| Current Conditions | ||
| Temp |  | -1.2 C |
| RH | | 16 % |
| Wind | | NNE 7 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 546 FXHW60 PHFO 220630 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 830 PM HST SAT NOV 21 2009 .SYNOPSIS... TRADE WINDS WILL WEAKEN SLIGHTLY AT THE BEGINNING OF NEXT WEEK AS HIGH PRESSURE FAR NORTHEAST OF THE ISLANDS MOVES EAST. SHOWERS WILL FOCUS ON WINDWARD AND MOUNTAIN SLOPES...WITH A FEW SHOWERS REACHING LEEWARD LOCATIONS. && .DISCUSSION... CURRENT RADAR IMAGERY SHOWS LIGHT TO MODERATE SHOWERS OVER WINDWARD KAUAI AND OAHU WITH MORE SCATTERED SHOWERS MOVING TOWARD THE WINDWARD COASTS OF ALL THE ISLANDS. TONIGHT...EXPECT PASSING SHOWERS OVER WINDWARD AREAS WITH AN ISOLATED SHOWER OR TWO REACHING THE LEEWARD SIDES OF THE SMALLER ISLANDS. AFTERNOON SOUNDINGS FROM HILO AND LIHUE CONTINUE TO SHOW LOW PRECIPITABLE WATER VALUES...SO RAINFALL AMOUNTS SHOULD CONTINUE ON THE LIGHT SIDE. A 1026 MB HIGH PRESSURE FAR NORTHEAST OF THE STATE IS MAINTAINING THE FRESH TO STRONG TRADE WINDS ACROSS THE ISLANDS. STORM SYSTEMS RACING ACROSS THE NORTH PACIFIC ARE FORECAST TO PUSH THE HIGH FARTHER EAST...AND ITS ASSOCIATED SURFACE RIDGE SOUTH EARLY IN THE WEEK... THEREBY RELAXING THE PRESSURE GRADIENT OVER THE STATE AND DECREASING THE TRADE WINDS INTO THE MODERATE TO FRESH RANGE MONDAY AND TUESDAY. THE GFS AND ECMWF BOTH SHOW A WEAK COLD FRONT APPROACHING KAUAI TUESDAY NIGHT AND WEDNESDAY...BUT NEVER REACHING THE GARDEN ISLE. THE MODELS DO SHOW TROPICAL MOISTURE BEING DRAWN UP FROM THE SOUTH IN RESPONSE TO THE FRONT...INCREASING PW VALUES NEAR THE BIG ISLAND TUESDAY NIGHT...AND THEN MAUI COUNTY AND OAHU ON WEDNESDAY. THIS SCENARIO WOULD BRING INCREASING SHOWERS TO WINDWARD AREAS OF THOSE ISLANDS. HOWEVER...MODELS ARE CONTINUING TO TREND WEAKER...AND FARTHER SOUTH WITH THIS FEATURE. THE WEAKENING TREND DOES NOT BODE MUCH CONFIDENCE FOR INCREASING TRADE SHOWERS FOR THE MIDDLE OF THE WEEK...SO THE FORECAST REMAINS WITH CLIMO TRADE WIND WEATHER. && .MARINE... VERY STRONG STORMS FORECAST TO MOVE ACROSS THE NORTH PACIFIC NEXT WEEK PROMISE TO GENERATE MULTIPLE HIGH SURF EPISODES. A HIGH SURF ADVISORY IS IN EFFECT SUNDAY MORNING FOR NORTH AND WEST KAUAI AND NIIHAU...AS WELL AS NORTH SHORES OF OAHU MOLOKAI AND MAUI. SURF WILL RISE EARLY SUNDAY MORNING ON KAUAI AND MOVE DOWN THE ISLAND CHAIN DURING THE DAY. THE FIRST SIGNS OF LONG PERIOD SWELL ENERGY BEGAN ARRIVING AT BUOY 51001 SATURDAY AFTERNOON. THE STRONG STORM RESPONSIBLE FOR THIS EXPECTED SWELL MOVED UP TO THE WESTERN ALEUTIAN ISLANDS THURSDAY NIGHT AND THEN EXPERIENCED A SECONDARY LOW THAT EXTENDED THE FETCH AREA. THIS WILL SERVE TO PROLONG THE HIGH SURF EPISODE THROUGH MONDAY...AND POSSIBLY INTO TUESDAY. ANOTHER LOW THAT WILL MOVE INTO THE CENTRAL NORTH PACIFIC LATE TOMORROW AND MONDAY WILL PRODUCE AN EVEN LARGER NORTHWEST SWELL TUESDAY NIGHT WITH THE PEAK WEDNESDAY. THE SWELL WILL THEN CONTINUE AS A LARGE NORTH NORTHWEST SWELL INTO THE SECOND HALF OF NEXT WEEK. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY FROM 6 AM SUNDAY TO 6 AM HST TUESDAY FOR NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-OAHU NORTH SHORE-OAHU KOOLAU- MOLOKAI-MAUI WINDWARD WEST-WINDWARD HALEAKALA. SMALL CRAFT ADVISORY UNTIL 5 PM HST SUNDAY FOR KAUAI CHANNEL- KAIWI CHANNEL-MAALAEA BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS. && $$ MORRISON Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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