025  
FXUS06 KWBC 082002  
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 08 2018  
 
6-10 DAY OUTLOOK FOR FEB 14 - 18 2018  
 
THE ENSEMBLE MEANS DEPICT A HIGH AMPLITUDE RIDGE EXTENDING FROM THE NORTHEAST  
PACIFIC TO ALASKA ALONG 140-150W LONGITUDE, A BROAD TROUGH OVER THE HIGHER  
LATITUDES OF CENTRAL NORTH AMERICA, AND A SUBTROPICAL RIDGE CENTERED OVER THE  
GULF OF MEXICO. MINOR WEIGHTING OF THE DETERMINISTIC 6Z GFS AND 0Z ECMWF MODELS  
IS USED IN CREATING THE MANUAL BLEND SINCE THESE MODEL SOLUTIONS ARE IN GOOD  
AGREEMENT WITH A DECREASE IN 500-HPA HEIGHTS ACROSS THE NORTHEAST AND FEATURING  
A 500-HPA CLOSED LOW OVER SOUTHERN CALIFORNIA. SPREAD AMONG GFS AND ECMWF  
ENSEMBLE MEMBERS REMAINS HIGH REGARDING THIS CLOSED LOW.  
 
THE SUBTROPICAL RIDGE (500-HPA HEIGHTS OVER 588 DM) OVER THE GULF OF MEXICO AND  
LARGE DAILY POSITIVE TEMPERATURE ANOMALIES THROUGH AT LEAST DAY 7 FAVORS  
ABOVE-NORMAL TEMPERATURES ACROSS THE SOUTHEAST AND MID-ATLANTIC. ARCTIC HIGH  
PRESSURE IS EXPECTED TO SHIFT SOUTH FROM CANADA DURING THIS PERIOD, INCREASING  
CHANCES FOR BELOW-NORMAL TEMPERATURES ACROSS THE NORTHERN GREAT PLAINS, UPPER  
MISSISSIPPI VALLEY, AND GREAT LAKES. RIDGING ALOFT FAVORS ABOVE-NORMAL  
TEMPERATURES ACROSS THE WESTERN CONUS EXCEPT FOR PARTS OF SOUTHERN CALIFORNIA  
AND THE DESERT SOUTHWEST WHERE THE LIKELY PRESENCE OF A CLOSED MID-LEVEL LOW IS  
EXPECTED TO MODERATE TEMPERATURES.  
 
THE CLOSED MID-LEVEL LOW ALONG WITH SUBTROPICAL MOISTURE ENHANCES ODDS FOR  
ABOVE-NORMAL PRECIPITATION ACROSS THE SOUTHWEST. PRECIPITATION TOOLS HAVE  
TRENDED WETTER FOR THIS REGION. ENHANCED ODDS FOR ABOVE-NORMAL PRECIPITATION  
ARE FORECAST FROM THE SOUTHERN PLAINS TO THE NORTHEASTERN CONUS ALONG AN  
INCREASING TEMPERATURE GRADIENT, WHILE UPSLOPE FLOW TILTS THE ODDS TO  
ABOVE-NORMAL PRECIPITATION ACROSS THE NORTHERN HIGH PLAINS. INCREASED CHANCES  
OF BELOW-NORMAL PRECIPITATION ARE FORECAST ACROSS FLORIDA AND MUCH OF THE WEST  
COAST DUE TO RIDGING ALOFT.  
 
AN UPPER-LEVEL TROUGH OVER THE BERING SEA COUPLED WITH SOUTHWEST FLOW AT THE  
SURFACE INCREASE CHANCES FOR ABOVE-NORMAL TEMPERATURES AND ABOVE-NORMAL  
PRECIPITATION ACROSS THE ALEUTIANS AND MAINLAND ALASKA. THE AMPLIFYING  
UPPER-LEVEL RIDGE LEADS TO ENHANCED ODDS FOR NEAR NORMAL TEMPERATURES AND  
PRECIPITATION FOR THE ALASKA PANHANDLE.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 6Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON  
DAY 8, 50% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 10% OF  
TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO  
IMPROVED AGREEMENT AMONG MODEL SOLUTIONS WITH A CLOSED 500-HPA LOW DEVELOPING  
OVER SOUTHERN CALIFORNIA AND SOUTHWEST OFFSET BY CONTINUED UNCERTAINTY IN HOW  
MUCH ARCTIC AIR SHIFTS SOUTH FROM CANADA.  
 
8-14 DAY OUTLOOK FOR FEB 16 - 22 2018  
 
POOR MODEL CONTINUITY CONTINUES TODAY AMONG THE MODEL SOLUTIONS DURING WEEK-2.  
TODAY'S ENSEMBLE MEANS ARE MORE SIMILAR TO TWO DAYS AGO WITH AN UPPER-LEVEL  
TROUGH EXTENDING FROM HUDSON BAY SOUTHWEST TO THE ROCKIES AND A SUBTROPICAL  
RIDGE REMAINING STRONG OVER THE GULF OF MEXICO. A COMMON FEATURE AMONG ENSEMBLE  
MEANS IS THE HIGH AMPLITUDE RIDGE OVER THE NORTHEAST PACIFIC AND ALASKA. THE  
RIDGE AXIS HAS SHIFTED SLIGHTLY WEST FROM ITS POSITION IN YESTERDAY'S MODEL  
RUNS. SINCE THE LONGWAVE PATTERN DERIVED FROM A TELECONNECTION UPON THE LARGE  
POSITIVE 500-HPA HEIGHT ANOMALY CENTER OVER THE NORTHEAST PACIFIC (50N-150W) IS  
SIMILAR TO DYNAMICAL MODELS, ITS TEMPERATURE AND PRECIPITATION GUIDANCE WAS  
USED IN THE OFFICIAL WEEK-2 OUTLOOKS.  
 
DUE TO A MORE AMPLIFIED RIDGE OVER THE NORTHEAST PACIFIC AND ALASKA ALONG WITH  
A SLIGHT WESTWARD SHIFT IN ITS AXIS, ARCTIC HIGH PRESSURE IS MORE LIKELY TO  
AFFECT THE CENTRAL AND NORTHWESTERN CONUS DURING MID TO LATE FEBRUARY.  
THEREFORE, A LARGER COVERAGE OF INCREASED CHANCES FOR BELOW-NORMAL TEMPERATURES  
IS FORECAST FOR THESE AREAS COMPARED TO YESTERDAY. ALTHOUGH INCREASED CHANCES  
FOR ABOVE-NORMAL TEMPERATURES ARE FORECAST FOR CALIFORNIA AND THE GREAT BASIN,  
STATISTICAL TOOLS CONTINUE TO OFFER A COLDER SOLUTION. THE ANOMALOUS  
SUBTROPICAL RIDGE OVER THE GULF OF MEXICO FAVORS A CONTINUATION OF ABOVE-NORMAL  
TEMPERATURES ACROSS THE SOUTHEAST AND MID-ATLANTIC.  
 
AN EXPECTED TEMPERATURE GRADIENT FAVORS NEAR TO ABOVE-NORMAL PRECIPITATION FROM  
THE GREAT LAKES AND NEW ENGLAND SOUTHWEST TO TEXAS. ENHANCED ODDS FOR  
BELOW-NORMAL PRECIPITATION ARE FORECAST FOR THE SOUTHEAST SINCE THE LONGWAVE  
PATTERN FAVORS A STORM TRACK TO THE NORTHWEST OF THIS REGION. SHORTWAVE TROUGHS  
AND UPSLOPE FLOW FAVOR NEAR TO ABOVE-NORMAL PRECIPITATION ACROSS THE NORTHERN  
AND CENTRAL ROCKIES AND HIGH PLAINS. UPSTREAM RIDGING INCREASES CHANCES FOR  
BELOW-NORMAL PRECIPITATION FOR MUCH OF THE NORTHWESTERN CONUS, WHILE THE CLOSED  
500-HPA LOW IS EXPECTED TO DEPART THE DESERT SOUTHWEST BY DAY 8 (PER LATEST  
MODEL RUNS).  
 
THE HIGHEST CONFIDENCE IN THE WEEK-2 OUTLOOKS FOR ALASKA EXISTS ACROSS THE  
ALEUTIANS AND WESTERN MAINLAND ALASKA WHERE AN UPPER-LEVEL TROUGH UPSTREAM  
FAVORS ABOVE-NORMAL TEMPERATURES AND ABOVE-NORMAL PRECIPITATION.  
 
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  
IMPROVED AGREEMENT AMONG TEMPERATURE TOOLS OFFSET BY POOR MODEL CONTINUITY THE  
PAST THREE DAYS AND UNCERTAINTY ON HOW FAST THE POTENTIAL MID-LEVEL LOW EXITS  
THE DESERT SOUTHWEST.  
 
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:  
19630119 - 19840119 - 19890212 - 19910128 - 19570125  
 
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:  
19630118 - 19840119 - 19630123 - 19820203 - 19890212  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR FEB 14 - 18 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON N B OREGON A B NRN CALIF A B  
SRN CALIF A A IDAHO N B NEVADA A B  
W MONTANA B A E MONTANA B A WYOMING N N  
UTAH A B ARIZONA A A COLORADO A B  
NEW MEXICO A A N DAKOTA B N S DAKOTA B B  
NEBRASKA B B KANSAS N B OKLAHOMA A N  
N TEXAS A A S TEXAS A N W TEXAS A A  
MINNESOTA B B IOWA B B MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN B B  
ILLINOIS B A MISSISSIPPI A A MICHIGAN B N  
INDIANA N A OHIO N A KENTUCKY A A  
TENNESSEE A A ALABAMA A N NEW YORK N A  
VERMONT N A NEW HAMP A A MAINE N N  
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 N  
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 A AK SO COAST A A AK PNHDL N N  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR FEB 16 - 22 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B B OREGON N B NRN CALIF A B  
SRN CALIF A B IDAHO A B NEVADA A B  
W MONTANA B A E MONTANA B A WYOMING N A  
UTAH A B ARIZONA A B COLORADO A N  
NEW MEXICO A A N DAKOTA B N S DAKOTA B B  
NEBRASKA B B KANSAS B B OKLAHOMA N A  
N TEXAS A A S TEXAS A A W TEXAS N A  
MINNESOTA B N IOWA B B MISSOURI B A  
ARKANSAS A A LOUISIANA A A WISCONSIN B N  
ILLINOIS B N MISSISSIPPI A A MICHIGAN B A  
INDIANA N A OHIO N 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 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 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 A AK SO COAST A A AK PNHDL N 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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