217  
FXUS06 KWBC 271947  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT FRI OCTOBER 27 2017  
 
6-10 DAY OUTLOOK FOR NOV 02 - 06 2017  
 
TODAY'S ENSEMBLE MEAN AND DETERMINISTIC SOLUTIONS HAVE COME INTO MUCH BETTER  
AGREEMENT ON AN AMPLIFIED 500-HPA FLOW PATTERN PREDICTED OVER MOST OF THE  
FORECAST DOMAIN. A HIGHLY AMPLIFIED RIDGE IS PREDICTED OVER THE EASTERN BERING  
SEA AND WESTERN ALASKA. THE OFFICIAL 500-HPA HEIGHT BLEND PREDICTS A POSITIVE  
HEIGHT ANOMALY OF NEARLY +400 METERS NEAR 60N/160W. DOWNSTREAM OF THIS RIDGE, A  
POSITIVELY-TILTED TROUGH IS ANTICIPATED TO EXTEND FROM NEAR BAFFIN ISLAND,  
CANADA SOUTHWESTWARD ACROSS WESTERN CANADA, THE NORTHWESTERN CONUS, AND  
CONTINUING OUT OVER THE FAR EASTERN PACIFIC OCEAN. THOUGH BROAD CYCLONIC  
CURVATURE IS FORECAST TO EXTEND OVER MOST OF THE CONUS, THE MANUAL BLEND MAP  
DEPICTS ANOMALOUS RIDGING AND RISING 500-HPA HEIGHTS ACROSS THE EASTERN CONUS.  
AT THE 5760-METER LEVEL, LOW TO MODERATE ENSEMBLE SPREAD IS INDICATED ACROSS  
THE CONUS TODAY, WHICH IS A CONSIDERABLE IMPROVEMENT COMPARED TO THE LAST FEW  
DAYS. TODAY'S OFFICIAL 500-HPA CIRCULATION BLEND DEPICTS WELL ABOVE NORMAL  
HEIGHTS OVER ALASKA AND THE YUKON, AND MUCH LOWER POSITIVE HEIGHT ANOMALIES  
(GENERALLY +30 TO +80 METERS) OVER APPROXIMATELY THE EASTERN HALF OF THE LOWER  
48 STATES. WELL BELOW NORMAL HEIGHTS ARE DEPICTED OVER MOST OF CANADA, AND  
APPROXIMATELY THE WESTERN HALF OF THE CONUS, WITH MAXIMUM DEPARTURES NEAR -180  
METERS OVER WASHINGTON STATE.  
 
IN ALASKA, ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS THE WESTERN HALF OF THE  
STATE, IN EXPECTATION OF WELL ABOVE NORMAL 500-HPA HEIGHTS AND ASSOCIATED  
SUBSIDENCE. NORTHERLY ANOMALOUS FLOW SUPPORTS ENHANCED ODDS OF NEAR TO BELOW  
NORMAL TEMPERATURES OVER THE CENTRAL AND EASTERN PORTIONS OF ALASKA,  
RESPECTIVELY. THE AMPLIFIED TROUGH EXPECTED FROM NORTHEASTERN TO SOUTHWESTERN  
PORTIONS OF NORTH AMERICA, AND ASSOCIATED BELOW NORMAL 500-HPA HEIGHTS, FAVORS  
BELOW NORMAL TEMPERATURES OVER THE NORTH-CENTRAL CONUS, THE NORTHERN ROCKIES,  
THE PACIFIC NORTHWEST, AND MOST OF CALIFORNIA. OVER THE EASTERN AND SOUTHERN  
CONUS, ODDS FOR ABOVE NORMAL TEMPERATURES ARE ELEVATED PRIMARILY DUE TO FACTORS  
SUCH AS ANOMALOUS RIDGING AND/OR SOUTHWESTERLY ANOMALOUS FLOW. THE SURFACE  
TEMPERATURE OUTLOOK ALIGNS WELL WITH TELECONNECTIONS OFF A POSITIVE HEIGHT  
ANOMALY CENTER NEAR 60N/160W, AND IS WELL SUPPORTED BY THE REFORECAST GEFS AND  
ECMWF TEMPERATURE FORECASTS.  
 
ABOVE NORMAL PRECIPITATION IS FAVORED IN FAR NORTHERN ALASKA (RELATED TO  
NORTHERLY ANOMALOUS FLOW OVER PRIMARILY ICE-FREE WATER), AND FOR MOST AREAS  
WEST OF THE CONTINENTAL DIVIDE IN THE LOWER 48 STATES. THIS IS DUE IN LARGE  
PART TO THE SUSPECTED DIGGING OF THE VERY DEEP TROUGH ACROSS THE WESTERN CONUS.  
ABOVE NORMAL PRECIPITATION IS FAVORED FROM ABOUT THE NORTHERN AND CENTRAL  
CONTINENTAL DIVIDE EASTWARD TO INCLUDE THE NORTHERN PLAINS AS FAR SOUTH AS  
NORTHERN NEBRASKA, THE MISSISSIPPI VALLEY AND ADJACENT PORTIONS OF THE SOUTHERN  
PLAINS, THE GREAT LAKES REGION, THE OHIO AND TENNESSEE VALLEYS, MOST OF THE  
APPALACHIANS, THE NORTHEAST, AND THE MID-ATLANTIC. THE NORTHERN PORTION OF THIS  
AREA OF PREDICTED ABOVE NORMAL PRECIPITATION IS ASSOCIATED WITH THE EXPECTED  
RETREAT OF THE RELATIVELY COLD AIR. THE SOUTHERN PORTION OF THIS AREA OF  
RELATIVE WETNESS IS CONSISTENT WITH THE INFLOW OF LOW-LEVEL GULF MOISTURE ALONG  
THE WESTERN PERIPHERY OF AN ANTICYCLONE EXPECTED NEAR THE EAST COAST. AREAS OF  
BELOW NORMAL PRECIPITATION ARE PREDICTED FOR THE SOUTHERN TWO-THIRDS OF ALASKA,  
THE CENTRAL AND SOUTHERN HIGH PLAINS, AND PARTS OF THE SOUTHEAST. THESE AREAS  
OF ANTICIPATED BELOW NORMAL PRECIPITATION ARE RELATED TO SEVERAL FACTORS,  
INCLUDING NORTHERLY ANOMALOUS FLOW, SUFFICIENT DISTANCE FROM STORM TRACKS, OR  
SUBSIDENCE ASSOCIATED WITH AREAS EAST OF A MEAN RIDGE AXIS.  
 
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, 10%  
OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 8, 20% 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  
IMPROVED MODEL AND TOOL AGREEMENT TODAY ON AN AMPLIFIED 500-HPA FLOW PATTERN,  
COMPARED TO THE LAST FEW DAYS.  
 
8-14 DAY OUTLOOK FOR NOV 04 - 10 2017  
 
ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT TODAY FOR THE WEEK-2 PERIOD OVER  
MOST OF THE FORECAST DOMAIN. THE DETERMINISTIC GFS RUNS, HOWEVER, CONTINUE TO  
FLUCTUATE ON THE ANTICIPATED FLOW PATTERN OVER THE WEST COAST OF NORTH AMERICA.  
TODAY'S 0Z AND 12Z GFS MODEL INTEGRATIONS PREDICT SIGNIFICANT DIGGING OF A  
TROUGH ACROSS WESTERN CANADA AND THE WESTERN CONUS, WHILE THE INTERMEDIATE 6Z  
RUN PREDICTS ZONAL FLOW THROUGH MUCH OF THIS REGION. THE OUTLIER 6Z GFS RUN WAS  
LARGELY DISCOUNTED TODAY. DISPERSION AMONG ENSEMBLE MEMBERS IS CONSIDERED  
MODERATE TO SOMEWHAT HIGH TODAY. THE OFFICIAL HEIGHT BLEND IS SIMILAR TO THAT  
FOR THE 6-10 DAY PERIOD, ALBEIT WITH CONSIDERABLY REDUCED HEIGHT ANOMALY  
VALUES. THIS PATTERN IS ALSO CONSISTENT WITH TELECONNECTIONS BASED ON A  
POSITIVE HEIGHT ANOMALY CENTER NEAR 60N/170W, AND WITH TELECONNECTIONS TO THE  
STRONG MJO THAT IS PROPAGATING EASTWARD OVER THE WESTERN TROPICAL PACIFIC AT  
THIS TIME.  
 
THE SURFACE TEMPERATURE OUTLOOK REFLECTS THE NOTION OF A GENERAL RETRACTION OF  
THE PREDICTED ANOMALOUSLY COLD AIR OVER THE NORTH-CENTRAL CONUS, AND A  
SOUTHWARD ADVANCE OF THE FAVORED BELOW NORMAL TEMPERATURES ACROSS CALIFORNIA  
AND MOST OF THE INTERMOUNTAIN WEST. AS A RESULT, ABOVE NORMAL TEMPERATURES ARE  
EXPECTED TO EXPAND IN COVERAGE OVER MOST OF THE EASTERN AND SOUTHERN CONUS. THE  
TEMPERATURE ANOMALY PATTERN IN ALASKA IS ANTICIPATED TO UNDERGO A SLIGHT  
WESTWARD SHIFT. THE PRECIPITATION OUTLOOK IS FORECAST TO BE SIMILAR TO THAT OF  
THE 6-10 DAY PERIOD, WITH THE ECMWF REFORECAST PRECIPITATION BEING SOMEWHAT  
DRIER TODAY THAN ITS GEFS COUNTERPART.  
 
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, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 25% OF  
TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOVE AVERAGE, 4 OUT OF 5, DUE  
TO BETTER MODEL CONVERGENCE TODAY COMPARED WITH THE PAST SEVERAL DAYS. THE  
THREE MAJOR HEIGHT ANOMALY CENTERS (TWO OVER THE CONUS AND ONE OVER ALASKA) ARE  
POSITIONED VERY SIMILARLY TO THAT OF A CANONICAL (AND SOMEWHAT MORE STABLE)  
NEGATIVE PNA TELECONNECTION PATTERN.  
 
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 - 20071105 - 19671102 - 19991018 - 19591024  
 
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:  
20071104 - 20081024 - 19671101 - 19621021 - 20041012  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 02 - 06 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 N A NEVADA N A  
W MONTANA B A E MONTANA B A WYOMING B A  
UTAH A A ARIZONA A A COLORADO A N  
NEW MEXICO A B N DAKOTA B A S DAKOTA B A  
NEBRASKA B A KANSAS N N OKLAHOMA A B  
N TEXAS A A S TEXAS A A W TEXAS A B  
MINNESOTA B A IOWA B A MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN B A  
ILLINOIS N A MISSISSIPPI A A MICHIGAN N 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 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 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 N N  
AK S INT N B AK SO COAST N B AK PNHDL B B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 04 - 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 A E MONTANA B A WYOMING B A  
UTAH N A ARIZONA N N COLORADO N N  
NEW MEXICO A B N DAKOTA B A S DAKOTA B A  
NEBRASKA N A KANSAS A A OKLAHOMA A A  
N TEXAS A A S TEXAS A A W TEXAS A B  
MINNESOTA B A IOWA N A MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN N A  
ILLINOIS A 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 N S CAROLINA A N GEORGIA A N  
FL PNHDL A B FL PENIN A B AK N SLOPE N N  
AK ALEUTIAN A B AK WESTERN A B AK INT BSN N B  
AK S INT N B AK SO COAST N 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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