310  
FXUS06 KWBC 311944  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT TUE OCTOBER 31 2017  
 
6-10 DAY OUTLOOK FOR NOV 06 - 10 2017  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT IN PREDICTING A FAIRLY  
AMPLIFIED 500-HPA FLOW PATTERN OVER MUCH OF THE FORECAST DOMAIN. A STRONG RIDGE  
IS PREDICTED OVER WESTERN ALASKA, WHILE A TROUGH IS EXPECTED OVER THE ALASKA  
PANHANDLE. BELOW NORMAL HEIGHTS AND CYCLONIC FLOW ARE EXPECTED OVER MUCH OF THE  
WESTERN CONUS WHILE RIDGING AND ABOVE NORMAL HEIGHTS ARE GENERALLY INDICATED  
FOR THE SOUTHERN PLAINS AND MUCH OF THE EASTERN CONUS. A TROUGH IS EXPECTED  
FARTHER TO THE NORTH OVER CENTRAL CANADA EXTENDING SOUTHWARD TO PARTS OF THE  
NORTHERN PLAINS. THE DETERMINISTIC 0Z ECMWF HAS THIS TROUGH FARTHER TO THE EAST  
OVER EASTERN CANADA, RESULTING IN LOWER HEIGHTS ACROSS THE NORTHEASTERN CONUS  
RELATIVE TO ITS ENSEMBLE MEAN. ENSEMBLE SPREAD IS GENERALLY LOW TO MODERATE  
OVER THE MAJORITY OF THE FORECAST DOMAIN. TODAY'S OFFICIAL 500-HPA MANUAL  
HEIGHT BLEND IS BASED PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS FROM THE GEFS,  
ECMWF, AND ENVIRONMENT CANADA.  
 
BELOW NORMAL HEIGHTS TILT THE ODDS TO BELOW NORMAL TEMPERATURES FOR THE WESTERN  
AND THE NORTH-CENTRAL CONUS. RIDGING AND ABOVE NORMAL HEIGHTS ENHANCE  
PROBABILITIES OF ABOVE NORMAL TEMPERATURES FOR THE SOUTH-CENTRAL AND EASTERN  
CONUS. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MOST OF MAINLAND ALASKA AND  
THE ALEUTIANS DUE TO A STRONG RIDGE. HOWEVER, A TROUGH NEAR THE ALASKA  
PANHANDLE LEADS TO ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES THERE.  
 
CYCLONIC FLOW AND BELOW NORMAL HEIGHTS FAVOR ABOVE NORMAL PRECIPITATION FOR  
MUCH OF THE WESTERN CONUS. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FROM THE  
GREAT LAKES AND PARTS OF THE NORTHEAST SOUTHWESTWARD TO THE PARTS OF THE  
CENTRAL AND SOUTHERN PLAINS DUE TO AN EXPECTED FRONTAL BOUNDARY. THERE ARE  
ENHANCED PROBABILITIES FOR BELOW NORMAL PRECIPITATION FOR THE NORTHERN PLAINS  
DUE TO EXPECTED SURFACE HIGH PRESSURE BEHIND THE FRONTAL BOUNDARY. RIDGING AND  
ABOVE NORMAL HEIGHTS LEAD TO ENHANCED PROBABILITIES FOR BELOW NORMAL  
PRECIPITATION FOR THE SOUTHEASTERN CONUS, GULF COAST REGION, AND PARTS OF THE  
SOUTHERN PLAINS. BELOW NORMAL PRECIPITATION IS ALSO FAVORED FOR MUCH OF  
SOUTHERN ALASKA DUE TO EXPECTED OFFSHORE FLOW. HOWEVER, ABOVE NORMAL  
PRECIPITATION PROBABILITIES ARE ENHANCED FOR NORTHWESTERN MAINLAND ALASKA  
UNDERNEATH SOUTHWESTERLY LOW LEVEL FLOW.  
 
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 20% OF TODAY'S 0Z GFS ENSEMBLE MEAN  
CENTERED ON DAY 8, 25% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 20%  
OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF YESTERDAY'S 12Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 7, 10% OF TODAY'S OPERATIONAL 0Z ECMWF  
CENTERED ON DAY 8, 15% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8,  
AND 5% OF YESTERDAY'S 12Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 7  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD MODEL AGREEMENT ON THE EXPECTED FLOW PATTERN OVER MUCH OF THE FORECAST  
DOMAIN.  
 
8-14 DAY OUTLOOK FOR NOV 08 - 14 2017  
 
DURING THE WEEK-2 PERIOD, MODELS ARE IN GOOD AGREEMENT IN PREDICTING A VERY  
STRONG RIDGE OVER WESTERN ALASKA. A TROUGH IS EXPECTED TO DIG DOWNSTREAM OF  
THIS RIDGE OVER THE ALASKA PANHANDLE AND THE EASTERN PACIFIC RESULTING IN BELOW  
NORMAL HEIGHTS FOR PARTS OF THE NORTHWESTERN CONUS. HEIGHTS ARE EXPECTED TO BE  
NEAR TO ABOVE NORMAL FOR MUCH OF THE REMAINDER OF THE CONUS. HOWEVER, HEIGHTS  
ARE EXPECTED TO BE LOWER FOR MUCH OF THE EASTERN CONUS RELATIVE TO THE 6-10 DAY  
PERIOD IN ASSOCIATION WITH A TROUGH EXPECTED OVER EAST-CENTRAL CANADA.  
CONVERSELY, A REDUCTION OF NEGATIVE HEIGHT ANOMALIES RELATIVE TO THE 6-10 DAY  
PERIOD ARE INDICATED FOR PARTS OF THE WESTERN CONUS AHEAD OF THE TROUGH OVER  
THE EASTERN PACIFIC. TODAY'S WEEK-2 MANUAL 500-HPA HEIGHT BLEND IS BASED  
PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS.  
 
THE WEEK-2 PROBABILISTIC TEMPERATURE OUTLOOK PATTERN IS SIMILAR TO THAT  
INDICATED FOR THE 6-10 DAY PERIOD. HOWEVER, THERE IS A REDUCTION OF ABOVE  
NORMAL TEMPERATURE PROBABILITIES FOR MUCH OF THE EASTERN CONUS AS STATISTICAL  
GUIDANCE INDICATE LOWER HEIGHTS DURING WEEK-2. CONVERSELY, PROBABILITIES FOR  
BELOW NORMAL TEMPERATURES ARE REDUCED RELATIVE TO THE 6-10 DAY PERIOD FOR PARTS  
OF THE WESTERN CONUS AHEAD OF THE TROUGH OVER THE EASTERN PACIFIC.  
 
THE PRECIPITATION OUTLOOK IS GENERALLY SIMILAR TO THAT OF THE 6-10 DAY PERIOD  
OVER MUCH OF THE FORECAST DOMAIN. AN EXCEPTION IS THE WEST-CENTRAL CONUS, WHERE  
BELOW NORMAL PRECIPITATION PROBABILITIES ARE ENHANCED DUE TO THE POTENTIAL FOR  
HIGHER 500-HPA HEIGHTS ACROSS THIS REGION RELATIVE TO THE 6-10 DAY PERIOD.  
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 25% OF TODAY'S 0Z GFS ENSEMBLE  
MEAN CENTERED ON DAY 11, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY  
11, 5% OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 11, 30% OF TODAY'S 0Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 5% OF YESTERDAY'S 12Z EUROPEAN  
ENSEMBLE MEAN CENTERED ON DAY 10, 10% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN  
CENTERED ON DAY 11, AND 5% OF YESTERDAY'S 12Z CANADIAN ENSEMBLE MEAN CENTERED  
ON DAY 10  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE  
TO FAIR AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS ON THE 500-HPA PATTERN,  
OFFSET BY LARGE DIFFERENCES BETWEEN STATISTICAL AND DYNAMICAL TEMPERATURE TOOLS  
ACROSS MUCH OF THE FORECAST DOMAIN.  
 
FORECASTER: SCOTT H  
 
NOTES:  
 
AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OCCASIONALLY MANUAL  
INTERVENTION IS NECESSARY TO ADDRESS QUALITY CONTROL AND CONSISTENCY ISSUES. IN  
THESE CASES, FORECASTS ARE MANUALLY DRAWN BUT A FULL DISCUSSION IS NOT ISSUED.  
 
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  
 
THE TEMPERATURE MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WARMER (ORANGE,  
"A"), COLDER (BLUE, "B"), OR CLOSE TO (UNSHADED, "N"). HISTORICAL AVERAGE  
VALUES FOR THE CALENDAR PERIOD OF THE FORECAST (DASHES, "F"). LABELS ON THE  
SHADED LINES GIVE THE PROBABILITY (> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  
PROBABILITY OF N IS ALWAYS < 40%.  
 
THE PRECIPITATION MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WETTER (GREEN,  
"A"), DRIER (TAN, "B"), OR CLOSE TO (UNSHADED, "N"). HISTORICAL MEDIAN VALUES  
FOR THE CALENDAR PERIOD OF THE FORECAST (DASHES, "INCHES"). LABELS ON THE  
SHADED LINES GIVE THE PROBABILITY (> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  
PROBABILITY OF N IS ALWAYS < 40%.  
 
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 CLIMATE PREDICTION CENTER USES 1981-2010 BASE PERIOD MEANS FOR  
TEMPERATURE...PRECIPITATION...AND 500-HPA HEIGHTS AS REFERENCE IN THE CLIMATE  
OUTLOOKS.  
 
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON  
NOVEMBER 16  
 
ANALOGS TO THE 5 DAY MEAN OBSERVED PATTERN CENTERED 3 DAYS AGO (D-3)  
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE  
INCLUDE THE 5 DAY PERIODS CENTERED ON THE FOLLOWING DATES:  
19591110 - 19811022 - 19661103 - 20031028 - 20041014  
 
ANALOGS TO THE 7 DAY MEAN OBSERVED PATTERN CENTERED 4 DAYS AGO (D-4)  
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE  
INCLUDE THE 7 DAY PERIODS CENTERED ON THE FOLLOWING DATES:  
19591109 - 19661103 - 19811021 - 20031027 - 19891101  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 06 - 10 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B A  
SRN CALIF B A IDAHO B A NEVADA B A  
W MONTANA B N E MONTANA B B WYOMING B A  
UTAH B A ARIZONA A A COLORADO A A  
NEW MEXICO A N N DAKOTA B B S DAKOTA B B  
NEBRASKA B B KANSAS A A OKLAHOMA A A  
N TEXAS A B S TEXAS A B W TEXAS A N  
MINNESOTA B N IOWA N A MISSOURI A A  
ARKANSAS A A LOUISIANA A B WISCONSIN N A  
ILLINOIS A A MISSISSIPPI A B MICHIGAN A A  
INDIANA A A OHIO A A KENTUCKY A A  
TENNESSEE A N ALABAMA A B NEW YORK A A  
VERMONT A A NEW HAMP A A MAINE A A  
MASS A A CONN A A RHODE IS A A  
PENN A A NEW JERSEY A A W VIRGINIA A A  
MARYLAND A N DELAWARE A N VIRGINIA A B  
N CAROLINA A B S CAROLINA A B GEORGIA A B  
FL PNHDL A B FL PENIN A B AK N SLOPE A A  
AK ALEUTIAN A B AK WESTERN A A AK INT BSN A A  
AK S INT A B AK SO COAST A B AK PNHDL B B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 08 - 14 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B A  
SRN CALIF B N IDAHO B A NEVADA B A  
W MONTANA B A E MONTANA B N WYOMING B B  
UTAH N B ARIZONA A B COLORADO A B  
NEW MEXICO A B N DAKOTA B N S DAKOTA B B  
NEBRASKA N N KANSAS A A OKLAHOMA A A  
N TEXAS A N S TEXAS A B W TEXAS A N  
MINNESOTA B N IOWA N A MISSOURI A A  
ARKANSAS A N LOUISIANA A B WISCONSIN B A  
ILLINOIS N A MISSISSIPPI A B MICHIGAN N A  
INDIANA A A OHIO A A KENTUCKY A A  
TENNESSEE A N ALABAMA A B NEW YORK A A  
VERMONT A A NEW HAMP A N MAINE A N  
MASS A N CONN A N RHODE IS A N  
PENN A A NEW JERSEY A N W VIRGINIA A A  
MARYLAND A N DELAWARE A N VIRGINIA A N  
N CAROLINA A B S CAROLINA A B GEORGIA A B  
FL PNHDL A B FL PENIN A B AK N SLOPE A A  
AK ALEUTIAN A B AK WESTERN A A AK INT BSN A A  
AK S INT A B AK SO COAST A B AK PNHDL B B  
 
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 KWBC - ON AWIPS AS  
PMDMRD.  
 

 
 
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