400
FXHW60 PHFO 021422
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
422 AM HST MON JUN 2 2025
SYNOPSIS
SURFACE HIGH PRESSURE LOCATED FAR NORTHEAST OF THE ISLANDS IS
STILL THE MAIN DRIVER TO THESE RECENT LIGHT TO LOCALLY BREEZY
WINDS. A WEAK SURFACE TROUGH WEST OF THE STATE WILL MAINTAIN AN
EAST TO SOUTHEAST COMPONENT TO THE WINDS EARLY TODAY. ENERGY
DIVING INTO A BROAD UPPER LEVEL TROUGH WEST OF THE STATE, WITH
HIGHER MOISTURE STREAMING IN FROM THE SOUTHWEST AHEAD OF THIS
TROUGH, WILL INCREASE THE CHANCE OF MORE FREQUENT SHOWER ACTIVITY
OVER THE WESTERN HALF OF THE ISLAND CHAIN TODAY. AN EAST SOUTHEAST
FLOW PATTERN THIS AFTERNOON WILL LIKELY FOCUS SHOWERS ALONG MORE
EASTERN-FACING EXPOSURES AND MAUKA SLOPES. SHELTERED LEEWARD
AREAS WILL EXPERIENCE DAYTIME SEA BREEZE-INDUCED THICKER CLOUDS
AND INTERMITTENT RAIN. TRADES WILL RETURN BY TUESDAY NIGHT AND
THIS WILL FOCUS SHOWERS OVER WINDWARD-FACING UPSLOPE MAUKA AND
WITHIN HIGHER TERRAIN. THIS TYPICAL TRADE PATTERN WILL HOLD
THROUGH THE REMAINDER OF THE WEEK.
DISCUSSION
EARLY MORNING SHORTWAVE INFRARED SATELLITE AND RADAR IMAGERY
CONTINUE TO SHOW THE DOMINANT EAST SOUTHEAST STEERING FLOW IN THE
LOWER LEVEL CLOUD FIELD AND THE WIDELY SCATTERED SHOWER ACTIVITY,
RESPECTIVELY. THE SLIGHTLY VEERED SOUTHEAST WIND PROFILE IS A
RESULT OF A BROAD UPPER TROUGH AND WEAK SURFACE REFLECTION LOCATED
JUST WEST NORTHWEST OF HAWAII. A DENSE CIRRUS DECK SHROUDS THE
MAJORITY OF THE ISLAND CHAIN AS SOUTHWESTERLY MOISTURE RIDES UP
AHEAD OF THIS BROAD TROUGHING. A DOMINANT RIDGE CENTERED FAR NORTH
NORTHEAST OF THE REGION IS STILL THE MAIN DRIVER TO THIS
GENERALLY EAST TRADE WIND PATTERN. ENERGY DIVING SOUTH INTO THE
WEST TROUGH CREATING MORE EFFICIENT UPPER DIVERGENCE DOWNSTREAM OF
THE NEAR MERIDIONAL TROUGH AXIS, WILL MAINTAIN HIGHER RAIN
CHANCES OVER KAUAI AND SURROUNDING WATERS.
LIGHT TO LOCALLY BREEZY EAST TO SOUTHEASTERLY LOW LEVEL FLOW
PATTERN IS EXPECTED TO CONTINUE THROUGH THE DAY. CLOUDS AND
SHOWERS WILL FAVOR WINDWARD AND MAUKA AREAS DURING THE OVERNIGHT
TO EARLY MORNING HOURS...SEA BREEZES DEVELOPING OVER LEEWARD AND
INTERIOR AREAS DURING THE AFTERNOON HOURS WILL INCREASE DAYTIME
SHOWERS OVER THESE COMMUNITIES. THIS FLOW MAY ALSO CREATE LOW
LEVEL CONVERGENT BOUNDARIES, OR PLUMES, THAT WILL FORM DOWNSTREAM
OF EACH ISLAND. THESE PLUMES COULD BE THE CATALYST TO HIGHER
RAINFALL ACROSS NEIGHBORING DOWNSTREAM ISLANDS DUE TO MORE
PARALLEL FLOW ALONG THE ISLAND CHAIN. ENHANCED SHOWER ACTIVITY MAY
OCCUR ACROSS THE WESTERN END OF THE STATE INTO THE LATE AFTERNOON
HOURS DUE TO HIGHER INSTABILITY ALOFT AND LOW LEVEL MOISTURE
UPPER TROUGHING DIGS FURTHER SOUTHWARD WEST OF KAUAI.
A RETURN TO BREEZY AND MORE STABLE TRADE WIND WEATHER IS EXPECTED
TONIGHT AS UPPER RIDING EXPANDING IN FROM THE NORTHEAST INCREASES
HEIGHTS IN TANDEM WITH DRIER MID LAYER AIR ADVECTING IN FROM THE
EAST. A EASTERLY TRADE WIND PATTERN WILL HOLD THROUGH THE MIDDLE
OF THE WEEK WITH SHOWERS FAVORING WINDWARD AND MAUKA AREAS...
PRIMARILY DRY CONDITIONS WILL PREVAIL ELSEWHERE. FOR THE LATTER
PART OF THE WEEK, TRADES WILL SLIGHTLY EASE AS WEAK UPPER LEVEL
TROUGHING MOVES OVERHEAD AND ANOTHER BROAD SURFACE TROUGH DEVELOPS
WEST OF THE STATE. HOWEVER, THE INSTABILITY ASSOCIATED WITH THE
TROUGH ALOFT AND THE AVAILABLE MOISTURE LOOK RATHER MEAGER. THUS,
NOT MUCH MORE THAN PERHAPS A SLIGHT ENHANCEMENT OF TRADE WIND
SHOWERS IS FORECAST FOR THE END OF THE FORECAST PERIOD.
VOG WILL CONTINUE TO FILTER ACROSS THE ISLAND CHAIN TRAPPED
WITHIN EASTERLY FLOW, TRANSITIONING WEST AND FURTHER SOUTH OF THE
SMALLER ISLANDS BY THE MIDDLE OF THE WEEK AS THE TRADES RETURN.
AVIATION
MODERATE TO LOCALLY BREEZY EAST-SOUTHEASTERLY WINDS SHOULD
PERSIST THROUGH THE REST OF TODAY AND LATE TONIGHT MOVE BACK TO A
MORE TYPICAL TRADE WIND PATTERN. TROUGHING TO THE WEST OF THE
ISLANDS HAS SIGNIFICANTLY INCREASED HIGH CLOUDS WHICH HAS ALSO
SUPPORTED OCCASIONAL SHRA AS MOISTURE EMBEDDED WITHIN THE ESE FLOW
MOVES OVER THE ISLANDS. LOW CIGS AND SHRA HAVE ON OCCASION
PRODUCED IFR/MVFR CONDS. VFR PREVAILS OUTSIDE OF ANY HEAVIER SHRA.
AIRMET SIERRA REMAINS IN EFFECT FOR MTN OBSC OVER KAUAI AND OAHU.
IT IS ALSO IN EFFECT FOR WINDWARD BIG ISLAND.
AIRMET TANGO IS IN EFFECT FOR MOD LOW-LEVEL TURB BLW 080 DOWNWIND
OF ISLAND TERRAIN. IT IS ALSO IN EFFECT FOR MOD TURB ABV FL250.
MARINE
FRESH EAST SOUTHEAST WINDS WILL OCCUR TODAY IN RESPONSE TO AN
UPPER LOW AND ASSOCIATED SURFACE TROUGH WEST OF HAWAII. THE TROUGH
WILL MOVE WESTWARD AND ALLOW SURFACE RIDGING TO EXPAND DOWN FROM
THE NORTH. THIS WILL RESULT IN TRADE WINDS BACKING TO A MORE
EASTERLY DIRECTION THROUGH THE DAY. A SMALL CRAFT ADVISORY (SCA)
IS IN EFFECT FOR WINDS OVER THE TYPICAL WINDY WATERS IN ADDITION
TO THE WINDWARD MAUI WATERS THROUGH TONIGHT. THE SCA WILL BE IN
EFFECT FOR THE TYPICALLY WINDY WATERS SURROUNDING MAUI AND BIG
ISLAND THROUGH TUESDAY NIGHT.
THE LATE SEASON NORTHWEST SWELL WILL CONTINUE ITS DECLINE THROUGH
THE DAY WITH NORTH AND WEST-FACING SHORE SURF DROPPING TO NEAR
JUNE AVERAGES BY TUESDAY.
SURF ALONG SOUTH-FACING SHORES WILL CONTINUE TO SEE A MIX OF SMALL
BACKGROUND SWELL THE NEXT FEW DAYS, FOLLOWED BY SMALL SOUTHWEST
SWELLS LATE TUESDAY AND WEDNESDAY. A LARGER, LONGER PERIOD SOUTH
SOUTHWEST SWELL WILL BUILD IN FRIDAY AND PEAK OVER THE WEEKEND.
THIS SHOULD PRODUCE ABOVE SEASONAL AVERAGE SURF ALONG MANY
SOUTHERN BEACHES.
EAST-FACING SHORE SURF WILL GRADUALLY BUILD TO NEAR OR ABOVE
SEASONAL AVERAGES THROUGH WEDNESDAY DUE TO FRESH TO LOCALLY STRONG
TRADES OVER AND UPSTREAM OF THE ISLANDS.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST TUESDAY FOR MAUI COUNTY
WINDWARD WATERS-BIG ISLAND WINDWARD WATERS.
SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...BLOOD
AVIATION...WALSH
MARINE...BLOOD
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page