630  
FXUS06 KWBC 111922  
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 11 2017  
 
6-10 DAY OUTLOOK FOR OCT 17 - 21 2017  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT ON THE 500-HPA FLOW  
PATTERN OVER THE FORECAST DOMAIN. A TROUGH IS FORECAST OVER ALASKA EXTENDING  
SOUTHEASTWARD NEAR THE PACIFIC NORTHWEST COAST, WHILE AN ANOMALOUS RIDGE IS  
EXPECTED FROM THE SOUTHWESTERN CONUS TO THE EASTERN CONUS. TODAY'S 500-HPA  
HEIGHT BLEND CHART DEPICTS BELOW NORMAL HEIGHTS OVER THE NORTHWESTERN CONUS AND  
ALASKA, WHILE NEAR TO ABOVE NORMAL HEIGHTS ARE FORECAST ACROSS THE REMAINDER OF  
THE CONUS. THE ENSEMBLE SPAGHETTI DIAGRAMS INDICATE SMALL TO MODERATE SPREAD  
ACROSS THE MAJORITY OF THE FORECAST DOMAIN. THE GREATEST WEIGHT FOR THE BLENDED  
HEIGHT FORECAST WAS GIVEN TO TODAY'S 00Z ECMWF ENSEMBLE MEAN BASED ON  
CONSIDERATIONS OF RECENT SKILL.  
 
THE FORECAST TROUGH NEAR THE PACIFIC NORTHWEST TILTS THE ODDS TO NEAR OR BELOW  
NORMAL TEMPERATURES FOR THE NORTHWESTERN CONUS. ABOVE NORMAL TEMPERATURES ARE  
FAVORED FOR MUCH OF THE REMAINDER OF THE CONUS UNDERNEATH ABOVE NORMAL HEIGHTS.  
THE PREDICTED TROUGH AND BELOW NORMAL HEIGHTS OVER ALASKA INCREASE  
PROBABILITIES OF BELOW NORMAL TEMPERATURES FOR MUCH OF THE STATE.  
 
THE TROUGH NEAR THE PACIFIC NORTHWEST COAST AND ENHANCED ONSHORE FLOW LEAD TO  
INCREASED CHANCES OF ABOVE NORMAL PRECIPITATION FOR THE SOUTHERN ALASKA  
PANHANDLE, THE PACIFIC NORTHWEST, NORTHERN CALIFORNIA, PARTS OF WESTERN  
MONTANA, IDAHO, AND NEVADA. BELOW NORMAL PRECIPITATION IS FAVORED FOR PARTS OF  
THE SOUTHWEST, THE ROCKIES, THE GREAT PLAINS, THE LOWER MISSISSIPPI VALLEY, THE  
TENNESSEE VALLEY, THE OHIO VALLEY, THE GREAT LAKES AND THE NORTHEASTERN CONUS,  
UNDERNEATH ABOVE NORMAL HEIGHTS. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR  
PORTIONS OF THE SOUTHEAST, FLORIDA AND COAST OF THE MIDDLE ATLANTIC, WHICH IS  
CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE GEFS ENSEMBLE MEMBERS. THE  
PREDICTED MEAN NORTHEASTERLY FLOW OVER MUCH OF ALASKA ELEVATES THE  
PROBABILITIES OF BELOW NORMAL PRECIPITATION OVER THE AREA.  
 
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 15% OF TODAY'S 0Z GFS ENSEMBLE MEAN  
CENTERED ON DAY 8, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 10%  
OF TODAY'S GFS SUPERENSEMBLE 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: AVERAGE, 3 OUT OF 5, DUE TO GOOD  
AGREEMENT AMONG ENSEMBLE MEANS, OFFSET BY DISAGREEMENT BETWEEN PRECIPITATION  
TOOLS OVER THE CENTRAL AND EASTERN CONUS.  
 
8-14 DAY OUTLOOK FOR OCT 19 - 25 2017  
 
DURING THE WEEK-2 PERIOD, THE ENSEMBLE MEAN SOLUTIONS PREDICT A TROUGH  
EXTENDING FROM ALASKA TO COAST OF THE PACIFIC NORTHWEST, WHILE AN ANOMALOUS  
RIDGE IS FORECAST FROM THE SOUTHWESTERN CONUS TO THE EASTERN CONUS. TODAY'S  
500-HPA HEIGHT BLEND INDICATES BELOW NORMAL HEIGHTS OVER THE NORTHWESTERN CONUS  
AND ALASKA, WHILE ABOVE NORMAL HEIGHTS ARE FORECAST OVER THE REMAINDER OF THE  
CONUS. TODAY'S WEEK-2 MANUAL 500-HPA HEIGHT BLEND IS WEIGHTED MOST HEAVILY  
TOWARD THE ENSEMBLE MEAN SOLUTION FROM THE 0Z ECMWF DUE TO BETTER SKILL OVER  
THE PAST 60 DAYS.  
 
THERE ARE INCREASED ODDS FOR BELOW NORMAL TEMPERATURES FROM ALASKA TO PARTS OF  
THE NORTHWESTERN CONUS DUE TO A PREDICTED TROUGH AND BELOW NORMAL HEIGHTS.  
ABOVE NORMAL TEMPERATURES ARE GENERALLY FAVORED FOR MUCH OF THE REMAINDER OF  
THE CONUS UNDERNEATH PREDICTED ABOVE NORMAL HEIGHTS.  
 
A FORECAST TROUGH NEAR THE PACIFIC NORTHWEST LEADS TO ENHANCED PROBABILITIES  
FOR ABOVE NORMAL PRECIPITATION FOR THE NORTHWESTERN CONUS, NORTHEASTERN ALASKA  
AND THE SOUTHERN ALASKA PANHANDLE. BELOW NORMAL PRECIPITATION IS FAVORED FOR  
PARTS OF THE SOUTHWEST, THE CENTRAL GREAT BASIN, THE CENTRAL AND SOUTHERN  
ROCKIES, AND THE HIGH PLAINS, ASSOCIATED WITH ABOVE NORMAL 500-HPA HEIGHTS.  
THERE ARE INCREASED ODDS FOR ABOVE NORMAL PRECIPITATION FOR PARTS OF THE  
MISSISSIPPI VALLEY, THE GREAT LAKES, THE OHIO VALLEY, THE TENNESSEE VALLEY, THE  
SOUTHEAST AND FLORIDA, CONSISTENT WITH CALIBRATED PRECIPITATION FORECAST  
ESTIMATES AND AN EXPECTED FRONTAL PASSAGE. ENHANCED PROBABILITIES FOR NEAR TO  
BELOW MEDIAN PRECIPITATION ARE INDICATED FOR ALASKA UNDERNEATH MEAN EASTERLY  
FLOW OVER MUCH OF THE STATE.  
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY'S 6Z GFS ENSEMBLE  
MEAN CENTERED ON DAY 11, 20% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY  
11, 10% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 11, AND 50% 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  
FAIR MODEL AGREEMENT, OFFSET BY POOR AGREEMENT AMONG PRECIPITATION TOOLS ALONG  
AND EAST OF THE ROCKIES.  
 
FORECASTER: Y. FAN  
 
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:  
19610925 - 19831004 - 19911023 - 19901008 - 20050923  
 
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:  
19831003 - 20050922 - 19610923 - 19901007 - 19911022  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 17 - 21 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF N A  
SRN CALIF A N IDAHO B A NEVADA N N  
W MONTANA N A 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 B  
N TEXAS A B S TEXAS A B W TEXAS A B  
MINNESOTA A N IOWA A N MISSOURI A N  
ARKANSAS A B LOUISIANA A N WISCONSIN A N  
ILLINOIS A B MISSISSIPPI A N MICHIGAN A B  
INDIANA A B OHIO A B KENTUCKY A B  
TENNESSEE A B ALABAMA A N NEW YORK A B  
VERMONT A B NEW HAMP A B MAINE A B  
MASS A B CONN A B RHODE IS A B  
PENN A B NEW JERSEY A B W VIRGINIA A B  
MARYLAND A B DELAWARE A B VIRGINIA A B  
N CAROLINA A N S CAROLINA A N GEORGIA A N  
FL PNHDL A A FL PENIN A A AK N SLOPE B N  
AK ALEUTIAN B N AK WESTERN B B AK INT BSN B B  
AK S INT B B AK SO COAST B B AK PNHDL B N  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 19 - 25 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF A N  
SRN CALIF A N IDAHO B A NEVADA N N  
W MONTANA N A E MONTANA A N WYOMING A N  
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 N  
N TEXAS A N S TEXAS A N W TEXAS A B  
MINNESOTA A A IOWA A A 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 N  
VERMONT A N NEW HAMP A N MAINE A N  
MASS A N CONN A N RHODE IS A N  
PENN A N NEW JERSEY A N W VIRGINIA A N  
MARYLAND A N DELAWARE A N VIRGINIA A N  
N CAROLINA A N S CAROLINA A N GEORGIA A A  
FL PNHDL A A FL PENIN A A AK N SLOPE B N  
AK ALEUTIAN B N AK WESTERN B B AK INT BSN B N  
AK S INT B N AK SO COAST B N AK PNHDL B 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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