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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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More Outlooks
    0.5mn JJA 2013
    1.5mn JAS 2013
    2.5mn ASO 2013
    3.5mn SON 2013
    4.5mn OND 2013
    5.5mn NDJ 2013
    6.5mn DJF 2013
    7.5mn JFM 2014
    8.5mn FMA 2014
    9.5mn MAM 2014
   10.5mn AMJ 2014
   11.5mn MJJ 2014
   12.5mn JJA 2014
    0.5mn Jun 2013


Tools Used (see Discussion for explanation)
   CCA
   OCN
   CMP
   SMT
   POE
 
HOME> Outlook Maps>Seasonal Forecast Discussion
 
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300PM EDT FRIDAY MAY 31 2013

30-DAY OUTLOOK DISCUSSION FOR JUNE 2013

ATMOSPHERIC AND OCEANIC CONDITIONS OVER THE TROPICAL PACIFIC CONTINUE TO
INDICATE ENSO-NEUTRAL CONDITIONS. EQUATORIAL SEA SURFACE TEMPERATURES (SSTS)
REMAIN NEAR LONG-TERM CLIMATOLOGICAL NORMAL VALUES WEST OF ABOUT 135W
LONGITUDE, BUT HAVE COOLED DURING THE MONTH OF MAY AND BECOME BELOW NORMAL OVER
THE EASTERN PACIFIC FROM ABOUT 135W TO THE SOUTH AMERICAN COAST. WHILE THE
AVERAGE SUBSURFACE OCEAN TEMPERATURES TO A DEPTH OF 300 METERS IN THE
EQUATORIAL PACIFIC ARE ONLY SLIGHTLY BELOW NORMAL, THERE IS A LARGE VOLUME OF
WARMER THAN NORMAL WATER BELOW THE SURFACE TO THE WEST OF THE DATE LINE, AND A
REGION OF COOLER THAN NORMAL WATER HAS DEVELOPED IN THE LAST MONTH TO THE EAST
OF 120W FROM THE SURFACE TO ABOUT 100 METERS DEPTH. DURING THE LAST MONTH
TROPICAL CONVECTION WAS ENHANCED IN THE REGION AROUND THE MARITIME CONTINENT
AND SUPPRESSED OVER THE CENTRAL AND EASTERN EQUATORIAL PACIFIC. THE
MADDEN-JULIAN OSCILLATION (MJO) IS NOT CURRENTLY ACTIVE.

THE JUNE 2013 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE UPDATED AT THE END OF
THE MONTH OF MAY USING THE LATEST GUIDANCE FROM DYNAMICAL WEATHER PREDICTION
MODELS, INCLUDING CALIBRATED FORECASTS FROM THE NCEP GLOBAL ENSEMBLE FORECAST
SYSTEM (GEFS) USING REFORECASTS AND THE NORTH AMERICAN ENSEMBLE FORECAST SYSTEM
(NAEFS) FOR THE FIRST TWO WEEKS OF JUNE AND FROM THE NCEP CLIMATE FORECAST
SYSTEM (CFSV2) FOR THE COMING MONTH. ADDITIONALLY, CLIMATE FORCING MECHANISMS
SUCH AS UNUSUALLY DRY SOIL CONDITIONS AND DECADAL-TIMESCALE CLIMATE TRENDS ALSO
PLAYED A ROLE IN THE MONTHLY UPDATE.

THE REVISED TEMPERATURE OUTLOOK FOR JUNE 2013 INDICATES A GREATER PROBABILITY
FOR ABOVE NORMAL MEAN TEMPERATURES FOR PARTS OF THE PACIFIC NORTHWEST AND GREAT
BASIN AND DECREASED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES IN THE CENTRAL
AND SOUTHERN PLAINS. ABOVE NORMAL MEAN MONTHLY TEMPERATURES ARE LESS LIKELY IN
THE GREAT PLAINS WITH CURRENT MODEL PREDICTIONS OF BELOW NORMAL TEMPERATURES IN
THE NEXT TWO WEEKS. BOTH SHORTER TERM AND MONTHLY MODEL FORECASTS PREDICT AN
INCREASED PROBABILITY OF ABOVE NORMAL TEMPERATURES IN THE WEST. THE FORECAST
FOR THE CALIFORNIA COAST CONTINUES TO INDICATE EQUAL CHANCES OF ABOVE, NEAR AND
BELOW NORMAL TEMPERATURES, WITH BELOW NORMAL SSTS EXPECTED TO MODERATE MONTHLY
MEAN TEMPERATURES.

THE REVISED PRECIPITATION OUTLOOK FOR JUNE 2013 INDICATES INCREASING
PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR PARTS OF THE SOUTHEAST AND
ESPECIALLY FLORIDA AND FOR THE ALASKAN PANHANDLE. THE PROBABILITIES OF BELOW
MEDIAN PRECIPITATION FOR THE SOUTHWEST AND THE SOUTHERN PLAINS HAVE DECREASED.
DYNAMICAL MODEL FORECASTS FOR THE FIRST TWO WEEKS OF JUNE INDICATE GREATER
CHANCES OF ABOVE MEDIAN PRECIPITATION FOR THE ALASKAN PANHANDLE, THE SOUTHERN
AND CENTRAL PLAINS, AND THE SOUTHEAST EARLY IN THE MONTH, REDUCING THE ODDS OF
BELOW MEDIAN TOTAL PRECIPITATION IN SOME AREAS. IN THE SOUTHWEST, THE CHANCES
OF BELOW MEDIAN PRECIPITATION IN REGIONS THAT HAVE A RELATIVELY DRY CLIMATOLOGY
ARE DECREASED.

*** THE HALF-MONTH LEAD MONTHLY OUTLOOK DISCUSSION FOR JUNE 2013 FOLLOWS. ***

ENSO-NEUTRAL CONDITIONS CONTINUE ACROSS THE TROPICAL PACIFIC BASIN. EQUATORIAL
SEA SURFACE TEMPERATURES (SSTS) FROM ABOUT 135W WESTWARD ACROSS THE CENTRAL AND
WESTERN PACIFIC ARE CLOSE TO LONG-TERM AVERAGES. FROM ABOUT 135W EASTWARD TO
THE SOUTH AMERICAN COAST, SSTS ARE GENERALLY 1-2 DEGREES C BELOW AVERAGE. THE
SUBSURFACE TEMPERATURE ANOMALY PATTERN IS WEAK AND LARGELY NON-DESCRIPT EAST OF
THE DATE LINE, WHILE WEST OF THE DATE LINE A LARGE VOLUME OF RELATIVELY WARM
WATER (COMPARED TO NORMAL) IS OBSERVED AT DEPTHS RANGING FROM 50-250 METERS.
THROUGHOUT THE MONTH OF APRIL, THE NEAR-EQUATORIAL UPPER-OCEAN HEAT CONTENT
REMAINED SLIGHTLY BELOW AVERAGE. THE OBSERVED TROPICAL CONVECTION PATTERN FOR
THE PAST 30 DAYS SHOWS ENHANCED CONVECTIVE ACTIVITY OVER THE FAR WESTERN
PACIFIC AND ADJACENT PORTIONS OF THE MARITIME CONTINENT REGION, AND SUPPRESSED
CONVECTIVE ACTIVITY ACROSS THE CENTRAL AND EAST-CENTRAL TROPICAL PACIFIC, FROM
ABOUT 170E TO 120W.

THE JUNE 2013 TEMPERATURE AND PRECIPITATION OUTLOOKS UTILIZED STATISTICAL AND
DYNAMICAL GUIDANCE, WHICH INCLUDED THE CLIMATE FORECAST SYSTEM MODEL (CFSV2),
THE NATIONAL MULTI-MODEL ENSEMBLE (NMME), THE CONSTRUCTED ANALOG ON SOIL
MOISTURE (CAS), THE SCREENING MULTIPLE LINEAR REGRESSION (SMLR), THE CANONICAL
CORRELATION ANALYSIS (CCA), AND THE OPTIMAL CLIMATE NORMALS (OCN).

THE JUNE TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES WEST OF THE
CONTINENTAL DIVIDE, EXCLUDING NEAR THE PACIFIC COAST WHERE EQUAL CHANCES (EC)
OF BELOW, NEAR, AND ABOVE-NORMAL TEMPERATURES ARE FAVORED. ABOVE-NORMAL
TEMPERATURES ARE ALSO FAVORED EAST OF THE DIVIDE OVER THE CENTRAL AND INTERIOR
SOUTHERN GREAT PLAINS. THIS PREDICTED PATTERN HAS GOOD SUPPORT FROM THE NMME,
AS WELL AS FROM ITS CONSTITUENT CLIMATE MODELS. THE AREAS OF EC ANTICIPATED
ALONG THE WEST COAST AND TEXAS COAST ARE DUE TO THE EXPECTED PERSISTENCE OF
ABNORMALLY COOL SSTS. IN THE EASTERN HALF OF THE CONTIGUOUS U.S., WHERE
STATISTICAL AND DYNAMICAL MODEL RUNS EXHIBITED CONFLICTING AND/OR WEAK SIGNALS,
A FORECAST OF EC WAS ASSIGNED. ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED OVER
NORTHERN ALASKA, BASED PRIMARILY ON THE TRADITIONAL STATISTICAL TOOLS (SMLR,
CCA, AND OCN) WHICH TEND TO EMPHASIZE LONGER-TERM TRENDS. ELSEWHERE ACROSS
ALASKA, EQUAL CHANCES (EC) OF BELOW, NEAR, AND ABOVE-NORMAL TEMPERATURES IS
PREDICTED.

THE JUNE PRECIPITATION OUTLOOK SHOWS ENHANCED ODDS OF BELOW-MEDIAN AMOUNTS OF
PRECIPITATION OVER THE PACIFIC NORTHWEST, CALIFORNIA, NEVADA, AND MUCH OF BOTH
THE ROCKIES AND CENTRAL AND SOUTHERN PLAINS. THIS FORECAST IS BASED LARGELY ON
THE NMME AND RECENTLY OBSERVED PRECIPITATION PATTERNS. UNSEASONABLY WET
CONDITIONS IN THE PAST FEW WEEKS ACROSS COLORADO AND EASTERN UTAH LEAD TO A
MORE CAUTIOUS EC FORECAST (AS OPPOSED TO INCREASED ODDS OF BELOW-MEDIAN
PRECIPITATION) IN THIS AREA. MOST OF THE AVAILABLE DYNAMICAL AND STATISTICAL
GUIDANCE INDICATES HIGHER PROBABILITIES FOR BELOW-MEDIAN PRECIPITATION OVER NEW
MEXICO, AND MUCH MORE UNCERTAINTY FOR ARIZONA. THIS SUGGESTS ANY MOISTURE
ASSOCIATED WITH THE ONSET OF THE SUMMER MONSOON MAY BE DIRECTED MOSTLY TOWARD
ARIZONA. FOR THE EASTERN HALF OF THE CONUS AND ALASKA, THE CLIMATE MODELS
SHOWED WEAK AND/OR CONFLICTING SIGNALS, DEEMED TOO UNRELIABLE TO INCLUDE IN THE
OFFICIAL OUTLOOK. THEREFORE, EC IS FAVORED IN THESE AREAS.

THE MAIN FACTORS WHICH 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) PERSISTANTLY 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 (CFS)
AND FOR ZERO-LEAD UPDATE FORECASTS THE NCEP GLOBAL ENSEMBLE FORECAST SYSTEM
(GEFS). THE EARLIER VERSION OF THE CFS MODEL WAS DISCONTINUED AS OF OCTOBER,
2012. AN EXPERIMENTAL FORECAST SYSTEM, THE NATIONAL MULTI-MODEL ENSEMBLE
(NMME), COMPRISED OF SEVERAL DYNAMICAL MODELS IS ALSO USED.


FORECASTER: DAN COLLINS


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.



THE NEXT MONTHLY OUTLOOK...FOR JUL ... WILL BE ISSUED ON THU JUN 20 2013


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

$$

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