ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1252 PM EST SUN FEB 23 2014 VALID 12Z THU FEB 27 2014 - 12Z MON MAR 03 2014 MOST GUIDANCE EXPECTS A CLOSED UPR HIGH NEAR THE ALASKA/YUKON BORDER AS OF EARLY DAY 4 THU TO PERSIST INTO DAY 6 SAT AND THEN WEAKEN... WITH RIDGING BUILDING WWD INTO SIBERIA BY WAY OF A COMBINATION OF A SHRTWV RIDGE THAT REACHES THE BERING SEA BY SAT AND A PORTION OF THE INITIAL RIDGE OVER THE ERN MAINLAND. MEANWHILE HGT FALLS DEPARTING FROM ERN ASIA WILL FEED INTO A LEADING CNTRL PAC TROUGH/CLOSED LOW TO YIELD A BROAD E-W AXIS OF LOW HGTS WITHIN A FEW DEGS LATITUDE OF 50N BY THE BEGINNING OF NEXT WEEK. BY THE D+8 TIME FRAME MULTI-DAY MEANS CONTINUE TO SHOW A CORE OF NEGATIVE HGT ANOMALIES NEAR 43N 160W WITH TELECONNECTIONS FAVORING A RIDGE AXIS FROM NEAR OR JUST E OF THE BC COAST THROUGH THE MAINLAND INTO ERN SIBERIA. SOME DETAIL ISSUES BECOME EVIDENT FAIRLY EARLY IN THE FCST... IN PARTICULAR WITH 00Z/06Z GFS RUNS BEING IN THE NRN PART OF THE FULL MODEL/ENSEMBLE SPREAD FOR NRN PAC/ALEUTIANS LOW PRESSURE. THE 12Z GFS COMPARES BETTER TO CONSENSUS INTO SAT. BY MID-LATE PERIOD THERE IS QUITE A BIT OF SPREAD FOR MID LVL DETAILS OVER/NEAR THE MAINLAND THOUGH FORTUNATELY WITH SOMEWHAT LESS EXTREME IMPACT ON THE SFC PATTERN... AS THE MAINLAND SHOULD REMAIN UNDER THE GRADIENT BETWEEN LOW PRESSURE OVER THE PAC AND HIGH PRESSURE OVER WRN CANADA AND EVENTUALLY N OF SIBERIA. THERE IS ALSO CONSIDERABLE SPREAD WITH MID LVL/SFC DETAILS WITHIN THE OVERALL AREA OF LOWER HGTS/SFC PRESSURE ACROSS THE NRN PAC/ALEUTIANS. FCST PREFS TODAY LEAN MOSTLY TO THE 06Z GEFS AND 00Z NAEFS/ECMWF ENSEMBLE MEANS IN LIGHT OF THE VARIOUS LOWER CONFIDENCE DETAILS SEEN IN OPERATIONAL GUIDANCE ACROSS THE FCST DOMAIN. THE EXCEPTION IS MINORITY INPUT FROM THE 12Z GFS/00Z ECMWF ON DAYS 4-5 THU-FRI WHEN THEY ARE CLOSE ENOUGH TO CONSENSUS IDEAS. AFTER THAT TIME CONFIDENCE IN OPERATIONAL MODEL SPECIFICS DECREASES SIGNIFICANTLY AND THE ENSEMBLE MEAN PATTERN STILL HAS REASONABLE SUPPORT FROM TELECONNECTIONS. AMONG OPERATIONAL SOLNS THE 12Z GFS SEEMS TO COME CLOSEST TO THE PREFERRED ENSEMBLE MEAN PATTERN ALOFT BY THE END OF THE PERIOD. RAUSCH