387  
FXUS06 KWBC 152002  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EST MON JANUARY 15 2018  
 
6-10 DAY OUTLOOK FOR JAN 21 - 25 2018  
 
A LONGWAVE PATTERN CHANGE IS LIKELY TO BECOME ESTABLISHED ACROSS THE NORTH  
PACIFIC AND NORTH AMERICA DURING THE LATTER HALF OF JANUARY. THE AMPLIFIED  
TROUGH THAT HAS PERSISTED OVER THE BERING SEA AND ALEUTIANS IS FORECAST TO BE  
REPLACED BY AN UPPER-LEVEL RIDGE. ENSEMBLE MEAN SOLUTIONS AND THEIR  
DETERMINISTIC MODEL RUNS ARE IN GOOD AGREEMENT, FEATURING A LARGE DECREASE IN  
500-HPA HEIGHTS OVER THE WESTERN U.S. AS A LONGWAVE TROUGH SHIFTS INLAND FROM  
THE EAST PACIFIC. AN AMPLIFIED UPPER-LEVEL RIDGE IS FORECAST TO DEVELOP OVER  
THE EASTERN U.S.  
 
ARCTIC HIGH PRESSURE IS FORECAST TO SHIFT OFFSHORE OF THE EAST COAST PRIOR TO  
THIS PERIOD, ALLOWING FOR A MAJOR WARMING TREND ACROSS THE EASTERN HALF OF THE  
CONUS. THIS WARMING TREND IS CONSISTENT WITH THE RECENT EASTWARD PROPAGATION OF  
THE MADDEN-JULIAN OSCILLATION (MJO) ACROSS THE INDIAN OCEAN. THE HIGHEST  
PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE FORECAST ACROSS THE NORTHEAST  
WHERE TEMPERATURES ARE EXPECTED TO AVERAGE MORE THAN 20 DEGREES F ABOVE-NORMAL  
ON DAYS 6 AND 7. THE AMPLIFIED UPPER-LEVEL TROUGH INCREASES CHANCES FOR  
BELOW-NORMAL TEMPERATURES ACROSS THE WESTERN CONUS.  
 
ONSHORE FLOW WITH ENTRAINMENT OF SUBTROPICAL MOISTURE RESULTS IN HIGH  
PROBABILITIES FOR ABOVE NORMAL PRECIPITATION ACROSS PARTS OF THE PACIFIC  
NORTHWEST, NORTHERN CALIFORNIA, AND THE NORTHERN GREAT BASIN. THE 6Z GFS AND 0Z  
ECMWF ENSEMBLE MEANS INDICATE 2 TO 4 INCHES OF PRECIPITATION ACROSS SOUTHWEST  
OREGON AND NORTHERN CALIFORNIA DURING THE 6-10 DAY PERIOD. MODEL SOLUTIONS  
DIFFER ON PRECIPITATION AMOUNTS ACROSS SOUTHERN CALIFORNIA. BASED ON THE MORE  
AMPLIFIED 500-HPA TROUGH PREDICTED BY THE 0Z ECMWF ENSEMBLE MEAN AND ITS  
DETERMINISTIC MODEL SOLUTION ALONG WITH BETTER CONTINUITY, NEAR TO ABOVE-NORMAL  
PRECIPITATION IS FAVORED AS FAR SOUTH AS THE LOS ANGELES AREA. A COUPLE OF LOW  
PRESSURE SYSTEMS ARE FORECAST TO DEVELOP ACROSS THE CENTRAL U.S. DURING THE  
5-DAY PERIOD. ROBUST GULF INFLOW FAVORS ABOVE-NORMAL PRECIPITATION FROM THE  
MISSISSIPPI VALLEY TO THE EAST COAST. A MAJOR WINTER STORM IS EXPECTED TO  
AFFECT THE CENTRAL GREAT PLAINS, UPPER MISSISSIPPI VALLEY, AND GREAT LAKES ON  
DAYS 6 AND 7. THEREFORE, PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ARE  
RELATIVELY HIGH FOR THESE AREAS. BELOW-NORMAL PRECIPITATION, ACROSS THE LOWER  
48, IS EXPECTED TO BE LIMITED TO PARTS OF THE SOUTHWESTERN U.S. WITH THE STORM  
TRACK REMAINING JUST NORTH OF THIS REGION.  
 
A STRONG SURFACE HIGH, TO THE NORTH OF KAMCHATKA PENINSULA, COUPLED WITH  
SURFACE LOW PRESSURE CENTERED OVER THE GULF OF ALASKA IS FORECAST TO RESULT IN  
ANOMALOUS NORTHEASTERLY FLOW ACROSS ALASKA. THIS PATTERN FAVORS BELOW-NORMAL  
TEMPERATURES AND PRECIPITATION.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 20% OF TODAY'S 6Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 8, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN  
CENTERED ON DAY 8, 25% OF TODAY'S OPERATIONAL 0Z ECMWF 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 AGREEMENT AMONG THE MODEL SOLUTIONS.  
 
8-14 DAY OUTLOOK FOR JAN 23 - 29 2018  
 
THE GFS AND ECMWF ENSEMBLE MEANS MAINTAIN AN UPPER-LEVEL TROUGH (RIDGE) OVER  
THE WESTERN (EASTERN) U.S. DURING WEEK-2. THE ENSEMBLE MEANS ARE IN GOOD  
AGREEMENT WITH A POSITIVE 500-HPA HEIGHT ANOMALY CENTER OVER THE NORTH PACIFIC.  
SINCE THE 0Z CANADIAN ENSEMBLE MEAN IS LESS AMPLIFIED WITH THE WESTERN U.S.  
TROUGH COMPARED TO THE GFS AND ECMWF ENSEMBLE MEANS, ITS SOLUTION WAS NOT USED  
IN CREATING THE 500-HPA MANUAL BLEND.  
 
THE WEEK-2 TEMPERATURE OUTLOOK IS BASED PRIMARILY ON THE ECMWF TEMPERATURE  
TOOLS WHICH ARE IN BETTER AGREEMENT WITH THE STATISTICAL GUIDANCE INCLUDING  
TELECONNECTIONS UPON A PAIR OF POSITIVE 500-HPA HEIGHT ANOMALY CENTERS NEAR THE  
EAST COAST AND OVER THE NORTH PACIFIC. THE AMPLIFIED UPPER-LEVEL RIDGE,  
ANOMALOUS SOUTHERLY FLOW, AND THE LIKELIHOOD FOR LARGE POSITIVE ANOMALIES EARLY  
IN WEEK-2 ENHANCE ODDS FOR ABOVE-NORMAL TEMPERATURES ACROSS THE EASTERN THIRD  
OF THE CONUS. BELOW-NORMAL TEMPERATURES ARE FAVORED ACROSS THE WESTERN U.S.  
WHICH IS LIKELY TO BE INFLUENCED BY AN AMPLIFIED UPPER-LEVEL TROUGH ALOFT.  
 
ALTHOUGH THE ENSEMBLE MEANS ARE IN GOOD AGREEMENT ON THE LONGWAVE PATTERN,  
LARGE SPREAD EXISTS AMONG THE GFS AND ECMWF ENSEMBLE MEMBERS WITH THE AMPLITUDE  
AND TRACK OF INDIVIDUAL SHORTWAVE TROUGHS EMERGING FROM THE LONGWAVE TROUGH  
OVER THE WESTERN U.S. THE TROUGH ALOFT AND MODEST ONSHORE FLOW INCREASE CHANCES  
FOR ABOVE-NORMAL PRECIPITATION ACROSS THE WESTERN U.S., WHILE THE EXPECTATION  
OF ANOMALOUS LOW-LEVEL MOISTURE AND THE TROUGH UPSTREAM ENHANCE ODDS FOR  
ABOVE-NORMAL PRECIPITATION FOR THE EASTERN THIRD OF THE CONUS. A SLIGHT TILT IN  
THE ODDS FOR ABOVE-NORMAL PRECIPITATION IS FORECAST FOR THE CENTRAL GREAT  
PLAINS WHERE THE STORM TRACK IS MOST LIKELY TO BECOME ESTABLISHED DURING LATE  
JANUARY. AWAY FROM THIS PREDICTED STORM TRACK, BELOW-NORMAL PRECIPITATION IS  
FAVORED FOR PARTS OF THE SOUTHWESTERN U.S. AND ALONG THE U.S.-CANADIAN BORDER.  
 
BELOW-NORMAL TEMPERATURES AND PRECIPITATION ARE EXPECTED TO CONTINUE ACROSS  
ALASKA INTO THE WEEK-2 PERIOD AS ANOMALOUS NORTHEAST SURFACE FLOW PERSISTS.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 40% OF TODAY'S 6Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, AND 60% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN  
CENTERED ON DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD  
AGREEMENT BETWEEN THE GFS AND ECMWF ENSEMBLE MEANS OFFSET BY LARGE SPREAD AMONG  
THEIR ENSEMBLE MEMBERS.  
 
FORECASTER: BRAD PUGH  
 
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  
JANUARY 18.  
 
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:  
19520127 - 20010120 - 19860124 - 19780122 - 19850101  
 
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:  
20010119 - 19860123 - 19520126 - 19610117 - 19631230  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 21 - 25 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 A E MONTANA B N WYOMING B A  
UTAH B A ARIZONA B B COLORADO B A  
NEW MEXICO B B N DAKOTA B N S DAKOTA B A  
NEBRASKA B A KANSAS N A OKLAHOMA A A  
N TEXAS N B S TEXAS N B W TEXAS B B  
MINNESOTA B 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 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 A A  
MARYLAND A A DELAWARE A A 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 B AK WESTERN B B AK INT BSN B B  
AK S INT B B AK SO COAST B B AK PNHDL B B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 23 - 29 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B A  
SRN CALIF B N IDAHO B A NEVADA B A  
W MONTANA B A E MONTANA B N WYOMING B A  
UTAH B A ARIZONA B N COLORADO B A  
NEW MEXICO N B N DAKOTA B B S DAKOTA B N  
NEBRASKA B A KANSAS N A OKLAHOMA A A  
N TEXAS N A S TEXAS N B W TEXAS N B  
MINNESOTA N N IOWA A A MISSOURI A A  
ARKANSAS A A LOUISIANA N A WISCONSIN N 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 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 A A  
MARYLAND A A DELAWARE A A 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 B AK WESTERN B B AK INT BSN B B  
AK S INT B B AK SO COAST B B AK PNHDL B B  
 
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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