135  
FXUS06 KWBC 251953  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT WED OCTOBER 25 2017  
 
6-10 DAY OUTLOOK FOR OCT 31 - NOV 04, 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 WESTERN MAINLAND ALASKA. THE GFS ENSEMBLE MEANS IN  
PARTICULAR FORECAST A TROUGH DOWNSTREAM OF THE STRONG RIDGE THAT IS STARTING TO  
UNDERCUT THE RIDGE FROM THE EAST. THE ENSEMBLE MEAN FROM ENVIRONMENT CANADA'S  
MODEL HINTS AT THIS UNDERCUTTING, BUT THE EUROPEAN MODEL HAS LITTLE IF ANY  
INDICATION OF IT. NEARLY ALL MODEL SOLUTIONS 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 THE CALIFORNIA COAST. AN AMPLIFIED  
TROUGH IS PREDICTED OVER EAST-CENTRAL NORTH AMERICA BY ALL ENSEMBLE MEANS WITH  
LOW ENSEMBLE SPREAD. TODAY'S 500-HPA OFFICIAL MODEL HEIGHT BLEND INDICATES  
POSITIVE HEIGHT ANOMALIES OVER ALASKA AND FAR WESTERN CANADA, MOST OF THE NORTH  
ATLANTIC POLEWARD OF 40N (INCLUDING THE MARITIME PROVINCES OF CANADA), AND MUCH  
OF RUSSIA. NEGATIVE HEIGHT ANOMALIES ARE DEPICTED OVER MUCH OF CENTRAL AND  
EASTERN NORTH AMERICA, EUROPE, AND IN A HORSESHOE-SHAPED BAND THAT STRETCHES  
FROM THE SEA OF OKHOTSK AROUND THE WESTERN AND SOUTHERN FLANKS OF THE LARGE  
ANOMALOUS ANTICYCLONE OVER ALASKA AND THE GULF OF ALASKA. THIS HEMISPHERIC FLOW  
PATTERN IS A GOOD EXAMPLE OF AN AMPLIFIED WAVENUMBER-3 CIRCULATION PATTERN.  
 
PREDICTED WELL ABOVE NORMAL HEIGHTS OVER ALASKA FAVOR ABOVE NORMAL TEMPERATURES  
OVER THE STATE, WITH THE EXCEPTION OF THE PANHANDLE, WHERE NEAR NORMAL  
TEMPERATURES ARE EXPECTED. MODESTLY POSITIVE HEIGHT ANOMALIES AHEAD OF A WEAK  
SOUTHERN STREAM TROUGH FAVOR ABOVE NORMAL TEMPERATURES FROM SOUTHWESTERN OREGON  
AND ALL OF CALIFORNIA EAST-SOUTHEASTWARD TO THE RIO GRANDE VALLEY IN TEXAS.  
SOUTHERLY ANOMALOUS FLOW AHEAD OF THE TROUGH ANTICIPATED OVER EAST-CENTRAL  
NORTH AMERICA TILTS THE ODDS TOWARDS ABOVE NORMAL TEMPERATURES FOR MUCH OF THE  
NORTHEAST, AND THE MID-ATLANTIC COAST. BELOW NORMAL TEMPERATURES ARE FAVORED  
FROM NORTHEASTERN PORTIONS OF WASHINGTON AND IDAHO EASTWARD AND SOUTHEASTWARD  
ACROSS MOST OF THE GREAT PLAINS, MISSISSIPPI VALLEY, GREAT LAKES REGION, AND  
INTO THE INTERIOR SOUTHEAST. THIS IS DUE TO THE PREDICTION OF AN UNUSUALLY DEEP  
TROUGH COVERING MOST OF CENTRAL AND EASTERN NORTH AMERICA.  
 
ABOVE NORMAL PRECIPITATION IS FAVORED IN EASTERN ALASKA EARLY IN THE PERIOD,  
DUE TO A DEPARTING FRONTAL SYSTEM, AND FROM MUCH OF THE NORTHERN GREAT PLAINS  
EASTWARD ACROSS THE FAR NORTHERN PORTIONS OF THE MISSISSIPPI VALLEY, THE GREAT  
LAKES REGION, AND INTERIOR PORTIONS OF THE NORTHEAST. ABOVE NORMAL  
PRECIPITATION IS ALSO PREDICTED OVER EAST TEXAS AND MUCH OF THE LOWER  
MISSISSIPPI VALLEY. THESE FORECAST AREAS OF ABOVE NORMAL PRECIPITATION ARE  
RELATED TO LOW PRESSURE SYSTEMS MOVING THROUGH THESE REGIONS. BELOW NORMAL  
PRECIPITATION IS FAVORED OVER WESTERN AND SOUTHWESTERN PORTIONS OF ALASKA, THE  
NORTHWESTERN CONUS AS FAR EAST AS CENTRAL IDAHO AND AS FAR SOUTH AS CENTRAL  
CALIFORNIA, FROM THE SOUTHERN HIGH PLAINS NORTHEASTWARD INTO THE MIDWEST, AND  
FROM MOST OF THE EAST GULF COAST REGION NORTHEASTWARD ACROSS THE CAROLINAS,  
VIRGINIA, AND TO THE MID-ATLANTIC COAST. THESE AREAS OF ANTICIPATED BELOW  
NORMAL PRECIPITATION ARE RELATED TO A GENERAL COMBINATION OF FACTORS, SUCH AS  
SUFFICIENT DISTANCE FROM STORM TRACKS, AREAS NEAR OR EAST OF A RIDGE AXIS, AND  
RELATIVELY DRY, NORTHERLY ANOMALOUS FLOW.  
 
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 0Z GFS 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, 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  
GOOD 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 02 - 08 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 (TO A LESSER DEGREE) 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.  
THERE APPEARS TO BE TWO SOMEWHAT CONFLICTING SCENARIOS IN PLAY HERE. THE FIRST  
SCENARIO FEATURES THE RETROGRESSION OF THE TROUGH INTO THE WESTERN CONUS, WHICH  
IS CONSISTENT WITH TELECONNECTIONS TO THE STRONG MJO CURRENTLY PROPAGATING  
EASTWARD OVER THE WESTERN TROPICAL PACIFIC. THE SECOND SCENARIO FEATURES MORE  
UNDERCUTTING OF THE ALASKA RIDGE FROM THE EAST, RESULTING IN INCREASED WESTERLY  
FLOW ACROSS THE CONUS. THE FIRST SCENARIO (WITH MJO FORCING) IS CONSIDERED  
SOMEWHAT MORE LIKELY THAN THE SECOND SCENARIO 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 SIGNIFICANT PORTION OF THE WESTERN/NORTHWESTERN CONUS.  
 
THE PREDICTED TEMPERATURE AND PRECIPITATION PATTERNS FOR WEEK 2 EMPHASIZE THE  
FORECASTED CHANGE IN THE CIRCULATION PATTERN FROM THE 6-10 DAY PERIOD. THE  
REGION OF BELOW NORMAL TEMPERATURES IS EXPECTED TO SHIFT WESTWARD INTO THE  
NORTHWESTERN AND NORTH-CENTRAL CONUS, WHILE ABOVE NORMAL TEMPERATURES ARE  
FORECAST TO RETURN TO APPROXIMATELY MOST OF THE EASTERN AND SOUTHERN THIRDS OF  
THE CONUS. IN EASTERN ALASKA, CURRENT SNOW COVER AND THE LIKELIHOOD OF  
LOW-LEVEL INVERSIONS ARE ANTICIPATED TO RESULT IN RELATIVELY COOLER  
TEMPERATURES, PERHAPS AVERAGING OUT TO NEAR OR EVEN LOCALLY BELOW NORMAL  
TEMPERATURES DURING THE WEEK 2 PERIOD. THE PRECIPITATION OUTLOOK SHOWS THE  
WIDESPREAD COVERAGE OF ABOVE NORMAL PRECIPITATION (COMPARED TO DAYS 6-10),  
RELATED TO THE PREDICTED RETROGRESSION OF THE 500-HPA TROUGH. SEVERAL EPISODES  
OF GULF MOISTURE STREAMING NORTHWARD ACROSS THE EAST-CENTRAL AND NORTHEASTERN  
CONUS ARE ANTICIPATED TO FAVOR ABOVE NORMAL PRECIPITATION AMOUNTS TO THOSE  
AREAS.  
 
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, 10% OF TODAY'S OPERATIONAL 6Z GFS 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: BELOW AVERAGE, 2 OUT OF 5, DUE  
TO INCREASED SPREAD AMONG THE ENSEMBLE MEMBERS OVER MUCH OF THE FORECAST  
DOMAIN, AND RELATIVELY POOR AGREEMENT AMONG SOME OF THE TEMPERATURE AND  
PRECIPITATION TOOLS.  
 
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:  
20081023 - 19611105 - 19971104 - 19551013 - 19671029  
 
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 - 19971103 - 19671028 - 20071024 - 19611105  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 31 - NOV 04, 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B B OREGON N B NRN CALIF A B  
SRN CALIF A N IDAHO B B NEVADA A N  
W MONTANA B A E MONTANA B A WYOMING B N  
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 A W TEXAS N B  
MINNESOTA B A IOWA B B MISSOURI B N  
ARKANSAS B A LOUISIANA N A WISCONSIN B N  
ILLINOIS B N MISSISSIPPI B N MICHIGAN B A  
INDIANA B A OHIO B A KENTUCKY B N  
TENNESSEE B N ALABAMA B B NEW YORK A A  
VERMONT A A NEW HAMP A N MAINE A A  
MASS A N CONN A N RHODE IS A N  
PENN N N NEW JERSEY A N W VIRGINIA B N  
MARYLAND N B DELAWARE A B VIRGINIA N B  
N CAROLINA N B S CAROLINA N B GEORGIA B B  
FL PNHDL N B FL PENIN N B AK N SLOPE A N  
AK ALEUTIAN A B AK WESTERN A B AK INT BSN A N  
AK S INT A N AK SO COAST A N AK PNHDL N B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR NOV 02 - 08 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B N 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 B A MISSISSIPPI A N MICHIGAN N A  
INDIANA N A OHIO A A KENTUCKY A A  
TENNESSEE A A ALABAMA A N NEW YORK A A  
VERMONT A A NEW HAMP A A MAINE A A  
MASS A N CONN A N RHODE IS A N  
PENN A A NEW JERSEY A N W VIRGINIA A N  
MARYLAND A N DELAWARE A N VIRGINIA A N  
N CAROLINA A B S CAROLINA A B GEORGIA A B  
FL PNHDL A B FL PENIN A N AK N SLOPE A A  
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A A  
AK S INT A N 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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