153
FXHW60 PHFO 071347
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST SAT NOV 7 2009
SYNOPSIS
HIGH PRESSURE TO THE NORTH OF THE ISLANDS WILL CONTINUE TO BRING
MODERATE TRADE WINDS TO THE AREA INTO NEXT WEEK. MOISTURE UPSTREAM
OF THE ISLANDS WILL BRING WET TRADE SHOWERS TO THE ISLANDS OVER THE
WEEKEND...AND THE MODERATE TRADES WILL HELP TO BRING SOME OF THESE
SHOWERS TO LEEWARD AREAS. HIGH CLOUDS WILL PERSIST THROUGH THE
WEEKEND.
DISCUSSION
NO BIG CHANGES IN THE FORECAST FOR THIS MORNING. THE HIGH PRESSURE
NORTH OF THE ISLANDS WILL CONTINUE TO BRING MODERATE TRADES TO THE
AREA TODAY. THE MODELS REMAIN IN GOOD AGREEMENT WITH THIS FEATURE.
OVERNIGHT WE SAW A BAND OF LOW LEVEL MOISTURE MOVE OVER THE WINDWARD
SIDES OF THE ISLANDS...BEING CARRIED IN ON THE TRADE WINDS. SEVERAL
GAGES ON KAUAI AND OAHU REPORTED RAINFALL AROUND A QUARTER OF AN
INCH. THE MOST RAIN BETWEEN 8PM AND 2AM WAS REPORTED AT MANOA LYON
ARBORETUM ON OAHU WHICH REPORT 0.41 INCHES. PORTIONS OF THE BAND ARE
STILL OFFSHORE...SO ANTICIPATE MORE RAINFALL IN THE PRE-DAWN HOURS.
UPPER LEVEL CLOUDS CONTINUE TO STREAM OVER THE ISLANDS FROM THE WEST
DUE TO A UPPER LEVEL LOW WEST NORTHWEST OF THE ISLANDS. THE MODELS
ARE IN GOOD AGREEMENT WITH THIS UPPER LOW STAYING TO THE WEST
THROUGH THE WEEKEND...SO EXPECT THE HIGH CLOUDS TO COME AND GO
THROUGHOUT. OVER THE WEEKEND THE MODELS SHOW THE LOW WEAKENING INTO
AN UPPER LEVEL TROUGH THAT WILL APPROACH KAUAI SUNDAY NIGHT. THE
TROUGH WILL BRING SOME UNSTABLE AIR TO THE ISLANDS...WHICH WILL
LIKELY INCREASE THE SHOWER ACTIVITY OVER THE AREA.
HEADING INTO THE MIDDLE OF THE WEEK...THE MODELS SHOW A STRONGER
UPPER LEVEL TROUGH MOVING OVER THE ISLANDS FROM THE NORTH. THE
LATEST RUNS OF THE MODELS HAVE A BIT MORE AGREEMENT WITH THE
PLACEMENT OF AN UPPER LEVEL LOW THAT WOULD DEVELOP OVER THE ISLANDS.
THE ECMWF...GFS AND NOGAPS NOW ALL HAVE THE LOW FORMING OVER THE
ISLANDS WEDNESDAY AFTERNOON AND OVERNIGHT. THERE REMAINS SOME
DISCREPANCY OVER THE STRENGTH OF THE UPPER LOW...WITH THE NOGAPS
BEING THE STRONGEST...WHILE THE ECMWF AND GFS ARE MORE IN LINE WITH
EACH OTHER. HAVE LEFT THE GRIDS IN THE LONG TERM WITH THE WET TRADE
PATTERN WHILE AWAITING ANOTHER RUN OR TWO OF THE MODELS TO SEE IF
THIS TREND CONTINUES.
MARINE
A SMALL CRAFT ADVISORY CONTINUES FOR COASTAL AREAS AROUND KAUAI
DUE TO COMBINED SEAS...AND AROUND THE WINDIER AREAS NEAR THE BIG
ISLAND AND MAUI FOR WINDS. DESPITE A NEW NORTH NORTHWEST
SWELL...SURF IS EXPECTED TO REMAIN BELOW ADVISORY LEVELS FOR THE
REST OF THE WEEKEND.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL NOON HST SATURDAY FOR KAUAI WINDWARD
WATERS-KAUAI LEEWARD WATERS-OAHU WINDWARD WATERS-KAIWI CHANNEL-
MAUI COUNTY WINDWARD WATERS-BIG ISLAND LEEWARD WATERS.
SMALL CRAFT ADVISORY UNTIL 6 AM HST SUNDAY FOR KAUAI NORTHWEST
WATERS-KAUAI CHANNEL-MAALAEA BAY-PAILOLO CHANNEL-ALENUIHAHA
CHANNEL-BIG ISLAND SOUTHEAST WATERS.
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