ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 140 PM EDT MON MAR 21 2016 VALID 12Z FRI MAR 25 2016 - 12Z TUE MAR 29 2016 GENERAL FLOW PATTERN & MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE GUIDANCE ADVERTISES INCREASINGLY SOUTHERLY FLOW FOR THE NORTH STAR STATE THIS PERIOD AS A DEEP CYCLONE MOVES FROM THE WESTERN PACIFIC INTO THE ALEUTIANS WITH TIME -- A RELATIVELY MILD PATTERN FOR THE STATE WITH WETNESS MOST FOCUSED NEAR THE SOUTHERN COAST. THE 06Z GFS/00Z ECMWF WERE IN GOOD AGREEMENT WITH EACH OTHER AND THE 06Z GEFS/00Z ECMWF ENSEMBLE MEAN SOLUTIONS. THE 00Z CANADIAN, 00Z UKMET, AND 12Z GFS SHOWED SOLUTIONS WHICH WERE A BIT MORE PROGRESSIVE THAN THE ABOVE CONSENSUS -- ENOUGH SO THAT THEY ESCAPE THE 00Z GLOBAL ENSEMBLE LOW CLUSTERING -- WHICH TENDS TO FIT KNOWN BIASES IN THE GFS/UKMET SOLUTIONS. THE PRESSURE AND WIND GRIDS WERE BASED ON A 70/30 BLEND OF THE 06Z GFS/00Z ECMWF TO DEAL WITH DETAIL ISSUES IN THE NORTHEAST PACIFIC OFFSHORE SOUTHEAST AK EARLY FRIDAY INTO EARLY SATURDAY BEFORE THE BLEND WAS EVENED OUT TO A MORE 50/50 BLEND BY EARLY SUNDAY. THEREAFTER, SLOWLY INCREASING AMOUNTS OF THE 06Z GEFS/00Z ECMWF ENSEMBLE MEAN SOLUTIONS WERE USED FOR EARLY NEXT WEEK. FOR THE TEMPERATURE/DEW POINT/CLOUDS/PRECIPITATION CHANCES/WEATHER GRIDS, THE AMOUNT OF ENSEMBLE MEAN CONTRIBUTION WAS DOUBLED AND DETERMINISTIC GUIDANCE WAS HALVED TO ACCOUNT FOR UNCERTAINTY AND DETERMINISTIC MODEL BIASES. WEATHER IMPACTS ~~~~~~~~~~~~~~~ THREE BOUTS OF HEAVY PRECIPITATION ARE EXPECTED ACROSS SOUTHERN AK THIS PERIOD WITHIN BROAD SOUTHWESTERLY FLOW ALOFT. THE FIRST IMPACT IS ACROSS SOUTH-CENTRAL AK FRIDAY INTO SATURDAY AS AN OCCLUDED LOW BECOMES BAROTROPIC AND APPROACHES THE REGION. A TRIPLE POINT LOW TO ITS SOUTHEAST THEN WRAPS UP AND MOVES TOWARDS THE AK PANHANDLE LATE SATURDAY AND SUNDAY BRINGING ANOTHER SKIRMISH OF HEAVY PRECIPITATION. AS A BURGEONING DEEP CYCLONE APPROACHES SOUTHWEST AK, A THIRD BOUT OF HEAVY PRECIPITATION IS EXPECTED ACROSS THE ALEUTIANS/AK PENINSULA LATE SATURDAY AND SUNDAY BEFORE PROGRESSING INTO SOUTH-CENTRAL AK LATE SUNDAY INTO NEXT TUESDAY. THE 00Z ECMWF ADVERTISES SOME HEFTY AMOUNTS NEXT MONDAY, WHICH IS POSSIBLE CONSIDERING THE DEEP SOUTHERLY FLOW/WARM CONVEYOR BELT CIRCULATION AROUND THE CYCLONE'S EASTERN SIDE WHICH APPEARS TO CEASE PROGRESSING EASTWARD AROUND THAT TIME. PRECIPITATION AMOUNTS ELSEWHERE ACROSS THE STATE SHOULD BE FAIRLY LIGHT. TEMPERATURES STATEWIDE WILL BE ABOVE AVERAGE, WITH LOWS CLOSE TO -10F ON THE NORTH SLOPE AND MAINLY IN THE 20S AND 30S TO THE SOUTH OF THE BROOKS RANGE. HIGHS WILL BE BALMY, IN THE SINGLE DIGITS ACROSS THE NORTH SLOPE AND THE 30S/40S SOUTH OF THE BROOKS RANGE. ROTH