PROGNOSTIC DISCUSSIONS FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EST WED FEB 06 2002 6 TO 10 DAY OUTLOOK FOR FEB 12 - FEB 16 2002 . . . . . . . . MODEL COMPARISONS: TODAY THE MAIN MODELS ARE IN REASONABLE AGREEMENT FOR THE FIRST FOUR DAYS BUT BY DAY 5 START TO DEVELOP SIGNIFICANT DIFFERENCES IN HOW A SHORT WAVE UPPER LEVEL TROUGH IS EXPECTED TO AMPLIFY OVER THE CENTER OF THE NATION AND THEN EXIT ACROSS THE SOUTHEAST. THE MRF...ECMWF...0Z AND 12Z UKMET...AND CANADIAN MODELS ALL AGREE ON AN ACTIVE BRANCH OF THE JET STREAM BEING OVER THE LOWER 48 STATES DURING THE FIRST FIVE DAYS...WITH ONE SHORT WAVE EXITING THE EAST COAST BETWEEN DAY 2 AND 3 AS THE NEXT SHORT WAVE IS COMING IN OVER THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. THE SECOND SHORT WAVE IS FORECAST TO AMPLIFY OVER THE CENTRAL PLAINS DURING DAY 3 AND CONTINUE DROPPING SOUTHEASTWARD. SOME FAIRLY MINOR DIFFERENCES IN TIMING AND AMPLITUDE DEVELOP ON DAYS 4 AND 5...BUT ALL MODELS TAKE THIS SYSTEM OFF THE SOUTHEAST COAST BY THE START OF THE 6 TO 10 DAY PERIOD EXCEPT THE 0Z UKMET WHICH WOULD STILL HAVE THE UPPER LEVEL TROUGH OVER ALABAMA AND THE ASSOCIATED LOW ON THE SOUTH CAROLINA COAST BY THE BEGINNING OF DAY 6. ONCE AGAIN TODAY ON DAY 6 THE MRF AND ECMWF HAVE BEGUN SHOWING A DIFFERENCE THAT ULTIMATELY AFFECTS THEIR D+8 MEANS...WITH THE ECMWF HAVING THE NEXT UPSTREAM SHORT WAVE OVER THE WESTERN GREAT LAKES AND MISSISSIPPI VALLEY WHEN THE MRF HAS IT FROM THE NORTHERN PLAINS TO THE SOUTHERN ROCKIES. FOR THE D+8 PERIOD THE MRF...MRF ENSEMBLE MEAN...ECMWF...AND DAVA ARE IN RATHER POOR AGREEMENT AGAIN TODAY...ALTHOUGH THEY HAVE COME SOMEWHAT CLOSER TOGETHER THAN THEY WERE YESTERDAY. ALL THE SOLUTIONS HAVE POSITIVE HEIGHT ANOMALIES AT MIDDLE LATITUDES NEAR THE DATELINE. THIS ANOMALY CENTER TELE- CONNECTS WITH A NEGATIVE PHASE OF THE PNA PATTERN...BUT NONE OF TODAYS SOLUTIONS STRONGLY PROJECT ONTO THAT MODE. TODAYS MRF IS SOMEWHAT MORE PROGRESSIVE THAN YESTERDAYS MRF. TODAYS ECMWF STILL HAS MORE RIDGE OVER THE CANADIAN ROCKIES THAN OTHER SOLUTIONS...AS IT DID YESTERDAY...BUT TODAYS ECMWF HAS MORE UNDERCUTTING OF THIS RIDGE OVER THE U.S. ROCKIES THAN IT DID YESTERDAY...AS WELL AS LESS TROUGH OVER THE EASTERN STATES. THE MRF ENSEMBLE MEAN PATTERN IS BASICALLY A LOWER AMPLITUDE VERSION OF THE MRF PATTERN...BUT WITH MORE DETAIL DIFFERENCES THAN USUAL. THAT AND EXAMINATION OF THE MRF ENSEMBLE TOOLS SHOWS AN UNUSUALLY LARGE SPREAD AMONG POSSIBLE SOLUTIONS TODAY. THE DAVA CONTINUES TO FORECAST POSITIVE HEIGHT ANOMALIES OVER MOST OF THE LOWER 48 STATES. CONFIDENCE IN ANY SOLUTION IS LOW AGAIN TODAY. . . . . . . . . CONFIDENCE IN TODAYS FORECAST IS WELL BELOW AVERAGE...1 ON A 1-5 SCALE...DUE TO MODEL DISAGREEMENT...LACK OF MODEL CONTINUITY...AND LACK OF TELECONNECTIVITY. THE OFFICIAL 500 HPA HEIGHT FORECAST FOR THE 6 TO 10 DAY PERIOD USES 40 PERCENT OF TODAYS MRF ENSEMBLE MEAN CENTERED ON DAY 8...40 PERCENT OF YESTERDAYS ENSEMBLE MEAN CENTERED ON DAY 7...10 PERCENT OF TODAYS ECMWF CENTERED ON DAY 7...AND 10 PERCENT OF TODAYS DAVA CENTERED ON DAY 8. . . . . . . . . MODEL OF THE DAY: ENSEMBLE MEAN THE TEMPERATURE PROG IS BASED PRIMARILY ON THE KLEIN AND THE NEURAL NET TEMPERATURE SPECIFICATIONS FROM THE OFFICIAL BLEND...WHICH WERE IN FAIR AGREEMENT...WITH CONSIDERATION OF THE COMPOSITE OF THE BEST PAST OBSERVED ANALOGS TO THE MRF ENSEMBLE MEAN HEIGHT FORECAST FOR ALASKA. THE PRECIPITATION PROG IS BASED MOSTLY ON THE NEURAL NET FROM THE OFFICIAL BLEND AND COMPOSITE PATTERN OF THE BEST PAST OBSERVED ANALOGS TO THE MRF ENSEMBLE MEAN HEIGHT FORECAST. 8 TO 14 DAY OUTLOOK FOR FEB 14 - 20 2002 MODEL COMPARISONS: MRF...MRF ENSEMBLE...AND DAVA 7-DAY 500 HPA MEANS FOR WEEK 2 ARE IN POOR AGREEMENT. THE MRF IS HIGHLY AMPLIFIED OVER THE PACIFIC AND WESTERN NORTH AMERICA AGAIN TODAY...WITH A 350 METER POSITIVE HEIGHT ANOMALY NEAR 45N/160W TODAY...WHILE DOWNSTREAM THE MRF HAS STRONG NEGATIVE ANOMALIES CENTERED JUST OFF THE CALIFORNIA COAST. THE MRF ALSO HAS WEAK NEGATIVE HEIGHT ANOMALIES OVER THE NORTHERN HALF OF THE NATION...BUT WITH A STRONG BRANCH OF THE JET STREAM CONTINUING ACROSS THE SOUTHERN HALF OF THE NATION AND WITH NO STRONG ANOMALOUS FLOW OUT OF THE ARCTIC TEMPERATURES WOULD NOT BE EXPECTED TO BE EXTREMELY BELOW NORMAL ANYWHERE EAST OF THE CONTINENTAL DIVIDE WITH THE MRF SOLUTION. THE MRF ENSEMBLE MEAN HAS FAIRLY STRONG POSITIVE HEIGHT ANOMALIES NEAR 50N/160W BUT IS QUITE DIFFERENT FROM THE MRF DOWNSTREAM...WITH POSITIVE HEIGHT ANOMALIES WEST OF THE DIVIDE AND ACROSS THE SOUTH AND NEGATIVE ANOMALIES FROM THE NORTHERN HALF OF THE GREAT PLAINS EASTWARD TO THE ATLANTIC COAST FROM NEW ENGLAND TO THE MID-ATLANTIC STATES. THE DAVA FORECASTS NO NEGATIVE HEIGHT ANOMALIES OVER THE LOWER 48 STATES. . . . . . . . . CONFIDENCE IN TODAYS FORECAST REMAINS VERY LOW...RATED 1 ON A SCALE OF 1-5. THE OFFICIAL 500 HPA HEIGHT FORECAST FOR THE 8 TO 14 DAY PERIOD USES 40 PERCENT OF TODAYS MRF ENSEMBLE MEAN CENTERED ON DAY 11...3O PERCENT OF TODAYS OPERATIONAL MRF CENTERED ON DAY 11...20 PERCENT OF TODAYS DAVA CENTERED ON DAY 11...AND 10 PERCENT OF TODAYS ECMWF 5-DAY MEAN CENTERED ON DAY 7. THE TEMPERATURE OUTLOOK IS BASED MAINLY ON THE KLEIN AND NEURAL NET SPECIFICATIONS FROM THE OFFICIAL BLEND. THE PRECIPITATION FORECAST IS BASED PRIMARILY ON THE NEURAL NET FROM THE OFFICIAL BLEND AND COMPOSITE PATTERNS OF THE PAST BEST ANALOGS TO THE ENSEMBLE MEAN AND MRF. FORECASTER: R. MARTIN . . . . . . . . NOTES: AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OTHERWISE - FORECASTS INCORPORATE FORECASTER INPUT. THE NOTATION FOR THE CATEGORICAL FORECAST INDICATED ON THE MAPS IS THE SAME AS THAT IN THE TABLES: A-ABOVE N-NEAR NORMAL B-BELOW IN THE SOUTHWEST AND OTHER CLIMATOLOGICALLY DRY REGIONS - THERE WILL BE A GREATER THAN 33.3% CHANCE OF NO PRECIPITATION AND OCCASIONALLY EVEN A NORMAL (I.E. MEDIAN) VALUE OF ZERO - ESPECIALLY DURING THE DRY SEASONS. IN SUCH CASES A FORECAST OF NEAR NORMAL IS EFFECTIVELY A FORECAST OF LITTLE OR NO PRECIPITATION. THE NARRATIVE DESCRIPTION OF THE FORECAST PATTERNS FOR TEMPERATURE AND PRECIPITATION FOR BOTH THE 6-10 OR 8-14 DAY PERIODS HAS BEEN DISCONTINUED. THE STATE TABLES FOR BOTH THE 6-10 AND 8-14 DAY PERIODS ARE NOW CONTAINED IN THIS MESSAGE...AVAILABLE AS PMDMRD ON AWIPS. EFFECTIVE THURSDAY MAY 17 2001...THE CLIMATE PREDICTION CENTER HAS SWITCHED TO 1971-2000 BASE PERIOD MEANS FOR TEMPERATURE...PRECIPITATION...AND 500-HPA HEIGHTS AS REFERENCE IN THE CLIMATE OUTLOOKS. THE 1971-2000 BASE PERIOD MEANS HAVE REPLACED THE 1961-1990 BASE PERIOD MEANS. . . . . . . . . GLOSSARY AND DEFINITIONS:----------------------------------------------------- ANOMALY - THE ARITHMETIC DIFFERENCE BETWEEN THE VALUE OF A VARIABLE AT A GIVEN PLACE AND TIME AND THE LONG-TERM AVERAGE OF THAT VARIABLE AT THAT PLACE AND TIME OF YEAR. AVN - THE RUN OF THE MRF MODEL INITIATED AT 12 UTC. BLEND - A WEIGHTED AVERAGE OF 500 HPA HEIGHT FORECAST MAPS FROM SEVERAL MODELS. WEIGHTS ARE CURRENTLY ASSIGNED SUBJECTIVELY BY THE FORECASTER. THE SUM OF THE WEIGHTS MUST BE 1. WEIGHTS ARE APPLIED BY MULTIPLYING EACH 500 HPA MAP BY ITS WEIGHT AND ADDING ALL OF THE WEIGHTED MAPS TOGETHER TO MAKE THE OFFICIAL 500 HPA FORECAST. CONUS - CONTINENTAL UNITED STATES. DAVA - DIVERGENT ANOMALY VORTICITY ADVECTION MODEL. THIS IS A BAROTROPIC MODEL WITH DIVERGENCE IN IT TO ALLOW MORE ACCURATE PREDICTION OF LONG WAVES THAN A STANDARD BAROTROPIC MODEL. REFERENCE: QIN J. AND H.M. VAN DEN DOOL - 1996: SIMPLE EXTENSIONS OF AN NWP MODEL. MON. WEA. REV. - VOL 124 - PP 277-287. EL NINO - THE WARM PHASE OF ENSO. LA NINA - THE COLD PHASE OF ENSO. ENSO - EL NINO/SOUTHERN OSCILLATION. FLOW PATTERN - THE PATTERN OF WIND INFERRED BY THE 500 HPA CONTOURS - THE WIND TENDS TO BLOW PARALLEL TO THE CONTOURS WITH LOW HEIGHT ON THE LEFT - IN THE NORTHERN HEMISPHERE - THE OPPOSITE IS TRUE IN THE SOUTHERN HEMISPHERE. WIND SPEED IS INVERSELY PROPORTIONAL TO THE SPACING BETWEEN THE CONTOURS. 500 HPA HEIGHT IS THE HEIGHT - IN METERS - ABOVE MEAN SEA LEVEL - WHICH ABOUT HALF OF THE MASS OF THE ATMOSPHERE LIES ABOVE AND BELOW - AS MEASURED BY THE PRESSURE. UPPER AIR STORM SYSTEMS TEND TO BE STEERED IN THE DIRECTION OF THE WINDS AT 500 HPA. 500-HPA SYSTEMS CORRELATE STRONGLY WITH SURFACE WEATHER. HPA - HECTO-PASCALS. 1 HPA = 1 MILLIBAR. MERIDIONAL FLOW PATTERN - OCCURS WHEN 500 HPA CONTOURS EXHIBIT LARGE NORTHWARD AND SOUTHWARD EXCURSIONS WITH EXTENSIVE AREAS OF SOUTHERLY AND NORTHERLY FLOW. MODEL BIAS - THE DIFFERENCE BETWEEN THE MODEL CLIMATOLOGY AND THE OBSERVED CLIMATOLOGY - EXPRESSED AS BIAS = MODEL CLIMO - OBSERVED CLIMO. MODEL OF THE DAY - FOR 6-10 DAYS - IS THE MODEL WHOSE SOLUTION IS CONSIDERED TO BE MORE RELIABLE THAN USUAL - AND MAY BE GIVEN HIGHER THAN TYPICAL WEIGHT IN THE BLEND. NO MODEL OF THE DAY IS CHOSEN FOR 8-14 DAYS. MOS - MODEL OUTPUT STATISTICS - A STATISITCAL TOOL FOR SPECIFYING THE SURFACCE TEMPERATURE (AND ITS ANOMALY) FROM MODEL FIELDS - CORRECTING AUTOMATICALLY FOR BOTH BIASES IN THE MODEL FIELDS AND THE SPECIFICATION METHOD. IT IS VALID AS LONG AS A GIVEN CONFIGURATION OF A MODEL IS NOT CHANGED OR MODIFIED. MRF - MEDIUM RANGE FORECAST MODEL. MRF ENSEMBLE - A SET OF MRF FORECASTS WHICH ARE ALL VALID AT THE SAME TIME BUT WHOSE STARTING CONDITIONS DIFFER BY SMALL AMOUNTS. THERE ARE CURRENTLY 25 MEMBERS IN THE MRF ENSEMBLE. THE AVERAGE OF THESE IS THE MRF ENSEMBLE MEAN. MJO - MADDEN-JULIAN OSCILLATION - ALSO CALLED TROPICAL INTRA-SEASONAL OSCILLA- TION - A SERIES OF WAVES WITH A PERIOD AVERAGING 50 DAYS THAT MOVES SLOWLY EAST- WARD NEAR THE EQUATOR ALTERNATELY ENHANCING AND SUPRESSING PRECIPITATION. NAO - NORTH ATLANTIC OSCILLATION TELECONNECTION PATTERN. PNA - PACIFIC NORTH AMERICAN TELECONNECTION PATTERN. PROG - PROGNOSIS - OR FORECAST. RIDGE - A REGION OF UNUSUALLY HIGH 500 HPA HEIGHT. SHORT WAVES - RELATIVELY LOW-AMPLITUDE - FAST-MOVING DISTURBANCES OF THE 500 HPA FIELD. SOUTHERN STREAM - A FLOW PATTERN WITH UNUSUALLY STRONG FLOW ACROSS THE SOUTHERN U.S. - ACCOMPANIED BY UNUSUAL STORMINESS IN THE SOUTH AND SOUTHEAST. SPECIFICATIONS - KLEIN AND NEURAL NETWORK SPECIFICATIONS GIVE THE HISTORICAL RELATIONSHIP BETWEEN 500-HPA HEIGHT ANOMALIES AND SURFACE TEMPERATURE AND PRECIPITATION. KLEIN SPECIFICATIONS TEND TO EMPHASIZE REGIONAL TELECONNECTIONS WHILE THOSE FROM THE NEURAL NETWORK WORK FROM GLOBAL TELECONNECTIONS. . . . . . . . . TELECONNECTIONS GIVE THE HISTORICAL RELATIONSHIP BETWEEN THE 500-HPA HEIGHT AT A GIVEN POINT AND ALL OTHER POINTS ON A MAP FOR A GIVEN TIME OF YEAR. WE AVERAGE THE TOP/BOTTOM 10% OF DAILY MAPS FROM 1950-1999 FOR THE SAME TIME OF YEAR HAVING THE HIGHEST/LOWEST 500-HPA HEIGHT AT THE SPECIFIED POINT. TROUGH - A REGION OF UNUSUALLY LOW 500 HPA HEIGHT. UTC - UNIVERSAL TIME COORDINATED - SAME AS GREENWICH MEAN TIME (GMT). WESTERLY WIND - WIND BLOWING FROM WEST TO EAST. EASTERLY WIND - WIND BLOWING FROM EAST TO WEST. NORTHERLY WIND - WIND BLOWING FROM NORTH TO SOUTH SOUTHERLY WIND - WIND BLOWING FROM SOUTH TO NORTH. 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. ------------------------------------------------------------------------------- THE NEXT MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON THURSDAY FEBRUARY 14. 6 to 10 day Outlook Table STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON N N NRN CALIF N B SRN CALIF N B IDAHO N N NEVADA N B W MONTANA N N E MONTANA A N WYOMING N N UTAH N N ARIZONA N B COLORADO N N NEW MEXICO N N N DAKOTA A N S DAKOTA A N NEBRASKA A N KANSAS A N OKLAHOMA A N N TEXAS A A S TEXAS A N W TEXAS N A MINNESOTA A N IOWA A N MISSOURI A N ARKANSAS A A LOUISIANA A A WISCONSIN A N ILLINOIS A N MISSISSIPPI A A MICHIGAN A A INDIANA A N OHIO A N KENTUCKY A A TENNESSEE A A ALABAMA A A NEW YORK A N VERMONT A A NEW HAMP N A MAINE N A MASS N N CONN A N RHODE ISL N N PENN A A NEW JERSEY A A W VIRGINIA A A MARYLAND A N DELAWARE A N VIRGINIA A A N CAROLINA A A S CAROLINA N N GEORGIA A N FL PNHDL N N FL PENIN N N AK N SLOPE N N AK ALEUTIAN N N AK WESTERN B N AK INT BSN B A AK S INT B N AK S COAST B N AK PNHDL B A 8 to 14 day Outlook Table STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B N OREGON B N NRN CALIF B N SRN CALIF B A IDAHO N N NEVADA B N W MONTANA N N E MONTANA N N WYOMING N N UTAH N N ARIZONA N A COLORADO N N NEW MEXICO N A N DAKOTA N N S DAKOTA N N NEBRASKA N B KANSAS N N OKLAHOMA A A N TEXAS A A S TEXAS A N W TEXAS N A MINNESOTA N A IOWA N N MISSOURI A A ARKANSAS A A LOUISIANA A N WISCONSIN N N ILLINOIS A A MISSISSIPPI A N MICHIGAN N N INDIANA A A OHIO A A KENTUCKY A A TENNESSEE A A ALABAMA A A NEW YORK N N VERMONT N B NEW HAMP N B MAINE N B MASS N B CONN N B RHODE ISL N B PENN A N NEW JERSEY A N W VIRGINIA A A MARYLAND A N DELAWARE A N VIRGINIA A N N CAROLINA A N S CAROLINA A N GEORGIA A N FL PNHDL A N FL PENIN A N AK N SLOPE N N AK ALEUTIAN A N AK WESTERN N A AK INT BSN N A AK S INT N N AK S COAST N N AK PNHDL B N LEGEND TEMPS WITH RESPECT TO NORMAL PCPN WITH RESPECT TO MEDIAN A - ABOVE N - NEAR NORMAL A - ABOVE N - NEAR MEDIAN B - BELOW B - BELOW THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE. FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 - ON AFOS AS NFDPMDMRD. NNNN NNNN