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) AVERAGE AT HIGH LATITUDES AND BELOW (ABOVE) AVERAGE AT MIDDLE LATITUDES - THE AO IS DEFINED AS NEGATIVE (POSITIVE) AND IS ASSOCIATED WITH BELOW (ABOVE) AVERAGE 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.

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.