ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 244 PM EDT SUN APR 03 2016 VALID 12Z THU APR 07 2016 - 12Z MON APR 11 2016 AROUND THU THE LATEST GUIDANCE EXPECTS LEADING SHRTWV ENERGY WILL BRIEFLY DENT THE LONG TERM MEAN RIDGE EXTENDING FROM THE NERN PAC/BC COAST INTO MAINLAND ALASKA. THEREAFTER THE RIDGE SHOULD REBUILD AND PERSIST IN RESPONSE TO ALEUTIANS/CNTRL PACIFIC DEVELOPMENT FOLLOWED BY A BROADER AREA OF LOW HGTS ALOFT/SFC LOW PRES FCST TO EMERGE FROM ERN ASIA AND ULTIMATELY SETTLE INTO/NEAR THE BERING SEA. OPERATIONAL MODEL RUNS PROVIDE SIGNALS THAT LOOSELY REFLECT THE EXPECTED LARGE SCALE EVOLUTION OVER MANY AREAS BUT SOME OF THEIR DETAILS DIFFER FROM EARLY IN THE FCST PERIOD ONWARD. SPREAD PERSISTS FOR THE NERN PAC WAVE FCST TO REACH NEAR THE PANHANDLE OR EXTREME SERN COAST OF THE MAINLAND BY 12Z THU. EWD TRENDS IN THE ENSEMBLE MEANS OVER THE PAST COUPLE DAYS AND A MODERATE EWD ADJUSTMENT IN THE PAST COUPLE ECMWF RUNS AFTER THE 00Z/02 CYCLE FAVOR A SIMILAR TREND FROM WPC CONTINUITY. HOWEVER THE DOWNSTREAM RIDGE ALOFT AND WWD SHIFT IN THE 00Z UKMET... A MODEL WHICH HAD TENDED TO BE ON THE ERN SIDE OF THE SPREAD... RECOMMEND A SOLN MOST SIMILAR TO A COMPROMISE OF THE 00Z ECMWF AND SLOWER 12Z/02 ECMWF VS FARTHER EWD 00Z/06Z GFS RUNS. THE 12Z GFS HAS TRENDED CLOSER TO THIS SCENARIO. MULTI-CYCLE TRENDS APPEAR TO BE OFFERING MORE SUPPORT FOR A GENERAL ECMWF SCENARIO OVER THE ALEUTIANS/NRN PAC THU-FRI... WITH THE 00Z CMC JOINING THE MAJORITY CLUSTER BY FRI. THESE RUNS ALONG WITH THE ENSEMBLE MEANS SUPPORT THE IDEA THAT INITIAL ALEUTIANS LOW PRES WILL GIVE WAY TO A STRENGTHENING NRN PAC WAVE BY 12Z FRI. FROM THIS POINT ON INTERRELATED UNCERTAINTIES PERSIST BTWN THIS SYSTEM AND ENERGY EMERGING FROM THE WRN PAC. ECMWF/CMC RUNS MAINTAIN A STRONGER IDENTITY TO A LEADING WRN-CNTRL PAC SYSTEM REACHING NEAR 180 LONGITUDE BY AROUND 12Z SAT WHILE TRACKING THE ERN ALEUTIANS/SERN BERING SYSTEM MORE QUICKLY NWWD. THE 00Z ECMWF IS A LITTLE SLOWER THAN THE PREVIOUS RUN WITH THE BERING SYSTEM THOUGH. DIFFS ARE SOMEWHAT LESS PRONOUNCED AMONG THE ENSEMBLE MEANS THOUGH THE 00Z ECMWF MEAN STILL HAS MORE EVIDENCE OF THE LEADING SYSTEM VS THE 06Z GEFS MEAN. IN SPITE OF DETAIL DIFFS THAT EXTEND THROUGH THE WEEKEND... THE GEFS/ECMWF MEANS END UP WITH REMARKABLY AGREEABLE SOLNS BY DAY 8 MON. FROM LATE WEEK INTO THE WEEKEND SOME GFS/CMC RUNS BRING HIGH LATITUDE ENERGY CLOSER TO THE NRN/NERN MAINLAND THAN MOST OTHER SOLNS. TELECONNECTIONS RELATIVE TO THE CORE OF POSITIVE ANOMALIES JUST OFF THE PANHANDLE AND DEVELOPING NEG ANOMALIES S/SW OF THE WRN ALEUTIANS SEEM TO FAVOR LEANING AWAY FROM A PRONOUNCED WEAKNESS ALOFT THAT CLOSE TO THE MAINLAND... THOUGH ROOM STILL EXISTS FOR A WEAKNESS A LITTLE FARTHER N AS PER GEFS/CMC MEANS. THE FCST STARTS WITH A 00Z/03-12Z/02 ECMWF BLEND DAY 4 THU TO ACCOUNT FOR TIMING/DETAIL DIFFS WITHIN AN OVERALL PREFERRED ECMWF SCENARIO. SOME 00Z ECMWF MEAN/00Z CMC ARE ADDED FRI GIVEN THEIR CLUSTERING FOR THE NRN PAC/ERN ALEUTIANS SYSTEM. A COMPROMISE AMONG THE 00Z CMC/ECMWF AND 06Z GEFS/00Z EC MEANS EXTENDS INTO DAY 6 SAT BEFORE TRENDING TO AN EVEN COMPROMISE OF THE TWO MEANS FOR DAYS 7-8 SUN-MON. RAUSCH