826  
FXUS06 KWBC 191902  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT FRI OCTOBER 19 2018  
 
6-10 DAY OUTLOOK FOR OCT 25 - 29 2018  
 
TODAY'S MODEL SOLUTIONS ARE GENERALLY IN GOOD AGREEMENT IN DEPICTING A FAIRLY  
AMPLIFIED 500-HPA PATTERN ACROSS MUCH OF THE FORECAST DOMAIN. AN AMPLIFIED  
RIDGE IS PREDICTED ACROSS THE WESTERN ALEUTIANS WHILE A TROUGH IS FORECAST  
DOWNSTREAM OVER WESTERN MAINLAND ALASKA, EXTENDING SOUTHWARD OVER THE GULF OF  
ALASKA. RIDGING AND ABOVE NORMAL HEIGHTS ARE GENERALLY ANTICIPATED FARTHER TO  
THE EAST OVER THE WESTERN CONUS. DOWNSTREAM, SPLIT FLOW IS FORECAST OVER MUCH  
OF NORTH AMERICA WITH A RIDGE ANTICIPATED OVER CENTRAL CANADA AND AN ACTIVE  
SOUTHERN STREAM TROUGH EXPECTED ALONG MUCH OF THE SOUTHERN TIER OF THE CONUS.  
AN ANOMALOUSLY STRONG RIDGE FOR THIS TIME OF YEAR IS FORECAST OVER THE NORTH  
ATLANTIC, SOUTHEAST OF GREENLAND, WHICH SUPPORTS MEAN TROUGH DEVELOPMENT  
UPSTREAM OVER EASTERN CANADA AND THE NORTHEASTERN CONUS.  
 
BELOW NORMAL TEMPERATURES ARE FAVORED FROM THE NORTHEASTERN CONUS SOUTHWESTWARD  
TO THE SOUTHERN PLAINS DUE TO MEAN TROUGHS ANTICIPATED OVER EASTERN NORTH  
AMERICA AND OVER THE SOUTH-CENTRAL CONUS. CONVERSELY, THERE ARE ENHANCED  
PROBABILITIES OF ABOVE NORMAL TEMPERATURES FOR CENTRAL AND EASTERN PARTS OF THE  
GULF COAST AND FOR FLORIDA AHEAD OF A SOUTHERN STREAM TROUGH ANTICIPATED OVER  
THE SOUTHERN PLAINS. AN INCREASE IN PACIFIC FLOW INCREASES CHANCES OF ABOVE  
NORMAL TEMPERATURES ACROSS THE WESTERN CONUS. RIDGING OVER CENTRAL CANADA  
SUPPORTS ABOVE NORMAL TEMPERATURES FOR THE NORTHERN AND CENTRAL GREAT PLAINS.  
 
ABOVE NORMAL PRECIPITATION IS FAVORED FOR THE SOUTHEASTERN CONUS WESTWARD TO  
PARTS OF THE SOUTHERN PLAINS DUE TO AN ANTICIPATED ACTIVE SOUTHERN STREAM AND  
ASSOCIATED TROUGHING AND CYCLONIC FLOW ACROSS MUCH OF THE SOUTHERN TIER OF THE  
CONUS. BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS PARTS OF THE GREAT LAKES  
REGION DUE TO RIDGING ALOFT OVER CENTRAL CANADA, WHILE THE ONSET OF PACIFIC  
FLOW INCREASES CHANCES OF ABOVE NORMAL PRECIPITATION ACROSS THE PACIFIC  
NORTHWEST. BELOW-NORMAL PRECIPITATION IS FAVORED OVER THE SOUTHWESTERN CONUS IN  
ASSOCIATION WITH THE RIDGING AND ABOVE-NORMAL 500-HPA HEIGHTS THERE.  
 
THE MODEL SOLUTIONS DEPICT A LARGE SURFACE CYCLONE CENTERED OVER THE GULF OF  
ALASKA. SOUTHERLY SURFACE FLOW ASSOCIATED WITH THIS LOW PRESSURE SYSTEM FAVORS  
ABOVE NORMAL TEMPERATURES ACROSS ALASKA AND ABOVE NORMAL PRECIPITATION ACROSS  
EASTERN AND NORTHERN MAINLAND ALASKA AND THE ALASKA PANHANDLE. BEHIND THIS LOW  
PRESSURE SYSTEM, AN INCREASED CHANCE OF BELOW NORMAL PRECIPITATION IS FORECAST  
ACROSS THE ALEUTIANS AND SOUTHWESTERN MAINLAND ALASKA.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT 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, 20% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 8, 20% OF  
TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 20% OF YESTERDAY'S 12Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 7  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD AGREEMENT BETWEEN THE GFS AND ECMWF ENSEMBLE MEANS AND THEIR DETERMINISTIC  
MODEL RUNS IN AN AMPLIFIED LONGWAVE PATTERN.  
 
8-14 DAY OUTLOOK FOR OCT 27 - NOV 02, 2018  
 
THE MEAN 500-HPA PATTERN FEATURES ABOVE NORMAL HEIGHTS OVER MUCH OF THE HIGH  
LATITUDES AND BELOW NORMAL HEIGHTS FARTHER TO THE SOUTH ACROSS MUCH OF THE  
EASTERN AND CENTRAL CONUS, CONSISTENT WITH THE NEGATIVE PHASE OF THE ARCTIC  
OSCILLATION (AO). THIS EVOLVING LONG-WAVE PATTERN IS LIKELY TO MAINTAIN BELOW  
NORMAL TEMPERATURES ACROSS MUCH OF THE SOUTHEASTERN CONUS DURING WEEK-2.  
ANTICIPATED RIDGE DEVELOPMENT NEAR THE WEST COAST FAVORS ABOVE NORMAL  
TEMPERATURES ACROSS MUCH OF THE WESTERN CONUS. INCREASED CHANCES FOR ABOVE  
NORMAL TEMPERATURES ACROSS ALASKA ARE BASED ON PREDICTED SOUTHERLY SURFACE  
FLOW, LACK OF SNOW COVER IN SOUTHEAST MAINLAND ALASKA, AND ABOVE NORMAL SEA  
SURFACE TEMPERATURES CURRENTLY OBSERVED IN THE BERING SEA.  
 
ABOVE NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE EASTERN AND NORTH-CENTRAL  
CONUS IN ASSOCIATION WITH ANTICIPATED TROUGHING AND CYCLONIC FLOW WITH THE  
GREATEST PROBABILITIES INDICATED AHEAD OF THE MEAN TROUGH AXIS ACROSS THE  
EASTERN CONUS. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED ACROSS THE PACIFIC  
NORTHWEST DUE TO THE POTENTIAL FOR ENHANCED PACIFIC FLOW. ANTICIPATED RIDGE  
DEVELOPMENT OVER THE WESTERN CONUS LEADS TO FAVORED BELOW NORMAL PRECIPITATION  
FOR MOST OF THE SOUTHWESTERN AND THE CENTRAL-SOUTHERN CONUS. THE FORECAST  
PATTERN NEAR ALASKA IS GENERALLY SIMILAR TO THE 6-10 DAY PERIOD, SO THE  
TEMPERATURE AND PRECIPITATION FORECAST PROBABILITIES IN THE WEEK-2 PERIOD ARE  
SIMILAR TO THE 6-10 DAY PERIOD.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND 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, 20% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11, 20% OF  
TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 20% OF YESTERDAY'S  
12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 10  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD AGREEMENT BETWEEN THE GFS AND ECMWF ENSEMBLE MEANS IN AN AMPLIFIED  
LONGWAVE PATTERN.  
 
FORECASTER: QIN Z  
 
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 15.  
 
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:  
19861008 - 19861102 - 19651027 - 19591031 - 19721018  
 
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:  
19651028 - 19591030 - 19861007 - 19521016 - 19741015  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 25 - 29 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A A OREGON A A NRN CALIF A B  
SRN CALIF A N IDAHO A A NEVADA A B  
W MONTANA A A E MONTANA A A WYOMING A B  
UTAH A B ARIZONA A N COLORADO A B  
NEW MEXICO A B N DAKOTA A A S DAKOTA A A  
NEBRASKA A A KANSAS A A OKLAHOMA B N  
N TEXAS B N S TEXAS B A W TEXAS N N  
MINNESOTA A A IOWA N A MISSOURI B N  
ARKANSAS B N LOUISIANA B A WISCONSIN N A  
ILLINOIS B N MISSISSIPPI B A MICHIGAN B B  
INDIANA B N OHIO B A KENTUCKY B A  
TENNESSEE B A ALABAMA B A NEW YORK B A  
VERMONT B A NEW HAMP B A MAINE B A  
MASS B A CONN B A RHODE IS B A  
PENN B A NEW JERSEY B A W VIRGINIA B A  
MARYLAND B A DELAWARE B A VIRGINIA B A  
N CAROLINA B A S CAROLINA B A GEORGIA B A  
FL PNHDL N A FL PENIN A A AK N SLOPE A A  
AK ALEUTIAN A A AK WESTERN A B AK INT BSN A A  
AK S INT A N AK SO COAST A N AK PNHDL A A  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR OCT 27 - NOV 02, 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A A OREGON A A NRN CALIF A B  
SRN CALIF A N IDAHO A A NEVADA A B  
W MONTANA A A E MONTANA A A WYOMING A A  
UTAH A B ARIZONA A N COLORADO A N  
NEW MEXICO A B N DAKOTA A A S DAKOTA A A  
NEBRASKA A A KANSAS A N OKLAHOMA N N  
N TEXAS N B S TEXAS N N W TEXAS N B  
MINNESOTA N A IOWA N A MISSOURI N N  
ARKANSAS B N LOUISIANA N A WISCONSIN N A  
ILLINOIS N A MISSISSIPPI B A MICHIGAN N A  
INDIANA N A OHIO N A KENTUCKY B A  
TENNESSEE B A ALABAMA B A NEW YORK N A  
VERMONT N A NEW HAMP N A MAINE N A  
MASS N A CONN N A RHODE IS N A  
PENN N A NEW JERSEY N A W VIRGINIA B A  
MARYLAND N A DELAWARE N A VIRGINIA B A  
N CAROLINA B A S CAROLINA B A GEORGIA B A  
FL PNHDL B A FL PENIN N A AK N SLOPE A A  
AK ALEUTIAN A B AK WESTERN A N AK INT BSN A A  
AK S INT A N AK SO COAST A B 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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