696  
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 THU FEBRUARY 15 2018  
 
6-10 DAY OUTLOOK FOR FEB 21 - 25 2018  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN VERY GOOD AGREEMENT ON THE EXPECTED  
500-HPA FLOW PATTERN OVER THE FORECAST DOMAIN. A DEEP TROUGH IS FORECAST NORTH  
OF HUDSON BAY EXTENDING EAST/SOUTHEAST OVER THE NORTH ATLANTIC, AND  
SOUTHWESTWARD OVER THE WESTERN CONUS. RIDGES ARE ANTICIPATED OVER THE  
CARIBBEAN/FLORIDA AND MAINLAND ALASKA. THE FLOW PATTERN IS PREDICTED TO BE  
RELATIVELY AMPLIFIED. THE ENSEMBLE SPAGHETTI CHARTS GENERALLY INDICATE  
RELATIVELY LOW SPREAD OVER THE CONUS, AND MODERATE TO LARGE SPREAD OVER THE  
PACIFIC. THE AO INDEX WHICH RECENTLY HAS BEEN STRONGLY POSITIVE IS FORECAST TO  
BE CLOSE TO ZERO BY DAY 7, BE STRONGLY NEGATIVE AT DAY 10, AND REMAIN STRONGLY  
NEGATIVE AT DAY 14. THERE IS LARGE SPREAD AMONG THE GFS ENSEMBLE MEMBERS  
REGARDING THE FORECAST STRENGTH OF THE AO INDEX ESPECIALLY BEYOND DAY 7. THE  
PNA INDEX WHICH RECENTLY HAS BEEN WEAKLY NEGATIVE IS FORECAST TO REMAIN WEAKLY  
NEGATIVE THROUGH DAY 14. TODAY'S 500-HPA BLEND CHART INDICATES NEAR TO ABOVE  
NORMAL HEIGHTS OVER MOST OF THE EASTERN TWO-THIRDS OF THE CONUS AND ALASKA, AND  
NEAR TO BELOW NORMAL HEIGHTS OVER MUCH OF THE WESTERN THIRD OF THE CONUS.  
 
HIGHLY ANOMALOUS RIDGING OVER ALASKA STRONGLY FAVORS ABOVE NORMAL TEMPERATURES  
FOR MOST OF ALASKA. ANOMALOUS NORTHERLY FLOW TILTS THE ODDS TO BELOW NORMAL  
TEMPERATURES FOR THE ALASKA PANHANDLE. PERSISTENT TROUGHING IN THE WESTERN  
CONUS LEADS TO INCREASED CHANCES FOR BELOW NORMAL TEMPERATURES FOR MUCH OF THE  
WESTERN AND NORTH-CENTRAL CONUS, ESPECIALLY FOR THE NORTHWESTERN CONUS WHERE  
NEGATIVE HEIGHT ANOMALIES ARE THE LARGEST. A STRONG RIDGE FORECAST OVER THE  
SOUTHEASTERN U.S. LEADS TO ENHANCED CHANCES OF ABOVE NORMAL TEMPERATURES FOR  
THE EASTERN CONUS AND THE SOUTHERN PLAINS.  
 
THE RIDGE FORECAST OVER ALASKA IS EXPECTED TO PUSH THE TYPICAL STORM TRACK  
FARTHER NORTH, LARGELY FAVORING ABOVE NORMAL PRECIPITATION FOR MUCH OF MAINLAND  
ALASKA, EXCEPT FOR THE SOUTHERN COAST AND ALASKA PANHANDLE WHERE A MORE  
NORTHERLY STORM TRACK WOULD FAVOR NEAR NORMAL PRECIPITATION. NEAR TO BELOW  
NORMAL PRECIPITATION IS FAVORED FOR THE WEST COAST (WITH THE EXCEPTION OF THE  
PACIFIC NORTHWEST), WEST OF THE TROUGH AXIS. UPSLOPE FLOW TILTS THE ODDS TO  
ABOVE NORMAL PRECIPITATION FOR PARTS OF THE NORTHERN ROCKIES. A STATIONARY  
FRONT IS EXPECTED TO SETUP ACROSS TEXAS, THE MIDDLE MISSISSIPPI VALLEY, OHIO  
VALLEY, AND NORTHEAST, FAVORING INCREASED STORM SYSTEM ACTIVITY AND ABOVE  
NORMAL PRECIPITATION. SUBSIDENCE BEHIND THE FRONTAL SYSTEM ENHANCES  
PROBABILITIES FOR BELOW NORMAL PRECIPITATION FOR PARTS OF THE SOUTHERN ROCKIES,  
SOUTHWEST, AND SOUTHERN PLAINS. BENEATH THE HIGHLY ANOMALOUS SOUTHEAST RIDGE,  
BELOW NORMAL PRECIPITATION IS FAVORED FOR PARTS OF GEORGIA, SOUTH CAROLINA, AND  
FLORIDA. A TROUGH EXPECTED TO IMPINGE ON THE PACIFIC NORTHWEST LATE IN THE  
PERIOD TILTS THE ODDS TO ABOVE NORMAL PRECIPITATION FOR COASTAL SECTIONS OF THE  
REGION.  
 
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 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 20% OF  
YESTERDAY'S 12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 7, 10% OF TODAY'S 0Z  
CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 10% OF YESTERDAY'S 12Z CANADIAN  
ENSEMBLE MEAN CENTERED ON DAY 7  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
VERY GOOD AGREEMENT AMONG THE MODELS AND TEMPERATURE TOOLS, OFFSET BY POOR  
AGREEMENT AMONG THE PRECIPITATION TOOLS OVER THE WESTERN CONUS  
 
8-14 DAY OUTLOOK FOR FEB 23 - MAR 01, 2018  
 
BY THE WEEK-2 PERIOD, THE LARGE-SCALE PATTERN OVER THE FORECAST DOMAIN IS  
EXPECTED TO BE SHIFTED SLIGHTLY WEST, AND BE SLIGHTLY LESS AMPLIFIED, BUT  
OTHERWISE REMAIN LARGELY UNCHANGED. THE HEIGHT ANOMALIES DEPICTED IN THE MANUAL  
500-HPA BLEND ARE RELATIVELY LARGE FOR THE WEEK-2 PERIOD, SUGGESTING VERY GOOD  
MODEL AGREEMENT AND CERTAINTY. ABOVE NORMAL HEIGHTS ARE EXPECTED OVER THE  
EASTERN TWO-THIRDS OF THE CONUS, WESTERN MAINLAND ALASKA, AND THE ALEUTIANS,  
WHILE BELOW NORMAL HEIGHTS ARE ANTICIPATED OVER THE WESTERN THIRD OF THE CONUS,  
EASTERN MAINLAND ALASKA, AND THE ALASKA PANHANDLE.  
 
THE WEEK-2 TEMPERATURE PROBABILITY FORECAST IS VERY SIMILAR TO THE 6-10 DAY  
FORECAST, EXCEPT SLIGHTLY LOWER PROBABILITIES DUE TO THE TYPICALLY INCREASED  
UNCERTAINTY IN THE WEEK-2 PERIOD, AND A GENERAL WESTWARD DISPLACEMENT OF THE  
TEMPERATURE ANOMALY PATTERN DUE TO AN EXPECTED RETROGRESSION OF THE OVERALL  
LONG WAVE HEIGHT PATTERN. THE WEEK-2 PRECIPITATION PROBABILITY FORECAST IS ALSO  
VERY SIMILAR TO THE 6-10 DAY FORECAST, EXCEPT MOST OF THE AREAS OF ANOMALOUS  
PRECIPITATION ARE SHIFTED A BIT WESTWARD. A WETTER PATTERN IS FAVORED OVER THE  
WESTERN CONUS AS THE TROUGH AXIS SHIFTS SLIGHTLY WESTWARD, WHILE MAINE IS  
FAVORED TO BE DRIER AS THE AREA OF ABOVE NORMAL HEIGHTS ALSO SHIFTS SLIGHTLY  
WESTWARD.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 15% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 11, 10% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11, 30% OF  
TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF YESTERDAY'S 12Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 10, 5% 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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
VERY GOOD AGREEMENT AMONG THE MODELS AND TEMPERATURE TOOLS OFFSET BY POOR  
AGREEMENT AMONG THE PRECIPITATION TOOLS OVER THE WESTERN CONUS.  
 
FORECASTER: RANDY S  
 
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:  
19850301 - 19970227 - 19850224 - 19890213 - 20010212  
 
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:  
19850228 - 19970228 - 19750125 - 19740125 - 20010212  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR FEB 21 - 25 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B N OREGON B N NRN CALIF B B  
SRN CALIF B N IDAHO B N NEVADA B N  
W MONTANA B A E MONTANA B N WYOMING B N  
UTAH B N ARIZONA B N COLORADO B B  
NEW MEXICO N B N DAKOTA B N S DAKOTA B N  
NEBRASKA B N KANSAS N N OKLAHOMA A A  
N TEXAS A A S TEXAS A A W TEXAS A N  
MINNESOTA N N IOWA N N MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN N N  
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 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 N N AK PNHDL B N  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR FEB 23 - MAR 01, 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B N  
SRN CALIF B A IDAHO B N NEVADA B N  
W MONTANA B N E MONTANA B N WYOMING B N  
UTAH B A ARIZONA B A COLORADO N B  
NEW MEXICO N N N DAKOTA B N S DAKOTA N N  
NEBRASKA A N KANSAS A N OKLAHOMA A A  
N TEXAS A A S TEXAS A A W TEXAS A N  
MINNESOTA A 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 N NEW YORK A A  
VERMONT A N NEW HAMP A N MAINE A B  
MASS A N CONN A N RHODE IS A N  
PENN A A NEW JERSEY A N W VIRGINIA A A  
MARYLAND A N DELAWARE A N VIRGINIA A N  
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 N A  
AK S INT B N 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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