159  
FXUS06 KWBC 161915  
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 16 2017  
 
6-10 DAY OUTLOOK FOR OCT 22 - 26 2017  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN RELATIVELY GOOD AGREEMENT ON AN  
AMPLIFIED FLOW PATTERN OVER MOST OF THE FORECAST DOMAIN. A DEEP CLOSED 500-HPA  
TROUGH IS FORECAST OVER PARTS OF WESTERN ALASKA, WITH NEGATIVE HEIGHT ANOMALIES  
EXTENDING SOUTHWARD TO HAWAII. DOWNSTREAM A STRONG RIDGE IS PREDICTED OVER THE  
WESTERN HALF OF THE CONUS. A TROUGH IS FORECAST OVER THE EASTERN HALF OF THE  
CONUS. TODAYS 500-HPA MANUAL BLEND FEATURES NEGATIVE HEIGHT ANOMALIES OVER ALL  
OF ALASKA, AND ABOVE NORMAL HEIGHTS OVER THE REST OF THE U.S., EXCEPT FOR  
SLIGHTLY NEGATIVE HEIGHT ANOMALIES FOR PARTS OF THE GREAT LAKES REGION.  
 
NEAR TO BELOW NORMAL TEMPERATURES ARE FAVORED FOR ALASKA DUE TO A DEEP TROUGH  
PREDICTED OVER MUCH OF ALASKA. A STRONG RIDGE PREDICTED OVER THE WESTERN CONUS  
HIGHLY FAVORS ABOVE NORMAL TEMPERATURES FOR MOST OF THE WESTERN U.S., EXCEPT  
FOR PARTS OF TEXAS WHERE NEGATIVE TEMPERATURE ANOMALIES ARE FORECAST TO PERSIST  
AFTER AN EXPECTED FRONTAL PASSAGE DURING THE PERIOD.  
 
STORM SYSTEM ACTIVITY IS FORECAST TO TRAVEL AROUND THE CLOSED LOW OVER PARTS OF  
ALASKA, INCREASING THE LIKELIHOOD FOR ABOVE NORMAL PRECIPITATION FROM THE  
ALEUTIANS AND THE SOUTHERN ALASKA COAST TO THE PACIFIC NORTHWEST. THE WESTERN  
RIDGE IS FORECAST TO CONTAIN THE SYSTEMS TO JUST THE PACIFIC NORTHWEST WITHIN  
THE CONUS, FAVORING BELOW NORMAL PRECIPITATION OVER MUCH OF THE REST OF THE  
WESTERN HALF OF THE CONUS. A FRONTAL SYSTEM ASSOCIATED WITH THE TROUGH  
PREDICTED IN THE EASTERN U.S. INCREASES THE CHANCES FOR ABOVE NORMAL  
PRECIPITATION FOR MUCH OF THE EASTERN HALF OF THE CONUS.  
 
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 50% OF TODAY'S 6Z GFS ENSEMBLE MEAN  
CENTERED ON DAY 8, AND 50% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD AGREEMENT AMONG THE ENSEMBLE MEANS AND TOOLS, OFFSET BY SOME LARGE-SCALE  
DIFFERENCES AMONG THE DETERMINISTIC MODEL RUNS  
 
8-14 DAY OUTLOOK FOR OCT 24 - 30 2017  
 
DURING THE WEEK-2 PERIOD, THE OVERALL 500-HPA FLOW PATTERN IS EXPECTED TO  
RETROGRADE SLIGHTLY, AND THE EASTERN TROUGH IS EXPECTED TO INTENSIFY.  
 
THE TEMPERATURE PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE SIMILAR  
TO THOSE FORECAST DURING THE WEEK-2 PERIOD, WITH A FEW EXCEPTIONS. SOME RIDGING  
IS EXPECTED TO BUILD WESTWARD INTO EASTERN PORTIONS OF ALASKA, FAVORING ABOVE  
NORMAL TEMPERATURES THERE. THE DEEPENING TROUGH IN THE EASTERN U.S. INCREASES  
THE LIKELIHOOD OF NEAR TO BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE EASTERN  
U.S.  
 
THE PRECIPITATION PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE SIMILAR  
TO THE WEEK-2 PERIOD, WITH SOME EXCEPTIONS. AS THE WESTERN RIDGE IS FORECAST TO  
RETROGRADE, ITS EXPECTED TO SUPPRESS STORM SYSTEM ACTIVITY IN THE PACIFIC  
NORTHWEST, ENHANCING THE LIKELIHOOD OF BELOW NORMAL PRECIPITATION THERE. A  
FRONTAL SYSTEM FORECAST TO TRAVEL ACROSS THE EASTERN U.S. DURING THE 6-10 DAY  
PERIOD IS FORECAST TO BE NEAR THE COAST BY THE BEGINNING OF THE WEEK-2 PERIOD,  
SHIFTING THE AREA OF FAVORED ABOVE NORMAL PRECIPITATION TO THE APPALACHIANS AND  
EASTWARD BY THE WEEK-2 PERIOD. THE SURFACE LOW ASSOCIATED WITH THIS SYSTEM IS  
FORECAST TO PERSIST IN THE GREAT LAKES, PERSISTING THE AREA OF FAVORED ABOVE  
NORMAL PRECIPITATION FOR PARTS OF THE GREAT LAKES REGION.  
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 30% OF TODAY'S 0Z GFS ENSEMBLE  
MEAN CENTERED ON DAY 11, 30% OF YESTERDAY'S OPERATIONAL 18Z GFS CENTERED ON DAY  
10, AND 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: AVERAGE, 3 OUT OF 5, DUE TO  
GOOD MODEL AGREEMENT, OFFSET BY SOME DIFFERENCES IN THE TOOLS, ESPECIALLY DUE  
TO A TEMPERATURE TRANSITION IN THE EASTERN U.S.  
 
FORECASTER: MIKE C  
 
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  
OCTOBER 19  
 
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:  
19901008 - 20070926 - 20011020 - 19891012 - 19811025  
 
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:  
19901009 - 20050926 - 19811025 - 20011019 - 19851012  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 22 - 26 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A A 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 B COLORADO A B  
NEW MEXICO A B N DAKOTA A B S DAKOTA A B  
NEBRASKA A B KANSAS A B OKLAHOMA A A  
N TEXAS A A S TEXAS N A W TEXAS A B  
MINNESOTA A B IOWA A N MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN A 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 N NEW HAMP A N MAINE A N  
MASS A N CONN A N RHODE IS A N  
PENN A A NEW JERSEY A N W VIRGINIA A A  
MARYLAND A N DELAWARE A N VIRGINIA A A  
N CAROLINA A A S CAROLINA A A GEORGIA A A  
FL PNHDL A A FL PENIN A A AK N SLOPE N N  
AK ALEUTIAN B A AK WESTERN B A AK INT BSN N N  
AK S INT B A AK SO COAST B A AK PNHDL B A  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 24 - 30 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A B OREGON A B NRN CALIF A B  
SRN CALIF A B IDAHO A B NEVADA A B  
W MONTANA A B E MONTANA A B WYOMING A B  
UTAH A B ARIZONA A B COLORADO A B  
NEW MEXICO A B N DAKOTA A B S DAKOTA A B  
NEBRASKA A B KANSAS A B OKLAHOMA N B  
N TEXAS N B S TEXAS N B W TEXAS A B  
MINNESOTA A B IOWA A B MISSOURI N B  
ARKANSAS B B LOUISIANA B B WISCONSIN A B  
ILLINOIS N B MISSISSIPPI B B MICHIGAN A N  
INDIANA B B OHIO N N KENTUCKY B B  
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 A A NEW JERSEY A A W VIRGINIA B A  
MARYLAND A A DELAWARE A A VIRGINIA N A  
N CAROLINA B A S CAROLINA N A GEORGIA B N  
FL PNHDL N N FL PENIN A N AK N SLOPE A A  
AK ALEUTIAN N A AK WESTERN N N AK INT BSN A A  
AK S INT A A AK SO COAST A A AK PNHDL A A  
 
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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