ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 143 PM EDT FRI MAR 20 2015 VALID 12Z TUE MAR 24 2015 - 12Z SAT MAR 28 2015 THE PATTERN FROM EASTERN ASIA ACROSS THE PACIFIC INTO NORTH AMERICA IS FORECAST TO AMPLIFY WITH TIME. VERY STRONG AND EXPANSIVE RIDGING FROM CHINA EASTWARD THROUGH JAPAN WILL FAVOR TROUGHING ALONG AND JUST EAST OF THE DATELINE LATE NEXT WEEK WITH INCREASED RIDGING OVER THE WESTERN CONUS UP THROUGH BC AND THE PANHANDLE. LEAD SYSTEM SHOULD PUSH INTO THE GULF AROUND THURSDAY BUT THE MODELS HAVE VACILLATED ON HOW TO INCORPORATE A SOUTHERN STREAM LOW TO THE NW OF HAWAII IN THE SHORT RANGE... WITH THE 00Z ECMWF KEEPING THIS SEPARATE WHICH ALLOWS IT TO SNEAK AHEAD OF THE MAIN SYSTEM. ENSEMBLES WOULD NOT BE ABLE TO CAPTURE THIS POSSIBILITY WELL EXCEPT FOR SOME SHARPNESS TO THE ISOBARS... WHICH EXISTS... BUT PREFER TO MAINTAIN A SIMPLER DEPICTION FOR NOW WITH A MORE TYPICAL FRONTAL PROGRESSION NORTHEASTWARD THAT SHOULD WEAKEN AS IT APPROACHES THE COAST AMIDST RISING HEIGHTS. TO THAT EFFECT... CONVENTIONAL WISDOM WOULD ARGUE FOR STRONGER/LONGER RIDGING IN LATER TIME PERIODS ESPECIALLY WITH THE UP/DOWNSTREAM PATTERN... WHICH WOULD FAVOR THE CANADIAN ENSEMBLES MOST... BUT THE COMPLICATED SPLIT FLOW NE OF HAWAII MEANS THAT THE TOP OF THE RIDGE... OVER NW CANADA... WOULD BE MORE SUSCEPTIBLE -- AT LEAST TEMPORARILY -- TO ENERGY PUSHING THROUGH IT. THIS IS EVIDENT IN THE ENSEMBLE SPREAD MAXIMUM SOUTH OF THE GULF BY SAT/D8 WHILE THE CORE OF THE POSITIVE HEIGHT ANOMALY SHOULD BE CENTERED OVER WA/OR/ID. ENDED UP USING A BLEND OF THE 12Z GFS WITH THE 00Z NAEFS/ECENS MEANS THAT TRADED THE GFS FOR THE 06Z GEFS MEAN FOR NEXT THU-SAT WHEN THE GFS TUGS THE SFC LOW MUCH FARTHER WEST THAN THE ENSEMBLES/CONTINUITY SUGGEST. THIS KEPT CHANGES TO A MINIMUM. TEMPERATURES SHOULD AVERAGE NEAR OR ABOVE NORMAL... ESPECIALLY THROUGH THE INTERIOR. PRECIPITATION SHOULD FOCUS ALONG SOUTHERN CENTRAL AREAS WITH SOUTHEASTERLY FLOW AS WELL AS THROUGH THE PANHANDLE WITH THE APPROACHING BUT WEAKENING LEAD FRONT... AND THEN THROUGH THE ALEUTIANS AND AKPEN WITH THE SECOND SYSTEM NEXT FRI/SAT. FRACASSO