ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1054 AM EST SAT MAR 04 2017 VALID 12Z WED MAR 08 2017 - 12Z SUN MAR 12 2017 MOST OF ALASKA WILL BE AFFECTED BY THE EASTERN PERIPHERY OF AN OMEGA-BLOCK CHARACTERIZED BY MUCH BELOW NORMAL TEMPERATURES AND DRY CONDITIONS AS THE COLD AIR IS PERIODICALLY REINFORCED BY THE NORTHERN STREAM CROSSING THE ARCTIC OCEAN...ALTHOUGH TEMPERATURES MAY MODERATE SLIGHTLY LATE IN THE PERIOD. MODELS ARE IN GOOD LARGE-SCALE AGREEMENT THROUGH DAY 8...WITH THE PRIMARY DIFFERENCE ABOUT THE PLACEMENT OF THE BLOCK...WITH THE GFS/GEFS SLIGHTLY EAST AND FLATTER THAN THE ECMWF/ECMWF ENSEMBLE MEAN...ALONG WITH MODEST SPREAD. THE DAY-TO-DAY DETAILS ARE MORE UNCERTAIN...PARTICULARLY WITH LOWS SLOWING DOWN IN THE GULF OF ALASKA AS WELL AS THE NORTHERN STREAM. GIVEN THE STRENGTH OF THE BLOCK AS WELL AS MODEL TRENDS...THERE'S SUFFICIENT SUPPORT TO LEAN TOWARD THE STRONGER BLOCKING DEPICTION OF THE ECMWF CAMP. THUS...THE MODEL CHOICES LEAN ABOUT 60 TO 70 PERCENT IN THAT DIRECTION...WITH A TRANSITION TO THE ENSEMBLES PERFORMED BY DAY 4 1/2 DUE TO THE GROWING SPREAD IN THE SMALL-SCALE DETAILS. CONFIDENCE IN THE BLOCK PERSISTING IS ABOVE AVERAGE...ALTHOUGH THE EVOLUTION ACROSS THE NORTH BEYOND DAY 6 IS BELOW AVERAGE DUE TO INFLUENCES FROM THE NORTHERN STREAM AND ACCOMPANYING HIGH MODEL SPREAD. JAMES