070  
FXUS06 KWBC 261952  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT THU OCTOBER 26 2017  
 
6-10 DAY OUTLOOK FOR NOV 01 - 05 2017  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN FAIR AGREEMENT ON AN AMPLIFIED FLOW  
PATTERN OVER MOST OF THE FORECAST DOMAIN. A HIGHLY AMPLIFIED RIDGE IS PREDICTED  
OVER THE EASTERN BERING SEA AND WESTERN ALASKA. THE GFS ENSEMBLE MEANS IN  
PARTICULAR FORECAST A DEEP TROUGH DOWNSTREAM OF THE STRONG RIDGE, OVER  
EAST-CENTRAL NORTH AMERICA, THAT IS STARTING TO UNDERCUT THE RIDGE FROM THE  
EAST. IN CONTRAST TO YESTERDAY'S RUNS, TODAY'S ECMWF ENSEMBLE MEAN HINTS AT  
THIS POSSIBLE UNDERCUTTING, WHILE THE CANADIAN ENSEMBLE MEAN HAS LITTLE IF ANY  
INDICATION OF IT. IN ADDITION, TODAY'S MODEL RUNS ARE NOT PREDICTING A WEAK,  
DISTINCT SOUTHERN STREAM TROUGH OVER THE EXTREME EASTERN PACIFIC. AT THE  
5760-METER LEVEL, THERE IS MODERATE TO HIGH SPREAD FOR ALL MODELS OVER THE  
PACIFIC AND SOUTHWESTERN CONUS, AND LOW TO MODERATE SPREAD OVER THE REMAINDER  
OF THE CONUS. TODAY'S 500-HPA OFFICIAL MODEL HEIGHT BLEND INDICATES POSITIVE  
HEIGHT ANOMALIES OVER ALASKA AND FAR WESTERN CANADA, AND MOST OF THE NORTH  
ATLANTIC POLEWARD OF 40N. NEGATIVE HEIGHT ANOMALIES ARE DEPICTED OVER MOST OF  
CANADA, AND THE NORTHERN AND WESTERN CONUS.  
 
PREDICTED WELL ABOVE NORMAL HEIGHTS OVER ALASKA FAVOR ABOVE NORMAL TEMPERATURES  
OVER WESTERN AND CENTRAL PORTIONS OF THE STATE. MODESTLY POSITIVE 500-HPA  
HEIGHT ANOMALIES FAVOR ABOVE NORMAL TEMPERATURES ACROSS SOUTHERN AND FAR  
EASTERN PORTIONS OF THE CONUS. BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE  
ALASKA PANHANDLE, PORTIONS OF THE PACIFIC NORTHWEST AND NORTHERN ROCKIES, THE  
NORTHERN AND CENTRAL PLAINS, THE UPPER AND MIDDLE MISSISSIPPI VALLEY, THE UPPER  
GREAT LAKES REGION, AND THE LOWER OHIO VALLEY. THIS IS DUE TO THE PREDICTION OF  
AN UNUSUALLY DEEP TROUGH COVERING MOST OF CENTRAL AND EASTERN NORTH AMERICA.  
THIS PATTERN ALIGNS WELL WITH TELECONNECTIONS OFF A POSITIVE HEIGHT ANOMALY  
CENTER NEAR 60N/160W.  
 
ABOVE NORMAL PRECIPITATION IS FAVORED IN NORTHERN ALASKA (RELATED TO NORTHERLY  
ANOMALOUS FLOW OVER PRIMARILY ICE-FREE WATER), AND FROM NORTHERN AND COASTAL  
CENTRAL CALIFORNIA NORTHEASTWARD INTO THE NORTHERN ROCKIES AND NORTHERN PLAINS  
(DUE TO THE EXPECTED TRANSITION OF THE MAJOR 500-HPA TROUGH FROM THE  
EAST-CENTRAL CONUS INTO THE WESTERN CONUS). THIS AREA OF ANTICIPATED ABOVE  
NORMAL PRECIPITATION CONTINUES EASTWARD AND SOUTHWARD ACROSS THE MISSISSIPPI  
VALLEY, EASTERN PORTIONS OF THE SOUTHERN PLAINS, THE GREAT LAKES REGION, THE  
NORTHEAST, THE MID-ATLANTIC, THE OHIO AND TENNESSEE VALLEYS, AND THE SOUTHERN  
APPALACHIANS. THESE LATTER AREAS CORRESPOND REASONABLY WELL WITH THE PREDICTED  
EASTERN AND SOUTHERN FLANKS OF THE UPPER TROUGH. BELOW NORMAL PRECIPITATION IS  
FAVORED OVER MOST AREAS SOUTH OF THE BROOKS RANGE IN ALASKA, WESTERN  
WASHINGTON, FROM MUCH OF THE FOUR CORNERS STATES EASTWARD TO THE CENTRAL AND  
SOUTHERN HIGH PLAINS, AND ALONG PARTS OF THE SOUTHERN ATLANTIC COAST REGION.  
THESE AREAS OF ANTICIPATED BELOW NORMAL PRECIPITATION ARE RELATED TO SEVERAL  
FACTORS, INCLUDING SUFFICIENT DISTANCE FROM STORM TRACKS, OR SUBSIDENCE  
ASSOCIATED WITH AREAS EAST OF A MEAN RIDGE AXIS.  
 
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 25% OF TODAY'S 0Z GFS ENSEMBLE MEAN  
CENTERED ON DAY 8, 25% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 30%  
OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN 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: NEAR AVERAGE, 3 OUT OF 5, DUE TO  
FAIR OVERALL AGREEMENT AMONG THE MODEL 500-HPA 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 03 - 09 2017  
 
SIGNIFICANT UNCERTAINTY WITH THE PREDICTED CIRCULATION PATTERN CONTINUES DURING  
THE WEEK 2 PERIOD, WITH GENERALLY MODERATE SPREAD AMONG ENSEMBLE MEMBERS OVER  
THE FORECAST DOMAIN. THE GFS-BASED SOLUTIONS FAVOR LOW-AMPLITUDE FLOW OVER THE  
CONUS, WHILE THE ECMWF AND CANADIAN ENSEMBLE MEANS PREDICT SOMEWHAT MORE  
AMPLITUDE OVERALL THAN THE GFS-BASED SOLUTIONS. THOUGH THERE ARE DIFFERENCES IN  
THE MODEL RUNS, THERE IS GENERAL AGREEMENT ON REDUCING THE AMPLITUDE OF THE  
TROUGH IN THE EAST-CENTRAL CONUS, AND RE-AMPLIFYING THE TROUGH OVER THE WESTERN  
CONUS. THIS IS ALSO CONSISTENT WITH TELECONNECTIONS BASED ON A POSITIVE HEIGHT  
ANOMALY CENTER NEAR 60N/160W, AND WITH TELECONNECTIONS TO THE STRONG MJO THAT  
IS PROPAGATING EASTWARD OVER THE WESTERN TROPICAL PACIFIC AT THIS TIME. TODAY'S  
500-HPA OFFICIAL MODEL HEIGHT BLEND FOR THE WEEK 2 PERIOD INDICATES WELL ABOVE  
NORMAL HEIGHTS OVER ALASKA, WITH MODEST POSITIVE HEIGHT ANOMALIES OVER MUCH OF  
THE EASTERN CONUS. MODEST NEGATIVE HEIGHT ANOMALIES ARE DEPICTED OVER A LARGE  
PORTION OF THE WESTERN CONUS. THE HEIGHT ANOMALY PATTERN IS THEREFORE EXPECTED  
TO EVOLVE TOWARDS A NEGATIVELY PHASED PNA PATTERN DURING WEEK 2. THE PREDICTED  
TEMPERATURE AND PRECIPITATION PATTERNS FOR WEEK 2 EMPHASIZE THE FORECASTED  
CHANGE IN THE CIRCULATION PATTERN FROM THE 6-10 DAY PERIOD. THE TEMPERATURE  
OUTLOOK PREDICTS THE REDUCTION IN COVERAGE OF ANOMALOUSLY COLD AIR EAST OF THE  
CONTINENTAL DIVIDE, WITH A CORRESPONDING INCREASE IN COVERAGE WEST OF THE  
DIVIDE. THIS ALLOWS EXPANSION OF ABOVE NORMAL TEMPERATURES ACROSS THE EASTERN  
AND SOUTHERN CONUS. THE PRECIPITATION OUTLOOK IS SIMILAR TO THAT FOR THE 6-10  
DAY PERIOD, BUT WITH INCREASED CONFIDENCE FOR ABOVE NORMAL PRECIPITATION TO  
SPREAD WEST OF THE DIVIDE.  
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 25% OF TODAY'S 0Z GFS ENSEMBLE  
MEAN CENTERED ON DAY 11, 25% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY  
11, 30% 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 IS: NEAR AVERAGE, 3 OUT OF 5, DUE  
TO UNCERTAINTY IN THE EXPECTED TIMING AND MAGNITUDE OF THE TRANSITION OF THE  
EAST-CENTRAL CONUS TROUGH TOWARDS THE WESTERN CONUS. IT IS ALSO RELATED TO THE  
PREDICTION OF A RAPIDLY DEAMPLIFYING CIRCULATION PATTERN DURING THE WEEK 2  
PERIOD.  
 
FORECASTER: ANTHONY A  
 
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:  
20081024 - 19671030 - 20071105 - 19591024 - 19611105  
 
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:  
20081023 - 20071104 - 19971103 - 19671031 - 19871026  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 01 - 05 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B N OREGON N A NRN CALIF N A  
SRN CALIF A N IDAHO N A NEVADA A N  
W MONTANA B A E MONTANA B A WYOMING B N  
UTAH A B ARIZONA A N COLORADO N B  
NEW MEXICO A B N DAKOTA B A S DAKOTA B A  
NEBRASKA B N KANSAS B B OKLAHOMA N N  
N TEXAS A A S TEXAS A A W TEXAS A B  
MINNESOTA B A IOWA B A MISSOURI B A  
ARKANSAS N A LOUISIANA A A WISCONSIN B A  
ILLINOIS B A MISSISSIPPI A A MICHIGAN B A  
INDIANA B A OHIO N A KENTUCKY N A  
TENNESSEE N A ALABAMA A A 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 N A NEW JERSEY A A W VIRGINIA N A  
MARYLAND A A DELAWARE A N VIRGINIA A A  
N CAROLINA A N S CAROLINA A N GEORGIA A N  
FL PNHDL A B FL PENIN A B AK N SLOPE A A  
AK ALEUTIAN A B AK WESTERN A B AK INT BSN A N  
AK S INT A B AK SO COAST A B AK PNHDL B B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 03 - 09 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B A  
SRN CALIF N A IDAHO B A NEVADA B A  
W MONTANA B A E MONTANA B A WYOMING B A  
UTAH N A ARIZONA A N COLORADO N N  
NEW MEXICO A N N DAKOTA B A S DAKOTA B A  
NEBRASKA B A KANSAS N A OKLAHOMA A A  
N TEXAS A A S TEXAS A N W TEXAS A N  
MINNESOTA B A IOWA B A MISSOURI N A  
ARKANSAS A A LOUISIANA A A WISCONSIN B A  
ILLINOIS N A MISSISSIPPI A A MICHIGAN A A  
INDIANA A A OHIO A A KENTUCKY A A  
TENNESSEE A A ALABAMA A A 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 A W VIRGINIA A A  
MARYLAND A A DELAWARE A N VIRGINIA A A  
N CAROLINA A A S CAROLINA A N GEORGIA A N  
FL PNHDL A N FL PENIN A N AK N SLOPE A N  
AK ALEUTIAN A B AK WESTERN A B AK INT BSN N B  
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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