604
FXHW60 PHFO 131319
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
319 AM HST SUN JUL 13 2025
SYNOPSIS
A TIGHT EASTERN PACIFIC PRESSURE GRADIENT CREATED FROM HIGH
PRESSURE LOCATED FAR NORTHEAST OF HAWAII WILL MAINTAIN MODERATE TO
LOCALLY BREEZY TRADE WINDS THE NEXT SEVERAL DAYS. SCATTERED CLOUDS
AND SHOWERS WILL MAINLY FOCUS ALONG WINDWARD EXPOSURES AND UPSLOPE
MAUKA. AN INCREASE IN SHOWER ACTIVITY WILL OCCUR MONDAY AFTERNOON
INTO TUESDAY.
DISCUSSION
THIS WEEK KICKS OFF WITH A LULL IN BOTH SHOWER ACTIVITY AND TRADE
WIND STRENGTH. THE PRIMARY REASONING FOR THIS MINOR DROP OFF IN
WINDS WILL BE THAT THE 1033 MB HIGH LOCATED APPROXIMATELY 1,500
MILES NORTHEAST OF THE ISLANDS WILL SUBTLY ADVANCE A TOUCH FURTHER
NORTHWARD THROUGH MONDAY. THIS MINOR MOVEMENT OF THE HIGH WILL
MAINTAIN A TIGHT ENOUGH DOWNSTREAM PRESSURE GRADIENT TO STILL
PRODUCE ISLAND-WIDE BREEZY TRADES ACROSS MANY OPEN EXPOSURES,
HIGHER TERRAIN AND THROUGH NARROW CHANNELS. SLIGHTLY DRIER AIR
MOVING THROUGH THIS MORNING WILL INITIATE A PERIOD OF RELATIVELY
LESS SHOWER ACTIVITY. OF COURSE, THERE WILL BE THE SCATTERED
SHOWERS OF LOW ACCUMULATION THAT INTERMITTENTLY PASS ACROSS
WINDWARD LOCALES, WITH THE OCCASIONAL SHOWER SPILLING OVER INTO
LEEWARD COMMUNITIES. THE DISCLAIMER EXCEPTION WILL BE AFTERNOON
SHOWERS THAT FORM ALONG BIG ISLAND'S KONA SLOPES. TODAY'S OVERALL
THEME WILL BE WARM AND BREEZY UNDER PARTLY CLOUDY SKIES.
RIBBONS OF INCREASED MOISTURE WILL PASS OVER THE ISLANDS MONDAY
AFTERNOON INTO TUESDAY. EXPECT AN INCREASE IN SHOWERS ON WINDWARD
BIG ISLAND MIDDAY MONDAY, THEN SHOWERS WILL SPREAD INTO THE
CENTRAL ISLANDS MONDAY NIGHT...PUSHING WEST INTO OAHU AND KAUAI
EARLY TUESDAY. AS THE UPPER LEVEL LOW CURRENTLY CHURNING SEVERAL
HUNDRED MILES NORTH OF THE STATE RETREATS FURTHER NORTH MONDAY,
MID TO UPPER LEVEL RIDGING WILL FILL IN ITS WAKE. THIS WILL SET
THE STAGE FOR SEVERAL DAYS OF STABLE, TYPICAL DRY SUMMER-LIKE
WEATHER. MODERATE TRADES WILL BE MAINSTAY FOR THE MAJORITY OF
THE WEEK, POSSIBLY BECOMING LOCALLY FRESH THROUGH EASTERN ISLAND
BAYS AND CHANNELS BY THE MIDDLE OF THE WEEK. THE EASTERN UPSTREAM
AIR MASS WILL BE NEAR TO SLIGHTLY BELOW NORMAL PER LATE JULY'S
MOISTURE STANDARDS. SO, THICKER CLOUDS AND THE BULK OF MID TO
LATE WEEK SHOWER ACTIVITY WILL BE THE RESULT OF TOPOGRAPHIC
ENHANCEMENT. THE CENTER OF THE NORTHEAST PACIFIC HIGH MAY DRIFT OR
EXPAND CLOSER TO THE STATE LATER IN THE WEEK, RE-TIGHTENING THE
LARGE SCALE GRADIENT AND RESULTING IN A SLIGHT UPTICK IN TRADE
WINDS.
AVIATION
MODERATE TRADES WILL PERSIST THROUGH THE DAY. CLOUDS AND SHOWERS
WILL GENERALLY FAVOR WINDWARD AND MOUNTAIN AREAS ACROSS ALL
ISLANDS AND MAY RESULT IN MVFR CONDITIONS AT TIMES. LOW CLOUDS AND
SHOWERS WILL LIKELY PERSIST FOR WINDWARD AREAS OF MOST ISLANDS
THROUGH THE AFTERNOON AND EVENING AS A BAND OF MOISTURE MOVES
THROUGH THE ISLAND CHAIN FROM THE EAST. OTHERWISE, VFR CONDITIONS
WILL GENERALLY PREVAIL.
MARINE
THE HIGH PRESSURE RIDGE WILL WEAKEN NORTH OF THE HAWAIIAN ISLANDS,
DECREASING TRADE WINDS SPEEDS THROUGH MONDAY. THE RIDGE WILL
STRENGTHEN FROM TUESDAY ONWARD INCREASING TRADE WIND SPEEDS BACK
INTO THE MODERATE TO LOCALLY STRONG RANGE THROUGH THE END OF THIS
WEEK. WIND SPEEDS WILL REMAIN JUST BELOW SMALL CRAFT ADVISORY
(SCA) LEVELS THROUGH THE WINDER EASTERN ISLAND BAY AND CHANNELS THIS
MORNING. SCA CONDITIONS MAY RETURN BY TUESDAY AS WIND SPEEDS
INCREASE OVER THESE NOTORIOUSLY WINDIER ZONES.
SURF ALONG SOUTH FACING SHORES WILL REMAIN SMALL TODAY AS SMALL
BACKGROUND SOUTH SOUTHWEST SWELL ENERGY MOVES THROUGH THE REGION.
A SMALL, LONG PERIOD SOUTH SWELL WILL ARRIVE LATER TONIGHT INTO
MONDAY MORNING AND PEAK LATE MONDAY INTO TUESDAY. SOUTH SWELL
ENERGY WILL GRADUALLY DIMINISH THROUGH THURSDAY. THE NEXT SMALL
LONG PERIOD SOUTH SWELL ARRIVES LATE FRIDAY AND WILL BOOST SOUTH
SHORE SURF INTO NEXT WEEKEND.
WIND WAVE DRIVEN SURF HEIGHTS ALONG EAST FACING SHORES WILL
REMAIN ON THE SMALL AND CHOPPY SIDE TODAY, THEN INCREASE SLIGHTLY
THROUGH MIDWEEK AS TRADE WIND SPEEDS STRENGTHEN. A VERY SMALL
NORTHWEST SWELL MAY PASS THROUGH EARLY NEXT WEEK, PROVIDING TINY
SURF ALONG NORTH FACING SHORES ON MONDAY AND TUESDAY BEFORE
BECOMING NEARLY FLAT THROUGH THE REMAIN FORECAST PERIOD.
FIRE WEATHER
TRADE WINDS WILL REMAIN IN THE MODERATE TO LOCALLY BREEZY THE NEXT
SEVERAL DAYS. WHILE THE ATMOSPHERE WILL BE RATHER DRY ON THROUGH
EARLY MONDAY, EXPECT TYPICAL SUMMER TIME FIRE WEATHER CONDITIONS.
HIGHER HUMIDITY IS FAVORED LATER MONDAY INTO TUESDAY, FOLLOWED BY
A RETURN TO DRIER AND TYPICAL LATE JULY CONDITIONS GOING INTO THE
MIDDLE OF THE WEEK.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...BLOOD
AVIATION...BLOOD
MARINE...BOHLIN
FIRE...BLOOD
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