171
FXHW60 PHFO 141302
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
302 AM HST MON APR 14 2025
SYNOPSIS
BREEZY TRADE WINDS WILL CONTINUE TODAY AND GRADUALLY EASE
TOMORROW, WITH PASSING CLOUDS AND SHOWERS FAVORING WINDWARD AND
MAUKA AREAS. LIGHTER WINDS ARE EXPECTED BY THE MIDDLE OF THE WEEK
WITH FEWER WINDWARD SHOWERS AND A GREATER CHANCE FOR AFTERNOON
INTERIOR SHOWERS THROUGH THE WEEKEND. AN UPPER LEVEL TROUGH AND
DEEP ATMOSPHERIC MOISTURE WILL ENHANCE SHOWER ACTIVITY ON THURSDAY
AND FRIDAY AND BRING THE POTENTIAL FOR HEAVY RAINFALL.
DISCUSSION
THIS MORNING'S RADAR AND INFRARED SATELLITE IMAGERY SHOW A BIT
MORE SHOWER ACTIVITY COMPARED TO LAST EVENING, WITH SCATTERED
SHOWERS MOVING INTO WINDWARD AND MAUKA AREAS ACROSS THE ISLAND
CHAIN. HIGH PRESSURE CENTERED TO THE NORTHEAST OF THE STATE WILL
MAINTAIN BREEZY TRADE WINDS ACROSS THE REGION THROUGH TONIGHT,
CONTINUING TO FOCUS CLOUDS AND SHOWERS OVER WINDWARD AND MAUKA
AREAS. IN ADDITION, WATER VAPOR IMAGERY SHOWS A WEAK UPPER-LEVEL
LOW SPINNING OVER THE STATE, WHICH WILL PROVIDE A MODEST AMOUNT OF
INSTABILITY ALOFT. MODEL GUIDANCE SHOWS THAT THIS UPPER LOW WILL
GRADUALLY MOVE ACROSS THE STATE THROUGH TUESDAY CONTRIBUTING TO A
SLOW EASTWARD SPREADING OF WEAK INSTABILITY, WHICH MAY ALLOW FOR
THE ENHANCEMENT OF WINDWARD SHOWERS MOVING IN ON THE BREEZY
TRADES. SOME OF THESE SHOWERS COULD DELIVER BRIEF DOWNPOURS THAT
WILL OCCASIONALLY SPILL OVER INTO LEEWARD AREAS.
MID-LEVEL RIDGING WILL BRIEFLY BUILD OVERHEAD LATE TOMORROW INTO
EARLY WEDNESDAY IN ADVANCE OF A MID-LEVEL SHORTWAVE TROUGH THAT
WILL DIVE SOUTHEAST ACROSS THE CENTRAL PACIFIC AND BEGIN TO EDGE
OVER HAWAII BY WEDNESDAY NIGHT. AT THE SURFACE, A STRONG LOW
PRESSURE SYSTEM TO THE FAR NORTH WILL DISPLACE THE RIDGE THAT'S
BEEN ANCHORED TO OUR NORTHEAST TO BRING IT CLOSER TO, OR OVER, THE
ISLAND CHAIN. THE PROXIMITY OF THIS RIDGE AXIS AND THE APPROACH
OF A COLD FRONT FROM THE NORTHWEST WILL BRING LIGHTER SOUTHEAST
WINDS ACROSS THE AREA, ALLOWING LAND AND SEA BREEZES TO EXPAND IN
COVERAGE BEGINNING ON WEDNESDAY. THE SHORTWAVE TROUGH WILL DIVE
DOWN THE ISLAND CHAIN THROUGH THE LATTER PART OF THE WEEK BEFORE
IT OPENS UP AND WEAKENS HEADING INTO EARLY NEXT WEEK. THE MOST
FAVORABLE UPPER-LEVEL DYNAMICS ASSOCIATED WITH THE ORIENTATION OF
THE SHORTWAVE TROUGH, THE COOLEST TEMPERATURES ALOFT (AROUND
-12C), AND THE DEEPEST ATMOSPHERIC MOISTURE (PRECIPITABLE WATER
AROUND 1.6 INCHES) ALL SEEM TO LINE UP BEST ON THURSDAY AND
FRIDAY. AS SUCH, THE POTENTIAL FOR HEAVY SHOWERS WILL BE GREATEST
ON THURSDAY AND FRIDAY AFTERNOONS WITH THE SEA BREEZE ACTIVITY.
LIGHT WINDS WILL CONTINUE INTO THE WEEKEND AS THE MID-LEVEL
SHORTWAVE WEAKENS RESULTING IN EITHER A LAND/SEA BREEZE PATTERN
WITH MORE MUTED DIURNAL CONVECTION OR A HYBRID SEA BREEZE PATTERN
WHICH WILL TEND TO FOCUS SHOWERS OVER WESTERN SLOPES OF EACH
ISLAND.
AVIATION
BREEZY TRADE WINDS WILL STEER BANDS OF CLOUDS AND LIGHT SHOWERS
OFF THE PACIFIC TOWARDS THE ISLANDS. SHOWERS WILL BE MOST ACTIVE
IN THE LATE NIGHT AND MORNING HOURS AND FAVOR WINDWARD SLOPES AND
COASTS.
AIRMET TANGO REMAINS IN EFFECT FOR OCCASIONAL MODERATE TURBULENCE
BELOW 8000 FEET OVER AND ALONG THE LEE SIDE OF ALL HAWAIIAN
ISLANDS AND IS EXPECTED TO REMAIN NECESSARY THROUGH EARLY EVENING
AND POSSIBLY BEYOND.
MARINE
HIGH PRESSURE NORTHEAST OF THE STATE WILL MAINTAIN MODERATE TO
STRONG TRADES THROUGH TONIGHT. A SMALL CRAFT ADVISORY (SCA) IS NOW
IN EFFECT FOR THE EASTERN HALF OF THE MARINE AREA THROUGH 6 AM
TUESDAY. THE SCA MAY EVENTUALLY NEED TO BE EXTENDED THROUGH
TUESDAY FOR SOME ZONES ON THE BIG ISLAND FAVORED IN AN EAST-
SOUTHEAST FLOW. THE TRADES WILL GRADUALLY EASE TUESDAY AND TUESDAY
NIGHT, THEN BECOME FURTHER DISRUPTED WEDNESDAY THROUGH FRIDAY AS
A FRONT APPROACHES, STALLS OUT, AND DISSIPATES NORTHWEST OF THE
STATE. WINDS WILL BECOME LIGHT AND VARIABLE DURING THE MID TO LATE
WEEK TIME FRAME OVER THE WESTERN WATERS, WHILE WINDS OVER THE
EASTERN END OF THE STATE SHIFT OUT OF THE EAST-SOUTHEAST AT LIGHT
TO MODERATE SPEEDS.
A SMALL TO MODERATE SIZED NORTHWEST SWELL WILL GIVE A BOOST TO
SURF ALONG NORTH AND WEST FACING SHORES TODAY AND TONIGHT,
FOLLOWED BY A DECLINE TUESDAY AND WEDNESDAY. A NEW MODERATE-SIZED
NORTH-NORTHWEST SWELL WILL ARRIVE THURSDAY, POTENTIALLY BRINGING
ADVISORY LEVEL SURF TO NORTH AND WEST FACING SHORES THURSDAY NIGHT
AND FRIDAY, THEN SLOWLY LOWERING OVER THE WEEKEND.
EAST SHORE SURF WILL REMAIN AT OR JUST ABOVE AVERAGE THROUGH
TUESDAY, AND WILL BE RATHER ROUGH DUE TO THE STRONG TRADES,
TODAY. AS THE TRADES DIMINISH DURING THE SECOND HALF OF THE WEEK,
SURF ALONG EAST FACING SHORES WILL DROP BELOW NORMAL.
SURF ALONG SOUTH FACING SHORES WILL REMAIN SMALL AND MOSTLY AT
BACKGROUND LEVELS THROUGH THURSDAY. A SERIES OF SMALL OVERLAPPING
SOUTH SWELLS COULD BRING SURF UP TO SEASONAL LEVELS FRIDAY
THROUGH NEXT WEEKEND.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST TUESDAY FOR KAIWI CHANNEL-
MAUI COUNTY WINDWARD WATERS-MAUI COUNTY LEEWARD WATERS-MAALAEA
BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND WINDWARD
WATERS-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.
DISCUSSION...FARRIS
AVIATION...BEDAL
MARINE...JELSEMA
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