PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST THU JANUARY 15 2004
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SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
THE SEASONAL OUTLOOK REFLECTS THE PRESENCE OF LONG TERM TRENDS ON U.S.
TEMPERATURE AND PRECIPITATION...STATISTICAL FORECAST TOOLS... WITH SOME INPUT
FROM NUMERICAL MODELS DURING THE FIRST SEVERAL SEASONS... AND THE LIKELY
CONTINUATION OF ENSO NEUTRAL CONDITIONS IN THE TROPICAL PACIFIC DURING THE NEXT
SEVERAL MONTHS. WHILE SSTS ALONG THE EQUATOR ARE WARMER THAN NORMAL OVER MUCH
OF THE EASTERN HALF OF THE PACIFIC OCEAN... THEY REMAIN BELOW THE THRESHOLD
TEMPERATURES REQUIRED TO PRODUCE SUBSTANTIAL IMPACTS ON U.S. CLIMATE ASSOCIATED
WITH EL NINO. CLIMATE MODELS RUN AT NCEP AND OTHER CENTERS SUGGEST THAT THE
UNUSUALLY WARM SSTS IN THE WESTERN EQUATORIAL PACIFIC WILL HAVE AN IMPACT ON
U.S. TEMPERATURE AND PRECIPITAION... AND THESE IMPACTS ARE REFLECTED IN THE
OUTLOOKS FOR FMA AND MAM 2004. THERE IS LITTLE CONSENSUS AMONG CLIMATE MODELS
FROM AMJ ONWARD REFLECTING BOTH A WEAKER ASSOCIATION BETWEEN TROPICAL PACIFIC
SSTS AND U.S. CLIMATE IN SPRINGTIME... AND A GREATER UNCERTAINTY IN THE STATE OF
THE SSTS IN THE REGIONS IMPORTANT TO THE U.S. CLIMATE. THUS THE OUTLOOK FOR AMJ
2004 AND BEYOND PRIMARILY REFLECT DECADAL TRENDS IN U.S. TEMPERATURE AND
PRECIPITATION. CURRENT INDICATIONS ARE THAT THE SSTS IN THE CENTRAL EQUATORIAL
PACIFIC WILL REMAIN ABOVE NORMAL... BUT WILL STAY WITHIN THE ENSO NEUTRAL RANGE
THROUGH MUCH OF THE YEAR.
THE OUTLOOK FOR FEBRUARY THROUGH APRIL 2004 CALLS FOR BETTER THAN AVERAGE ODDS
OF ABOVE NORMAL TEMPERATURES OVER MOST OF THE WESTERN HALF OF THE NATION AND
ALASKA... SUPPORTED BOTH BY RECENT TRENDS AND THE CIRCULATION PATTERNS PREDICTED
BY THE CLIMATE MODELS. THE CLIMATE MODELS FAVOR A CIRCULATION PATTERN THAT
ELEVATES THE CHANCES OF BELOW NORMAL TEMPERATURES IN THE SOUTHEASTERN U.S.
EXCEPT FOR SOUTHERN FLORIDA. THE CHANCE FOR BELOW-MEDIAN PRECIPITATION IS
GREATER THAN AVERAGE OVER THE INTERIOR SOUTHWEST - AND ALONG THE EASTERN GULF
COAST AND NORTHERN FLORIDA. ABOVE-MEDIAN PRECIPITATION HAS ENHANCED LIKELIHOOD
IN PORTIONS OF THE PACIFIC NORTHWEST.
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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
SSTS ALONG THE EQUATOR IN THE EASTERN PACIFIC OCEAN CURRENTLY AVERAGE ABOUT .5
DEGREE C ABOVE NORMAL... WITH CONSIDERABLE VARIATION DUE TO THE INFLUENCE OF A
RECENT MADDEN-JULIAN OSCILLATION. SSTS FROM THE SOUTH AMERICAN COAST TO THE
DATE LINE RANGE FROM .5 DEGREE C BELOW NORMAL TO JUST OVER 1. DEGREE C ABOVE
NORMAL. EQUATORIAL SSTS REMAIN ABOVE NORMAL WEST OF THE DATE LINE WITH
ANOMALIES OF 1 DEGREE C EXTENDING TO ABOUT 150E. SUB-SURFACE TEMPERATURES
ALONG THE EQUATOR REMAIN NEAR TO SLIGHTLY ABOVE NORMAL IN THE EASTERN PACIFIC...
AND ABOVE NORMAL IN THE WESTERN PACIFIC. THE LARGE SCALE ATMOSPHERIC
CIRCULATION... TRADE WINDS... AND CONVECTION IN THE TROPICAL PACIFIC HAVE SHOWN
NO SIGNIFICANT TRENDS IN THE MEAN AND SHOW CONSIDERABLE WEEK TO WEEK VARIABILITY
IN RESPONSE TO AN ACTIVE MJO... WHICH CURRENTLY HAS ITS CONVECTIVE PHASE OVER
THE CENTRAL PACIFIC OCEAN.
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PROGNOSTIC DISCUSSION OF SST FORECASTS
FORECASTS FROM STATISTICAL AND NUMERICAL MODELS FOR SSTS IN THE TROPICAL PACIFIC
MOSTLY INDICATE THAT SSTS WILL REMAIN WARMER THAN NORMAL IN THE NEXT FEW
SEASONS. THERE IS CONSIDERABLE SPREAD AMONG THE TOOLS... WITH SOME MODELS
PREDICTING SSTS IN THE NINO 3.4 REGION EDGING UPWARD TO PRODUCE A WEAK WARM
EVENT... WHILE OTHERS PREDICT THAT ANOMALIES WILL SLOWLY DIMINISH TOWARD ZERO.
A CONSOLIDATION FORECAST OF NCEP SST MODELS INDICATES THAT NINO 3.4
TEMPERATURE ANOMALIES WILL REMAIN NEARLY STEADY... AVERAGING JUST UNDER .5
DEGREE C THROUGH SON 2004. NINO 3.4 PREDICTABILITY FROM WINTER INTO SPRING AND
SUMMER IS LOW... AND INDIVIDUAL SOLUTIONS FOR THIS SUMMERS NINO 3.4 SSTS RANGE
FROM VERY SLIGHTLY BELOW NORMAL TO A WEAK WARM EVENT WITH ANOMALIES AROUND 1
DEGREE C. CONSENSUS SUGGETS NEUTRAL ENSO CONDITIONS WILL CONTINUE THROUGH LATE
2004... WITH NO CONSENSUS FOR EITHER WARM OR COLD EPISODE CONDITIONS NEXT
WINTER. TO SEE THESE FORECASTS GO TO: http://
www.cpc.ncep.noaa.gov/products/predictions/90day/tools/briefing/index.pri.html
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 2004 THROUGH MJJ 2004 AND A CONSENSUS OF THESE TOOLS WAS USED
IN PREPARING THE FORECASTS FOR THESE SEASONS. ALSO - SOME CONSIDERATION OF
COMPOSITE OBSERVED TEMPERATURE AND PRECIPITATION ANOMALY PATTERNS OVER THE CONUS
FOR PAST CASES OF NEUTRAL AND NEGATIVE AO REGIMES STRATIFIED BY NEUTRAL NINO 3.4
SSTS WERE CONSIDERED IN PREPARING THE FORECASTS FOR THE FIRST FEW LEADS.
THE PRIMARY TOOLS USED IN THE FMA THROUGH MAM FORECASTS WERE OCN AND CCA...
TWO-TIER FORECASTS FROM SIX MODELS PROVIDED BY CDC... DYNAMICAL MULTI-MODEL
ENSEMBLES FROM IRI AND DYNAMICAL MODEL FORECASTS FROM THE NCEP ENVIRONMENTAL
MODELING CENTER. THERE IS SOME AGREEMENT AMONG DYNAMICAL MODELS RUN AT NCEP...
CDC AND IRI FOR AN UPPER AIR CIRCULATION PATTERN THAT FAVORS ANOMALOUSLY LOW
HEIGHTS SOUTH OF THE ALEUTIANS... POSITIVE 500-HPA HEIGHT ANOMALIES OVER
WESTERN NORTH AMERICA... AND HEIGHTS NEAR NORMAL OR SLIGHTLY BELOW IN THE
EASTERN U.S. DYNAMICAL MODEL FORECASTS FOR AMJ AND MJJ WERE NOT EMPHASIZED
BECAUSE THEY LACKED A CLEAR CONSENSUS.
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PROGNOSTIC DISCUSSION OF OUTLOOKS - FMA 2004 TO FMA 2005
TEMPERATURE:
THE CIRCULATION PATTERN PREDICTED FOR FMA AND MAM 2004 BY A CONSENSUS OF CLIMATE
MODELS FAVORS WARMER THAN NORMAL TEMPERATURES IN THE WESTERN U.S. AND ALASKA...
WITH TEMPERATURES NEAR THE LONG TERM NORMAL... OR SLIGHTLY BELOW IN THE EAST.
WITH RECENT TEMPERATURE TRENDS FACTORED IN... THE MODEL CONSENSUS INDICATE
ELEVATED CHANCES OF BELOW NORMAL TEMPERATURES ONLY FOR THE SOUTHEASTERN U.S.
THE TEMPERATURE PATTERN FORECAST BY THE CLIMATE MODELS IS SUPPORTED BY CCA AND
OCN FORECASTS IN THE WESTERN U.S. AND ALASKA. A COMPOSITE OF PAST CASES FOR
TREND-ADJUSTED ENSO-NEUTRAL CONDITIONS SUGGEST AN INCREASE IN THE ODDS OF BELOW
NORMAL TEMPERATURES IN PORTIONS OF THE NORTHERN PLAINS IN MAM AND AMJ 2004.
THE OUTLOOK FROM AMJ AND MJJ 2004 IS DERIVED MAINLY FROM CCA AND OCN AND
FEATURES BETTER THAN AVERAGE CHANCES FOR ABOVE NORMAL TEMPERATURES THROUGH MUCH
OF THE WESTERN U.S... PARTS OF THE SOUTHERN U.S. AND ALASKA. INDICATIONS
FOR ABOVE NORMAL TEMPERATURE FROM DYNAMIC MODELS WERE USED IN ALASKA. THE
OUTLOOK FOR JJA 2004 AND BEYOND IS BASED MOSTLY ON CCA AND OCN AND FAVORS WARMER
THAN NORMAL TEMPERATURES OVER THE SOUTHWEST DURING ALL LEAD TIMES... EXTENDING
TO INCLUDE MUCH OF THE SOUTHERN AND SOUTHEASTERN U.S. IN THE SUMMER. THE
CONFIDENCE IN THE FORECAST OVER SEVERAL LOCATIONS WHERE THE TEMPERATURE TRENDS
ARE THE STRONGSET WAS INCREASED OVER LAST MONTHS OUTLOOKS FOR THE CORRESPONDING
SEASONS. THESE CHANGES WERE MAINLY FOR LOCATIONS IN ARIZONA AND SOUTHERN
NEVADA... SOUTHERN TEXAS... AND IN SOUTHERN FLORIDA. THE FORECAST FOR THE
WINTER OF 2004-2005 REFLECTS REGIONAL TEMPERATURE TRENDS... SINCE THE ENSO
STATE FOR THAT TIME IS UNCERTAIN.
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PRECIPITATION:
THE DYNAMIC MODELS SUGGEST ABOVE MEDIAN PRECIPITATION IN FMA 2004 FOR THE
PACIFIC NORTHWEST... AND BELOW MEDIAN AMOUNTS FOR MUCH OF THE REMAINDER OF THE
WEST. AN ACTIVE MJO... AS HAS BEEN OBSERVED SO FAR THIS WINTER... FAVORS
PERIODS OF SIGNIFICANT PRECIPITATION FROM CENTRAL CALIFORNIA NORTHWARD. WHILE
THERE IS NO ASSURANCE THAT AN ACTIVE MJO WILL CONTINUE IN THE COMING MONTHS...
ITS CURRENT ACTIVITY INTRODUCES ENOUGH UNCERTAINTY INTO THE FORECAST TO
RESTRICT THE CALL FOR BELOW MEDIAN PRECIPTIATION TO ONLY INTERIOR PORTIONS OF
THE SOUTHWEST WHERE CCA... SMLR... AND OTHER STATISTICAL TOOLS LEND SOME
ADDITIONAL SUPPORT. THERE IS GENERAL MODEL CONSENSUS FOR DRY CONDITIONS IN
FMA 2004 OVER THE SOUTHEAST... PROVIDED THAT NINO 3.4 SSTS REMAIN IN THE
NEUTRAL RANGE.
CLIMATE MODELS AND OCN GIVE INDICATIONS FOR ENHANCED CHANCES OF ABOVE MEDIAN
PRECIPITATION FOR THE PACIFIC NORTHWEST IN MAM TO MJJ 2004. THERE WERE FEW
RELIABLE PRECIPITATION SIGNALS FOR JJA THROUGH SON 2004 - WITH THE EXCEPTION OF
DRY CONDITIONS FORECAST FOR PORTIONS OF THE FAR WEST DURING JAS AND ASO AND
FOR ENHANCED CHANCES OF ABOVE MEDIAN PRECIPITATION CENTERED OVER WESTERN
NEBRASKA IN SON AND OND INDICATED BY OCN. OCN ALSO INDICATES ELEVATED CHANCES
OF ABOVE MEDIAN PRECIPITATION AMOUNTS OVER SOUTHERN FLORIDA FROM JAS TO SON
2004... WHICH HAS BEEN ADDED TO THIS OUTLOOK. INDICATIONS FOR ABOVE MEDIAN
PRECIPITATION IN THE SOUTHERN PLAINS AND TEXAS ARE FROM TRENDS.
NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL
PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES).
FORECASTER: D. UNGER
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GLOSSARY AND DEFINITIONS:
ANALOG (NATURAL ANALOG) - A WEATHER MAP THAT RESEMBLES ANOTHER WEATHER MAP -
USUALLY FROM DIFFERENT YEARS BUT THE SAME SEASON IN THE HISTORICAL RECORD. THE
CRITERION FOR SELECTING AN ANALOG IS OFTEN THE PATTERN CORRELATION BETWEEN THE
MAPS. TWO MAPS WILL JUST BEGIN TO RESEMBLE EACH OTHER TO THE HUMAN EYE AT A
PATTERN CORRELATION OF ABOUT 40%. TO BE USEFUL - ANALOGS NEED TO HAVE MUCH
HIGHER CORRELATIONS TO THE ORIGINAL MAP THAN THAT - 80% OR MORE. ANALOGS ARE
INCREASINGLY DIFFICULT TO FIND AS THE GEOGRAPHIC REGION BEING COMPARED
INCREASES IN SIZE. PERFECT ANALOGS TO THE ENTIRE NORTHERN HEMISPHERE SIMPLY
DO NOT EXIST - FOR PRACTICAL PURPOSES. THIS IS WHY SIMPLE ANALOG FORECAST
METHODS DO NOT WORK VERY WELL.
ANNUAL CYCLE - AT MOST LOCATIONS THE CLIMATE STATE VARIABLES - T - P - SST-
WIND - AND OTHERS DISPLAY A REGULAR VARIATION WHICH FOLLOWS THAT OF THE
ELEVATION OF THE SUN IN THE SKY. A GRAPH OF THE 30 YEAR AVERAGE OF A
VARIABLE FOR EACH DAY OF THE YEAR VERSUS DATE SHOWS A WAVE-FORM WHICH -
FOR T AT DES MOINES FOR EXAMPLE - RANGES SMOOTHLY FROM LOWEST VALUES IN THE
WINTER TO HIGHEST VALUES IN THE SUMMER.
ANOMALY - THE ARITHMETIC DIFFERENCE BETWEEN THE VALUE OF A VARIABLE AT A GIVEN
PLACE AND TIME AND THE LONG-TERM AVERAGE (USUALLY 30 YEARS) FOR THE LOCATION
AND TIME OF YEAR.
AO - ARCTIC OSCILLATION - A MEASURE OF THE DIFFERENCE IN PRESSURE (AT SEA LEVEL)
OR 500-HPA HEIGHT (IN THE MIDDLE TROPOSPHERE) BETWEEN THE NORTHERN POLAR REGION
AND MIDDLE LATITUDES. WHEN PRESSURES AND HEIGHTS ARE ABOVE (BELOW) NORMAL AT
HIGH LATITUDES AND BELOW (ABOVE) NORMAL AT MIDDLE LATITUDES - THE AO IS DEFINED
AS NEGATIVE (POSITIVE) AND IS ASSOCIATED WITH BELOW (ABOVE) NORMAL TEMPERATURES
OVER MIDDLE LATITUDES - INCLUDING THE CONUS.
CA - CONSTRUCTED ANALOG - A LINEAR COMBINATION OF PAST OBSERVED ANOMALY
PATTERNS SUCH THAT THE COMBINATION IS AS CLOSE AS DESIRED TO THE INITIAL
STATE. A FORECAST IS OBTAINED BY PERSISTING THE WEIGHTS ASSIGNED TO EACH
YEAR IN THE HISTORICAL RECORD AND LINEARLY COMBINING THE STATES FOLLOWING
THE INITIAL TIME IN THE HISTORICAL YEARS.
CAS - CONSTRUCTED ANALOG SOIL MOISTURE PREDICTION TECHNIQUE.
CCA - CANONICAL CORRELATION ANALYSIS - A TECHNIQUE WHICH PREDICTS THE STATUS OF
U.S. T AND P FOR SOME FUTURE TARGET SEASON USING THE MOST RECENT 4 NON-
OVERLAPPING SEASONAL OBSERVATIONS OF TROPICAL PACIFIC SST - CIRCULATION AND
U.S. T OR P TO CHARACTERIZE THE RECENT BEHAVIOR OF THE CLIMATE - AND PAST
OBSERVATIONS TO PLACE RECENT BEHAVIOR INTO A HISTORICAL CONTEXT.
CDC - CLIMATE DIAGNOSTIC CENTER. A NOAA ENVIRONMENTAL RESEARCH AND DEVELOPMENT
FACILITY. http://www.cdc.noaa.gov
CLIMATOLOGY - THE 30-YEAR AVERAGE OF A VARIABLE - LIKE TEMPERATURE - AT A
GIVEN LOCATION AND TIME OF YEAR.
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CONUS - CONTERMINOUS UNITED STATES
CONVECTION - A PROCESS WHEREBY AIR BECOMES BUOYANT RELATIVE TO ITS SURROUNDINGS
AND BEGINS TO RISE IN A CONCENTRATED COLUMN - WHILE THE SURROUNDINGS SUBSIDE
OVER A MUCH LARGER AREA. THE TERM IS OFTEN USED TO DESCRIBE THE OCCURENCE OF
DEEP CUMULUS CONVECTION IN THE TROPICAL OCEANS.
CPC - CLIMATE PREDICTION CENTER. A NOAA FACILITY WHICH PRODUCES OPERATIONAL
PREDICTIONS FOR 6-10-, 8-14-DAYS, MONTHLY AND SEASONAL TIME FRAMES.
http://www.cpc.ncep.noaa.gov
DATELINE - A HYPOTHETICAL LINE APPROXIMATELY ALONG THE 180TH MERIDIAN DESIGNATED
AS THE PLACE WHERE EACH CALENDAR DAY BEGINS.
DYNAMICAL MODEL - A PREDICTION METHOD WHICH USES EQUATIONS DESCRIBING THE
PHYSICAL BEHAVIOR OF A SYSTEM AND A COMPREHENSIVE SET OF CURRENT OBSERVATIONS
OF THE VALUES OF THE VARIABLES DESCRIBING THE CURRENT STATE OF THE SYSTEM
(INITIAL CONDITIONS) TO PREDICT THE VALUES OF THOSE VARIABLES A SHORT TIME-STEP
IN THE FUTURE. THOSE VALUES ARE - IN TURN - USED AS THE INITIAL CONDITIONS FOR
A SUBSEQUENT PREDICTION - AND SO ON - UNTIL THE DESIRED FUTURE PREDICTION TIME
IS REACHED.
EASTERLY WIND - WIND BLOWING FROM EAST TO WEST.
EC - EQUAL CHANCES - THE PROBABILITY OF THE MOST LIKELY CATEGORY CANNOT BE
DETERMINED AND THE EXPECTED LIKELIHOODS OF ABOVE - NORMAL AND BELOW DO NOT
DIFFER FROM THEIR CLIMATOLOGICAL ODDS OF 33 1/3% EACH. EC REPLACES CL.
EL NINO - THE WARM PHASE OF THE ENSO CYCLE
ENSO - EL NINO/SOUTHERN OSCILLATION
FORCED OR FORCING - GENERALLY REFERS TO WARM OCEAN SURFACE TEMPERATURES IN
THE TROPICAL OCEANS WHICH SUCCESSIVELY INFLUENCE THE STRENGTH OF TROPICAL
CUMULUS CONVECTION - THE TROPICAL LARGE-SCALE ATMOSPHERIC CIRCULATION - THE
JET STREAMS AND FINALLY - THE MIDDLE LATITUDE CIRCULATION.
GCM - GENERAL CIRCULATION MODEL - A GENERIC TERM APPLIED TO GLOBAL DYNAMICAL
MODELS.
IRI - INTERNATIONAL RESEARCH INSTITUTE FOR CLIMATE PREDICTION - A NOAA-FUNDED
NON-GOVERNMENTAL ORGANIZATION WHICH PREPARES INTERNATIONAL CLIMATE FORECASTS.
http://iri.columbia.edu
ITCZ - INTERTROPICAL CONVERGENCE ZONE - A LINE WHERE THE SOUTHEASTERLY AND
NORTHEASTERLY TRADE WINDS CONVERGE - CHARACTERIZED BY ENHANCED CONVECTION.
IT MAY BE IN EITHER THE NORTHERN OR SOUTHERN HEMISPHERE - AND OCCASIONALLY
A DOUBLE ITCZ MAY BE SEEN IN BOTH HEMISPHERES NOT FAR FROM THE EQUATOR.
LA NINA - THE COLD PHASE OF THE ENSO CYCLE
MJO - MADDEN-JULIAN OSCILLATION - ALSO CALLED TROPICAL INTRA-SEASONAL OSCILLA-
TION - A DISTURBANCE IN TROPICAL CONVECTION - PRECIPITATION - WIND AND
PRESSURE. MJO PRECIPITATION AND CLOUDINESS ARE ENHANCED ONLY IN REGIONS WHERE
SSTS ARE VERY WARM - E.G. INDIAN OCEAN AND WEST PACIFIC. THE PRESSURE AND WIND
DISTURBANCE ASSOCIATED WITH MJO IS OBSERVED TO MOVE FROM WEST TO EAST
COMPLETELY AROUND THE GLOBAL TROPICS IN ABOUT 30 TO 60 DAYS.
NAO - NORTH ATLANTIC OSCILLATION TELECONNECTION PATTERN - WHICH MAY BE
CONSIDERED AS THE ATLANTIC HALF OF THE AO. NOTE THAT THE STATUS OF THE
AO/NAO AND OTHER SLOWLY VARYING CIRCULATION MODES - WHILE VERY IMPORTANT
IN DETERMINING THE TEMPERATURE AND PRECIPITATION REGIMES OVER THE U.S. - ARE
UNPREDICTABLE BEYOND A WEEK OR TWO AHEAD AT BEST BY CURRENT TECHNOLOGY AND ARE
NOT EXPLICITLY INCLUDED IN OUR FORECAST PROCESS AS RELIABLE PREDICTORS.
NORTHERLY WIND - WIND BLOWING FROM NORTH TO SOUTH.
OCN - OPTIMAL CLIMATE NORMALS - A FORECAST BASED ON PERSISTING THE AVERAGE
OF THE LAST 10 YEARS FOR TEMPERATURE AND THE LAST 15 YEARS FOR PRECIPITATION.
OLR - OUTGOING LONGWAVE RADIATION (HEAT) WHICH IS OBSERVED BY SATELLITE. IN
THE TROPICS - LOWER THAN AVERAGE OLR INDICATES ENHANCED DEEP CUMULUS CLOUDS
AND RAIN (SATELLITE IS SEEING COLD CLOUD TOPS) - WHILE HIGHER THAN AVERAGE OLR
INDICATES AN ABNORMAL ABSENCE OF CLOUDS AND RAIN (SATELLITE IS SEEING WARM
LOW LAYERS (SHALLOW CLOUDS) OF THE ATMOSPHERE OR THE SURFACE).
PNA - PACIFIC NORTH AMERICAN TELECONNECTION PATTERN.
QBO - QUASI-BIENNIAL OSCILLATION - AN OSCILLATION OF THE WIND IN THE LOWER
STRATOSPHERE BETWEEN EASTERLY AND WESTERLY WHICH REVERSES ON A NEARLY-
2 YEAR TIME SCALE. QBO IS ONE OF THE MOST REGULAR OSCILLATIONS KNOWN.
SIGNAL - THAT PART OF THE VARIATION OF THE ENVIRONMENT WHICH CORRESPONDS TO
A REAL - PHYSICAL PHENOMENON. WHEN THE SIGNAL IS LARGE - ITS SIGNATURE STANDS
OUT ABOVE THE REMAINDER TO THE VARIATION OF THE ENVIRONMENT - CALLED THE NOISE.
SIGNAL IS SOMETIMES PREDICTABLE. NOISE IS NOT. THE RELATIONSHIP BETWEEN
SIGNAL AND NOISE IS EXPRESSED AS A NUMBER - CALLED THE SIGNAL-TO-NOISE RATIO
OR S/N. WHEN S/N IS GREATER THAN 1 - SIGNAL IS LARGER THAN NOISE - AND THE
SIGNATURE OF THE DISTURBANCE CAUSING THE SIGNAL CAN BE SEEN. WHEN S/N IS
LESS THAN 1 WE HAVE NO HOPE OF SEEING OR PREDICTING THE DISTURBANCE.
SMLR - SCREENING MULTIPLE LINEAR REGRESSION - A TECHNIQUE WHICH SELECTS THE BEST
SET OF PREDICTORS - FITTING THEM TO THE OBSERVATIONS TO CREATE EQUATIONS WHICH
CAN BE USED TO MAKE PREDICTIONS.
SOUTHERLY WIND - WIND BLOWING FROM SOUTH TO NORTH.
SPREAD - A MEASURE OF THE VARIATION - OR AGREEMENT AMONG MODEL FORECASTS WHICH
ARE VALID AT THE SAME TIME. LARGE SPREAD INDICATES POOR AGREEMENT. SMALL
SPREAD GENERALLY INDICATES GOOD AGREEMENT AMONG FORECASTS.
SST - SEA SURFACE TEMPERATURE
STATISTICAL PREDICTIONS - PREDICTIONS BASED MAINLY ON LARGE OBSERVATIONAL DATA
SETS. CCA - OCN - SMLR - CAS - CA ARE EXAMPLES OF THESE.
TAO - TROPICAL OCEAN-ATMOSPHERE PROJECT. A SOURCE OF REAL-TIME OBSERVATIONS OF
THE STATUS OF THE TROPICAL PACIFIC. DEVELOPED AND MAINTAINED BY THE PACIFIC
MARINE ENVIRONMENTAL LABORATORY (PMEL) - A NOAA FACILITY.
http://www.pmel.noaa.gov
TELECONNECTIONS - THESE GIVE THE HISTORICAL RELATIONSHIP BETWEEN A GIVEN POINT
AND ALL OTHER POINTS OVER A LARGE AREA - LIKE THE NORTHERN HEMISPHERE - FOR A
GIVEN TIME OF THE YEAR. THE POINTS ON THE MAP USUALLY CONSIST OF A SET OF
MORE OR LESS EVENLY SPACED LOCATIONS CALLED GRID POINTS.
TREND - AT A GIVEN LOCATION AND TIME OF YEAR - THE DIFFERENCE BETWEEN THE
AVERAGE OF THE MOST RECENT 10 (15) YEARS OF OBSERVATIONS OF T (P) AND THE
CLIMATOLOGY.
UPPER AIR HEIGHT PATTERN - A PATTERN FORMED BY THE CONTOURS WHICH MAP THE
TOPOGRAPHY OF THE HEIGHT ABOVE SEA LEVEL OF A SURFACE ALONG WHICH THE PRESSURE
IS EVERYWHERE THE SAME. THE LINES ON THIS MAP FORM A SERIES OF UNDULATING BUT
MORE OR LESS CIRCULAR SHAPES WHICH ARE CONCENTRIC ABOUT THE POLES AND WHICH
RESEMBLE A CROSS SECTION OF AN ONION. WELL ABOVE THE GROUND THE WIND BLOWS
PARALLEL TO THE CONTOURS WITH LOW PRESSURE TO THE NORTH (SOUTH) IN THE
NORTHERN (SOUTHERN) HEMISPHERE - GENERALLY FROM WEST TO EAST - WITH SPEED
PROPORTIONAL TO THE SLOPE OF THE SURFACE. THE CLOSER (FARTHER APART) THE
CONTOURS ARE TOGETHER (THE STEEPER (SHALLOWER) THE SLOPE) THE FASTER (SLOWER)
THE WIND SPEED.
WESTERLY WIND - WIND BLOWING FROM WEST TO EAST.
ZONAL FLOW PATTERN - OCCURS WHEN 500-HPA CONTOURS LIE IN AN EAST-WEST DIRECTION
PARALLEL TO LATITUDE CIRCLES WITH NEARLY PURE WEST-TO-EAST FLOW.
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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 LOWER CASE LETTERS)
NOTES - THESE CLIMATE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF
THEIR VALID PERIODS. 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 FEB 19 2004.
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM 1971-2000 AVERAGES.
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