221  
FXUS06 KWBC 241952  
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 24 2017  
 
6-10 DAY OUTLOOK FOR OCT 30 - NOV 03, 2017  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT ON AN AMPLIFIED FLOW  
PATTERN OVER MOST OF THE FORECAST DOMAIN. A 500-HPA TROUGH IS FORECAST OVER THE  
WESTERN ALEUTIAN ISLANDS AND THE NORTHWESTERN PACIFIC. A STRONG RIDGE IS  
PREDICTED DOWNSTREAM NEAR THE PACIFIC COAST OF NORTH AMERICA AND OVER EASTERN  
ALASKA. MODELS PREDICT A WEAK TROUGH OVER THE PACIFIC OCEAN TO THE WEST OF THE  
CONUS. THERE IS SIGNIFICANT UNCERTAINTY ON THE STRENGTH AND LOCATION OF  
TROUGHING OFF OF THE CALIFORNIA COAST, WITH SOME ENSEMBLE MEMBERS PREDICTING A  
CUT-OFF LOW, SUCH AS THE DETERMINISTIC, HIGH-RESOLUTION ECMWF MODEL. THE ECMWF  
ENSEMBLE MEAN INDICATES MORE AMPLIFIED TROUGHING NEAR THE COAST OF CALIFORNIA  
THAN THE NCEP AND ENVIRONMENT CANADA MODELS. AN AMPLIFIED TROUGH IS PREDICTED  
OVER EASTERN NORTH AMERICA BY ALL ENSEMBLE MEANS WITH LOW ENSEMBLE SPREAD.  
TODAY'S 500-HPA OFFICIAL MODEL HEIGHT BLEND INDICATES POSITIVE HEIGHT ANOMALIES  
OVER ALASKA, WESTERN CANADA, AND MUCH OF THE PACIFIC NORTHWEST, AS WELL AS  
PARTS OF EASTERN MAINE AND QUEBEC. WITH THE EXCEPTION OF PARTS OF MAINE,  
NEGATIVE HEIGHT ANOMALIES ARE INDICATED FROM THE GREAT PLAINS STATES EASTWARD.  
 
PREDICTED ABOVE NORMAL HEIGHTS OVER THE WESTERN CONUS HIGHLY FAVOR ABOVE NORMAL  
TEMPERATURES FOR MUCH THE WEST, WITH HIGHEST PROBABILITIES FOR THE SOUTHWEST  
REGION. WITH PREDICTED ABOVE NORMAL HEIGHTS EXTENDING INTO ALASKA, HIGH  
PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE INDICATED. NORTHERLY FLOW AND  
BELOW NORMAL HEIGHTS, ASSOCIATED WITH THE PREDICTED TROUGH OVER THE EASTERN  
CONUS, INCREASE THE LIKELIHOOD OF BELOW NORMAL TEMPERATURES FROM THE NORTHERN  
ROCKIES, EASTWARD TO THE GREAT LAKES REGION, AND ACROSS THE NORTHERN AND  
CENTRAL GREAT PLAINS AND MISSISSIPPI VALLEY INTO THE SOUTHEAST CONUS. FOR  
EASTERN AREAS OF THE NORTHEAST, ANOMALOUS SOUTHERLY FLOW, AHEAD OF THE  
PREDICTED TROUGH AXIS, AND NEAR AVERAGE HEIGHT ANOMALIES FAVOR ABOVE NORMAL  
TEMPERATURES.  
 
EAST OF THE TROUGH FORECAST TO THE WEST OF ALASKA, THE LIKELIHOOD OF ABOVE  
NORMAL PRECIPITATION IS ENHANCED FOR MUCH OF THE STATE, EXCLUDING THE WESTERN  
ALEUTIANS AND THE ALASKA PANHANDLE. THE PREDICTED RIDGE OVER THE PACIFIC  
NORTHWEST LEADS TO A HIGH PROBABILITY OF BELOW NORMAL PRECIPITATION FOR THE  
REGION. BELOW NORMAL PRECIPITATION IS MOST LIKELY FOR PARTS OF THE CENTRAL AND  
SOUTHERN PLAINS AND THE SOUTHEAST REGION, BEHIND THE PREDICTED TROUGH AXIS.  
ABOVE NORMAL PRECIPITATION IS LIKELY FOR PARTS OF MONTANA AND WYOMING AS THE  
TROUGH RETROGRADES TO THE WEST. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR  
THE GREAT LAKES AND NORTHEAST REGIONS AHEAD OF THE PREDICTED LOCATION OF THE  
TROUGH EARLY IN THE 6-10 DAY PERIOD.  
 
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 20% OF TODAY'S 0Z GFS ENSEMBLE MEAN  
CENTERED ON DAY 8, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 35%  
OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF TODAY'S  
OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND 15% OF TODAY'S 0Z CANADIAN ENSEMBLE  
MEAN CENTERED ON DAY 8  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO  
GOOD AGREEMENT AMONG THE MODEL CIRCULATION FORECASTS ON AN AMPLIFIED FLOW  
PATTERN, OFFSET BY SOME DISAGREEMENT AMONG THE TEMPERATURE AND PRECIPITATION  
TOOLS AND UNCERTAINTY RELATED TO THE PREDICTED RETROGRESSION OF THE TROUGH OVER  
THE CONUS.  
 
8-14 DAY OUTLOOK FOR NOV 01 - 07 2017  
 
UNCERTAINTY ON THE PREDICTED CIRCULATION PATTERN INCREASES DURING THE WEEK 2  
PERIOD, AS ENSEMBLE SPREAD AND MODEL DISAGREEMENT INCREASES OVER MUCH OF THE  
FORECAST DOMAIN. THE NCEP GEFS, ECMWF, AND ENVIRONMENT CANADA ENSEMBLE MEANS  
APPEAR IN RELATIVE AGREEMENT ON RETROGRESSION OF THE PREDICTED TROUGH OVER  
NORTH AMERICA. HOWEVER, WEAK ANOMALIES OVER THE CONUS IN THE ENSEMBLE MEANS ARE  
AN INDICATION OF THE SPREAD AMONG ENSEMBLE MEMBERS. DETERMINISTIC,  
HIGH-RESOLUTION FORECASTS OF THE NCEP GFS, WHILE VARIABLE ON THE EXACT  
LOCATION, GENERALLY PREDICT AN AMPLIFIED TROUGH DIGGING INTO THE SOUTHWEST  
CONUS AHEAD OF THE RIDGE OVER ALASKA AND THE NORTH PACIFIC. THIS PATTERN IS  
CONSISTENT WITH TELECONNECTIONS TO THE STRONG MJO CURRENTLY PROPAGATING  
EASTWARD OVER THE WESTERN TROPICAL PACIFIC. TODAY'S 500-HPA OFFICIAL MODEL  
HEIGHT BLEND FOR THE WEEK 2 PERIOD INDICATES POSITIVE HEIGHT ANOMALIES OVER  
ALASKA AND MID-ATLANTIC STATES AND WEAK NEGATIVE HEIGHT ANOMALIES OVER  
CALIFORNIA AND THE NORTH-CENTRAL CONUS.  
 
THE PREDICTED TEMPERATURE PATTERN DURING THE WEEK 2 PERIOD IS SIMILAR TO THE  
6-10 DAY PERIOD FORECAST WITH AN INCREASE IN THE PROBABILITIES OF BELOW NORMAL  
TEMPERATURES OVER THE NORTHWEST AND A DECREASE IN PROBABILITIES OF BELOW NORMAL  
TEMPERATURES OVER THE SOUTHEAST, RELATED TO THE LIKELY RETROGRESSION OF THE  
TROUGH OVER THE CONUS. ABOVE NORMAL TEMPERATURES ARE NOW MOST LIKELY ALONG THE  
COASTS OF THE GULF OF MEXICO AND THE ATLANTIC, AND NEAR NORMAL TEMPERATURES ARE  
MORE LIKELY OVER PARTS OF THE WEST, AS THE TROUGH DEAMPLIFIES OVER THE EAST AND  
DIGS INTO THE SOUTHWEST.  
 
THE PRECIPITATION PATTERN FORECAST DURING THE WEEK 2 PERIOD REPRESENTS CHANGES  
RELATED TO THE RETROGRESSION OF THE PREDICTED TROUGH OVER THE CONUS, RELATIVE  
TO THE 6-10 DAY PERIOD FORECAST. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FROM  
PARTS OF THE SOUTHWEST NORTHWARD INTO EASTERN MONTANA AND FROM THE SOUTHERN  
PLAINS NORTHWARD THROUGH THE CENTRAL MISSISSIPPI AND OHIO VALLEYS INTO THE  
GREAT LAKES REGION. AREAS OF LIKELY BELOW NORMAL PRECIPITATION PERSIST INTO  
WEEK 2 OVER THE PACIFIC NORTHWEST AND THE SOUTHEAST. MUCH OF ALASKA IS LIKELY  
TO HAVE ABOVE NORMAL PRECIPITATION AHEAD OF THE PREDICTED TROUGH TO THE WEST.  
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY'S 0Z GFS ENSEMBLE  
MEAN CENTERED ON DAY 11, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY  
11, 45% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 15% OF  
TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE  
TO LARGE SPREAD AMONG THE ENSEMBLE MEMBERS OVER MUCH OF THE FORECAST DOMAIN,  
AND RELATIVELY POOR AGREEMENT AMONG SOME OF THE TEMPERATURE AND PRECIPITATION  
TOOLS.  
 
FORECASTER: D COLLINS  
 
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:  
19951012 - 19671023 - 19991030 - 20071020 - 19681020  
 
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:  
19951011 - 19681020 - 20071020 - 19711003 - 19671027  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 30 - NOV 03, 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON N B OREGON A B NRN CALIF A B  
SRN CALIF A N IDAHO B B NEVADA A N  
W MONTANA B N E MONTANA B A WYOMING B A  
UTAH A N ARIZONA A N COLORADO B N  
NEW MEXICO A B N DAKOTA B A S DAKOTA B N  
NEBRASKA B B KANSAS B B OKLAHOMA B B  
N TEXAS B B S TEXAS A B W TEXAS A B  
MINNESOTA B N IOWA B B MISSOURI B N  
ARKANSAS B B LOUISIANA B B WISCONSIN B A  
ILLINOIS B N MISSISSIPPI B B MICHIGAN B A  
INDIANA B N OHIO B A KENTUCKY B N  
TENNESSEE B B ALABAMA B 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 B A NEW JERSEY A A W VIRGINIA B N  
MARYLAND B N DELAWARE N B VIRGINIA B B  
N CAROLINA B B S CAROLINA B B GEORGIA B B  
FL PNHDL B B FL PENIN B B AK N SLOPE A A  
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A A  
AK S INT A A AK SO COAST A A AK PNHDL A B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 01 - 07 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B B OREGON N B NRN CALIF N N  
SRN CALIF N N IDAHO B N NEVADA N N  
W MONTANA B A E MONTANA B A WYOMING B A  
UTAH A A ARIZONA A N COLORADO B A  
NEW MEXICO A N N DAKOTA B A S DAKOTA B A  
NEBRASKA B A KANSAS B A OKLAHOMA N A  
N TEXAS A A S TEXAS A A W TEXAS A N  
MINNESOTA B A IOWA B A MISSOURI B A  
ARKANSAS B A LOUISIANA N A WISCONSIN B A  
ILLINOIS B A MISSISSIPPI N N MICHIGAN B A  
INDIANA B A OHIO B A KENTUCKY B A  
TENNESSEE B N ALABAMA N B NEW YORK A N  
VERMONT A N NEW HAMP A N MAINE A N  
MASS A N CONN A B RHODE IS A B  
PENN N N NEW JERSEY A B W VIRGINIA N N  
MARYLAND A B DELAWARE A B VIRGINIA N B  
N CAROLINA N B S CAROLINA N B GEORGIA N B  
FL PNHDL A B FL PENIN A N AK N SLOPE A A  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A  
AK S INT A A AK SO COAST A A AK PNHDL N 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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