EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 253 AM EDT WED JUN 03 2015 VALID 12Z SAT JUN 06 2015 - 12Z WED JUN 10 2015 ...OVERVIEW... LATEST GUIDANCE IS SHOWING FAIRLY RAPID WEAKENING/SHEARING OF THE UPR LOW FCST TO BE OVER CA/NV EARLY IN THE PERIOD AS A SRN PLAINS RIDGE ALOFT MAY TRY TO RETROGRADE TOWARD/INTO NRN MEXICO. BTWN THESE TWO FEATURES THERE IS STILL POTENTIAL FOR SOME ERN PAC TROPICAL MSTR... PRIMARILY FROM HURCN BLANCA... TO FLOW INTO PARTS OF THE WEST BUT WITH A FAIR DEGREE OF UNCERTAINTY AS TO SPECIFICS AT THIS TIME. MEANWHILE AGREEMENT REMAINS GOOD WITH THE GENERAL IDEA OF AN AMPLIFYING ERN NOAM TROUGH ALBEIT WITH SIGNIFICANT DETAIL DIFFS YET TO BE RESOLVED. ...GUIDANCE EVALUATION/PREFERENCES... WITH OPERATIONAL MODELS DIFFERING FROM EACH OTHER AND THE ENSEMBLE MEANS FOR SOME INDIVIDUAL SFC FEATURES AS EARLY AS DAY 3 SAT... THE UPDATED FCST STARTS WITH A 70/30 BLEND OF THE 12Z ECMWF MEAN/NAEFS MEAN THROUGH THE FCST PERIOD. THIS SOLN PROVIDES BETTER CONTINUITY THAN OTHER OPTIONS WHILE REFLECTING RECENT TRENDS TOWARD MORE PROGRESSIVE NERN PAC INTO WRN CANADA FLOW BY THE MIDDLE OF NEXT WEEK. OVER THE WEST... TRENDS NOTED BESIDES THOSE FOR NRN STREAM FLOW INCLUDE A SOMEWHAT EARLIER WEAKENING OF THE INITIAL UPR LOW AS WELL AS GREATER WWD EXTENT AND/OR FASTER RETROGRESSION OF THE SRN PLAINS/NRN MEXICO RIDGE. BY MID-LATE PERIOD THERE IS CONSIDERABLE SPREAD REGARDING THE ULTIMATE EVOLUTION/TRACK OF ONE OR MORE PIECES OF ENERGY ORIGINALLY ASSOC WITH THE UPR LOW AND SURROUNDING FLOW. IN ADDITION THERE IS VERY WIDE TIMING SPREAD FOR EPAC HURCN BLANCA WITH GFS RUNS TENDING TO BE ON THE FAST SIDE. CONSULT NHC PRODUCTS FOR LATEST INFO REGARDING BLANCA AND WEAKENING HURCN ANDRES FARTHER TO THE W. THE LIKELIHOOD THAT THE AMPLIFYING ERN NOAM TROUGH WILL CONSIST OF MULTIPLE PIECES OF ENERGY COMPLICATES THE FCST OVER THE CNTRL-ERN STATES. THERE IS A DECENT SIGNAL TOWARD A SFC WAVE TRACKING FROM THE PLAINS THROUGH THE UPR GRTLKS SAT-MON BEFORE MERGING WITH TRAILING CANADIAN LOW PRES... BUT POOR AGREEMENT ON STRENGTH/TIMING. ECMWF/UKMET SOLNS MAY BE A LITTLE TOO STRONG WITH THIS WAVE BASED ON EVOLUTION ALOFT SO THE MAJORITY-WEIGHTED ECMWF MEAN SOLN PROVIDES A GOOD REFLECTION OF A MORE MODEST WAVE. AFTER PASSAGE OF THIS WAVE THERE ARE STILL UNCERTAINTIES WITH SHRTWV DETAILS THAT ARE BEST DOWNPLAYED VIA THE ENSEMBLE MEANS FOR THE TIME BEING. ...SENSIBLE WEATHER HIGHLIGHTS... THE INITIAL UPR LOW/SURROUNDING TROUGH OVER THE WEST SHOULD BRING A BROAD AREA OF UNSETTLED WEATHER TO THE REGION. TIMING ISSUES WITH EPAC HURCN BLANCA AND LINGERING DETAIL DIFFS WITH FLOW ALOFT TO ITS N KEEP CONFIDENCE LOWER THAN DESIRED REGARDING THE AMOUNT AND PRECISE PATH OF TROPICAL MSTR THAT MAY BE DRAWN INTO THE SWRN CONUS... MOST LIKELY OVER AZ/NM INTO THE CNTRL ROCKIES. GIVEN OPPOSING GFS/ECMWF TIMING AND INTERMEDIATE TIMING OF THE NHC TRACK FROM THE 03Z ADVISORY A GFS/ECMWF COMPROMISE WOULD BE A REASONABLE STARTING POINT FOR RESOLVING THE AMOUNT OF MSTR THAT MAY REACH INTO THE CONUS. CLOUDS/RNFL SHOULD KEEP HIGHS BELOW NORMAL OVER THE SRN 2/3 OF THE WEST THOUGH WITH A NOTICEABLE WARMING TREND NEXT WEEK ESPECIALLY OVER/NEAR CA. THE NORTHWEST SHOULD BE QUITE WARM AND MOSTLY DRY... WITH PLUS 10-20F OR SLIGHTLY GREATER ANOMALIES FOR TEMPS ESPECIALLY SAT INTO MON. CONTINUE TO SEE POTENTIAL FOR SOME CALENDAR DAY RECORDS AND SOMEWHAT MORE LIKELY FOR WARM LOWS VERSUS DAYTIME HIGHS. ASIDE FROM THE SRN PLAINS THAT WILL BE UNDER A RIDGE ALOFT... MANY PLACES FROM THE HIGH PLAINS TO EAST COAST SHOULD SEE ONE OR MORE EPISODES OF RNFL DURING PERIOD WITH PARTICULAR FOCUS ALONG FRONTAL BOUNDARIES AND IN ADVANCE OF SHRTWV IMPULSES EJECTING FROM THE WEST. ASIDE FROM A PSBL AREA OF CONVECTION TRACKING ACROSS THE NRN TIER STATES... CURRENT SPREAD FOR SHRTWV DETAILS ALOFT IS SUFFICIENTLY GREAT TO YIELD LOW CONFIDENCE IN PINPOINTING MOST FAVORED AREAS FOR HEAVIEST RNFL AT THIS TIME. CONSULT SPC OUTLOOKS FOR FURTHER INFO REGARDING ANY SEVERE THREATS. EXPECT TEMPS TO BE WITHIN 10F OF NORMAL MOST DAYS THOUGH WITH MIN TEMPS TENDING TO RUN MORE CONSISTENTLY ABOVE NORMAL OVER MOST AREAS E OF THE ROCKIES. RAUSCH