PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EDT THU MAR 15 2007 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAIN FACTORS WHICH USUALLY INFLUENCE SEASONAL CLIMATE INCLUDE: 1) EL NINO AND LA NINA - WHICH COMPRISE EL NINO/SOUTHERN OSCILLATION OR ENSO 2) TRENDS - APPROXIMATED BY 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 1971-2000) 3) TROPICAL 30-60-DAY OSCILLATION - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS. 4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING THE COLD SEASONS. THESE PHENOMENA ARE CURRENTLY KNOWN TO BE PREDICTABLE ONLY OVER A WEEK OR SO. 5) PERSISTENTLY DRY OR WET SOILS IN THE 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. 6) AN OBJECTIVE CONSOLIDATION (CALLED CON IN THE TEXT) OF THE OCN, CCA, SMLR AND CFS FORECASTS IS USED AS A FIRST-GUESS IN PREPARING THE FORECAST MAPS. THIS TECHNIQUE MAKES OPTIMUM USE OF THE KNOWN SKILL OF OUR FORECAST TOOLS. EQUATORIAL SEA SURFACE TEMPERATURES (SST) IN THE PACIFIC OCEAN ARE NEAR THEIR LONG-TERM AVERAGE DURING THE MONTHLY PERIOD JUST ENDING. THE EL NINO PERIOD OF LAST WINTER CAME TO A VERY QUICK END. THE ATMOSPHERIC INDICATORS DURING THE PAST TWO MONTHS WERE ALSO CONSISTENT WITH VANISHING EL NINO CONDITIONS. PERHAPS MOST SIGNIFICANTLY... THE EQUATORIAL UPPER-OCEAN TOTAL HEAT CONTENT OF THE PACIFIC OCEAN... WHICH PEAKED IN LATE NOVEMBER... HAS DECREASED RAPIDLY SINCE THEN TO A MODERATELY NEGATIVE ANOMALY VALUE IN THE MOST RECENT WEEK. THIS IMPLIES THE POSSIBILITY OF A LA NINA AT SOME LATER TIME. THE AVERAGE OF SSTS IN THE NINO 3.4 REGION - A BOX BOUNDED BY 120W AND 170W AND BY 5N AND 5S - IS OFTEN USED AS AN INDICATOR OF THE STRENGTH OF AN EL NINO EVENT. SSTS IN THIS REGION PEAKED AT A LITTLE MORE 1 DEGREE C ABOVE NORMAL... BEFORE DECREASING TO NEAR 1 DEG C IN EARLY JANUARY - TO ABOUT 0.4 DEG C IN EARLY FEBRUARY AND TO ESSENTIALLY ZERO IN MARCH. NEARLY ALL PREDICTION TOOLS INDICATE THAT SST ANOMALIES IN THE NINO 3.4 REGION WILL CONTINUE TO DECREASE DURING THE NEXT FEW MONTHS... ALTHOUGH AT VARYING SPEEDS. ENSO-NEUTRAL CONDITIONS ARE EXPECTED TO BE IN PLACE IN THE APRIL-JUNE 2007 SEASON. WE DO NOT EXPECT ANY EL NINO OR LA NINA IMPACTS ON THE CLIMATE OF THE UNITED STATES DURING THE AMJ 2007 SEASON. A CONSENSUS OF STATISTICAL AND COUPLED DYNAMICAL CLIMATE MODELS SUGGESTS THAT THERE IS A POSSIBLILITY THAT BY SOMETIME IN THE SUMMER CONDITIONS COULD BE IN WEAK LA NINA TERRITORY... BUT IT IS TOO WEAK TO PUT MUCH CONFIDENCE IN THIS FOR U.S. IMPACTS LATER IN THE YEAR. THE TEMPERATURE OUTLOOK FOR APR-MAY-JUNE (AMJ) 2007 CALLS FOR WARMER THAN NORMAL CONDITIONS OVER MOST OF THE WESTERN TWO THIRDS OF THE NATION... INCLUDING MUCH OF ALASKA... WITH SOME WARMTH EXTENDING INTO THE SOUTHEAST. COLDER THAN NORMAL CONDITIONS ARE EXPECTED ONLY ALONG THE IMMEDIATE COASTAL AREAS OF SOUTHERN CALIFORNIA. ELSEWHERE THERE ARE EQUAL CHANCES OF WARMER-THAN- ... COOLER-THAN- ... OR NEAR-NORMAL TEMPERATURES. BELOW MEDIAN PRECIPITATION IS EXPECTED FOR AMJ 2007 IN PARTS OF UTAH - COLORADO AND ADJACENT STATES INTO THE SOUTHERN HALF OF CALIFORNIA. A SECOND AREA OF BELOW MEDIAN PRECIPITATION IS EXPECTED IN EAST TEXAS AND ADJACENT PARTS OF LOUISIANA AND OKLAHOMA. ELSEWHERE THERE ARE EQUAL CHANCES OF ABOVE-... BELOW-... OR NEAR-MEDIAN PRECIPITATION DURING AMJ. BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK 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 THE MOST RECENT MONTHLY MEAN SSTS IN THE EQUATORIAL PACIFIC ARE CLOSE TO NORMAL NEARLY EVERYWHERE. THE ONLY EXCEPTIONS ARE AN AREA OF MORE THAN 0.5 DEG C ABOVE NORMAL WEST OF THE DATE LINE NEAR 160E AND AN AREA OF MORE THAN 0.5 DEG BELOW NORMAL FROM 135W TO 100W. THE COLDER THAN AVERAGE TEMPERATURES IN THE EAST PACIFIC ARE THE TIP OF A BIGGER SUBSURFACE COLD ANOMALY THAT HAD MOVED EAST AND HAS NOW SURFACED. THE UPPER OCEAN HEAT CONTENT IN THE EQUATORIAL PACIFIC HAS RECENTLY STRENGTHENED TO WELL BELOW THE LONG-TERM AVERAGE. THE ATMOSPHERIC INDICATORS DURING THE PAST TWO MONTHS WERE ALSO CONSISTENT WITH RAPIDLY VANISHING EL NINO CONDITIONS. THERE HAVE BEEN BRIEF PERIODS OF WEAK MJO EVENTS, BUT NONE CURRENTLY. PROGNOSTIC DISCUSSION OF SST FORECASTS MANY SST FORECAST TOOLS INDICATE COLDER CONDITIONS IN THE NINO 3.4 AREA. THE MAIN DISAGREEMENT AMONG THE VARIOUS MODEL SOLUTIONS IS THE SPEED WITH WHICH SST ANOMALIES WILL CONTINUE TO DECREASE OR WHETHER THE DEPARTURES REMAIN WARM... AS DOES THE CCA... APPROACH ZERO... AS DOES THE CONSENSUS... OR EVEN BECOME SIGNIFICANTLY COLD... AS DOES THE CFS MODEL. THE NCEP CONSOLIDATION SHOWS THAT NINO 3.4 IS PREDICTED TO BE ONLY +0.2 DEG C BY AMJ. FORECAST CONSOLIDATION VALUES REMAIN NEAR ZERO THROUGHOUT 2007. CONSOLIDATION OF THE CFS TOOL - WHICH HAS DONE WELL LATELY - ON ITS OWN WOULD - AFTER CORRECTION OF BIAS IN THE MEAN AND THE STANDARD DEVIATION - RESULT IN ABOUT A -0.5 DEG C PREDICTION FOR MOST OF 2007. EVEN THIS COLD SCENARIO IS NOT ENOUGH FOR EXPECTING LARGE IMPACTS OVER THE US AT ANY TIME DURING 2007. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE OUTLOOKS FOR AMJ 2007 THROUGH JAS 2007 ARE BASED ON THE CONSOLIDATION TOOL... WHICH IS A SKILL-WEIGHTED OBJECTIVE BLEND OF CFS... CCA... SMLR... AND OCN. SST ANOMALIES WERE CONSIDERED FOR COASTAL CALIFORNIA. THE CAS TOOL WAS ALSO CONSIDERED STRONGLY ... AS WE ARE APPORACHING THE TIME WHEN IT HAS THE GREATEST A PRIORI SKILL... FOR FORECASTS INITIATED IN THE EARLY SPRING. UNFORTUNATELY THE INITIAL SOIL MOSITURE ANOMALIES IN EARLY MARCH 2008 ARE NEITHER STRONG NOR LARGE SCALE. SIGNALS FROM EL NINO OR LA NINA COMPOSITIES WERE NOT WEIGHTED IN ANY OF THE FORECASTS. THE OUTLOOKS FOR ASO 2007 THROUGH AMJ 2008 LARGELY REFLECT TRENDS. TEMPERATURE TRENDS ARE POSITIVE AND SUBSTANTIAL FOR THE SOUTHWESTERN U.S. IN MOST OF THE YEAR AND OVER MUCH OF THE COUNTRY IN THE WINTER... AND ARE WEAKEST IN THE FALL. PRECIPITATION TRENDS APPEAR ONLY IN SCATTERED AREAS AND ARE WEAK. WET CONDITIONS ARE INDICATED IN COASTAL AREAS OF THE SOUTHEAST FOR THE LATE SUMMER AND EARLY FALL SEASONS... REFLECTING TREND AND OR THE MULTI-DECADAL CYCLE IN ATLANTIC TROPICAL ACTIVITY... BUT SHOULD NOT BE INTERPRETEED AS AN INDICATION OF HURRICANE STRIKE PROBABILITIES. FORECASTS OF DRY CONDITIONS ALONG THE GULF COAST FOR WINTER 2008 REFLECT WEAK BUT CONSISTENT TRENDS... AND WOULD HAVE ADDITIONAL SUPPORT IF EVEN A WEAK LA NINA CONDITIONS WERE TO BE IN PLACE BY THAT TIME. PROGNOSTIC DISCUSSION OF OUTLOOKS - AMJ 2007 TO AMJ 2008 TEMPERATURE: THE TEMPERATURE OUTLOOK FOR AMJ 2007 CALLS FOR ELEVATED CHANCES OF ABOVE NORMAL SEASONAL AVERAGE TEMPERATURE OVER MUCH OF THE WESTERN TWO THIRDS OF THE NATION... AS WELL AS THE SOUTHEAST. BELOW NORMAL SSTS OFF THE COAST ARE EXPECTED TO REDUCE TEMPERATURES ALONG MUCH OF SOUTHERN COASTAL CALIFORNIA. AN AREA OF ABOVE NORMAL IN THE NORTHWEST WAS DELETED IN FAVOR OF EC BECAUSE OF CONFLICTS WITH THE LATEST TOOLS. OUTLOOKS FOR AMJ THROUGH JAS 2007 ARE BASED PRIMARILY ON THE CONSOLIDATION TOOL WHICH IS OFTEN DOMINATED BY THE TREND... ALTHOUGH THE CFS MODEL IS AN IMPORTANT COMPONTENT DURING THESE EARLY LEADS. CAS AND MODELS FROM OTHER CENTERS WERE ALSO CONSIDERED AND USED TO SOMEWHAT ENLARGE AREASS AND PROBABILITIES SHOWING EXPECTED ABOVE NORMAL TEMPERATURES WHEN THEY AGREED WITH THE CON TOOL. BEGINNING WITH ASO 2007 AND CONTINUING THROUGH AMJ 2008... FORECASTS FOR BOTH THE CONUS AND ALASKA WERE BASED ON THE CON TOOL... WHICH IS DOMINATED BY LONG-TERM TRENDS. PRECIPITATION: THE PRECIPITATION OUTLOOKS FOR AMJ 2007 CALL FOR BELOW-MEDIAN PRECIPITATION FOR PARTS OF THE INTERIOR SOUTHWEST AND THE CENTRAL GULF COAST REGION. THE AREAL COVERAGE OF THE BELOW MEDIAN AREAS FOR AMJ THRU JAS WAS EXTENDED RELATIVE TO THE FORECASTS PREPARED ONE MONTH AGO MAINLY BECAUSE OF THE CAS FORECAST. THE EXTENSION INTO SOUTHERN CALIFORNIA WAS DONE TO BE CONSISTENT WITH THE MONTHLY OUTLOOK FOR APRIL 2008. THE ABOVE MEDIAN FORECAST FOR THE PACIFIC NORTHWEST WAS REMOVED BECAUSE OF CONFLICTING TOOLS. FOR AMJ 2007 AND BEYOND... THE PRECIPITATION OUTLOOK MAINLY REFLECTS WEAK TRENDS... FOR RELATIVELY WET CONDITIONS IN PARTS OF THE PACIFIC NORTHWEST DURING AMJ AND MJJ... AND RELATIVE DRYNESS OVER PARTS OF THE GREAT BASIN FOR AMJ THROUGH JJA... EXPANDING FURTHER TO THE NORTH AND WEST DURING JAS AND ASO. ABOVE MEDIAN RAINFALL IS EXPECTED OVER MUCH OF THE FLORIDA PENINSULA AND ALONG THE SOUTHEASTERN SEABOARD DURING JAS AND ASO DUE TO THE LONG-TERM INTERDECADAL CYCLE IN ATLANTIC TROPICAL STORM ACTIVITY... BUT THIS SHOULD NOT BE INTERPRETED AS A FORECAST FOR ABOVE AVERAGE HURRICANE STRIKE PROBABILITIES AS EASTERLY WAVES AND WEAK SYSTEMS NORMALLY CONTRIUBTE THE BULK OF WARM SEASON RAINFALL IN THIS AREA. THE PRECIPITIATION PROBABILITIES FOR WINTER 2007-08 AND THE FOLLOWING SPRING PRIMARILY REFLECT ONLY CLIMATOLOGY BECAUSE OF A WIDE SCATTER IN THE ENSO FORECAST FOR NEXT WINTER. HOWEVER... THERE ARE SOME WEAK BUT CONSISTENT INDICATIONS FROM CON... PRIMARILY DUE TO TREND... THAT IT COULD BE DRY ALONG PARTS OF THE SOUTHEASTERN COAST AND GULF COAST DURING WINTER 2008 AND WE EXTENDED THIS DRY AREA SOUTHWARD DOWN THE FLORIDA PENNINSULA BECAUSE EVEN A WEAK LA NINA WOULD ALSO FAVOR DRYNESS THERE. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: H. VAN DEN DOOL STARTING WITH THE SEASONAL OUTLOOK RELEASED IN FEBRUARY, 2006, THE GLOSSARY OF TERMS WILL NO LONGER APPEAR WITH THIS MESSAGE. INSTEAD, TERMS THAT ARE IN THE GLOSSARY WILL BE LINKED TO THEIR DEFINITION. FOR A DESCRIPTION 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/90DAY/DISC.HTML (USE LOWER CASE LETTERS) INFORMATION ON THE FORMULATION AND SKILL OF THE CAS FORECASTS MAY BE FOUND AT: HTTP://WWW.CPC.NCEP.NOAA.GOV/SOILMST/FORECASTS.HTML (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 THU APR 19 2007. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE $$