| Current Conditions | ||
| Temp |  | -1.8 C |
| RH | | 14 % |
| Wind | | ENE 3 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 156 FXHW60 PHFO 221349 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 349 AM HST SUN NOV 22 2009 .SYNOPSIS... TRADE WINDS WILL WEAKEN SLIGHTLY MONDAY AND TUESDAY 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. TRADE WINDS INCREASE AGAIN ON WEDNESDAY AS HIGH PRESSURE BUILDS TO THE NORTH. && .DISCUSSION... SCATTERED SHOWERS HAVE CONTINUED TO MOVE OVER WINDWARD AREAS OF THE SMALLER ISLANDS OVERNIGHT. THE LARGEST RAINFALL TOTALS FOR 6-HOUR PERIODS FALL BETWEEN FROM A QUARTER TO A HALF INCH WITH THE EXCEPTION BEING MT WAIALEALE ON KAUAI WHICH HAS PICKED UP AN INCH IN THE PAST 6 HOURS. THE WINDWARD BIG ISLAND HAS SEEN LIMITED SHOWERS OVERNIGHT WITH MOST PASSING BY TO THE NORTH. SOUNDINGS FROM HILO AND LIHUE CONTINUE TO SHOW LOW PRECIPITABLE WATER VALUES...SO RAINFALL AMOUNTS SHOULD REMAIN AT LIGHT TO MODERATE AMOUNTS. A 1027 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. HIGH PRESSURE BUILDING TO THE NORTH ON WEDNESDAY WILL BUMP THE TRADES UP A NOTCH FOR THE SECOND HALF OF THE WEEK. 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 WEDNESDAY. SHOWERS WILL LIKELY INCREASE OVER THE WINDWARD BIG ISLAND IN RESPONSE TO THE INCREASED MOISTURE...BUT HEAVY RAINS ARE NOT EXPECTED. && .MARINE... A HIGH SURF ADVISORY IS IN EFFECT FOR NORTH AND WEST KAUAI AND NIIHAU...AS WELL AS NORTH SHORES OF OAHU MOLOKAI AND MAUI. SURF WILL RISE EARLY THIS MORNING ON KAUAI AND MOVE DOWN THE ISLAND CHAIN DURING THE DAY. 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 UNTIL 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 THIS AFTERNOON 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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