639  
FXUS05 KWBC 191254  
PMD90D  
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830 AM EDT THU APR 19 2018  
 
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS  
 
ACCORDING TO THE ENSO DIAGNOSTIC DISCUSSION ISSUED APRIL 12, 2018, A LA NINA  
ADVISORY IS STILL IN EFFECT. LA NINA IS EXPECTED TO TRANSITION TO ENSO-NEUTRAL  
DURING APRIL-MAY, WITH ENSO-NEUTRAL THEN LIKELY (GREATER THAN 50% CHANCE) TO  
CONTINUE THROUGH BOREAL SUMMER 2018.  
 
THE MAY-JUN-JUL (MJJ) 2018 TEMPERATURE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES  
OVER MUCH OF THE CONTIGUOUS UNITED STATES (CONUS), THE EXCEPTION BEING THE  
VICINITY OF THE NORTHERN GREAT PLAINS AND UPPER MISSISSIPPI VALLEY, WHERE EQUAL  
CHANCES (EC) OF BELOW, NEAR, AND ABOVE NORMAL TEMPERATURES ARE FAVORED. THE  
GREATEST PROBABILITIES REACH OR EXCEED 60% ACROSS PORTIONS OF THE SOUTHWEST.  
PROBABILITIES REACH OR EXCEED 50% OVER THE NORTHEAST. ABOVE NORMAL TEMPERATURES  
ARE ALSO FAVORED FOR ALL OF ALASKA, WITH MAXIMUM PROBABILITIES REACHING OR  
EXCEEDING 50% OVER MUCH OF THE NORTH SLOPE, THE EXTREME WESTERN PARTS OF THE  
STATE, THE ALASKA PENINSULA, AND THE EASTERN ALEUTIANS.  
 
THE MJJ 2018 PRECIPITATION OUTLOOK FAVORS ABOVE NORMAL PRECIPITATION OVER MOST  
OF MAINLAND ALASKA, THE ALASKA PENINSULA AND ALEUTIANS, AND OVER THE GREAT  
LAKES REGION, NORTHEAST, MID-ATLANTIC, AND MOST OF THE OHIO VALLEY.  
PROBABILITIES REACH OR EXCEED 50% ACROSS THE VICINITY OF THE SEWARD PENINSULA  
IN WESTERN ALASKA. BELOW NORMAL PRECIPITATION IS FAVORED FROM THE EASTERN  
FOOTHILLS OF THE NORTHERN AND CENTRAL ROCKIES WESTWARD TO THE PACIFIC COAST  
ABOUT AS FAR SOUTH AS CENTRAL CALIFORNIA.  
 
EQUAL CHANCES (EC) ARE FORECAST IN AREAS WHERE CLIMATOLOGICAL PROBABILITIES ARE  
INDICATED FOR SEASONAL MEAN TEMPERATURES AND SEASONAL ACCUMULATED PRECIPITATION  
AMOUNTS.  
 
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  
 
BELOW AVERAGE SEA SURFACE TEMPERATURES (SSTS) CONTINUED ACROSS MUCH OF THE  
CENTRAL AND EASTERN EQUATORIAL PACIFIC OCEAN, THOUGH THE NEGATIVE SST ANOMALIES  
ARE MODEST (-0.5C). THE VERY LATEST WEEKLY SST DEPARTURE VALUE FOR THE NINO-3.4  
REGION IS -0.4C, UP SLIGHTLY FROM TWO WEEKS AGO. AS THE NEGATIVE SST ANOMALIES  
WERE WEAKENING NEAR THE SURFACE, THE SUB-SURFACE TEMPERATURES (50-250 METERS  
DEEP) OF THE EQUATORIAL CENTRAL AND EASTERN PACIFIC WARMED DUE TO THE EASTWARD  
PROPAGATION OF DOWNWELLING EQUATORIAL OCEANIC KELVIN WAVES. THE GREATEST  
POSITIVE TEMPERATURE ANOMALIES, +4 TO +6 DEG C, WERE LOCATED JUST EAST OF THE  
DATE LINE, AT A DEPTH OF ABOUT 150 METERS. INCIDENTALLY, CLOSE TO THE COAST OF  
SOUTH AMERICA, SUB-SURFACE TEMPERATURE ANOMALIES OF -1 TO -4 DEG C BELOW  
AVERAGE WERE OBSERVED. ALTHOUGH SOME OF THIS RELATIVELY COOL WATER AT DEPTH MAY  
BE ASSOCIATED WITH THE LAST VESTIGES OF LA NINA, IT APPEARS THAT EASTERLY OR  
NORTHEASTERLY TRADE WINDS ON A HIGHER-FREQUENCY TIME SCALE MAY BE THE MAIN  
DRIVER BEHIND THE UPWELLING IN THIS AREA.  
 
OUTGOING LONGWAVE RADIATION (OLR) ANOMALIES AVERAGED OVER THE PAST MONTH DEPICT  
ENHANCED CONVECTION NORTHEAST OF AUSTRALIA ACROSS THE CORAL SEA (IN PART  
RELATED TO TROPICAL CYCLONE ACTIVITY), WHICH CONTINUES SOUTHEASTWARD ALONG THE  
GENERAL LOCATION OF THE SOUTH PACIFIC CONVERGENCE ZONE (SPCZ). OLR ANOMALIES  
WERE SLIGHTLY NEGATIVE OVER THE MARITIME CONTINENT REGION, AND MODERATELY  
POSITIVE NEAR THE DATE LINE, BOTH OF WHICH ARE CONSISTENT WITH A RESIDUAL LA  
NINA. DURING THE PAST 30-DAYS, NEAR-EQUATORIAL LOW-LEVEL (850-HPA) WIND  
ANOMALIES WERE WESTERLY NEAR AND JUST EAST OF THE MARITIME CONTINENT, AND  
EASTERLY NEAR AND EAST OF THE DATE LINE. AT UPPER-LEVELS (200-HPA), TWO LARGE  
CYCLONIC VORTICES STRADDLED THE EQUATOR OVER THE EASTERN PACIFIC. OVERALL,  
OCEANIC AND ATMOSPHERIC INDICATORS ARE CONSISTENT WITH A RESIDUAL LA NINA IN  
THE PROCESS OF TRANSITIONING TO ENSO-NEUTRAL.  
 
OTHER FACTORS TO CONSIDER INCLUDE SOIL MOISTURE AND PRECIPITATION ANOMALIES.  
THE SOIL MOISTURE CHANGE MAP FOR THE PAST SEASON (FEBRUARY THROUGH MID-APRIL  
2018) DEPICTS ANOMALOUSLY WET SOILS FROM EASTERN PORTIONS OF THE SOUTHERN GREAT  
PLAINS EASTWARD AND NORTHEASTWARD ACROSS THE SOUTHERN HALF OF THE MISSISSIPPI  
VALLEY, THE CENTRAL GREAT LAKES REGION, AND THE OHIO AND TENNESSEE VALLEYS.  
ANOMALOUSLY DRY SOILS ARE NOTED OVER THE SOUTH-CENTRAL GREAT PLAINS AND THE  
FLORIDA PENINSULA. THE PRECIPITATION ANOMALY PATTERN GENERALLY MIRRORS THE SOIL  
MOISTURE ANOMALY PATTERN FOR THE SAME PERIOD. FARTHER NORTH, SNOW COVER IS  
STILL A CONCERN FOR PARTS OF THE DAKOTAS, MINNESOTA, WISCONSIN, NORTHERN IOWA  
AND MICHIGAN, ESPECIALLY AFTER THE RECENT SNOWSTORM WHICH DEPOSITED UP TO 20  
INCHES OF SNOW IN THE TWIN CITIES AREA OF MINNEAPOLIS-ST. PAUL.  
 
PROGNOSTIC DISCUSSION OF SST FORECASTS  
 
THE CPC SST CONSOLIDATION (CON) FORECAST FOR THE NINO 3.4 REGION PREDICTS A  
SLOW, GRADUAL INCREASE IN ANOMALY VALUES FROM ABOUT -0.5C TO +0.4C OVER THE  
NEXT SIX MONTHS OR SO, PEAKING AT A MAXIMUM SST ANOMALY OF +0.6C (JUST INSIDE  
WEAK EL NINO TERRITORY) BY NDJ 2018/19. THE CON CLOSELY PARALLELS THE CFS SST  
ANOMALY FORECAST THROUGH OND 2018. SOME OF THE INPUTS TO THE CON FORECAST, SUCH  
AS THE CCA AND THE CONSTRUCTED ANALOG (CA), PREDICT SOLUTIONS THAT ARE SOMEWHAT  
COOLER AND WARMER (RESPECTIVELY) THAN THE CON. THE CPC-IRI CONSENSUS PREDICTS  
THE PROBABILITY FOR ENSO-NEUTRAL TO REACH A PEAK OF 70% IN MJJ, GRADUALLY  
DECLINING THROUGHOUT THE SUMMER AND AUTUMN TO ABOUT 40% BY NDJ 2018/19. IN  
CONTRAST, THE PROBABILITY OF AN EL NINO STARTS OFF NEAR 10% IN MJJ, AND  
STEADILY RISES TO JUST UNDER 50% BY NDJ 2018/19. IT IS DURING THE OND SEASON  
THAT THE CHANCES OF AN EL NINO EXCEED THOSE OF A NEUTRAL EVENT. CHANCES FOR A  
LA NINA DROP RAPIDLY FROM JUST UNDER 20% IN MJJ TO 10-15% IN JJA, AND CONTINUE  
AT THAT REDUCED LEVEL THROUGHOUT THE SUMMER AND AUTUMN MONTHS. THE NMME AND  
IMME SST PLUMES FORECAST SST ANOMALIES TO RISE FROM ABOUT -0.5C THROUGH NEUTRAL  
TERRITORY (-0.49 TO +0.49), EVENTUALLY REACHING THE MINIMAL THRESHOLD FOR EL  
NINO (+0.5C) BY SEPTEMBER AND OCTOBER, RESPECTIVELY. THE ECMWF SST ANOMALY  
FORECAST, WHICH USES A 51-MEMBER ENSEMBLE, IS THE WARMEST OF ALL SOLUTIONS,  
WITH ALL 51 MEMBERS FORECASTING AT LEAST POSITIVE SST ANOMALIES FOR THE NINO  
3.4 REGION BY OCTOBER, AND MOST OF THOSE MEMBERS BEING CONSIDERABLY WARMER AND  
MORE BULLISH FOR A EL NINO. SOME MEMBERS REACH THE NOMINAL EL NINO THRESHOLD AS  
EARLY AS JULY.  
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS  
 
THE FIRST FEW LEADS OF THE CURRENT SUITE OF SEASONAL TEMPERATURE OUTLOOKS ARE  
SLIGHTLY COOLER OVER THE MIDSECTION OF THE CONUS COMPARED TO THE SET OF  
OUTLOOKS ISSUED LAST MONTH, WHICH IS CONSISTENT WITH SLIGHTLY INCREASED ODDS OF  
AN EL NINO. INITIALLY, A SMALL AREA OF BELOW NORMAL TEMPERATURES WAS FORECAST  
OVER PART OF THE NORTH-CENTRAL CONUS IN JJA AND JAS, BUT THIS FORECAST WAS  
DEEMED UNLIKELY TO VERIFY IN THE ABSENCE OF A PRONOUNCED WET SIGNAL IN THIS  
SAME AREA. FOR THE MJJ-ASO SEASONS, ENSO-NEUTRAL CONDITIONS ARE EXPECTED TO  
DOMINATE, WITH A SLIGHTLY INCREASING INFLUENCE FROM A POTENTIAL INCIPIENT EL  
NINO. THE POSSIBLE IMPACTS OF AN EL NINO ARE WEIGHTED A BIT MORE FOR THE SON  
2018 TO MAM 2019 SEASONS. THOUGH WE APPEAR HEADED TOWARD A COLD-SEASON EL NINO,  
THERE HAVE BEEN SEVERAL FALSE STARTS IN RECENT YEARS WHERE PROMISING EL NINOS  
SIMPLY FADED AWAY. IT IS TOO EARLY IN THE CALENDAR YEAR TO PREDICT A  
FULL-FLEDGED EL NINO AT THIS TIME, SO FOR THIS PARTICULAR SET OF OUTLOOKS, WE  
CONSERVATIVELY INTRODUCE POTENTIAL EL NINO INFLUENCES LATER THIS SUMMER, AND  
ASSUME A WEAK EL NINO DURING THE UPCOMING WINTER SEASON 2018-19. MODELS AND  
TOOLS USED IN THE CONSTRUCTION OF THESE SEASONAL OUTLOOKS INCLUDE  
BIAS-CORRECTED AND CALIBRATED MODEL OUTPUT FROM THE NMME DYNAMICAL MODEL SUITE,  
THE IMME, CFS, CON, AND THE CONSTRUCTED ANALOG WHICH INCORPORATES PACIFIC SST  
INFORMATION (CA-SST). A BASELINE TOOL THAT COMBINES THE INFLUENCES OF ENSO AND  
DECADAL TEMPERATURE AND PRECIPITATION TRENDS ANCHORED TO THE CPC NINO 3.4 SST  
CON FORECAST (ENSO-OCN TOOL) WAS HEAVILY RELIED UPON DURING LEADS 5-11 (SON  
2018 THROUGH MAM 2019). FOR LEADS 12-13 (AMJ AND MJJ 2019), DECADAL TRENDS  
IMPLICIT IN THE CON TOOL WERE USED.  
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2018 TO MJJ 2019  
 
TEMPERATURE  
 
THE TEMPERATURE OUTLOOK FOR MJJ FAVORS ABOVE NORMAL TEMPERATURES OVER MUCH OF  
THE CONUS, AND ALL OF ALASKA. THIS IS SUPPORTED BY SUCH TOOLS AS THE ENSO-OCN  
TOOL, SST-CA, CALIBRATED NMME, AND CON. THE HIGHER PROBABILITIES FOR ABOVE  
NORMAL TEMPERATURES ACROSS THE SOUTHWEST AND NORTHEAST REFLECT HISTORICAL  
TRENDS. FOR THE NORTH-CENTRAL CONUS, EC IS CONSIDERED THE BEST CATEGORY,  
SUPPORTED BY THE CON, IMME, CA-SST, ENSO-CON, AND THE TRADITIONAL STATISTICAL  
TOOLS (SMLR, CCA, AND OCN). THE IDEA OF THE NORTH-CENTRAL CONUS BEING SLIGHTLY  
COOLER THAN ITS SURROUNDINGS IS A NOD IN THE DIRECTION OF THE EARLY STAGES OF A  
POTENTIAL EL NINO. AS ALLUDED TO EARLIER, SEVERAL TOOLS PREDICTED BELOW NORMAL  
TEMPERATURES ACROSS PORTIONS OF THIS REGION NOT ONLY DURING MJJ, BUT ALSO JJA  
AND JAS. ONE OF THE BIGGEST PROPONENTS FAVORING ANOMALOUS COLD (ESPECIALLY IN  
JJA) IS THE BRIDGED COMPONENT OF THE CBAM TOOL, WHICH OVERWHELMS THE MINOR  
CONTRIBUTION FROM THE WARMER CALIBRATION COMPONENT IN THIS AREA. THE PRIMARY  
REASON FOR NOT FORECASTING BELOW NORMAL TEMPERATURES IN THIS AREA IS THE  
ANTICIPATED LACK OF A PRONOUNCED WET SIGNAL IN THIS SAME GENERAL REGION, WHICH  
MAKES THE FORECAST FOR ANOMALOUS COLD MUCH LESS LIKELY. FOR JJA AND JAS, THE  
MAIN DIFFERENCE COMPARED WITH MJJ IS THE EXPECTED INCREASE IN COVERAGE OF EC  
ACROSS THE CENTRAL STATES, DUE IN PART TO THE BRIDGED COMPONENT OF THE CBAM  
TOOL AS NOTED PREVIOUSLY, AND ALSO THE UNCERTAINTY REGARDING THE POTENTIAL  
UPCOMING WARM PHASE OF ENSO. BY ASO, THIS LARGE REGION OF PREDICTED EC IS  
FORECAST TO DIMINISH SIGNIFICANTLY IN SIZE. THE OUTLOOKS FROM SON 2018 THROUGH  
MAM 2019 ARE TILTED IN THE DIRECTION OF A WEAK EL NINO, AND ARE BASED HEAVILY  
ON THE ENSO-OCN TOOL. ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS THE ENTIRE  
CONUS IN SON, WITH AN INCREASE IN UNCERTAINTY (EXPRESSED AS EC) ACROSS PORTIONS  
OF THE SOUTHEAST AND PACIFIC NORTHWEST IN OND. THE EXPECTED COVERAGE OF EC  
INCREASES DURING NDJ, DJF, AND JFM OF NEXT YEAR. BY JFM, ANOMALOUS WARMTH IS  
FAVORED FOR APPROXIMATELY THE WESTERN HALF OF THE CONUS, WITH EC PREDICTED  
ELSEWHERE. BY FMA, ANOMALOUS WARMTH IS FORECAST TO EXPAND ACROSS THE  
SOUTHEASTERN QUARTER OF THE CONUS, AND CONTINUE EXPANDING ACROSS THE  
MID-ATLANTIC, NORTHEAST, AND EASTERN GREAT LAKES REGION DURING MAM 2019. THE  
ONLY AREA OF PREDICTED EC IS AGAIN LOCATED OVER THE NORTH-CENTRAL STATES BY  
THIS TIME. FOR THE FINAL TWO SEASONS (AMJ AND MJJ 2019), HISTORICAL TRENDS  
IMPLICIT IN THE CON TOOL ARE THE PRIMARY FORECAST TOOL, PRODUCING AN OVERALL  
TEMPERATURE PATTERN SIMILAR TO MAM. THE DIFFERENCE IS THAT WARMING TREND  
SIGNALS BECOME STRONGER IN PARTS OF THE EASTERN AND SOUTHERN CONUS, WARRANTING  
HIGHER PROBABILITIES FOR ABOVE NORMAL TEMPERATURES. IN ALASKA DURING SON,  
NEARLY ALL TOOLS AGREED ON ABOVE NORMAL TEMPERATURES, WITH THE HIGHEST  
PROBABILITIES OVER NORTHERN AND WESTERN PORTIONS OF THE STATE ATTRIBUTED TO  
EARLIER-THAN-NORMAL BREAKUP OF SEA ICE, AND RELATIVELY WARM SSTS (ESPECIALLY  
NEAR THE SOUTHWEST COAST). SEA ICE TRENDS RELATED TO THE DELAYED ONSET OF SEA  
ICE IN RECENT YEARS IS THE DRIVING FACTOR BEHIND PROBABILITIES FOR ABOVE NORMAL  
TEMPERATURES REACHING OR EXCEEDING 60 PERCENT ACROSS THE NORTH SLOPE IN SON,  
AND AT LEAST 50% IN OND. DECADAL TEMPERATURE TRENDS PLAY A LARGE ROLE FOR THE  
49TH STATE THROUGHOUT THE WINTER AND SPRING SEASONS.  
 
PRECIPITATION  
 
THE PRECIPITATION OUTLOOK FOR MJJ DEPICTS ENHANCED ODDS OF ABOVE NORMAL  
PRECIPITATION FOR MOST OF MAINLAND ALASKA, THE ALASKA PENINSULA, AND THE  
ALEUTIANS, WITH PROBABILITIES REACHING OR EXCEEDING 50% IN THE VICINITY OF THE  
SEWARD PENINSULA. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FOR THE GREAT  
LAKES REGION, THE NORTHEAST, MID-ATLANTIC, AND MOST OF THE OHIO VALLEY. THESE  
WET ANOMALIES ARE SUPPORTED (TO VARYING DEGREES) BY THE CA-SST, SMLR, OCN, CFS,  
CALIBRATED NMME, IMME, CON, CALIBRATED COMPONENT OF THE CBAM, AND ESPECIALLY  
THE ENSO-OCN TOOL. BELOW NORMAL PRECIPITATION IS FAVORED FROM ABOUT THE EASTERN  
FOOTHILLS OF THE NORTHERN AND CENTRAL ROCKIES WESTWARD TO THE PACIFIC COAST, AS  
FAR SOUTH AS CENTRAL CALIFORNIA. THIS DRY ANOMALY ALSO DRAWS MUCH OF ITS  
SUPPORT FROM THE ENSO-OCN TOOL, CCA, OCN, CFS, CALIBRATED NMME, IMME, AND CON.  
THE ENSO-OCN TOOL, IN PARTICULAR, REVEALS THE SIGNIFICANT CONTRIBUTIONS FROM  
THE ENSO PHASE AND DECADAL TRENDS IN THE MJJ PRECIPITATION FORECAST. FOR JJA  
AND JAS, THESE THREE PRECIPITATION ANOMALIES CONTINUE, THOUGH VARY IN SPATIAL  
COVERAGE. IN ADDITION, THERE ARE ELEVATED CHANCES FOR WETTER-THAN-NORMAL  
CONDITIONS IN NEW MEXICO AND THE FLORIDA PENINSULA (JJA), AND FOR MOST OF THE  
FOUR CORNERS REGION AND THE FLORIDA PENINSULA IN JAS. WELL BELOW NORMAL WINTER  
SNOWPACK ACROSS MOST OF THE FOUR CORNERS REGION TENDS TO FAVOR THE EARLY ONSET  
OF THE SOUTHWEST MONSOON. SOME TOOLS, SUCH AS THE CA-SST, SMLR, OCN, CBAM,  
IMME, FORECAST (TO VARYING DEGREES), ABOVE NORMAL PRECIPITATION IN THE MONSOON  
REGION DURING JJA AND JAS. THE CFS IS BULLISH ON ITS PREDICTION OF AN ACTIVE  
MONSOON, BUT SKILL MAPS THAT TAKE INTO ACCOUNT PRIOR PERFORMANCE DO NOT SUPPORT  
THIS SCENARIO. IN ADDITION, THE ENSO-OCN TOOL DOES NOT PREDICT ANY SUBSTANTIAL  
SIGNAL FOR AN ACTIVE MONSOON SEASON. THE FLORIDA PENINSULA WET SIGNAL DRAWS ITS  
SUPPORT FROM THE CA-SST, CON, AND THE ENSO-OCN. THE CFS AND CALIBRATED NMME  
PROVIDE, AT BEST, MARGINAL SUPPORT FOR THIS WET SIGNAL. BY ASO, ONLY THE  
NORTHEAST/MID-ATLANTIC COAST AND ALASKA WET SIGNALS REMAIN, WITH THE FORMER  
DISAPPEARING BY SON, AND THE LATTER DISAPPEARING BY OND. WITH SIGNIFICANT  
UNCERTAINTY REGARDING THE ENSO PHASE DURING THIS UPCOMING COLD SEASON, IT WAS  
DECIDED TO GO WITH EC FOR ALL AREAS. THIS WILL LIKELY CHANGE OVER THE NEXT FEW  
MONTHS, AS THE NEW ENSO PHASE BECOMES BETTER ESTABLISHED. BY NEXT SPRING (AMJ &  
MJJ 2019), HISTORICAL TRENDS BEGIN TO FAVOR WETNESS ACROSS THE GREAT LAKES  
REGION AND NORTHEAST, BUT THEY ARE FAIRLY WEAK AND NOT INCORPORATED INTO THIS  
SET OF SEASONAL OUTLOOKS.  
 
FORECASTER: ANTHONY ARTUSA  
 
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 17 2018  
 
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011  
FORECAST RELEASE.  

 
 
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