421  
FXUS06 KWBC 272029  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EST TUE FEBRUARY 27 2018  
 
6-10 DAY OUTLOOK FOR MAR 05 - 09 2018  
 
TODAY'S MODEL SOLUTIONS FEATURE STRONG POSITIVE 500-HPA ANOMALIES AT HIGH  
LATITUDES CONSISTENT WITH A NEGATIVE AO PATTERN. RIDGES ARE PREDICTED SOUTH OF  
THE ALEUTIANS AS WELL AS OVER EASTERN CANADA CENTERED OVER OR JUST TO THE NORTH  
OF NORTHERN QUEBEC. FARTHER TO THE SOUTH, NEAR TO BELOW NORMAL HEIGHTS ARE  
EXPECTED FOR MUCH OF THE CONUS AS A TROUGH OVER THE WEST-CENTRAL CONUS EARLY IN  
THE PERIOD PROGRESSES TOWARD THE EASTERN CONUS LATER IN THE PERIOD. SLIGHTLY  
POSITIVE HEIGHT ANOMALIES ARE INDICATED FOR PARTS OF THE SOUTHWESTERN CONUS AS  
HEIGHTS RISE IN ADVANCE OF A TROUGH PREDICTED OVER THE EASTERN PACIFIC LATE IN  
THE PERIOD. POSITIVE HEIGHT ANOMALIES ARE ALSO EXPECTED FOR PARTS OF THE GREAT  
LAKES AND NORTHEAST IN ASSOCIATION WITH THE MEAN RIDGE OVER EASTERN CANADA.  
ENSEMBLE SPREAD IS MODERATE TO HIGH TODAY OVER MUCH OF THE FORECAST DOMAIN, BUT  
LOWER THAN YESTERDAY'S MODEL SUITE. TODAY'S MANUAL 500-HPA HEIGHT BLEND IS  
BASED PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS.  
 
TROUGHING AND BELOW NORMAL HEIGHTS LEAD TO ENHANCED PROBABILITIES OF BELOW  
NORMAL TEMPERATURES ACROSS THE WESTERN CONUS, PARTICULARLY EARLY IN THE PERIOD.  
NEAR TO ABOVE NORMAL HEIGHTS ASSOCIATED WITH THE RIDGE OVER EASTERN CANADA  
FAVOR ABOVE NORMAL TEMPERATURES FOR THE GREAT LAKES AND NORTHEAST. THERE ARE  
ENHANCED PROBABILITIES OF BELOW NORMAL TEMPERATURES FOR MUCH OF THE SOUTHEAST  
AND PARTS OF THE MID-ATLANTIC DUE TO BELOW NORMAL HEIGHTS AND ANOMALOUS  
NORTHERLY 500-HPA FLOW. RIDGING EARLY IN THE PERIOD AND ABOVE NORMAL SSTS LEAD  
TO FAVORED ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE ALEUTIANS AND WESTERN  
AND NORTHERN MAINLAND ALASKA. TROUGHING DOWNSTREAM FAVORS BELOW NORMAL  
TEMPERATURES FOR PARTS OF SOUTHEASTERN MAINLAND ALASKA AND THE PANHANDLE.  
 
AS A TROUGH PROGRESSES FROM WEST TO EAST ACROSS THE CONUS, ABOVE NORMAL  
PRECIPITATION IS FAVORED FOR MUCH OF THE EAST-CENTRAL CONUS. WEAK RIDGING LEADS  
TO SLIGHTLY ENHANCED PROBABILITIES OF BELOW NORMAL PRECIPITATION FOR MUCH OF  
THE WEST-CENTRAL CONUS. MOIST FLOW AHEAD OF A TROUGH IN THE EASTERN PACIFIC  
LEADS TO ENHANCED PROBABILITIES OF ABOVE NORMAL PRECIPITATION FOR PARTS OF  
CALIFORNIA. ENHANCED WESTERLY 500-HPA FLOW AND THE POTENTIAL FOR SHORTWAVE  
TROUGHS LEAD TO INCREASED PROBABILITIES OF ABOVE NORMAL PRECIPITATION FOR  
MAINLAND ALASKA AND THE ALEUTIANS. OFFSHORE FLOW IS ANTICIPATED FOR PARTS OF  
THE ALASKA PANHANDLE, FAVORING BELOW NORMAL PRECIPITATION THERE.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 20% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 8, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 8, 5% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 8, 35% OF TODAY'S 0Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF YESTERDAY'S 12Z EUROPEAN  
ENSEMBLE MEAN CENTERED ON DAY 7, 10% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED  
ON DAY 8, AND 10% 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 FAIR  
MODEL AGREEMENT OFFSET BY MODERATE TO HIGH SPREAD AMONG THE COMPONENT ENSEMBLE  
MEMBERS.  
 
8-14 DAY OUTLOOK FOR MAR 07 - 13 2018  
 
DURING THE WEEK-2 PERIOD POSITIVE 500-HPA HEIGHT ANOMALIES CONTINUE OVER MUCH  
OF THE HIGH LATITUDES DUE TO RIDGES SOUTH OF THE ALEUTIANS AND OVER EASTERN  
CANADA. BETWEEN THESE TWO FEATURES, HEIGHTS ARE EXPECTED TO LOWER OVER MAINLAND  
ALASKA AS TROUGHS ARE EXPECTED TO DEVELOP NEAR THE BERING STRAIT AS WELL AS  
OVER THE GULF OF ALASKA. THE TROUGH OVER THE GULF OF ALASKA IS FORECAST TO  
EXTEND SOUTHWARD OVER THE EASTERN PACIFIC, OFF THE WEST COAST OF THE CONUS,  
ALLOWING FOR A WEAK RIDGE TO DEVELOP DOWNSTREAM OVER PARTS OF THE WEST-CENTRAL  
CONUS. CYCLONIC FLOW IS EXPECTED FARTHER TO THE EAST OVER THE EASTERN CONUS.  
THE GREATEST WEIGHT IN THE WEEK-2 MANUAL 500-HPA HEIGHT BLEND WAS GIVEN TO THE  
0Z ECMWF ENSEMBLE MEAN SOLUTION DUE TO CONSIDERATIONS OF RECENT SKILL.  
 
BELOW NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE CONUS UNDERNEATH NEAR TO  
BELOW NORMAL HEIGHTS. HOWEVER, ABOVE NORMAL TEMPERATURES ARE SLIGHTLY FAVORED  
FOR PARTS OF THE NORTHEASTERN CONUS IN ASSOCIATION WITH THE RIDGE OVER EASTERN  
CANADA. NEAR TO ABOVE NORMAL HEIGHTS LEAD TO SLIGHTLY ELEVATED CHANCES FOR  
ABOVE NORMAL TEMPERATURES FOR PARTS OF THE SOUTHWEST. TROUGH DEVELOPMENT OVER  
MAINLAND ALASKA LEADS TO ENHANCED PROBABILITIES OF BELOW NORMAL TEMPERATURES  
ACROSS MUCH OF THE STATE. HOWEVER, ABOVE NORMAL SSTS AND BELOW NORMAL SEA ICE  
EXTENT FAVOR ABOVE NORMAL TEMPERATURES FOR PARTS OF THE ALEUTIANS AND PARTS OF  
WESTERN MAINLAND ALASKA.  
 
THERE ARE LARGE DISAGREEMENTS AMONG RAW AND CALIBRATED DYNAMICAL MODEL  
PRECIPITATION GUIDANCE LEADING TO LOWER THAN NORMAL CONFIDENCE. PROBABILITIES  
OF ABOVE NORMAL PRECIPITATION ARE ELEVATED FOR PARTS OF THE SOUTHEAST CONUS  
EXTENDING NORTHWARD ALONG PARTS OF THE EAST COAST AHEAD OF THE TROUGH FORECAST  
OVER THE EASTERN CONUS. DUE, IN PART, TO TELECONNECTIONS FROM THE EXPECTED  
POSITIVE HEIGHT ANOMALY CENTER OVER EASTERN CANADA, ENHANCED ABOVE NORMAL  
PRECIPITATION PROBABILITIES EXTEND WESTWARD TO THE LOWER MISSISSIPPI VALLEY.  
BELOW NORMAL PRECIPITATION IS FAVORED FOR THE NORTHERN PLAINS AND GREAT LAKES  
DUE TO SUBSIDENCE BEHIND THE MEAN TROUGH AXIS. WEAK RIDGING SLIGHTLY FAVORS  
BELOW NORMAL PRECIPITATION ACROSS THE WEST-CENTRAL CONUS. THERE ARE ENHANCED  
PROBABILITIES OF ABOVE NORMAL PRECIPITATION FOR THE WEST COAST OF THE CONUS  
AHEAD OF A TROUGH OVER THE EASTERN PACIFIC. THE POTENTIAL FOR SHORTWAVE ENERGY  
ASSOCIATED WITH TROUGHS NEAR THE BERING STRAIT AND GULF OF ALASKA LEAD TO  
INCREASED PROBABILITIES OF ABOVE NORMAL PRECIPITATION FOR MUCH OF ALASKA.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 11, 5% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 11, 45% OF TODAY'S  
0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 5% OF YESTERDAY'S 12Z EUROPEAN  
ENSEMBLE MEAN CENTERED ON DAY 10, 15% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN  
CENTERED ON DAY 11, AND 5% OF YESTERDAY'S 12Z CANADIAN ENSEMBLE MEAN CENTERED  
ON DAY 10  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO  
FAIRLY HIGH MODEL SPREAD AND POOR AGREEMENT AMONG THE PRECIPITATION TOOLS.  
 
FORECASTER: SCOTT 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  
MARCH 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:  
19630313 - 19900212 - 19850303 - 19640308 - 19550312  
 
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:  
19510206 - 19520206 - 19530206 - 19540206 - 19550206  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR MAR 05 - 09 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B N OREGON B N NRN CALIF B A  
SRN CALIF B N IDAHO B B NEVADA B B  
W MONTANA B B E MONTANA B B WYOMING B B  
UTAH B B ARIZONA B B COLORADO B B  
NEW MEXICO B B N DAKOTA B A S DAKOTA B A  
NEBRASKA B B KANSAS B B OKLAHOMA B N  
N TEXAS B A S TEXAS N A W TEXAS N B  
MINNESOTA B A IOWA N A MISSOURI N A  
ARKANSAS B A LOUISIANA N A WISCONSIN N A  
ILLINOIS N A MISSISSIPPI B A MICHIGAN A A  
INDIANA N A OHIO N A KENTUCKY N A  
TENNESSEE B A ALABAMA B 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 N N NEW JERSEY N N W VIRGINIA B A  
MARYLAND N N DELAWARE N N VIRGINIA B N  
N CAROLINA B N S CAROLINA B A GEORGIA B A  
FL PNHDL B A FL PENIN B N AK N SLOPE A A  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A  
AK S INT N A AK SO COAST N A AK PNHDL B B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR MAR 07 - 13 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B A  
SRN CALIF B A IDAHO B A NEVADA B A  
W MONTANA B N E MONTANA B B WYOMING B B  
UTAH B N ARIZONA A N COLORADO N B  
NEW MEXICO A B N DAKOTA B B S DAKOTA B B  
NEBRASKA B N KANSAS N N OKLAHOMA B N  
N TEXAS B N S TEXAS N N W TEXAS N B  
MINNESOTA B B IOWA B N MISSOURI B N  
ARKANSAS B A LOUISIANA B A WISCONSIN N B  
ILLINOIS B N MISSISSIPPI B A MICHIGAN N B  
INDIANA B B OHIO B B KENTUCKY B N  
TENNESSEE B N ALABAMA B A NEW YORK N N  
VERMONT A N NEW HAMP A N MAINE A N  
MASS A A CONN N A RHODE IS A A  
PENN N N NEW JERSEY N A W VIRGINIA B N  
MARYLAND B A DELAWARE B A VIRGINIA B A  
N CAROLINA B A S CAROLINA B A GEORGIA B A  
FL PNHDL B A FL PENIN B A AK N SLOPE N A  
AK ALEUTIAN N A AK WESTERN B A AK INT BSN B A  
AK S INT B A AK SO COAST B A 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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