606  
FXUS06 KWBC 172002  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EST FRI NOVEMBER 17 2017  
 
6-10 DAY OUTLOOK FOR NOV 23 - 27 2017  
 
TODAY'S DYNAMICAL MODEL SOLUTIONS ARE IN GOOD AGREEMENT ON THEIR 500-HPA  
CIRCULATION FORECASTS FOR THE 6-10 DAY PERIOD OVER THE NORTH AMERICAN REGION. A  
STRONG RIDGE IS FORECAST OVER THE ALEUTIANS, WHILE A TROUGH IS PREDICTED OVER  
MUCH OF MAINLAND ALASKA, EXTENDING INTO THE NORTHEAST PACIFIC. ANOTHER TROUGH  
IS FORECAST OVER THE EASTERN CONUS WITH A BLOCKING RIDGE OVER THE DAVIS STRAIT.  
ABOVE NORMAL 500-HPA HEIGHTS ARE PREDICTED OVER EXTREME SOUTHWESTERN MAINLAND  
ALASKA AND ACROSS THE WESTERN TWO-THIRDS OF THE CONUS. BELOW NORMAL 500-HPA  
HEIGHTS ARE FORECAST OVER THE REMAINDER OF THE CONUS AND MUCH OF ALASKA.  
 
BELOW NORMAL TEMPERATURES ARE LIKELY FOR MUCH OF ALASKA, UNDER NEGATIVE 500-HPA  
HEIGHT ANOMALIES AND OFFSHORE FLOW. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR  
PARTS OF WESTERN MAINLAND ALASKA AND THE WESTERN ALEUTIANS, DUE TO ABOVE NORMAL  
SEA SURFACE TEMPERATURES IN SURROUNDING AREAS. ABOVE NORMAL TEMPERATURES ARE  
MOST LIKELY FOR THE WESTERN HALF OF THE CONUS UNDER PREDICTED ABOVE NORMAL  
500-HPA HEIGHTS. BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE EASTERN CONUS  
FROM THE LOWER MISSISSIPPI VALLEY AND THE SOUTHEAST U.S. NORTHWARD TO PARTS OF  
THE EASTERN GREAT LAKES AND THE NORTHEAST, DUE TO ANOMALOUS NORTHERLY FLOW.  
 
ABOVE NORMAL PRECIPITATION IS FAVORED FOR WESTERN PARTS OF MAINLAND ALASKA, DUE  
TO THE FORECAST TROUGH UPSTREAM AND ONSHORE FLOW. BELOW NORMAL PRECIPITATION IS  
MOST LIKELY FOR EASTERN REGIONS OF MAINLAND ALASKA, AHEAD OF A PREDICTED RIDGE  
AND OFFSHORE FLOW. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR CENTRAL AND  
NORTHERN CALIFORNIA, NORTHWESTERN NEVADA, THE PACIFIC NORTHWEST, AND THE GREAT  
BASIN, EAST OF A PREDICTED TROUGH OVER THE NORTH PACIFIC. ABOVE NORMAL  
PRECIPITATION IS FAVORED FOR THE FLORIDA PENINSULA, DUE TO SURFACE LOW  
DEVELOPMENT IN THE GULF OF MEXICO. BELOW NORMAL PRECIPITATION IS FORECAST FOR  
MOST OF THE REMAINING AREAS OF THE CONUS.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 15% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 8, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 8, 10% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 8, 5% OF  
TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 8, 40% OF TODAY'S 0Z EUROPEAN  
ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON  
DAY 8, AND 10% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD MODEL AGREEMENT ON THE EXPECTED CIRCULATION PATTERN  
 
8-14 DAY OUTLOOK FOR NOV 25 - DEC 01, 2017  
 
THE OVERALL 500-HPA CIRCULATION PATTERN PREDICTED FOR THE WEEK 2 PERIOD IS  
SIMILAR TO THE 6-10 DAY PERIOD ACROSS NORTH AMERICA, BUT THE HIGH AMPLITUDE  
RIDGE OVER THE BERING SEA IS FORECAST TO WEAKEN. THE ENSEMBLE SPAGHETTI  
DIAGRAMS INDICATE MODERATE TO LARGE SPREAD ACROSS THE MAJORITY OF THE FORECAST  
DOMAIN. THE GREATEST WEIGHT FOR THE BLENDED 500-HPA HEIGHT FIELD WAS GIVEN TO  
THE ECMWF 0Z ENSEMBLE MEAN BASED ON CONSIDERATIONS OF RECENT SKILL AND ANALOG  
CORRELATIONS.  
 
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF THE WESTERN ALEUTIANS AND  
PARTS OF NORTHERN MAINLAND ALASKA, DUE TO PREDICTED SOUTHERLY FLOW AND ABOVE  
NORMAL SEA SURFACE TEMPERATURES IN SURROUNDING AREAS. ABOVE NORMAL TEMPERATURES  
ARE LIKELY FOR THE WESTERN AND CENTRAL CONUS, UNDER PREDICTED ABOVE NORMAL  
500-HPA HEIGHTS. BELOW NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE  
MID-ATLANTIC AND PARTS OF THE SOUTHEAST U.S., ASSOCIATED WITH PREDICTED  
ANOMALOUS NORTHERLY FLOW.  
 
A SLIGHT ABOVE NORMAL PRECIPITATION IS TILT IN THE ADDS FOR FORECAST FOR  
CENTRAL AND NORTH CALIFORNIA, PARTS OF THE NORTHERN INTERMOUNTAIN EASTWARD TO  
NORTHERN PARTS OF THE NORTHERN PLAINS AND THE UPPER MISSISSIPPI VALLEY, AHEAD  
OF A PREDICTED TROUGH. BELOW NORMAL PRECIPITATION IS INDICATED FOR MOST OF THE  
REMAINING AREAS OF THE CONUS. AREAS OF EASTERN MAINLAND ALASKA ARE PREDICTED TO  
HAVE BELOW NORMAL PRECIPITATION, WHILE ABOVE NORMAL PRECIPITATION IS LIKELY FOR  
SOUTHWESTERN MAINLAND ALASKA AND THE ALEUTIANS, UNDER PREDICTED ONSHORE AND  
CYCLONIC FLOW.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 15% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 11, 15% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11, 5% OF  
TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN  
ENSEMBLE MEAN CENTERED ON DAY 11, AND 10% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN  
CENTERED ON DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE  
TO GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS ON THE 500-HPA CIRCULATION  
PATTERN DURING WEEK 2, OFFSET BY MODERATE TO LARGE SPREAD AMONG THE ENSEMBLE  
MEMBERS  
 
FORECASTER: Y. FAN  
 
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  
DECEMBER 21  
 
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:  
19661113 - 19701129 - 19731110 - 19701124 - 19661201  
 
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:  
19701127 - 19661113 - 19731110 - 19701122 - 19661130  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 23 - 27 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A A OREGON A A NRN CALIF A A  
SRN CALIF A N IDAHO A A NEVADA A A  
W MONTANA A A E MONTANA A N WYOMING A N  
UTAH A B ARIZONA A B COLORADO A B  
NEW MEXICO A B N DAKOTA A N S DAKOTA A N  
NEBRASKA A B KANSAS A B OKLAHOMA A B  
N TEXAS A B S TEXAS N B W TEXAS A N  
MINNESOTA A N IOWA A B MISSOURI A B  
ARKANSAS N B LOUISIANA N B WISCONSIN N B  
ILLINOIS N B MISSISSIPPI B B MICHIGAN N B  
INDIANA B B OHIO B B KENTUCKY B B  
TENNESSEE B B ALABAMA B B NEW YORK B B  
VERMONT B B NEW HAMP B B MAINE B N  
MASS B B CONN B B RHODE IS B B  
PENN B B NEW JERSEY B B W VIRGINIA B B  
MARYLAND B B DELAWARE B B VIRGINIA B B  
N CAROLINA B B S CAROLINA B B GEORGIA B B  
FL PNHDL B B FL PENIN B A AK N SLOPE N A  
AK ALEUTIAN A A AK WESTERN B A AK INT BSN B B  
AK S INT B B AK SO COAST B B AK PNHDL B B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 25 - DEC 01, 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A N OREGON A N NRN CALIF A N  
SRN CALIF A N IDAHO A A NEVADA A N  
W MONTANA A N E MONTANA A A WYOMING A A  
UTAH A N ARIZONA A B COLORADO A N  
NEW MEXICO A B N DAKOTA A N S DAKOTA A N  
NEBRASKA A N KANSAS A B OKLAHOMA A B  
N TEXAS A B S TEXAS A B W TEXAS A B  
MINNESOTA A N IOWA A N MISSOURI A B  
ARKANSAS A B LOUISIANA A B WISCONSIN A N  
ILLINOIS A B MISSISSIPPI A B MICHIGAN A N  
INDIANA N B OHIO N B KENTUCKY N B  
TENNESSEE N B ALABAMA N B NEW YORK N B  
VERMONT N B NEW HAMP N B MAINE N N  
MASS N B CONN N B RHODE IS N B  
PENN N B NEW JERSEY B B W VIRGINIA N B  
MARYLAND B B DELAWARE B B VIRGINIA B B  
N CAROLINA B B S CAROLINA B B GEORGIA B B  
FL PNHDL N B FL PENIN B B AK N SLOPE A N  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN N N  
AK S INT N A AK SO COAST N A AK PNHDL N 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 KWBC - ON AWIPS AS  
PMDMRD.  
 

 
 
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