, transition period JJA – ENSO becoming neutral, transition period difficult to predict, when La Niña pattern difficult to predict, when La Niña pattern disappearsdisappears

Heat “bubble” across southwestern U.S. and Heat “bubble” across southwestern U.S. and southern plains could develop and become southern plains could develop and become dominating weather pattern for western and dominating weather pattern for western and central Nebraskacentral Nebraska

More likely over southwest NebraskaMore likely over southwest NebraskaIf “heat ridge” does develop, above normal If “heat ridge” does develop, above normal

temperatures and dry will become more temperatures and dry will become more widespread, possible drought?widespread, possible drought?

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