845  
FXUS06 KWBC 141902  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT FRI AUGUST 14 2020  
 
6-10 DAY OUTLOOK FOR AUG 20 - 24 2020  
 
TODAY'S 6-10 DAY 500-HPA GEOPOTENTIAL HEIGHT OUTLOOKS SHOW GOOD AGREEMENT AMONG  
DYNAMICAL MODEL GUIDANCE AND FEATURE ANOMALOUS RIDGING OVER THE BERING SEA AND  
OVER THE WESTERNHALF OF THE CONUS. A DEEP ANOMALOUS TROUGH IS PREDICTED OVER  
THE GULF OF ALASKA. POSITIVE 500-HPA HEIGHTS OVER MOST OF ALASKA AND THE  
WESTERN CONUS ARE FAVORED DURING THE PERIOD, AND NEGATIVE 500-HPA HEIGHTS ARE  
PREDICTED OVER THE EASTERN CONUS, ASSOCIATED WITH PREDICTED TROUGHING.  
 
ANOMALOUS MID-LEVEL RIDGING OVER THE BERING SEA FAVORS ABOVE NORMAL  
TEMPERATURES OVER ALASKA. THE WESTERN HALF OF THE CONUS IS FORECAST TO REMAIN  
UNDER THE INFLUENCE OF RIDGING AND POSITIVE 500-HPA HEIGHT ANOMALIES, ENHANCING  
CHANCES OF ABOVE NORMAL TEMPERATURES. THE GREATEST PROBABILITIES OF ABOVE  
NORMAL TEMPERATURES ARE OVER THE GREAT BASIN. INTRUSION OF RELATIVELY COLD  
CANADIAN AIR IS FORECAST TO LOWER TEMPERATURES ACROSS MUCH OF THE EASTERN HALF  
OF THE CONUS DURING THE PERIOD. THIS FAVORS BELOW NORMAL TEMPERATURES FOR MUCH  
OF THE EASTERN CONUS. ABOVE NORMAL TEMPERATURES ARE FAVORED OVER PARTS OF NEW  
ENGLAND CONSISTENT WITH THE CONSOLIDATION FORECAST TOOL. ABOVE NORMAL  
TEMPERATURES ARE FAVORED FOR THE FLORIDA PENINSULA, WHICH IS EXPECTED TO REMAIN  
SOUTH OF THE FORECAST SURFACE FRONT.  
 
BELOW NORMAL PRECIPITATION IS FAVORED FOR MOST OF ALASKA UNDERNEATH ABOVE  
NORMAL 500-HPA HEIGHTS. A DEEP TROUGH FORECAST OVER THE EASTERN GULF OF ALASKA  
INCREASES CHANCES OF ABOVE NORMAL PRECIPITATION OVER THE SOUTHERN ALASKA  
PANHANDLE. BENEATH AND DOWNSTREAM OF THE RIDGE AXIS OVER THE WESTERN CONUS,  
BELOW NORMAL PRECIPITATION IS FAVORED FROM THE PACIFIC NORTHWEST EASTWARD  
THROUGH MOST OF THE GREAT PLAINS AND PARTS OF THE MISSISSIPPI VALLEY. ENHANCED  
PROBABILITIES OF ABOVE NORMAL PRECIPITATION ARE FAVORED FOR SOUTHERN  
CALIFORNIA, AS A SHIFT IN THE MEAN SURFACE HIGH POSITION AND POTENTIAL TROPICAL  
ACTIVITY IN THE EASTERN PACIFIC MAY PROMOTE INCREASED MOISTURE FLOW INTO THE  
REGION. ENHANCED RAINFALL NEAR A PREDICTED SURFACE TROUGH INCREASES THE CHANCES  
OF ABOVE NORMAL PRECIPITATION FOR PARTS OF SOUTHERN TEXAS, THE SOUTHEAST,  
MID-ATLANTIC, GREAT LAKES AND NORTHEAST.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 15% OF TODAY'S 6Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 8, 15% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED  
ON DAY 8, 10% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 8, 30% OF TODAY'S  
0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF TODAY'S OPERATIONAL 0Z  
ECMWF CENTERED ON DAY 8, AND 20% 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 AGREEMENT AMONG THE MODELS FOR MOST OF THE FORECAST DOMAIN AND FAIRLY GOOD  
AGREEMENT AMONG THE TEMPERATURE AND PRECIPITATION TOOLS.  
 
8-14 DAY OUTLOOK FOR AUG 22 - 28 2020  
 
DURING THE WEEK-2 PERIOD, THE 500-HPA PATTERN FROM THE BERING SEA EAST TO THE  
EASTERN CONUS IS FORECAST TO BE VERY SIMILAR TO THE 6-10 DAY PERIOD, EXCEPT  
LOWER IN AMPLITUDE DUE TO AN INCREASE IN SPREAD AMONG ENSEMBLE MEMBERS.  
 
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR ALASKA, UNDERNEATH FORECAST ABOVE  
NORMAL 500-HPA HEIGHTS. ABOVE NORMAL TEMPERATURES REMAIN FAVORED FOR MUCH OF  
THE WESTERN HALF OF THE CONUS DUE TO FORECAST RIDGING. NEGATIVE HEIGHT  
ANOMALIES ASSOCIATED WITH THE TROUGH PREDICTED OVER PARTS OF THE MIDWEST DURING  
THE FIRST HALF OF THE WEEK-2 PERIOD SUPPORT INCREASED CHANCES OF BELOW NORMAL  
TEMPERATURES FOR PARTS OF THE MIDWEST. HOWEVER, A RETURN TO SOUTHERLY FLOW  
PREDICTED IN THE SECOND HALF OF THE PERIOD ENHANCES THE LIKELIHOOD OF ABOVE  
NORMAL TEMPERATURES FOR PARTS OF THE NORTHEAST AND MID-ATLANTIC COAST. BELOW  
NORMAL TEMPERATURES ARE LIKELY OVER PARTS OF THE LOWER MISSISSIPPI VALLEY  
CONSISTENT WITH THE CONSOLIDATION FORECAST TOOL. THE FLORIDA PENINSULA IS  
EXPECTED TO REMAIN SOUTH OF THE SURFACE FRONT, FAVORING ABOVE NORMAL  
TEMPERATURES THERE.  
 
THE PRECIPITATION OUTLOOK FOR THE WEEK-2 PERIOD IS SIMILAR TO THE 6-10 DAY  
PERIOD, WITH PROBABILITIES FOR BELOW NORMAL PRECIPITATION ELEVATED FOR MUCH OF  
THE CENTRAL AND SOUTHERN ROCKIES, GREAT PLAINS AND MISSISSIPPI VALLEY.  
PROBABILITIES ARE A BIT LOWER DUE TO AN INCREASE IN UNCERTAINTY AND A MORE  
TRANSIENT PATTERN EXPECTED TO DEVELOP. THE GEFS REFORECAST TOOL (WETTER) AND  
ECMWF REFORECAST TOOL (DRIER) CONTINUE TO DIFFER ACROSS THE WESTERN CONUS.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 15% OF TODAY'S 6Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, 15% OF TODAY'S GFS SUPERENSEMBLE MEAN  
CENTERED ON DAY 11, 10% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 11, 40%  
OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 20% OF TODAY'S 0Z  
CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO FAIR  
AGREEMENT AMONG THE MODELS FOR MUCH OF THE FORECAST DOMAIN AND UNCERTAINTY  
AMONG THE TEMPERATURE AND PRECIPITATION TOOLS.  
 
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  
AUGUST 20.  
 
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:  
20020727 - 20040826 - 19620823 - 19840827 - 19760819  
 
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:  
20020727 - 19600820 - 20090814 - 19620823 - 19950814  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR AUG 20 - 24 2020  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A B OREGON A B NRN CALIF A N  
SRN CALIF A A IDAHO A B NEVADA A N  
W MONTANA A B E MONTANA A B WYOMING A B  
UTAH A B ARIZONA A B COLORADO A B  
NEW MEXICO A B N DAKOTA A B S DAKOTA A B  
NEBRASKA A B KANSAS B B OKLAHOMA B B  
N TEXAS B B S TEXAS A B W TEXAS A B  
MINNESOTA B B IOWA B B MISSOURI B B  
ARKANSAS B B LOUISIANA B B WISCONSIN B N  
ILLINOIS B B MISSISSIPPI B B MICHIGAN B A  
INDIANA B N OHIO B A KENTUCKY B A  
TENNESSEE B A ALABAMA B N NEW YORK N A  
VERMONT A A NEW HAMP A A MAINE A A  
MASS A A CONN A A RHODE IS A A  
PENN N A NEW JERSEY A A W VIRGINIA B A  
MARYLAND N A DELAWARE A A VIRGINIA B A  
N CAROLINA B A S CAROLINA B A GEORGIA B A  
FL PNHDL B A FL PENIN A A AK N SLOPE A B  
AK ALEUTIAN A B AK WESTERN A B AK INT BSN A B  
AK S INT A B AK SO COAST A B AK PNHDL A N  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR AUG 22 - 28 2020  
 
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 N NEVADA A N  
W MONTANA A N E MONTANA A N WYOMING A N  
UTAH A N ARIZONA A B COLORADO A B  
NEW MEXICO A B N DAKOTA N B S DAKOTA N B  
NEBRASKA N B KANSAS N B OKLAHOMA N B  
N TEXAS N B S TEXAS A N W TEXAS A B  
MINNESOTA B B IOWA N B MISSOURI N B  
ARKANSAS B B LOUISIANA B B WISCONSIN B N  
ILLINOIS N N MISSISSIPPI B N MICHIGAN B A  
INDIANA N N OHIO N A KENTUCKY N N  
TENNESSEE N N ALABAMA N N NEW YORK N A  
VERMONT N A NEW HAMP A A MAINE A A  
MASS A A CONN A A RHODE IS A A  
PENN N A NEW JERSEY A A W VIRGINIA N A  
MARYLAND N A DELAWARE A A VIRGINIA N A  
N CAROLINA N N S CAROLINA N N GEORGIA N N  
FL PNHDL N N FL PENIN A N AK N SLOPE A B  
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A B  
AK S INT A B AK SO COAST A B AK PNHDL A 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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