652
FXHW60 PHFO 021351
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
351 AM HST MON DEC 2 2024
SYNOPSIS
RELATIVELY DRY AND STABLE CONDITIONS WILL PERSIST THROUGH MID
WEEK WITH LIGHT WINDS THAT WILL ALLOW FOR SEA BREEZES EACH DAY AND
LAND BREEZES OVERNIGHT. A COLD FRONT WILL MOVE THROUGH THE
WESTERN END OF THE STATE ON THURSDAY AND THEN DISSIPATE ACROSS
MAUI COUNTY, INCREASING THE CHANCE OF RAIN AHEAD OF AND ALONG THE
FRONTAL BOUNDARY AND BRINGING MODERATE TO BREEZY NORTHEAST WINDS
IN ITS WAKE. FORECAST DETAILS FOR NEXT WEEKEND BECOME A BIT MURKY
DUE TO SIGNIFICANT MODEL DIFFERENCES.
DISCUSSION
RELATIVELY DRY AND STABLE CONDITIONS WILL CONTINUE THROUGH THE
FIRST HALF OF THE WEEK AS RIDGING ALOFT AND AT THE SURFACE
DOMINATE AND MOISTURE REMAINS LIMITED. UPPER AIR SOUNDINGS FROM
EARLY THIS MORNING AT HILO AND LIHUE CONFIRM THESE CONDITIONS WITH
TEMPERATURE INVERSION HEIGHTS AROUND 5000 TO 5500 FEET AND
PRECIPITABLE WATER VALUES ONLY NEAR AN INCH. THE ORIENTATION OF A
SURFACE RIDGE CENTERED TO THE EAST-NORTHEAST OF HAWAII ALONG WITH
A COLD FRONT APPROACHING FROM THE NORTHWEST WILL MAINTAIN LIGHT
SOUTHERLY WINDS THROUGH WEDNESDAY, AHEAD OF THE FRONT. THIS
LIGHTER FLOW WILL ALLOW FOR THE DEVELOPMENT OF AFTERNOON SEA
BREEZES THAT WILL BRING CLOUDS AND ISOLATED SHOWERS OVER ISLAND
INTERIORS AND FOR OVERNIGHT LAND BREEZES THAT WILL HELP TO CLEAR
OUT THESE INTERIOR CLOUDS AND SHOWERS.
THE AFOREMENTIONED COLD FRONT IS EXPECTED TO REACH KAUAI'S
DOORSTEP SOMETIME LATE WEDNESDAY NIGHT INTO THURSDAY MORNING, WITH
DECENT AGREEMENT AMONGST THE DETERMINISTIC GFS AND ECMWF IN THIS
TIMING. SOME PREFRONTAL MOISTURE LOOKS TO STREAM ACROSS THE
WESTERN HALF OF THE STATE ON WEDNESDAY, POSSIBLY BRINGING A
LITTLE BOOST TO THE DIURNAL SEA BREEZE SHOWERS. THEN RAIN CHANCES
WILL INCREASE ALONG THE FRONTAL BOUNDARY AS IT MOVES DOWN THE
ISLAND CHAIN ON THURSDAY AND DISSIPATES SOMEWHERE IN THE VICINITY
OF MAUI COUNTY. MODERATE TO BREEZY NORTHEAST WINDS WILL FILL IN
BEHIND THE FRONT ON THURSDAY, THEN MODERATE EASTERLY TRADES WILL
PERSIST FRIDAY INTO SATURDAY MORNING WITH HIGH PRESSURE DOMINATING
TO THE FAR NORTHEAST.
THE FORECAST DETAILS BECOME A BIT MURKIER SATURDAY AND BEYOND AS
THE GLOBAL MODEL SOLUTIONS BEGIN TO DIVERGE MORE SIGNIFICANTLY.
THE ECMWF HAS A FAIRLY STRONG COLD FRONT BARGE THROUGH THE ISLAND
CHAIN ON SUNDAY, BRINGING SOME GUSTY NORTHERLY WINDS AND
INCREASING RAIN CHANCES ACROSS THE STATE. AT THE SAME TIME, IT
ALSO HAS A DEEP UPPER LEVEL TROUGH DIG IN ACROSS THE STATE AND
INCREASE INSTABILITY. WHILE THE 06Z GFS NOW HAS A SLIGHTLY MORE
SIMILAR SOLUTION TO THE ECMWF, IT HAS A SLOWER COLD FRONT THAT
GETS PUSHED WESTWARD BY A TROUGH, POSSIBLY BEFORE IT EVEN REACHES
THE STATE. AS SUCH, FORECAST CONFIDENCE REMAINS ON THE LOWER SIDE
FOR THIS WEEKEND AND BEYOND.
AVIATION
A STUBBORN RIDGE OF HIGH PRESSURE TO THE NORTHEAST OF THE STATE
WILL KEEP TRADE WINDS AT BAY THROUGH MOST OF THE WEEK. LOW LEVEL
FLOW WILL REMAIN WEAK BUT SUFFICIENT TO STEER OCCASIONAL BANDS OF
LIGHT SHOWERS TOWARDS SOUTH AND EAST FACING COASTS OF THE BIG
ISLAND AND MAUI. ELSEWHERE, DAYTIME SEA BREEZES AND NIGHTTIME LAND
BREEZES WILL DRIVE LOCAL WEATHER PATTERNS. EXPECT CUMULUS BUILD-
UPS OVER ISLAND INTERIORS DURING THE AFTERNOON AND EARLY EVENING
HOURS. CLEAR SKIES WILL PREVAIL OVERNIGHT, ESPECIALLY ALONG WEST
AND NORTHWEST FACING SLOPES AND COASTS.
NO AIRMETS ARE IN EFFECT OR ANTICIPATED AT THIS TIME.
MARINE
A RIDGE OF HIGH PRESSURE OVER THE STATE WHICH WILL MAINTAIN
GENTLE SOUTH TO SOUTHEAST WINDS THROUGH WEDNESDAY AS THE FRONT
PASSES NORTH OF THE STATE. A SECOND FRONT MAY MOVE INTO THE
NORTHWEST OFFSHORE BOUNDARY WEDNESDAY AND THEN MOVE DOWN THE STATE
THROUGH THURSDAY BEFORE STALLING NEAR MAUI AND THE BIG ISLAND AND
DISSIPATING FRIDAY. NORTHERLY WINDS BEHIND THE FRONT WILL QUICKLY
BECOME NORTHEASTERLY AS THE FRONT WEAKENS AND A WEAK HIGH
DEVELOPS NORTHWEST OF THE STATE.
A SERIES OF NORTHWEST SWELLS GENERATED BY A COMPLEX GALE LOW
SYSTEM SOUTH OF THE ALEUTIAN ISLANDS WILL KEEP SURF ELEVATED ALONG
NORTH AND WEST FACING SHORES THROUGHOUT THE WEEK. A MODERATE,
MEDIUM PERIOD NORTHWEST (320-330 DEGREE) IS EXPECTED TO FILL IN
THIS AFTERNOON AND PEAK LATE NIGHT INTO TUESDAY. A SECOND,
OVERLAPPING MODERATE, AND SLIGHTLY LONGER PERIOD NORTHWEST SWELL
IS EXPECTED TO FILL IN TUESDAY MORNING. LATEST MODEL GUIDANCE IS
SLIGHTLY LARGER THAT LAST MODEL RUN. SURF HEIGHTS ARE THUS
ANTICIPATED TO PEAK NEAR ADVISORY LEVELS TUESDAY THEN HOLD JUST
BELOW ADVISORY LEVELS THROUGH WEDNESDAY. A COUPLE OF LARGER
NORTHWEST SWELLS (310-330 DEGREE) MAY FURTHER BOOST SURF WELL
ABOVE ADVISORY LEVELS LATER IN THE WEEK THURSDAY INTO FRIDAY. THE
COMPOUNDING SWELLS MAY ALSO ELEVATE SIGNIFICANT WAVE HEIGHTS ABOVE
SMALL CRAFT THRESHOLDS OF 10 FEET DURING THIS TIME.
AN OUT OF SEASON LONG PERIOD, SMALL SOUTH SWELL WILL PEAK TODAY,
GENERATING NEAR SUMMERTIME AVERAGE SURF ALONG SOUTH FACING SHORES.
THIS SWELL WILL SLOWLY TREND DOWN THROUGH WEDNESDAY. THE NEXT
SMALL, LONG PERIOD SOUTH SWELL IS EXPECTED SLOWLY FILL IN DURING
THE SECOND HALF OF THE WEEK AND PEAK OVER THE WEEKEND.
SURF ALONG EAST FACING SHORES WILL DECLINE AS A LINGERING SMALL,
SHORT PERIOD NORTH-NORTHEAST SWELL FADES THROUGH TODAY AND WIND
SWELLS REMAIN SMALL DUE TO LIGHT SOUTHERLY FLOW DURING THE FIRST
HALF OF THE WEEK.
FIRE WEATHER
CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH THE
WEEK. EVEN THOUGH DAYTIME RELATIVE HUMIDITY VALUES MAY BRIEFLY
APPROACH CRITICAL LEVELS EARLY IN THE WEEK, WINDS WILL REMAIN
LIGHT AND PRECLUDE ANY FIRE WEATHER CONCERNS. INCREASING MOISTURE
AND RAINFALL TRENDS WILL DEVELOP THURSDAY INTO NEXT WEEKEND AS A
WEAKENING COLD FRONT MOVES DOWN THE ISLAND CHAIN, THEN DISSIPATES
NEAR MAUI COUNTY.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION/FIRE WEATHER...FARRIS
AVIATION...BEDAL
MARINE...ALMANZA
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