173  
FXUS06 KWBC 101912  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT TUE OCTOBER 10 2017  
 
6-10 DAY OUTLOOK FOR OCT 16 - 20 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  
SOUTHWARD NEAR THE PACIFIC NORTHWEST COAST, WHILE A RIDGE IS EXPECTED OVER THE  
SOUTHERN 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 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  
NEAR TO BELOW NORMAL TEMPERATURES FOR MUCH OF THE STATE.  
 
THE TROUGH NEAR THE PACIFIC NORTHWEST COAST LEADS TO INCREASED CHANCES OF ABOVE  
NORMAL PRECIPITATION FOR THE PACIFIC NORTHWEST, NORTHERN CALIFORNIA, PARTS OF  
WESTERN MONTANA, IDAHO, AND NEVADA. BELOW NORMAL PRECIPITATION IS FORECAST FOR  
PARTS OF THE SOUTHWEST, THE GREAT PLAINS, THE LOWER AND MIDDLE MISSISSIPPI  
VALLEY, THE OHIO VALLEY, THE TENNESSEE VALLEY, AND THE GREAT LAKES, UNDERNEATH  
ABOVE NORMAL HEIGHTS. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR PORTIONS OF THE  
SOUTHEAST, THE MIDDLE ATLANTIC, AND THE UPPER GREAT LAKES, WHICH IS CONSISTENT  
WITH PRECIPITATION ESTIMATES FROM THE GEFS ENSEMBLE MEMBERS. THE TROUGH OVER  
ALASKA ELEVATES THE PROBABILITIES OF ABOVE NORMAL PRECIPITATION FOR MUCH OF THE  
STATE.  
 
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 10% OF TODAY'S 0Z GFS ENSEMBLE MEAN  
CENTERED ON DAY 8, 10% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 10%  
OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 8, 5% OF TODAY'S OPERATIONAL  
0Z GFS CENTERED ON DAY 8, 5% OF TODAY'S OPERATIONAL 6Z GFS 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 MODEL AGREEMENT.  
 
8-14 DAY OUTLOOK FOR OCT 18 - 24 2017  
 
DURING THE WEEK-2 PERIOD, MOST MODEL RUNS PREDICT A TROUGH EXTENDING FROM  
ALASKA TO THE PACIFIC NORTHWEST COAST, WHILE A RIDGE IS FORECAST CENTERED NEAR  
THE SOUTHERN PLAINS. TODAY'S 500-HPA HEIGHT BLEND INDICATES BELOW NORMAL  
HEIGHTS OVER THE NORTHWESTERN CONUS AND ALASKA, WHILE ABOVE NORMAL HEIGHTS AE  
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.  
 
ABOVE NORMAL TEMPERATURES ARE GENERALLY FAVORED FOR MUCH OF THE CENTRAL AND  
EASTERN CONUS UNDERNEATH PREDICTED ABOVE NORMAL HEIGHTS. THERE ARE INCREASED  
ODDS FOR BELOW NORMAL TEMPERATURES FOR ALASKA AND THE NORTHWESTERN CONUS  
EXTENDING SOUTH TO PARTS OF NEVADA AND CALIFORNIA DUE TO A PREDICTED TROUGH AND  
BELOW NORMAL HEIGHTS.  
 
A TROUGH NEAR THE PACIFIC NORTHWEST LEADS TO ENHANCED PROBABILITIES FOR ABOVE  
NORMAL PRECIPITATION FOR THE NORTHWESTERN CONUS. BELOW NORMAL PRECIPITATION IS  
FAVORED FOR PARTS OF THE GREAT PLAINS, THE CENTRAL AND SOUTHERN ROCKIES, THE  
SOUTHWEST, AND MUCH OF THE AREAS ALONG THE EASTERN SEABOARD, ASSOCIATED WITH  
ABOVE NORMAL 500-HPA HEIGHTS. THERE ARE INCREASED ODDS FOR ABOVE NORMAL  
PRECIPITATION FOR PARTS OF THE GREAT LAKES, THE MIDDLE AND UPPER MISSISSIPPI  
VALLEY, THE OHIO VALLEY, SOUTHERN FLORIDA, SOUTHERN TEXAS, AND SOUTHERN  
LOUISIANA, CONSISTENT WITH CALIBRATED PRECIPITATION ESTIMATES FROM THE GEFS  
ENSEMBLE MEMBERS. ENHANCED PROBABILITIES FOR NEAR TO BELOW MEDIAN PRECIPITATION  
ARE INDICATED FOR ALASKA UNDERNEATH MEAN NORTHERLY FLOW OVER MUCH OF THE STATE.  
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 10% OF TODAY'S 0Z GFS ENSEMBLE  
MEAN CENTERED ON DAY 11, 10% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY  
11, 10% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11, 40% OF TODAY'S 0Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 30% OF TODAY'S 0Z CANADIAN  
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.  
 
FORECASTER: LUKE H  
 
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:  
19901009 - 19610925 - 19831003 - 19811024 - 20070925  
 
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 - 19610922 - 19831003 - 20070924 - 19610927  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 16 - 20 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 B A E MONTANA N N WYOMING N B  
UTAH N N 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 N W TEXAS A B  
MINNESOTA A N IOWA A N MISSOURI A B  
ARKANSAS A B LOUISIANA A N WISCONSIN A A  
ILLINOIS A B MISSISSIPPI A N MICHIGAN A N  
INDIANA A B OHIO A N KENTUCKY A N  
TENNESSEE A N ALABAMA A N 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 A  
N CAROLINA A A S CAROLINA A A GEORGIA A A  
FL PNHDL A A FL PENIN A A AK N SLOPE B N  
AK ALEUTIAN B N AK WESTERN N N AK INT BSN B N  
AK S INT B B AK SO COAST B B AK PNHDL B N  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 18 - 24 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B A  
SRN CALIF N N IDAHO B A NEVADA B N  
W MONTANA B A E MONTANA N N WYOMING N N  
UTAH N N ARIZONA A B COLORADO A B  
NEW MEXICO A B N DAKOTA A N S DAKOTA A B  
NEBRASKA A B KANSAS A N OKLAHOMA A N  
N TEXAS A N S TEXAS A A W TEXAS A B  
MINNESOTA A A IOWA A A MISSOURI A A  
ARKANSAS A A LOUISIANA A N WISCONSIN A A  
ILLINOIS A A MISSISSIPPI A N MICHIGAN A A  
INDIANA A A OHIO A N KENTUCKY A N  
TENNESSEE A N 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 B S CAROLINA A B GEORGIA A B  
FL PNHDL A N FL PENIN A A AK N SLOPE B N  
AK ALEUTIAN B B AK WESTERN B B AK INT BSN B B  
AK S INT B B AK SO COAST B B AK PNHDL B 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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