102  
FXUS06 KWBC 231947  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT MON OCTOBER 23 2017  
 
6-10 DAY OUTLOOK FOR OCT 29 - NOV 02, 2017  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN VERY 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 NORTHERN PACIFIC. DOWNSTREAM A STRONG RIDGE IS  
PREDICTED OVER THE WESTERN HALF OF NORTH AMERICA FROM THE WESTERN CONUS TO  
EASTERN ALASKA. A TROUGH IS FORECAST OVER EASTERN NORTH AMERICA FROM THE GULF  
OF MEXICO TO THE CANADIAN MARITIMES. TODAY'S 500-HPA OFFICIAL MODEL HEIGHT  
BLEND INDICATES POSITIVE HEIGHT ANOMALIES OVER ALASKA AND MOST OF THE WESTERN  
CONUS AS WELL AS PARTS OF EASTERN MAINE AND QUEBEC. NEGATIVE HEIGHT ANOMALIES  
ARE INDICATED OVER THE REMAINDER OF THE CONUS FROM THE GREAT PLAINS STATES  
EASTWARD.  
 
A STRONG RIDGE PREDICTED OVER THE WESTERN CONUS HIGHLY FAVORS ABOVE NORMAL  
TEMPERATURES FOR THE WEST, WITH HIGHEST PROBABILITIES FOR CALIFORNIA AND THE  
GREAT BASIN REGION. THIS PREDICTED RIDGE EXTENDS INTO ALASKA, LEADING TO A  
CONFIDENT FORECAST OF ABOVE NORMAL TEMPERATURES FOR THE ENTIRE STATE. A  
PREDICTED TROUGH OVER THE EASTERN CONUS INCREASES THE LIKELIHOOD OF BELOW  
NORMAL TEMPERATURES FOR MUCH OF THE EAST. HOWEVER, FOR EASTERN AREAS OF THE  
NORTHEAST, ANOMALOUS SOUTHERLY FLOW, AHEAD OF THE PREDICTED TROUGH AXIS, AND  
NEAR AVERAGE HEIGHT ANOMALIES FAVOR ABOVE NORMAL TEMPERATURES.  
 
AHEAD OF THE TROUGH FORECAST TO THE WEST OF ALASKA, STORM SYSTEM ACTIVITY IS  
EXPECTED TO ENHANCE THE LIKELIHOOD OF ABOVE NORMAL PRECIPITATION FOR MOST OF  
THE STATE. THE PREDICTED RIDGE OVER THE U.S. WEST LEADS TO A HIGH LIKELIHOOD OF  
BELOW NORMAL PRECIPITATION FOR MUCH OF THE WESTERN CONUS, OUTSIDE OF  
CLIMATOLOGICALLY DRY REGIONS OF THE SOUTHWEST. PREDICTED NORTHERLY FLOW BEHIND  
THE RIDGE ACCESS OVER THE EASTERN CONUS LEADS TO AN INCREASED LIKELIHOOD OF  
BELOW NORMAL PRECIPITATION OVER MUCH OF THE CENTRAL CONUS AND SOUTHEAST. ABOVE  
NORMAL PRECIPITATION IS MOST LIKELY FOR PARTS OF THE EASTERN GREAT LAKES AND  
NORTHEAST REGION AHEAD OF THE PREDICTED LOCATION OF THE TROUGH.  
 
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 10% OF TODAY'S 0Z GFS ENSEMBLE MEAN  
CENTERED ON DAY 8, 30% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 40%  
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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD AGREEMENT AMONG THE MODEL CIRCULATION FORECASTS ON AN AMPLIFIED FLOW  
PATTERN AND RELATIVELY GOOD AGREEMENT AMONG THE TEMPERATURE AND PRECIPITATION  
TOOLS, OFFSET BY RELATIVELY LARGE ENSEMBLE SPREAD.  
 
8-14 DAY OUTLOOK FOR OCT 31 - NOV 06, 2017  
 
THERE IS INCREASED UNCERTAINTY ON THE CIRCULATION PATTERN DURING THE WEEK 2  
PERIOD RELATIVE TO THE 6-10 DAY PERIOD FORECAST, AS WELL AS LARGE SPREAD AMONG  
THE ENSEMBLE MEMBERS OVER MUCH OF THE FORECAST DOMAIN, ESPECIALLY OVER THE  
NORTH PACIFIC AND WESTERN CONUS. ENSEMBLE MEANS OF THE NCEP GEFS, ECMWF, AND  
ENVIRONMENT CANADA ENSEMBLE PREDICTION SYSTEMS APPEAR IN RELATIVE AGREEMENT ON  
PERSISTENCE OF A RIDGE OVER WESTERN CANADA AND THE U.S. NORTHWEST AND A TROUGH  
OVER EASTERN CANADA AND THE U.S. NORTHEAST. DETERMINISTIC, HIGH-RESOLUTION  
FORECASTS OF THE NCEP GFS, WHILE VARIABLE ON THE EXACT LOCATION, GENERALLY  
PREDICT AN AMPLIFIED TROUGH, LOCATED TO THE WEST OF THE PREDICTED TROUGH IN THE  
6-10 DAY PERIOD. THIS PATTERN OF AN AMPLIFIED TROUGH OVER THE CENTRAL OR  
WESTERN CONUS IS CONSISTENT WITH A TELECONNECTION 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 PARTS OF THE NORTHWESTERN CONUS AND NEGATIVE HEIGHT  
ANOMALIES OVER THE NORTHEASTERN CONUS.  
 
THE TEMPERATURE PATTERN FORECAST DURING THE WEEK 2 PERIOD ARE GENERALLY SIMILAR  
TO THE 6-10 DAY PERIOD FORECAST, WITH A SIGNIFICANT DECREASE IN PROBABILITIES,  
DUE TO SIGNIFICANTLY INCREASED UNCERTAINTY IN THE LARGE-SCALE CIRCULATION  
PATTERN. BELOW NORMAL TEMPERATURES ARE FORECAST TO BE MOST LIKELY FOR PARTS OF  
MONTANA AND THE NORTHERN GREAT PLAINS WITH THE INCREASED LIKELIHOOD OF AN  
AMPLIFIED TROUGH OVER THE REGION.  
 
THE PRECIPITATION PATTERN FORECAST DURING THE WEEK 2 PERIOD IS GENERALLY  
SIMILAR TO THE 6-10 DAY PERIOD FORECAST WITH LOWER PROBABILITIES. HOWEVER,  
ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR PARTS OF EASTERN MONTANA AND THE  
WESTERN GREAT LAKES REGION IN THE WEEK 2 PERIOD WITH THE POTENTIAL FOR A  
WESTWARD SHIFT IN THE TROUGH OVER THE CONUS.  
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 10% OF TODAY'S 0Z GFS ENSEMBLE  
MEAN CENTERED ON DAY 11, 30% OF TODAY'S 6Z GFS ENSEMBLE MEAN 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 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 - 19631023 - 19671022 - 19681020 - 19771030  
 
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:  
19681019 - 19951011 - 19631023 - 20071019 - 19831020  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 29 - NOV 02, 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A B OREGON A B NRN CALIF A B  
SRN CALIF A N IDAHO A B NEVADA A B  
W MONTANA A B E MONTANA A B WYOMING A B  
UTAH A B ARIZONA A N COLORADO A B  
NEW MEXICO A B N DAKOTA N B S DAKOTA B B  
NEBRASKA B B KANSAS B B OKLAHOMA B B  
N TEXAS B B S TEXAS B B W TEXAS N B  
MINNESOTA B B IOWA B B MISSOURI B B  
ARKANSAS B B LOUISIANA B B WISCONSIN B B  
ILLINOIS B B MISSISSIPPI B B MICHIGAN B N  
INDIANA B B OHIO B N KENTUCKY B B  
TENNESSEE B B ALABAMA B B 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 B A NEW JERSEY N A W VIRGINIA B N  
MARYLAND B A DELAWARE B A VIRGINIA B N  
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 N  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 31 - NOV 06, 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 N B NEVADA A B  
W MONTANA B N E MONTANA B A WYOMING N A  
UTAH A B ARIZONA A N COLORADO A B  
NEW MEXICO A B N DAKOTA B A S DAKOTA B A  
NEBRASKA B N KANSAS B N OKLAHOMA N B  
N TEXAS A B S TEXAS A B W TEXAS A B  
MINNESOTA B A IOWA B N MISSOURI B N  
ARKANSAS N N LOUISIANA N N WISCONSIN B N  
ILLINOIS B N MISSISSIPPI N B MICHIGAN B A  
INDIANA B N OHIO B N KENTUCKY B B  
TENNESSEE B B ALABAMA N B NEW YORK A N  
VERMONT A N NEW HAMP A N MAINE A N  
MASS A N CONN A N RHODE IS A N  
PENN N N NEW JERSEY N B W VIRGINIA N B  
MARYLAND N B DELAWARE N B VIRGINIA N B  
N CAROLINA N B S CAROLINA N B GEORGIA N B  
FL PNHDL N B FL PENIN N 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 N  
 
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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