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Official 90-day Outlooks are issued once each month near mid-month at 8:30am Eastern Time. Please consult the schedule of 30 & 90-day outlooks for exact release dates.

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    0.5mn JJA 2015
    1.5mn JAS 2015
    2.5mn ASO 2015
    3.5mn SON 2015
    4.5mn OND 2015
    5.5mn NDJ 2015
    6.5mn DJF 2015
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   10.5mn AMJ 2016
   11.5mn MJJ 2016
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    0.5mn Jun 2015


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   CCA
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HOME> Outlook Maps>Seasonal Forecast Discussion
 
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EDT THURSDAY MAY 21 2015

30-DAY OUTLOOK DISCUSSION FOR JUNE 2015

EQUATORIAL SEA-SURFACE TEMPERATURE (SST) ANOMALIES REMAINED ABOVE NORMAL FOR
MUCH OF THE EQUATORIAL PACIFIC, AND ALONG THE WEST COAST OF MUCH OF NORTH
AMERICA. COUPLING BETWEEN THE ATMOSPHERE AND OCEAN OVER THE TROPICAL PACIFIC
REMAINS STRONG, WITH ENHANCED CONVECTION AND ANOMALOUS LOW-LEVEL WESTERLIES
OBSERVED OVER THE PAST SEVERAL WEEKS NEAR THE DATE LINE.

DYNAMICAL MODEL GUIDANCE IS GENERALLY IN GOOD AGREEMENT ON BOTH THE TEMPERATURE
AND PRECIPITATION FORECASTS FOR JUNE. A PLETHORA OF DYNAMICAL GUIDANCE WAS
CONSULTED, INCLUDING DETERMINISTIC AND PROBABILISTIC GUIDANCE FROM THE WMO
GLOBAL PRODUCING CENTERS, WHICH INCLUDES MODELS FROM THE ECMWF AND UKMET, AMONG
OTHERS. GIVEN THE LATE TIME AT WHICH THIS FORECAST WAS ISSUED, THE MAPS WERE
SLIGHTLY TWEAKED TO REFLECT THE LATEST GUIDANCE ON WEEKS 3 AND 4 FROM THE ECMWF
AND CFS COUPLED SYSTEMS.

THE STATISTICAL GUIDANCE CONSULTED INCLUDED THE FOLLOWING: CONSTRUCTED ANALOG
BASED ON SOIL MOISTURE, COMPOSITE ANALOG BASED ON TROPICAL AND MIDLATITUDE SSTS
NEAR NORTH AMERICA, AND SEASONAL CORRELATIONS BETWEEN ENSO AND SURFACE
PARAMETERS FOR JJA. THESE TOOLS GENERALLY AGREED WITH THE LARGEST SIGNALS FROM
THE DYNAMICAL MODELS, HOWEVER, THEY INTRODUCED UNCERTAINTY OVER THE NORTHEAST,
WHERE THE NMME SUITE FAVORED ABOVE-NORMAL TEMPERATURES, AS WELL AS OVER THE
SOUTHWEST, WHERE THE DYNAMICAL MODELS MAY HAVE BEEN A BIT WARM. IT MAY INTEREST
THE USER THAT THE FORECAST IS ALSO CONSISTENT WITH 2-MONTH LAGGED CORRELATIONS
BETWEEN THE PDO AND AMO INDICES. THAT INFORMATION IS PARTLY CONTAINED WITHIN
THE AFOREMENTIONED COMPOSITE ANALOG BASED ON SST.

THE LARGEST SIGNAL FOR BELOW-NORMAL TEMPERATURES IS CENTERED OVER NORTH
TEXAS/OKLAHOMA, WHERE SOIL MOISTURE CURRENTLY EXCEEDS THE 90TH PERCENTILE AND
ALL GUIDANCE IS IN AGREEMENT. LIKEWISE, THE TOOLS ARE IN GOOD AGREEMENT OVER
THE PACIFIC NORTHWEST AND SOUTHERN ALASKA, WHERE THE BEST CHANCES OF
ABOVE-NORMAL TEMPERATURES RESIDE. UNCERTAINTY IS LARGEST NEAR THE EAST COAST
AND GREAT LAKES, WHERE EVERYTHING WAS SUBJECTIVELY COMBINED TO YIELD THE MAP AS
IT STANDS.

THE ONLY SUBSTANTIAL SIGNALS FOR PRECIPITATION COME FROM UNANIMOUS DYNAMICAL
AGREEMENT FAVORING ABOVE-MEDIAN RAINFALL OVER PARTS OF THE WEST-CENTRAL CONUS,
EXTENDING TOWARD THE SOUTHEAST. STATISTICAL GUIDANCE IS REASONABLY ON BOARD
WITH THIS, THOUGH PROBABILITIES ARE GENERALLY LOW TO REFLECT HISTORICALLY POOR
FORECAST SKILL IN THE 0.5 MONTH LEAD PRECIPITATION OUTLOOK.

IN AREAS WHERE THERE ARE NO STATISTICALLY SIGNIFICANT CLIMATE SIGNALS, SUCH
THAT THE LIKELIHOODS OF MONTHLY MEAN TEMPERATURES OR MONTHLY ACCUMULATED
PRECIPITATION AMOUNTS ARE EQUAL TO CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES
(EC) IS INDICATED.

THE MAIN FACTORS THAT USUALLY INFLUENCE THE MONTHLY CLIMATE OUTLOOK INCLUDE:
1) EL NINO AND LA NINA - WHICH COMPRISE ENSO. IMPACTS OF THESE EVENTS ARE
SUMMARIZED BY SEPARATING 3-MONTH OBSERVATIONS FROM THREE OR MORE DECADES INTO
EL NINO, NEUTRAL AND LA NINA SETS, AVERAGING EACH SEPARATELY, AND THEN
COMPUTING ANOMALIES. THESE ARE CALLED "COMPOSITES" AND USED AT TIMES TO
SUBJECTIVELY MODIFY THE FORECAST.
2) TRENDS - APPROXIMATED BY THE OCN TOOL AS THE DIFFERENCE BETWEEN THE MOST
RECENT 10-YEAR MEAN OF TEMPERATURE OR 15-YEAR MEAN OF PRECIPITATION FOR A GIVEN
LOCATION AND TIME OF YEAR AND THE 30-YEAR CLIMATOLOGY PERIOD (CURRENTLY
1981-2010).
3) THE TROPICAL 30-60 DAY OSCILLATION - CALLED THE MADDEN JULIAN OSCILLATION
(MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS.
4) THE ARCTIC OSCILLATION (AO), THE SIMILAR NORTH ATLANTIC OSCILLATION (NAO),
AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE
ANOMALY PATTERN ESPECIALLY DURING BOREAL WINTER AND ARE GENERALLY CONSIDERED TO
HAVE LOW PREDICTABILITY.
5) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE
VARIABILITY AFFECTING THE TROPICS AND THE NORTH PACIFIC AND NORTH AMERICAN
REGIONS, BUT WHICH VARIES ON A MUCH LONGER TIME-SCALE THAN ENSO.
6) PERSISTENTLY DRY OR WET SOILS IN THE SPRING AND SUMMER AND SNOW AND ICE
COVER ANOMALIES IN THE WINTER. THESE FACTORS TEND TO PERSIST FOR LONG PERIODS
AND ACT AS A KIND OF MEMORY IN THE CLIMATE SYSTEM.
7) STATISTICAL FORECAST MODELS - CANONICAL CORRELATION ANALYSIS (CCA),
SCREENING MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOG (CA), AND
ENSEMBLE CCA (ECCA).
8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM
VERSION 2 (CFS) AND FOR THE ZERO-LEAD UPDATE FORECASTS THE NCEP GLOBAL ENSEMBLE
FORECAST SYSTEM (GEFS).  AN EXPERIMENTAL FORECAST SYSTEM, THE NATIONAL
MULTI-MODEL ENSEMBLE (NMME), COMPRISED OF SEVERAL DYNAMICAL MODELS IS ALSO USED.


FORECASTER: STEPHEN BAXTER


THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, FOLLOWING
THE WORLD METEOROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3
COMPLETE DECADES AS THE CLIMATE REFERENCE PERIOD.  THE PROBABILITY ANOMALIES
FOR TEMPERATURE AND PRECIPITATION BASED ON THESE NEW NORMALS BETTER REPRESENT
SHORTER TERM CLIMATIC ANOMALIES THAN THE FORECASTS BASED ON OLDER NORMALS.



AN UPDATED MONTHLY OUTLOOK... FOR JUN WILL BE ISSUED ON SUN MAY 31 2015


THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.

$$

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