HAWAII EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 716 AM EDT THU APR 05 2012 VALID 00Z FRI APR 06 2012 - 00Z FRI APR 13 2012 MODELS AND ENSEMBLES AGREE REASONABLY WELL WITH SATELLITE IMAGERY AND INDICATE THAT A WELL DEFINED CLOSED LOW NOW ALOFT TO THE WEST OF THE HAWAIIAN ISLANDS NEAR 170W WILL DRIFT SLOWLY WESTWARD WHILE WEAKENING TOWARD THE DATELINE INTO THE WEEKEND. HIGH PRECIPITABLE WATER VALUES AND HEAVY RAINFALL WITH THIS LOW HOLDS WELL WEST OF THE STATE. MEANWHILE...GUIDANCE ALSO AGREES THAT MID-UPPER LEVEL NRN STREAM FLOW AMPLIFICATION WILL BUILD A POTENT MEAN TROUGH OVER THE ERN PACIFIC THIS WEEKEND INTO NEXT WEEK WITH AN AXIS NEAR 140W. THIS MAY ALLOW FOR MORE MODERATE ISLAND TRADES AND THE PASSAGE OF SOME SHEARLINE SHOWERS THROUGH THE ISLANDS SUN/MON BEFORE ENTERING A PERIOD OF BELOW NORMAL MOISTURE AND RAINFALL AS HEIGHTS GRADUALLY RISE. THIS IS DESPITE MODERATE TO LOCALLY BRISK TRADES THAT MAY BUILD IN THE WAKE OF THE SHEARLINE AS A HIGH PRESSURE CELL BRIDGES JUST TO THE NORTH OF THE STATE NEXT WEEK. SCHICHTEL