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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 JAS 2014
    1.5mn ASO 2014
    2.5mn SON 2014
    3.5mn OND 2014
    4.5mn NDJ 2014
    5.5mn DJF 2014
    6.5mn JFM 2015
    7.5mn FMA 2015
    8.5mn MAM 2015
    9.5mn AMJ 2015
   10.5mn MJJ 2015
   11.5mn JJA 2015
   12.5mn JAS 2015
    0.5mn Jul 2014


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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
300PM EDT MONDAY JUN 30 2014

30-DAY OUTLOOK DISCUSSION FOR JULY 2014

THE REVISED JULY OUTLOOK IS CHANGED SLIGHTLY OVER THE CONUS, WITH THE LARGEST
CHANGE INTRODUCED IN THE PRECIPITATION OUTLOOK FOR ALASKA.  THE FORECASTS FROM
THE CFS REMAIN LARGELY CONSISTENT FROM RUN-TO-RUN OVER THE PAST WEEK.  THE MOST
RECENT OFFICIAL 6-10 AND 8-14 DAY OUTLOOKS FROM CPC, AS WELL AS THE RECENT CFS
RUNS INDICATE ABOVE-NORMAL 500-HPA HEIGHTS ACROSS THE NORTHERN TIER OF THE
CONUS AND WESTERN ALASKA FOR MOST OF THE NEXT MONTH.

RECENT CFS OUTPUTS, SOIL MOISTURE BASED ANALOGS, AND COMPOSITES BASED ON RECENT
SST PATTERNS LEAD TO AN EXPANSION OF THE AREA WHERE BELOW NORMAL TEMPERATURES
ARE FAVORED. THE SOIL MOISTURE BASED ANALOGS FROM JUNE 29 DEPICT A MUCH COOLER
FORECAST FOR MOST OF THE CONTIGUOUS 48 STATES THAN WAS INDICATED ON THE 0.5
MONTH LEAD JULY OUTLOOK. ABOVE NORMAL TEMPERATURES WERE EXPANDED SLIGHTLY UP
THE EAST COAST, REFLECTING MANY OF THE RECENT CFS RUNS AND SOME TRENDS IN SOIL
MOISTURE.

THE AREA WHERE BELOW MEDIAN PRECIPITATION IS FAVORED OVER THE LOWER MISSISSIPPI
VALLEY WAS SHIFTED NORTHEAST.  THAT CHANGE REFLECTS THE LATEST MODEL GUIDANCE
ON PRECIPITATION AND SOIL MOISTURE CONSTRUCTED ANALOG, AS WELL AS ALIGNING WITH
UPPER-LEVEL PATTERNS FROM DYNAMICAL MODELS.

CONSISTENT WITH THE CFS FORECASTS AND RECENT SST PATTERNS, ABOVE-NORMAL
TEMPERATURES ARE FORECAST OVER WESTERN ALASKA, WITH SLIGHTLY MORE COVERAGE AND
A HIGHER PROBABILITY. STRONGER THAN AVERAGE RIDGING IS PREDICTED BY THE CFS
OVER WESTERN ALASKA, LEADING TO A WESTWARD SHIFT IN THE AREA FAVORING BELOW
MEDIAN RAINFALL IN COMPARISON THE OUTLOOK ISSUE EARLIER THIS MONTH.  BELOW
MEDIAN PRECIPITATION IS NOW FAVORED OVER WESTERN ALASKA.

PREVIOUS DISCUSSION:

THE JULY OUTLOOK IS BASED ON EVOLVING ENSO CONDITIONS, SOIL MOISTURE, AND SEA
SURFACE TEMPERATURE (SST) ANOMALIES, AS WELL AS GUIDANCE FROM NUMERICAL CLIMATE
PREDICTION MODELS.

EL NINO IS FORECAST TO DEVELOP DURING THE NEXT SEVERAL MONTHS, WITH THE LATEST
CONSENSUS CPC/IRI FORECAST PLACING PROBABILITIES OF EL NINO OVER 70% FOR JAS.
THE CURRENT NORTH PACIFIC SSTS PROJECT QUITE STRONGLY ONTO THE POSITIVE PHASE
OF THE PDO (INDEX VALUE OF +1.80). IT IS REASONABLE TO EXPECT THIS BOUNDARY
FORCING TO PERSIST THROUGH JULY GIVEN THE CURRENTLY FAVORED EMERGENCE OF EL
NINO CONDITIONS.

RECENT SOIL MOISTURE OBSERVATIONS INDICATE ANOMALOUSLY WET CONDITIONS ACROSS
MUCH OF THE NORTHERN ROCKIES AND THE GULF COAST, WITH DRY SOILS OBSERVED FROM
THE MIDWEST TO THE SOUTHERN GREAT PLAINS, SOUTHWEST AND CALIFORNIA.

THE LATEST CFS FORECAST FAVORS ANOMALOUS RIDGING OVER WESTERN NORTH AMERICA,
EXPANDING EASTWARD OVER THE EASTERN TWO-THIRDS OF THE CONUS THROUGH THE MIDDLE
OF JULY. CONSTITUENTS OF THE NMME (NATIONAL MULTI-MODEL ENSEMBLE) EXHIBITED A
HIGH LEVEL OF AGREEMENT FOR SURFACE PARAMETERS. THE STATISTICAL TOOLS WERE
GENERALLY IN GOOD AGREEMENT WITH THE DYNAMICAL TOOLS AS WELL, ALTHOUGH THE
EXACT PLACEMENT OF FEATURES WAS SLIGHTLY DIFFERENT.

NUMERICAL GUIDANCE, CORRELATIONS BETWEEN THE PDO AND RECENT TEMPERATURES, AND
MUCH DRIER THAN NORMAL SOILS SUPPORT ENHANCED PROBABILITIES OF ABOVE-NORMAL
TEMPERATURES ACROSS MOST OF THE WEST, WEST OF THE CONTINENTAL DIVIDE.  MOST OF
THE DYNAMICAL MODEL GUIDANCE AND SOME OF THE STATISTICAL TOOLS INDICATED
ENHANCED ODDS FOR BELOW-NORMAL TEMPERATURES ACROSS THE NORTHERN GREAT PLAINS,
WITH SOME INPUTS FAVORING BELOW-NORMAL TEMPERATURES ACROSS THE GREAT LAKES AS
WELL. ENSO COMPOSITES ALSO HIGHLIGHT A SLIGHT TILT TOWARD BELOW-NORMAL
TEMPERATURES ACROSS THE FRONT RANGE OF THE CENTRAL ROCKIES AND PORTIONS OF THE
HIGH PLAINS. A STRONGER SUBTROPICAL RIDGE DEVELOPING LATER IN JULY (WEEK3/4
GUIDANCE FROM CFS) IS LIKELY TO CONTRIBUTE TO ABOVE-NORMAL TEMPERATURES ACROSS
THE SOUTH-CENTRAL AND SOUTHEAST CONUS. THE ODDS FOR ABOVE-NORMAL TEMPERATURES
ARE CONSTRAINED OVER THE SOUTHEAST AS THE CONSTRUCTED ANALOG FROM SOIL MOISTURE
(CAS) CONTRADICTS THE DYNAMICAL GUIDANCE.  THE STATISTICAL AND DYNAMICAL TOOLS
INDICATE NEAR OR ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR ALASKA, WITH
ABOVE-NORMAL SSTS IN THE NORTH PACIFIC LIKELY A CONTRIBUTING FACTOR.

THE PRECIPITATION OUTLOOK CALLS FOR ENHANCED ODDS OF ABOVE-MEDIAN PRECIPITATION
ALONG MOST OF THE ROCKIES.  DYNAMICAL GUIDANCE AND ENSO COMPOSITES KEYED TO
EL-NINO CONDITIONS INDICATE THE HIGHEST PROBABILITIES FOR ABOVE-MEDIAN
PRECIPITATION ACROSS THE CENTRAL AND NORTHERN ROCKIES.  CCA AND CON OUTPUT ALSO
INDICATE ABOVE-MEDIAN PRECIPITATION ACROSS THE NORTHERN ROCKIES, ALTHOUGH
CORRELATIONS BETWEEN THE PDO AND PRECIPITATION DO NOT SHOW A STRONG SIGNAL
EITHER WAY ACROSS THE NORTHERN ROCKIES. CORRELATIONS WITH THE PDO AND
COMPOSITES BASED ON EL NINO DO SHOW DRY CONDITIONS ACROSS SOUTHERN ARIZONA, SO
THE AREA OF ENHANCED ODDS FOR ABOVE-MEDIAN PRECIPITATION DOES NOT INCLUDE
SOUTHERN ARIZONA.  DYNAMICAL MODEL GUIDANCE IS NEARLY UNANIMOUS IN CALLING FOR
NEAR TO BELOW-MEDIAN PRECIPITATION FROM THE GULF COAST AND LOWER MISSISSIPPI
VALLEY TO SOUTHERN PORTIONS OF THE MIDWEST.  ANOMALOUS RIDGING LINKED TO
ABOVE-NORMAL SSTS OVER THE NORTH PACIFIC FAVORS BELOW-MEDIAN PRECIPITATION FOR
THE ALASKAN PANHANDLE, AS INDICATED BY MOST MODELS IN THE NMME AND IMME.

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: MATTHEW ROSENCRANS


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 AUG ... WILL BE ISSUED ON THU JUL 17 2014


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

$$

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