PROGNOSTIC DISCUSSION FOR LONG-LEAD OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMPS SPRINGS MD
3 PM EDT THURSDAY JANUARY 16 2003
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SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
THIS SET OF OUTLOOKS CONTINUES TO BE INFLUENCED BY TWO MAIN FACTORS - EL NINO
AND THE LONG-TERM TREND. THE OUTLOOK FOR FEBRUARY-APRIL 2003 CALLS FOR ABOVE
NORMAL TEMPERATURES OVER MUCH OF THE NORTHERN AND WESTERN U.S. THIS IS DUE TO EL
NINO OVER THE PACIFIC NORTHWEST AND THE MIDWEST AND AND THE TREND IN THE
REMAINDER OF THE WEST AND NORTH. BELOW NORMAL TEMPERATURES ARE EXPECTED OVER
THE SOUTHEAST FROM TEXAS TO FLORIDA - DUE ENTIRELY TO EL NINO. PRECIPITATION
IS EXPECTED TO BE BELOW NORMAL IN THE PACIFIC NORTHWEST AND MONTANA - AND IN
THE OHIO VALLEY - DUE TO EL NINO. PRECIPITATION IS EXPECTED TO BE ABOVE NORMAL
FOR MUCH OF THE SOUTHERN U.S. FROM CALIFORNIA - ACROSS THE SOUTHWEST - THE
SOUTHERN PLAINS AND THE SOUTHEAST - AND ALSO IN THE CENTRAL PLAINS. THIS IS
ALSO IN RESPONSE TO EL NINO WITH SUPPORT FROM THE TREND IN COLORADO. THE
TEMPERATURE OUTLOOK FOR ALASKA DURING FEBRUARY-APRIL 2003 CALLS FOR ABOVE NORMAL
TEMPERATURES OVER MOST OF THE STATE WITH EQUAL CHANCES (CLIMATOLOGICAL
PROBABILITIES) FORECAST FOR PRECIPITATION OVER ALL BUT THE SOUTHERN SECTIONS -
INCLUDING THE PANHANDLE.
EQUATORIAL PACIFIC SEA SURFACE TEMPERATURES DURING DECEMBER REMAINED AT OR
ABOVE ONE DEGREE C ABOVE NORMAL OVER THE ENTIRE EQUATORIAL PACIFIC BETWEEN 170E
AND THE WEST COAST OF SOUTH AMERICA - WITH DEPARTURES EXCEEDING TWO DEGREES
BETWEEN 175W AND 140W AND ALSO BETWEEN 120W AND 105W. CURRENT CONDITIONS
CONTINUE TO INDICATE A MODERATE STRENGTH EL NINO EPISODE. THE US OUTLOOKS FOR
FEBRUARY-APRIL REFLECT THIS - SHOWING ABNORMALLY WARM CONDITIONS OVER THE
NORTHERN CONTINENTAL U.S. WITH BELOW NORMAL TEMPERATURES IN THE SOUTHEAST.
DRIER THAN NORMAL CONDITIONS OVER SECTIONS OF THE NORTHWEST - THE NORTHERN
ROCKIES - AND THE GREAT LAKES-OHIO VALLEY REGION AND WETTER THAN NORMAL
CONDITIONS ACROSS MUCH OF THE SOUTHERN TIER OF THE U.S. ARE ALSO CONSISTENT
WITH MODERATE EL NINO CONDITIONS. THIS BASIC PATTERN IS FORECAST TO PERSIST
INTO THE SPRING.
THE FORECAST REVERTS TO THE TREND - MAINLY WARMER THAN NORMAL TEMPERATURES IN
THE SOUTHWEST AND THE SOUTHEAST - BY LATE SPRING AND SUMMER 2003 AND CONTINUES
THROUGHOUT THE REMAINDER OF 2003 INTO FEBRUARY-APRIL 2004.
NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL
PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES).
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BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK
THIS OUTLOOK REFLECTS THE EXPECTED UNITED STATES CLIMATE ANOMALIES BASED ON THE
LONG TERM TREND - AS ESTIMATED BY OCN - AND STATISTICALLY-BASED RELATIONSHIPS
BETWEEN PRESENT OCEANIC AND ATMOSPHERIC CONDITIONS AND U.S. TEMPERATURE AND
PRECIPITATION. DYNAMICAL FORECASTS FROM GENERAL CIRCULATION MODELS WERE ALSO
CONSIDERED FOR THE FIRST FOUR SEASONS. EL NINO COMPOSITES WERE USED
EXTENSIVELY FOR THE FEBRUARY-APRIL AND MARCH-MAY SEASONS. THUS THE OUTLOOKS
FOR FMA AND MAM 2003 REFLECT EXPECTED MODERATE EL NINO CONDITIONS.
CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS
MODERATE WARM EPISODE (EL NINO) CONDITIONS PREVAILED DURING DECEMBER 2002 AS
AVERAGE SST ANOMALIES ACROSS THE EQUATORIAL PACIFIC EXCEEDED +1.0 DEGREE C
ALONG THE EQUATOR FROM THE JUST WEST OF THE DATE LINE TO THE SOUTH AMERICAN
COAST. ATMOSPHERIC INDICATORS OF A WARM EPISODE INCLUDE CONSISTENTLY NEGATIVE
VALUES OF THE SOUTHERN OSCILLATION INDEX (SOI) - SINCE MARCH 2002 - AND
GENERALLY WEAKER THAN AVERAGE LOW-LEVEL EASTERLY WINDS DURING MAY-DECEMBER 2002
THROUGHOUT THE EQUATORIAL PACIFIC - ESPECIALLY IN THE WESTERN AND CENTRAL
PACIFIC.
THE MADDEN JULIAN OSCILLATION (MJO) WAS A MAJOR SOURCE OF WEEK-TO-WEEK AND
MONTH-TO-MONTH VARIABILITY IN THE ATMOSPHERIC CIRCULATION OF THE TROPICS
AND SUBTROPICS DURING THE EARLY PART OF 2002 BEFORE IT HAD WEAKENED AS EL
NINO CONDITIONS BECOME SOLIDLY ESTABLISHED. DURING NOVEMBER AND DECEMBER MJO
ACTIVITY STRENGTHENED - ALTHOUGH CONVECTION REMAINED LOCKED-IN NEAR THE
DATELINE.
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PROGNOSTIC DISCUSSION OF SST FORECASTS
THE OCEANIC AND ATMOSPHERIC VARIABLES DISCUSSED ABOVE REFLECT THE PRESENCE OF
MODERATE EL NINO CONDITIONS. MOST DYNAMICAL COUPLED OCEAN-ATMOSPHERE MODEL AND
STATISTICAL MODEL FORECASTS INDICATE EL NINO CONDITIONS ARE LIKELY TO CONTINUE
THROUGH SPRING 2003. THE LATEST OBSERVED SEASONAL AVERAGE - OND - FOR NINO 3.4
IS A +1.6 DEGREE C ANOMALY. THE CONSENSUS OF VARIOUS FORECAST METHODS IS FOR
SSTS TO REMAIN MORE THAN 1.0 DEGREE C ABOVE NORMAL UNTIL MAM. THIS MAY BE
A BIT CONSERVATIVE GIVEN THAT RECENT WEEKLY AVERAGES HAVE BEEN ABOVE 1.5 DEGREES
AND WARM EVENTS TYPICALLY MATURE DURING THE WINTER. NEVERTHELESS THE CURRENT
EVENT IS EXPECTED TO BE WEAKER THAN 97/98 WHICH FEATURED 2.5 DEGREE ANOMALIES
FOR NINO 3.4. NOTE THAT THE GLOBAL IMPACTS OF THIS WARM EPISODE SHOULD BE
CORRESPONDINGLY WEAKER THAN THOSE OBSERVED DURING THE VERY STRONG 1997 - 98 EL
NINO. MOST TOOLS ARE LESS CLEAR ABOUT WHAT WILL HAPPEN WITH EL NINO BEYOND
AMJ 2003.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK
THE STATISTICAL TOOLS - CCA - OCN - SMLR - WERE CONSULTED AT ALL LEAD TIMES.
DYNAMICAL MODEL FORECASTS FROM NCEP AND OTHER FORECAST CENTERS WERE EXAMINED
FOR THE PERIOD FMA 2003 - MJJ 2003. THE LARGE-SCALE CIRCULATION PATTERNS
ARE EXPECTED TO REFLECT WARM EPISODE (EL NINO) CONDITIONS DURING THE REMAINDER
OF THE WINTER AND EARLY SPRING - SO WARM EPISODE COMPOSITES WERE USED
PROMINENTLY FOR FMA AND MAM 2003. A NEW RENDERING OF SUCH COMPOSITES BASED ON
OFFICIAL NOAA 0.5 DEGREE ANOMALY THRESHOLD HAS 11 CASES FOR FMA AND ONLY 8
CASES FOR MAM. BOTH A HIGH FREQUENCY (NO TREND) AND A TREND-ADJUSTED VERSION
OF THESE COMPOSITES HAVE BEEN PREPARED FOR USE BY THE FORECASTERS.
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PROGNOSTIC DISCUSSION OF OUTLOOKS - FMA 2003 TO FMA 2004
TEMPERATURE:
TEMPERATURES FOR FMA AND MAM 2003 REFLECT THE COMBINED INFLUENCE OF LONG
TERM TRENDS AND A MATURE MODERATE STRENGTH EL NINO. EL NINO COMPOSITES
SUPPORT WARMER THAN NORMAL TEMPERATURES ACROSS THE NORTHERN TIER OF STATES
DURING FMA AND IN MOST OF THE WEST DURING MAM. BELOW NORMAL TEMPERATURES
ACROSS MUCH OF THE SOUTH FOR FMA AND MAM 2003 ARE CONSISTENT WITH THE EL
NINO SIGNAL - WITH SUPPORT FROM THE SCREENING MULTIPLE LINEAR REGRESSION TOOL
FOR FMA. OCN - WITH VARYING AMOUNTS OF SUPPORT FROM CCA - INDICATES WARMER THAN
NORMAL TEMPERATURES FOR MOST OF THE REMAINING SEASONS IN THE SOUTHWEST - AND
THROUGHOUT MUCH OF THE SOUTH AND EAST AND WEST COASTS DURING THE SUMMER MONTHS -
AND ACROSS MUCH OF THE CONUS DURING NEXT WINTER.
THE EXPECTED EL NINO SIGNAL FAVORS ABOVE NORMAL TEMPERATURES OVER THE
SOUTHEASTERN PORTION OF ALASKA DURING FMA. THE ABOVE NORMAL OVER MUCH OF THE
REMAINDER OF ALASKA IS BASED ON OCN DURING FMA THROUGH MJJ 2003 - WITH THE OCN
SIGNAL PEAKING DURING MJJ AND THEN WEAKENING.
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PRECIPITATION:
BELOW MEDIAN PRECIPITATION IS EXPECTED DURING FMA 2003 FROM EASTERN SECTIONS OF
THE PACIFIC NORTHWEST AND MONTANA. MUCH OF THIS AREA IS ALSO EXPECTED TO
EXPERIENCE BELOW NORMAL PRECIPITATION DURING MAM AS WELL. DRIER THAN NORMAL
CONDITIONS ARE ALSO EXPECTED OVER THE OHIO VALLEY AND THE GREAT LAKES DURING FMA
AND MAM 2003 - BASED ON ENSO COMPOSITES. ABOVE NORMAL PRECIPITATION IS FORECAST
IN THE SOUTHWEST - THE SOUTH CENTRAL - AND THE SOUTHEASTERN U.S. DURING FMA AND
MAM 2003 - BASED ON ENSO COMPOSITES - TRENDS AND NEARLY ALL FORECAST TOOLS.
ABOVE MEDIAN PRECIPITATION IS MAINTAINED IN THE SOUTHWEST DURING AMJ SUPPORTED
BY EL NINO COMPOSITES AND EL NINO LAGGED COMPOSITES RELATIVE TO JFM. BELOW-
MEDIAN PRECIPITATION FOR PORTIONS OF THE GREAT BASIN IS INDICATED BY OCN WITH
SOME SUPPORT FROM SMLR DURING JJA AND JAS 2003.
THERE ARE NO RELIABLE FORECAST INDICATIONS FOR ALASKA PRECIPITATION AT ANY LEAD
BY THE TOOLS WE HAVE. NEVERTHELESS SYNOPTIC REASONING WOULD SUGGEST ON-SHORE
FLOW AROUND THE DEEPER THAN NORMAL ALEUTIAN LOW. HENCE WE FORECAST ABOVE-MEDIAN
PRECIPITATION FOR THE SE PART OF THE STATE FOR FMA 2003.
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These guys just keep proving to us that they are not monitoring latest ENSO trends. It has clearly been weakening over the past few months, plus 30 and 90 day avg SOI values are getting closer to neutral. Not to mention what is occurring with the subsurface SSTA. It has been exactly 2 months since TWW and I forecasted the El Nino to dissipate this Spring and a La Nina to form this summer. Are we sticking to this forecast or changing it some?? You'll find out in about a week or so when our next update is released!!
sorry for the stupid questions, still learning....Rainband