928  
FXUS06 KWBC 092001  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EST FRI FEBRUARY 09 2018  
 
6-10 DAY OUTLOOK FOR FEB 15 - 19 2018  
 
THE 0Z ECMWF AND 0Z CANADIAN ENSEMBLE MEANS CONTINUE TO TREND TOWARDS A MORE  
AMPLIFIED UPPER-LEVEL RIDGE OVER THE NORTH PACIFIC AND ALASKA. THESE ENSEMBLE  
MEANS FEATURE A 500-HPA HEIGHT ANOMALY CENTER OF 300 METERS OR MORE AT  
50N-150W. SINCE THE DETERMINISTIC 0Z ECMWF MODEL IS QUITE SIMILAR TO THE  
PREFERRED 0Z ECMWF AND 0Z CANADIAN ENSEMBLE MEANS (BASED ON GOOD CONTINUITY),  
IT IS INCLUDED IN CREATING THE 500-HPA MANUAL BLEND. DUE TO POOR CONTINUITY,  
THE GFS ENSEMBLE MEANS ARE EXCLUDED AS A WEIGHT IN THE MANUAL 500-HPA BLEND.  
DOWNSTREAM OF THE AMPLIFYING RIDGE OVER THE NORTH PACIFIC AND ALASKA, AN  
UPPER-LEVEL TROUGH IS EXPECTED TO AMPLIFY OVER THE NORTHWESTERN CONUS LATER IN  
THIS PERIOD. MODEL SOLUTIONS CONTINUE TO FEATURE AN ANOMALOUS SUBTROPICAL RIDGE  
(MAXIMUM 500-HPA HEIGHTS NEAR 592 DM) CENTERED OVER SOUTH FLORIDA, CUBA, AND  
THE BAHAMAS.  
 
THE SUBTROPICAL RIDGE FAVORS ABOVE-NORMAL TEMPERATURES ACROSS THE SOUTHEAST AND  
GULF COAST STATES WHERE MINIMUM TEMPERATURES ARE LIKELY TO AVERAGE AS MUCH AS  
20 DEGREES F ABOVE NORMAL. A TIGHT THERMAL GRADIENT WITH INCREASING UNCERTAINTY  
IN THE TEMPERATURE OUTLOOK IS EXPECTED FROM THE OHIO VALLEY EAST TO THE  
NORTHERN MID-ATLANTIC. ARCTIC HIGH PRESSURE IS EXPECTED TO BUILD SOUTH FROM  
CANADA, INCREASING CHANCES FOR BELOW-NORMAL TEMPERATURES ACROSS THE NORTHERN  
TIER OF THE CONUS, WITH THE MOST ANOMALOUS COLD ACROSS THE NORTHERN HIGH  
PLAINS. INCREASED CHANCES OF ABOVE-NORMAL TEMPERATURES ARE FORECAST ACROSS  
CALIFORNIA AND THE SOUTHWEST, BUT FORECAST CONFIDENCE IS LOW DUE TO A CLOSED  
500-HPA LOW AT THE BEGINNING OF THE PERIOD AND AN EXPECTATION FOR MODERATING  
TEMPERATURES AS NORTHERN STREAM FLOW BECOME MORE DOMINANT BY THE END OF THIS  
PERIOD.  
 
THE AMPLIFYING TROUGH OVER THE WESTERN CONUS WITH TIME FAVORS A BROAD AREA WITH  
INCREASED CHANCES OF ABOVE-NORMAL PRECIPITATION FROM THE ROCKIES EASTWARD  
EXCEPT THE GULF COAST AND PARTS OF THE SOUTHEASTERN CONUS DUE TO STRONG RIDGING  
ALOFT. AN EJECTING MID-LEVEL LOW ALONG WITH SUBTROPICAL MOISTURE FURTHER  
ENHANCES ODDS FOR ABOVE-NORMAL PRECIPITATION ACROSS THE SOUTHWESTERN CONUS. THE  
HEAVIEST PRECIPITATION IS LIKELY ACROSS THE LOWER TO MIDDLE MISSISSIPPI VALLEY  
AND OHIO VALLEY DUE TO A NEARLY STATIONARY FRONT AND ROBUST GULF INFLOW. THE  
DETERMINISTIC 0Z ECMWF INDICATES 3 TO 5 INCHES OF PRECIPITATION ACROSS THESE  
AREAS. THEREFORE, THE HIGHEST PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ARE  
FORECAST FOR THESE AREAS. INCREASED CHANCES OF BELOW-NORMAL PRECIPITATION ARE  
FORECAST ACROSS NORTHERN CALIFORNIA, ALBEIT WITH LOWER PROBABILITIES THAN  
PREVIOUS DAYS CONSIDERING THE RETROGRESSION OF THE UPPER-LEVEL RIDGE AWAY FROM  
THE WEST COAST.  
 
ALTHOUGH ENHANCED ODDS FOR ABOVE-NORMAL TEMPERATURES AND PRECIPITATION ARE  
FORECAST FOR MUCH OF ALASKA, THE PREDICTED RETROGRESSION AND AMPLIFICATION OF  
THE UPPER-LEVEL RIDGE OVER THE NORTH PACIFIC FAVORS NEAR NORMAL TEMPERATURES  
AND PRECIPITATION FOR THE ALASKA PANHANDLE.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 50% OF TODAY'S 0Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 20% OF TODAY'S OPERATIONAL 0Z ECMWF  
CENTERED ON DAY 8, AND 30% 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 BETWEEN THE ECMWF AND CANADIAN ENSEMBLE MEANS OFFSET BY CONTINUED  
POOR CONTINUITY AMONG THE GFS ENSEMBLE MEANS DURING THE PAST FEW DAYS.  
 
8-14 DAY OUTLOOK FOR FEB 17 - 23 2018  
 
THE 0Z ECMWF AND 0Z CANADIAN ENSEMBLE MEANS ARE IN EXCELLENT AGREEMENT DURING  
WEEK-2 AND FEATURE A HIGHLY AMPLIFIED UPPER-LEVEL PATTERN WITH AN UPPER-LEVEL  
RIDGE OVER THE NORTH PACIFIC AND ALASKA, AN UPPER-LEVEL TROUGH ACROSS WESTERN  
NORTH AMERICA, AND A SUBTROPICAL RIDGE CENTERED OVER THE SOUTHEASTERN CONUS.  
THE DETERMINISTIC 12Z GFS HAS TRENDED TOWARDS THE PREFERRED 0Z ECMWF AND 0Z  
CANADIAN ENSEMBLE MEANS DURING WEEK-2. TELECONNECTIONS UPON THE THREE LARGEST  
500-HPA HEIGHT ANOMALY CENTERS THROUGHOUT THE FORECAST DOMAIN PROVIDE SIMILAR  
TEMPERATURE AND PRECIPITATION OUTPUTS, INCREASING FORECAST CONFIDENCE THAT THE  
LONGWAVE PATTERN BECOMES MORE STABLE DURING MID TO LATE FEBRUARY.  
 
TEMPERATURE TOOLS HAVE TRENDED COLDER ACROSS THE WESTERN CONUS DUE TO THE MORE  
AMPLIFIED TROUGH OVER WESTERN NORTH AMERICA AND ARE MORE CONSISTENT WITH  
STATISTICAL GUIDANCE. THEREFORE, THE COVERAGE OF NEAR TO BELOW-NORMAL  
TEMPERATURES IS EXPANDED FROM YESTERDAY TO INCLUDE MORE OF THE WESTERN CONUS.  
THE HIGHEST PROBABILITIES OF BELOW-NORMAL TEMPERATURES ARE FORECAST ACROSS THE  
NORTHERN GREAT PLAINS WHERE ARCTIC SURFACE HIGH PRESSURE IS LIKELY TO PREVAIL.  
ANOMALOUS WARMTH IS LIKELY TO PERSIST ACROSS THE SOUTHEASTERN CONUS UNDERNEATH  
THE SUBTROPICAL RIDGE.  
 
THE PRECIPITATION OUTLOOK IS BASED PRIMARILY ON THE ECMWF REFORECAST TOOL ALONG  
WITH 7-DAY PRECIPITATION AMOUNTS FROM THE 0Z ECMWF ENSEMBLE MEAN. NEAR TO  
ABOVE-NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE NORTHERN AND CENTRAL  
ROCKIES, GREAT BASIN, AND PACIFIC NORTHWEST DUE TO THE AMPLIFYING TROUGH ALOFT.  
DOWNSTREAM OF THE AMPLIFYING TROUGH OVER THE WESTERN CONUS, WAVES OF LOW  
PRESSURE ARE EXPECTED TO INTERACT WITH ANOMALOUS LOW-LEVEL MOISTURE AND ELEVATE  
CHANCES FOR ABOVE-NORMAL PRECIPITATION FOR PARTS OF TEXAS NORTHEAST TO THE OHIO  
VALLEY. THE 0Z ECMWF ENSEMBLE MEAN INDICATES MORE THAN 2 INCHES OF  
PRECIPITATION ACROSS THE OHIO RIVER VALLEY DURING WEEK-2. BASED ON THE  
PREDICTED STORM TRACK, ENHANCED ODDS FOR BELOW-NORMAL PRECIPITATION ARE  
FORECAST ALONG THE GULF COAST, FLORIDA, AND COASTAL AREAS OF THE SOUTHEAST.  
 
SOUTHWEST FLOW AT THE SURFACE, AT LEAST EARLY IN THE WEEK-2 PERIOD, INCREASES  
CHANCES FOR ABOVE-NORMAL TEMPERATURES AND PRECIPITATION ACROSS THE ALEUTIANS  
AND WESTERN MAINLAND ALASKA. STRENGTHENING SURFACE HIGH PRESSURE OVER NORTHWEST  
CANADA FAVORS NEAR TO BELOW-NORMAL TEMPERATURES ACROSS THE ALASKA PANHANDLE.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 70% 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: AVERAGE, 3 OUT OF 5, DUE TO  
IMPROVEMENT AGREEMENT AMONG THE DYNAMICAL AND STATISTICAL TOOLS OFFSET BY HIGH  
UNCERTAINTY IN THE PRECIPITATION OUTLOOK ACROSS THE WESTERN CONUS.  
 
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  
FEBRUARY 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:  
19630122 - 19890212 - 19820205 - 19570125 - 20030208  
 
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:  
19630119 - 19890213 - 19820204 - 19630124 - 19570128  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR FEB 15 - 19 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON N N NRN CALIF A B  
SRN CALIF A B IDAHO A A NEVADA A N  
W MONTANA B A E MONTANA B A WYOMING B A  
UTAH A A ARIZONA A A COLORADO A A  
NEW MEXICO A A N DAKOTA B A S DAKOTA B A  
NEBRASKA B A KANSAS N A OKLAHOMA A A  
N TEXAS A A S TEXAS A N W TEXAS A A  
MINNESOTA B A IOWA B A MISSOURI A A  
ARKANSAS A A LOUISIANA A N WISCONSIN B A  
ILLINOIS N A MISSISSIPPI A A MICHIGAN B A  
INDIANA A A OHIO A A KENTUCKY A A  
TENNESSEE A A ALABAMA A A NEW YORK N A  
VERMONT B A NEW HAMP N A MAINE B A  
MASS N A CONN N A RHODE IS N A  
PENN A A NEW JERSEY N A W VIRGINIA A A  
MARYLAND A A DELAWARE A A VIRGINIA A A  
N CAROLINA A N S CAROLINA A N GEORGIA A B  
FL PNHDL A B FL PENIN A B AK N SLOPE A A  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A  
AK S INT A N AK SO COAST A N AK PNHDL N N  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR FEB 17 - 23 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B N OREGON B N NRN CALIF B B  
SRN CALIF N B IDAHO B A NEVADA A N  
W MONTANA B A E MONTANA B A WYOMING B A  
UTAH A N ARIZONA A B COLORADO N N  
NEW MEXICO A B N DAKOTA B A S DAKOTA B N  
NEBRASKA B N KANSAS N B OKLAHOMA A A  
N TEXAS A A S TEXAS A A W TEXAS A A  
MINNESOTA B A IOWA B A MISSOURI A A  
ARKANSAS A A LOUISIANA A B WISCONSIN N A  
ILLINOIS N A MISSISSIPPI A A MICHIGAN N 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 N 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 N S CAROLINA A B GEORGIA A B  
FL PNHDL A B FL PENIN A B AK N SLOPE A A  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A  
AK S INT A N AK SO COAST A N 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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