PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EDT THU APR 19 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 EASTERN PACIFIC OCEAN ARE AT 
LEAST 0.5 DEG C COLDER THAN AVERAGE FROM ABOUT 135W TO NEAR THE SOUTH AMERICAN 
COAST... AND TEMPERATURES ARE 2 TO 3 DEGREES CENTIGRADE COLDER THAN AVERAGE 
BETWEEN THE GALAPAGOS ISLANDS AND THE SOUTH AMERICAN COAST.  AN AREA OF 
RELATIVE WARMTH (AT LEAST +0.5 DEG C ABOVE AVERAGE) AT THE OCEAN SURFACE IS 
LOCATED WEST OF THE DATE LINE BETWEEN 160E AND 170E.  ELSEWHERE ACROSS THE 
EQUATORIAL PACIFIC...SEA SURFACE TEMPERATURES ARE NEAR AVERAGE. THE EQUATORIAL 
UPPER-OCEAN TOTAL HEAT CONTENT OF THE PACIFIC (OVER THE LONGITUDE BAND 180W TO 
100W) REACHED A MAXIMUM IN LATE NOVEMBER 2006 AND THEN DECREASED RAPIDLY 
THEREAFTER REACHING ZERO ANOMALY IN EARLY JANUARY 2007.  NEGATIVE ANOMALIES 
HAVE ENSUED SINCE THEN... WITH CURRENT ANOMALOUS HEAT CONTENT VALUES NEAR -0.9 
DEG C.

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 OR 
LA NINA EVENT.  SSTS IN THIS REGION WERE ABOUT 1.0 DEG C ABOVE NORMAL AT THE 
START OF JANUARY 2007 ... AND RAPIDLY DECREASED TO NEAR ZERO IN MID-FEBRUARY 
AND HAVE FLUCTUATED NEAR ZERO SINCE THEN.  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 
CURRENTLY IN PLACE AND IT IS UNCLEAR WHETHER OR NOT LA NINA CONDITIONS WILL 
DEVELOP DURING THE MAY-JUNE-JULY SEASON.  THE POSSIBLE MAGNITUDE AND DURATION 
OF LA NINA CONDITIONS IS ALSO UNCLEAR... WITH MOST TOOLS SUGGESTING EITHER 
NEUTRAL ENSO OR WEAK LA NINA CONDITIONS THIS SUMMER.  THEREFORE NO SIGNIFICANT 
ENSO IMPACTS ARE ANTICIPATED ON THE CLIMATE OF THE UNITED STATES DURING THE MJJ 
2007 SEASON.

THE TEMPERATURE OUTLOOK FOR MAY-JUN-JUL (MJJ) 2007 CALLS FOR WARMER THAN NORMAL 
CONDITIONS OVER MOST OF THE SOUTHWESTERN U.S... THE RIO GRANDE VALLEY... THE 
GULF AND SOUTH ATLANTIC COASTS... AND MUCH OF WESTERN AND SOUTHERN ALASKA.  
BELOW AVERAGE TEMPERATURES ARE PREDICTED OVER PARTS OF THE NORTHERN PLAINS. 
ELSEWHERE THERE ARE EQUAL CHANCES OF WARMER-THAN- ... COOLER-THAN- ... OR 
NEAR-AVERAGE TEMPERATURES.

BELOW MEDIAN PRECIPITATION IS EXPECTED FOR MJJ 2007 ACROSS PARTS OF THE CENTRAL 
ROCKIES... CENTRAL BASIN... AND EASTERN OREGON.   ELSEWHERE THERE ARE EQUAL 
CHANCES OF ABOVE-... BELOW-... OR NEAR-MEDIAN PRECIPITATION DURING MJJ.  

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 AT LEAST 0.5 
DEG C BELOW NORMAL FROM 135W TO NEAR THE SOUTH AMERICAN COAST... WITH ANOMALIES 
BETWEEN -2.0 AND -3.0 DEG C BETWEEN THE GALAPAGOS ISLANDS AND THE COAST OF 
ECUADOR.  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. 
NEAR AVERAGE SSTS DOMINATE MOST OF THE REMAINDER OF THE EQUATORIAL PACIFIC WITH 
THE EXCEPTION OF RELATIVELY WARM SURFACE WATERS (+0.5 TO +1.0 DEG C) WEST OF 
THE DATE LINE BETWEEN 145E AND 175E LONGITUDE.   THE UPPER OCEAN HEAT CONTENT 
IN THE EQUATORIAL PACIFIC HAS RECENTLY DECLINED TO WELL BELOW THE LONG-TERM 
AVERAGE.  ATMOSPHERIC INDICATORS (SUCH AS 850-HPA WINDS AND OLR ANOMALIES) 
DURING THE PAST MONTH WERE CONSISTENT WITH NEUTRAL ENSO CONDITIONS... WITH A 
TREND TOWARD WEAK LA NINA CONDITIONS.  THE MADDEN JULIAN OSCILLATION (MJO) HAS 
BEEN LARGELY INCOHERENT AND WEAK IN THE PAST FEW WEEKS.

PROGNOSTIC DISCUSSION OF SST FORECASTS

MOST SST FORECAST TOOLS INDICATE EITHER NEUTRAL ENSO OR WEAK LA NINA CONDITIONS 
ARE EXPECTED THROUGHOUT THE REST OF 2007... WITH MORE THAN HALF OF THE 
AVAILABLE MODELS LEANING TOWARD A NEUTRAL EVENT.  SOME OF THE MODELS WHICH 
ANTICIPATE A COLD EVENT ARE THE UKMO DYNAMICAL MODEL (WHICH PREDICTS A NINO 3.4 
ANOMALY OF -1.0 DEG C BY JJA 2007)... THE LDEO DYNAMICAL MODEL (WHICH PREDICTS 
A GRADUAL DROPOFF UNTIL OND 2007 WITH A MINIMUM ANOMALY NEAR -1.4 DEG C) ... 
AND THE NCEP CONSOLIDATION WHICH BOTTOMS OUT AROUND -1.4 DEG C IN JAS 2007 AND 
RECOVERS TO NEAR -0.7 DEG C BY NDJ 2007-08.   THE SPREAD IN SOLUTIONS AMONG THE 
VARIOUS STATISTICAL AND DYNAMICAL MODELS UNDERSCORES CONSIDERABLE UNCERTAINTY 
IN NINO 3.4 SST FORECASTS FOR THE UPCOMING SUMMER AND AUTUMN SEASONS.

PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS

THE OUTLOOK FOR MJJ 2007 IS BASED MAINLY ON THE CONSOLIDATION TOOL... WHICH IS 
A SKILL-WEIGHTED OBJECTIVE BLEND OF CFS... CCA... SMLR... AND OCN.  THIS FAVORS 
RELATIVE WARMTH ACROSS THE SOUTHWESTERN CONUS... THE GULF COAST AND THE 
SOUTHEAST COAST.  THE IRI AND CAS ALSO FAVOR MUCH OF THE WARMTH PREDICTED IN 
THOSE AREAS.  ABOVE AVERAGE TEMPERATURES ARE ALSO FORECAST OVER WESTERN AND 
SOUTHERN PORTIONS OF ALASKA ... BASED ON THE CFS - CCA - OCN - AND TO A LESSER 
EXTENT THE SMLR.  SST ANOMALIES WERE CONSIDERED FOR COASTAL CALIFORNIA.   THERE 
IS CONSIDERABLE UNCERTAINTY INDICATED FOR THE PACIFIC NORTHWEST... AS THE CFS 
IS FORECASTING COLD AND THE IRI PREDICTS NEAR NORMAL TEMPERATURES.  MOST OTHER 
TOOLS INDICATE WARMTH ACROSS THE NORTHWEST.  THIS UNCERTAINTY LEADS TO AN EC 
FORECAST.  THE CONSOLIDATION... CFS... CCA... AND TO A LESSER EXTENT THE IRI... 
ALL SUGGEST BELOW AVERAGE TEMPERATURES ACROSS PORTIONS OF THE NORTH-CENTRAL 
STATES FOR MJJ.  THE OUTLOOKS FOR JJA 2007 THROUGH MJJ 2008 ARE BASED PRIMARILY 
ON THE CONSOLIDATION TOOL AND LONG-TERM 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 ... 
REFLECTING TREND AND/OR THE MULTI-DECADAL CYCLE IN ATLANTIC TROPICAL 
ACTIVITY... BUT SHOULD NOT BE INTERPRETED AS AN INDICATION OF HURRICANE STRIKE 
PROBABILITIES.  IT IS NOT CLEAR WHETHER OR NOT NEXT WINTER WILL BE DOMINATED BY 
NEUTRAL OR LA NINA CONDITIONS.  BY DJF 2007/8 AND JFM 2008 THE CONSOLIDATION OF 
CCA... OCN... AND SMLR (THE CFS IS NOT AVAILABLE AT THESE LEADS) FAVORS A TILT 
TOWARD DRY CONDITIONS ACROSS THE SOUTHEAST.  FOR NOW... ENSO COMPOSITES ARE NOT 
CONSIDERED IN ANY OF THE FORECASTS. 

PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2007 TO MJJ 2008

TEMPERATURE:

THE TEMPERATURE OUTLOOK FOR MJJ 2007 CALLS FOR ELEVATED CHANCES OF ABOVE NORMAL 
SEASONAL AVERAGE TEMPERATURE OVER MUCH OF THE SOUTHWESTERN U.S... AS WELL AS 
ALONG THE RIO GRANDE VALLEY... THE GULF AND SOUTH ATLANTIC COASTS... AND OVER 
MUCH OF WESTERN AND SOUTHERN ALASKA.  THIS IS BASED LARGELY ON THE CON TOOL AND 
ITS COMPONENT INPUTS... WITH THE IRI AND CAS TOOLS ALSO SUPPORTING THE 
SOUTHWESTERN WARMTH.  THE WARMTH IN ALASKA COMES FROM CFS... CCA... OCN... AND 
TO A LESSER DEGREE THE SMLR.  BELOW AVERAGE TEMPERATURES ARE FORECAST ONLY FROM 
EASTERN MONTANA TO WESTERN MINNESOTA BASED ON AGREEMENT AMONG THE CFS... CCA... 
AND CON TOOLS... WITH SOME CONSIDERATION OF THE IRI TOOL.  BELOW NORMAL SSTS 
OFF THE CALIFORNIA COAST ARE EXPECTED TO REDUCE TEMPERATURES ALONG MUCH OF 
COASTAL CALIFORNIA. ELSEWHERE... EQUAL CHANCES FOR ABOVE AVERAGE - NEAR AVERAGE 
- AND BELOW AVERAGE TEMPERATURES IS FORECAST.  THE OUTLOOKS FOR JJA AND JAS 
2007 SHOW AN INCREASE IN RELATIVE WARMTH ACROSS THE EAST COAST STATES WITH A 
SUBSEQUENT WESTWARD EXPANSION OF THIS ANOMALOUS WARMTH ACROSS THE OHIO AND 
TENNESSEE VALLEYS INTO THE MISSISSIPPI RIVER VALLEY.  OUTLOOKS FOR ASO 2007 
THROUGH MJJ 2008 ARE BASED PRIMARILY ON THE CONSOLIDATION TOOL WHICH IS OFTEN 
DOMINATED BY THE TREND... ALTHOUGH THE CFS MODEL IS AN IMPORTANT COMPONENT 
DURING THE EARLY LEADS.  

PRECIPITATION:

THE PRECIPITATION OUTLOOK FOR MJJ 2007 CALLS FOR BELOW-MEDIAN PRECIPITATION 
FROM CENTRAL PARTS OF THE ROCKIES AND GREAT BASIN TO EASTERN OREGON.  THIS IS 
ATTRIBUTED TO THE CAS (WHICH HISTORICALLY HAS HAD SKILL IN THESE AREAS AND 
SEASON) ... THE CFS... AND TO SOME EXTENT THE IRI AND ECCA TOOLS. ELSEWHERE... 
WHICH INCLUDES THE VAST MAJORITY OF THE CONUS AND ALL OF ALASKA... EQUAL 
CHANCES OF BELOW - NEAR - AND ABOVE MEDIAN PRECIPITATION IS FORECAST.  FOR JJA 
AND ESPECIALLY JAS 2007... BELOW MEDIAN PRECIPITATION IS FORECAST ACROSS THE 
INTERIOR NORTHWEST... WITH INCREASING SUPPORT FROM THE CONSOLIDATION TOOL AT 
THE LATTER LEAD.  THE CON TOOL INPUTS (OCN... CCA... SMLR... AND CFS) GIVE 
MODERATELY STRONG SIGNALS FOR THIS DRY AREA OVER THE NORTHWEST.  FOR JAS - ASO 
- AND SON 2007... THERE IS A SLIGHTLY ELEVATED CHANCE OF ABOVE MEDIAN RAINFALL 
OVER FLORIDA AND ALONG THE SOUTHEAST COAST 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 CONTRIBUTE THE BULK OF WARM SEASON RAINFALL IN 
THIS AREA.  BEYOND THIS... THE PRECIPITATION FORECASTS PRIMARILY REFLECT ONLY 
CLIMATOLOGICAL PROBABILITIES BECAUSE OF SIGNIFICANT SCATTER IN THE ENSO 
FORECAST FOR NEXT WINTER.  HOWEVER... THERE ARE SOME CONSISTENT INDICATIONS 
FROM CON... PRIMARILY DUE TO TREND AND CCA... THAT IT COULD BE RELATIVELY DRY 
ALONG PARTS OF THE SOUTHEASTERN AND GULF COASTS DURING WINTER 2007-8.

NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL 
PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES).

FORECASTER: A. ARTUSA

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 MAY 17 2007.

1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001
FORECAST RELEASE

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