HAWAII EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 755 AM EDT SUN OCT 07 2012 VALID 00Z MON OCT 08 2012 - 00Z MON OCT 15 2012 BLOCKING PATTERN OVER THE NORTHEAST PACIFIC IN THE FORM OF A LARGE UPPER ANTICYCLONE REACHES FULL STRENGTH BY MONDAY...AS UPPER TROUGH LIFTS NORTHEASTWARD NORTH OF THE ISLANDS AND WEAKENS WHILE ANOTHER LARGE UPPER LOW DIVES SOUTHEASTWARD ACROSS THE CENTRAL PACIFIC TO NEAR 40N. BOTH TROUGH SYSTEMS BRING SURFACE COLD FRONTS JUST TO THE NORTHWEST OF THE ISLANDS CONTINUING TO DISRUPT THE TRADES. THIS PERSISTENT PATTERN BEGINS TO BREAK DOWN INTO THE MIDDLE OF THE WEEK AS THE LAST IN A SERIES OF DIGGING SHORT WAVES NOW BEGINS TO LIFT NORTHWARD ACROSS THE NORTH CENTRAL PACIFIC...AND BREAKING DOWN THE UPPER ANTICYCLONE OVER THE NORTHEAST PACIFIC. THIS PATTERN SHIFT IS NOT OCCURRING IN ISOLATION AS THE BREAKDOWN OF THE UPPER RIDGE OVER THE NORTHEAST PACIFIC WILL LIKELY RESULT IN THE EVENTUAL END OF THE SUCCESSION OF COLD FRONT DIVING SOUTHEASTWARD OVER THE LOWER 48 WHICH IS ALSO SHOWING SIGNS OF TRANSITION IN THE MEDIUM RANGE. THE CURRENT PATTERN SHOWS MODELS WITH HIGHEST PW VALUES POOLING NORTH OF THE ISLANDS AS WELL AS LARGEST PRECIPITATION AMOUNTS ASSOCIATED WITH THE LOCATION OF THE COLD FRONTS. HOWEVER...DISRUPTED WIND FLOW ASSOCIATED WITH THIS PATTERN WILL HAVE IMPACTS ON LOCAL FORECASTS AS INDICATED IN STATE FORECAST DISCUSSION THROUGH MIDWEEK. ON TUESDAY IN WEDNESDAY...AS MAJOR UPPER LOW LIFTS NORTHWARD...MODELS IN EXCELLENT AGREEMENT SHOWING AMPLIFYING RIDGE OVER AND TO THE NORTHEAST OF ISLANDS...WHICH APPEARS TO CONTINUE THROUGH TO THE WEEKEND. STORM SYSTEMS OVER THE NORTH PACIFIC ARE EXPECTED TO STAY WELL NORTH OF RECENT SYSTEMS ALLOWING TRADE WIND REGIME TO BECOME REESTABLISHED MIDWEEK THROUGH THE END OF THE WEEKEND. HIGHEST PW VALUES MOVE WELL NORTH OF THE ISLANDS AS FRONTAL BOUNDARIES LIFT NORTHWARD...BUT EASTERLIES STILL KEEP MODEST FORECAST VALUES OF .75 TO 1.25 INCHES OVER THE ISLANDS THROUGHOUT THE END OF THE FORECAST. KOCIN