90 Day Narrative

401 
FXUS05 KWBC 201230
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU APR 20 2017
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
THE MAY-JUNE-JULY (MJJ) 2017 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL 
TEMPERATURES FOR MUCH OF THE FORECAST DOMAIN. FOR THE CONTIGUOUS U.S., 
ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE MOST LIKELY FOR THE PACIFIC COASTAL 
STATES AND ACROSS THE SOUTHWEST REGION AND THE CENTRAL AND SOUTHERN PLAINS INTO 
THE EASTERN U.S., WITH THE GREATEST ODDS INDICATED FOR PARTS OF THE SOUTHWEST, 
THE GULF COAST AND ATLANTIC COASTAL REGIONS. ABOVE-NORMAL TEMPERATURES ARE ALSO 
FAVORED FOR MUCH OF ALASKA.   
THE MJJ 2017 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF 
ABOVE-MEDIAN PRECIPITATION FOR AREAS OF THE ROCKY MOUNTAINS AND JUST EAST, FROM 
CENTRAL MONTANA SOUTHWARD INCLUDING WYOMING, COLORADO AND NEW MEXICO, AS WELL 
AS FOR WESTERN AREAS OF THE GULF COAST, AND FOR EASTERN INTERIOR REGIONS OF 
ALASKA. BELOW-MEDIAN SEASONAL PRECIPITATION AMOUNTS ARE FAVORED FOR THE WESTERN 
AND CENTRAL GREAT LAKES REGION.
EQUAL CHANCES (EC) ARE FORECAST OVER AREAS WHERE ODDS OF ABOVE-, BELOW-, OR 
NEAR-NORMAL SEASONAL MEAN TEMPERATURES AND SEASONAL ACCUMULATED PRECIPITATION 
AMOUNTS ARE EXPECTED TO BE SIMILAR TO CLIMATOLOGICAL PROBABILITIES.
BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS
NOTE:  FOR GRAPHICAL DISPLAYS OF THE FORECAST TOOLS DISCUSSED BELOW SEE:
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/90DAY/TOOLS/BRIEFING
CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS
OCEANIC AND ATMOSPHERIC OBSERVATIONS ACROSS THE EQUATORIAL PACIFIC AS A WHOLE 
INDICATE ENSO-NEUTRAL CONDITIONS ARE CONTINUING. A RESIDUAL, SMALL AREA OF 
SLIGHTLY BELOW NORMAL SEA SURFACE TEMPERATURES (SSTS) REMAINS IN PROXIMITY TO 
THE DATE LINE, FROM LAST WINTER'S LA NINA, BUT IN AREAS TO THE WEST AND EAST 
ALONG THE EQUATOR, SSTS ARE NOW ABOVE AVERAGE. THE HEAT CONTENT ANOMALY OF THE 
UPPER-OCEAN LAYERS, TO A DEPTH OF 300 METERS, SUMMED ACROSS THE BASIN FROM THE 
DATE LINE TO 100W IS NOW NEAR ZERO AFTER DECREASING FROM POSITIVE HEAT CONTENT 
ANOMALIES DURING FEBRUARY AND MARCH.
IN THE ATMOSPHERE OVER THE PAST MONTH, EASTERLY WIND ANOMALIES CONTINUED TO BE 
OBSERVED OVER THE CENTRAL AND WESTERN TROPICAL PACIFIC. OVER THE SAME PERIOD, 
MEASUREMENTS OF TROPICAL CONVECTION INDICATED CONTINUED SUPPRESSED CONVECTION 
IN THE CENTRAL PACIFIC AND CONTINUING ENHANCED CONVECTION OVER MUCH OF THE 
MARITIME CONTINENT. THIS ANOMALOUS CONVECTION PATTERN APPEARS TO BE A RESIDUAL 
OF THE WEAK LA NINA EVENT THAT HAS OTHERWISE ENDED.
PROGNOSTIC DISCUSSION OF SST FORECASTS
THE CPC NINO 3.4 SST CONSOLIDATION FORECAST, WHICH INCLUDES CANONICAL 
CORRELATION ANALYSIS (CCA), CONSTRUCTED ANALOG (CA), AND MARKOV STATISTICAL 
FORECASTS, ALONG WITH THE CFS DYNAMICAL MODEL, PREDICTS A MEDIAN TEMPERATURE 
ANOMALY OF +0.4C FOR THE COMING SEASONS FROM APPROXIMATELY MJJ THROUGH OND 
2017, WITH EL NINO AS MOST LIKELY FROM LATE SUMMER THROUGH AUTUMN. A 
CONSIDERABLE DIFFERENCE BETWEEN THE CFS AND THE STATISTICAL GUIDANCE APPEARS IN 
THE CONSOLIDATION, HOWEVER, WITH THE CFS FORECASTING A RAPID INCREASE IN SSTS 
EARLY IN THE OUTLOOK PERIOD AND EL NINO CONDITIONS BEGINNING WITH THE MJJ 2017 
SEASON, WHILE THE CA STATISTICAL FORECAST EXCEEDS THE +0.5C THRESHOLD FOR EL 
NINO STARTING IN JAS 2017, AND THE CCA AND MARKOV MODELS REMAIN IN ENSO NEUTRAL 
THROUGHOUT THE FORECAST PERIOD.  THIS SEPARATION BETWEEN THE STATISTICAL AND 
DYNAMICAL MODELS IS ALSO DEPICTED BY THE LATEST IRI NINO3.4 SST FORECAST PLUME. 
MOREOVER, FORECASTS FROM THE DYNAMICAL SUITE OF MODELS FROM THE NMME ALSO 
INDICATE A MORE RAPID INCREASE IN NINO 3.4 SST DURING THE SPRING AND SUMMER 
MONTHS. THE LATEST OFFICIAL ENSO OUTLOOK FROM CPC/IRI INDICATES ENSO-NEUTRAL 
CONDITIONS ARE LIKELY TO CONTINUE THROUGH AT LEAST THE NORTHERN HEMISPHERE 
SPRING WITH INCREASING ODDS FOR THE DEVELOPMENT OF EL NINO CONDITIONS AS AUTUMN 
APPROACHES WITH PROBABILITIES FOR EL NINO OF ABOUT 50% FROM ASO 2017 CONTINUING 
THROUGH NDJ 2017. THE CONSENSUS FORECAST INDICATES THE LIKELIHOOD OF A REPEAT 
LA NINA EVENT TO BE VERY SMALL DURING THIS FORECAST PERIOD.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS
THE PRIMARY TOOLS USED FOR THIS SET OF SEASONAL OUTLOOKS INCLUDED BOTH 
STATISTICAL AND DYNAMICAL MODEL FORECAST GUIDANCE, AND IN PARTICULAR AT LONGER 
LEADS, DECADAL TEMPERATURE AND PRECIPITATION TRENDS. THE DYNAMICAL MODEL 
GUIDANCE FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) AND ITS INDIVIDUAL 
MODELS, INCLUDING THE NCEP CFS, WERE IMPORTANT CONTRIBUTORS TO THE OUTLOOKS 
THROUGH SON 2017. ANTECEDENT SOIL MOISTURE AND SNOWPACK ANOMALIES IN CERTAIN 
REGIONS ALSO IMPACTED THE OUTLOOKS, PRIMARILY AT EARLY LEADS. LIKELY 
ENSO-NEUTRAL CONDITIONS IN EARLY SEASONS, LEADS TO RELIANCE PRIMARILY ON THE 
DYNAMICAL MODEL FORECASTS, WHILE THE INCREASING CHANCE OF EL NINO IN LATE 
SUMMER AND AUTUMN WAS CONSIDERED IN THE TEMPERATURE AND PRECIPITATION OUTLOOKS 
INTO WINTER SEASONS. 
PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2017 TO MJJ 2018
TEMPERATURE
THE LATEST MJJ AND JJA 2017 TEMPERATURE OUTLOOKS INDICATE ABOVE-NORMAL 
TEMPERATURES ARE MOST LIKELY FOR MUCH OF THE FORECAST DOMAIN, WITH THE 
EXCEPTION OF PARTS OF THE NORTHERN ROCKIES AND NORTHERN PLAINS. THE CHANCES OF 
ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE SLIGHTLY ENHANCED FOR MUCH OF THE 
PACIFIC NORTHWEST, BUT THE PROBABILITY OF ABOVE-NORMAL TEMPERATURES IS 
MODERATED BY RECENT POSITIVE SNOW AND SOIL MOISTURE ANOMALIES. ABOVE-NORMAL 
TEMPERATURES ARE PARTICULARLY ENHANCED FOR A REGION STRETCHING FROM THE 
SOUTHWEST, EASTWARD ACROSS THE CENTRAL AND SOUTHERN PLAINS INTO THE EASTERN 
U.S. THE GREATEST PROBABILITIES EXCEED 50% FOR PARTS OF THE SOUTHWEST AND ALONG 
THE GULF AND ATLANTIC COASTS, FOLLOWING THE CALIBRATED PROBABILISTIC GUIDANCE 
FROM THE NMME. NEGATIVE SOIL MOISTURE ANOMALIES IN THE SOUTHEAST REGION ALSO 
CONTRIBUTE TO THE LIKELIHOOD OF ANOMALOUS WARMTH. DECADAL CLIMATE TRENDS ALSO 
SUPPORT THE OUTLOOK AND ARE A COMPONENT OF THE DYNAMICAL MODEL GUIDANCE. THESE 
FORECAST TOOLS ALSO SUPPORT ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES 
FOR ALASKA.
SHORT TERM CLIMATE MODEL FORECASTS FOR THE BEGINNING OF MAY AND WEAKER SIGNALS 
IN THE SEASONAL MODEL GUIDANCE FOR PARTS OF THE NORTHERN ROCKIES INTO THE 
NORTHERN PLAINS RESULTS IN AN AREA OF EQUAL CHANCES (EC) OVER THESE REGIONS.
LITTLE CHANGE WAS MADE TO PREVIOUS OUTLOOKS FOR REMAINING SEASONS THROUGH 2017 
INTO THE FIRST HALF OF 2018. ENHANCED PROBABILITIES OF ABOVE-NORMAL 
TEMPERATURES ARE INDICATED THROUGHOUT THE FORECAST DOMAIN THROUGH DJF 
2017-2018. FROM THE JFM THROUGH MJJ 2018 SEASONS, REGIONS OF ENHANCED 
PROBABILITIES OF ABOVE-NORMAL TEMPERATURES FOLLOW STATISTICAL GUIDANCE, 
PRIMARILY RESULTING FROM DECADAL CLIMATE TRENDS.
HIGH PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED FOR THE NORTH 
SLOPE OF ALASKA DURING SON AND OND 2017 DUE TO DECADAL TRENDS IN THE SEASONAL 
CYCLE OF SEA ICE.
PRECIPITATION
FOR PRECIPITATION, THE MJJ AND JJA 2017 OUTLOOKS INDICATE ABOVE-MEDIAN 
PRECIPITATION FOR AREAS OF THE ROCKY MOUNTAINS AND JUST TO THE EAST, FROM 
CENTRAL MONTANA SOUTHWARD INCLUDING PARTS OF WYOMING, UTAH, COLORADO AND NEW 
MEXICO, AS WELL AS FOR WESTERN AREAS OF THE GULF COAST, AND FOR EASTERN 
INTERIOR REGIONS OF ALASKA. BELOW-MEDIAN SEASONAL PRECIPITATION AMOUNTS ARE 
FAVORED FOR THE WESTERN AND CENTRAL GREAT LAKES REGION. THE OUTLOOKS FOR THE 
MJJ THROUGH SON 2017 SEASONS ARE PRIMARILY BASED ON WEAK SIGNALS THAT APPEAR IN 
CALIBRATED PROBABILISTIC GUIDANCE FROM THE NMME. ELEVATED CHANCES FOR 
ABOVE-MEDIAN PRECIPITATION CONTINUE FOR AREAS IN THE CENTRAL AND NORTHERN 
ROCKIES AND NORTHERN HIGH PLAINS FOR JJA AND JAS 2017, AND FOR THE CENTRAL 
ROCKIES FOR ASO AND SON 2017. FROM ASO THROUGH OND 2017, INCREASING CHANCES FOR 
EL NINO CONDITIONS AND DYNAMICAL MODEL FORECASTS OF GREATER THAN AVERAGE SSTS 
IN THE EASTERN TROPICAL PACIFIC LEAD TO A SOUTHWARD SHIFT OF THIS REGION OF 
LIKELY ABOVE-MEDIAN PRECIPITATION INTO THE SOUTHWEST CONUS INCLUDING SOUTHERN 
CALIFORNIA AND ARIZONA IN OND 2017. 
FOR LATE AUTUMN AND WINTER, FROM NDJ 2017-2018 THROUGH JFM 2018, THE LOW 
PROBABILITY OF A LA NINA AND ELEVATED CHANCES FOR A POSSIBLE EL NINO RESULT IN 
REMOVAL OF A SIGNAL FOR DRIER THAN NORMAL CONDITIONS FROM THE DECADAL CLIMATE 
TRENDS FOR THE SOUTHWEST. FOLLOWING FMA 2018, WEAK SIGNALS DUE TO DECADAL 
TRENDS IN PRECIPITATION ARE INDICATED, INCLUDING BELOW-MEDIAN PRECIPITATION FOR 
PARTS OF THE SOUTHWEST BEGINNING WITH THE FMA 2018 SEASON AND ABOVE-MEDIAN 
PRECIPITATION IN THE NORTHERN-CENTRAL CONTIGUOUS U.S. BEGINNING WITH MAM 2018. 
FORECASTER: DAN COLLINS
THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, FOLLOWING 
THE WORLD METEROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3 
COMPLETE DECADES AS THE CLIMATIC 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.
FOR A DESCRIPTION OF OF THE STANDARD FORECAST TOOLS - THEIR SKILL- AND THE
FORECAST FORMAT PLEASE SEE OUR WEB PAGE AT
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/LONG_RANGE/TOOLS.HTML
(USE LOWER CASE LETTERS)
INFORMATION ON THE FORMATION OF SKILL OF THE CAS FORECASTS MAY BE FOUND AT:
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING/US/OUTLOOK/OUTLOOK.SHTM
L
(USE LOWERCASE LETTERS)
NOTES - THESE CLIMATE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF THEIR 
VALID PERIOD.  WITHIN ANY GIVEN VALID PERIOD OBSERVATIONS AND SHORT AND MEDIUM 
RANGE FORECASTS SHOULD BE CONSULTED.
THIS SET OF OUTLOOKS WILL BE SUPERSEDED BY THE ISSUANCE OF THE NEW SET NEXT 
MONTH ON MAY 18 2017
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 
FORECAST RELEASE.
$$