239
FXZS60 NSTU 060100
AFDPPG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PAGO PAGO AS
200 PM SST FRI JUN 5 2026
SHORT TERM [TONIGHT THROUGH SUNDAY NIGHT]
00Z RAOB UPPER-AIR OBSERVATION THIS AFTERNOON CONTINUES TO REVEAL
A VERY DRY AND STABLE ATMOSPHERIC PROFILE WITH A MID-LEVEL
TEMPERATURE INVERSION. ANY CONVECTION THAT DOES OCCUR IN THIS
ENVIRONMENT WOULD BE BRIEF AND SHALLOW, UNABLE TO BUILD ABOVE THE
STABLE INVERSION LAYER. A DEVELOPING EQUATORIAL SURFACE TROUGH IS
OBSERVED ON SATELLITE TO THE NORTH OF THE TERRITORY. SURFACE HIGH
PRESSURE TO THE SOUTH WILL CONTINUE TO HOLD THIS TROUGH NORTH OF
THE ISLANDS THROUGH THE PERIOD, BRINGING STABLE WEATHER
CONDITIONS AND BREEZY TRADE WINDS FOR AMERICAN SAMOA. THE RIDGE
OF HIGH PRESSURE TO THE SOUTH WILL SLOWLY MIGRATE EASTWARD,
GRADUALLY DECREASING TRADE WINDS TO AROUND 10 MPH BY SUNDAY. ALL
AVAILABLE DATA POINTS TOWARDS A SIMILAR EVOLUTION MAKING
CONFIDENCE IN THE FORECAST FOR THE SHORT TERM FORECAST PERIOD
VERY HIGH: BELOW AVERAGE RAINFALL WITH ANY ISOLATED SHOWERS BEING
BRIEF IN NATURE AS TRADE WINDS GRADUALLY WEAKEN INTO SUNDAY
LONG TERM [MONDAY THROUGH FRIDAY]
A NEW RIDGE OF HIGH PRESSURE CURRENTLY DEVELOPING OVER AUSTRALIA
WILL PUSH EASTWARD INTO THE SOUTHWEST PACIFIC BASIN AND DRIVE THE
WEATHER PATTERN FOR THE LONG TERM FORECAST PERIOD. THIS RIDGE IS
FORECAST TO BEGIN BUILDING SOUTHEASTERLY SURFACE TRADE WINDS OVER
AMERICAN SAMOA BY MONDAY, NEARING 30 MPH BY LATE TUESDAY AND
REMAINING STRONG FOR THE REST OF THE WEEK. THIS RIDGE SHOULD HOLD
THE AFOREMENTIONED EQUATORIAL TROUGH NORTH OF AMERICAN SAMOA
THROUGH THE FIRST HALF OF THE WEEK. HOWEVER, THE RIDGE IS
FORECAST TO PUSH ANOTHER TROUGH THAT IS CURRENTLY NEAR NEW
ZEALAND AND VANUATU EASTWARD AND INTO THE AREA BY EARLY NEXT
WEEK. MODELS DEPICT THAT THIS TROUGH WILL WEAKEN SIGNIFICANTLY
BEFORE REACHING THE SAMOAN ISLANDS, BUT SHOULD STILL INCREASE
ATMOSPHERIC MOISTURE ENOUGH TO INCREASE RAIN CHANCES TO SCATTERED
EARLY NEXT WEEK.
BY MIDWEEK, THE EQUATORIAL TROUGH TO THE NORTH IS FORECAST TO
STRENGTHEN AS EQUATORIAL LOW PRESSURE PUSHES THE TROUGH SOUTHWARD
AND NEAR THE AMERICAN SAMOA ISLANDS BY THE LATTER HALF OF THE
WEEK. NUMEROUS TO WIDESPREAD SHOWERS ARE LIKELY FOR THE THURSDAY
THROUGH FRIDAY TIMEFRAME. IT IS TOO EARLY TO DETERMINE IF THIS
TROUGH WILL BRING A THREAT FOR FLASH FLOODING DUE TO HEAVY
UNCERTAINTIES IN IT'S EXACT PROGRESSION AT THIS EXTENDED RANGE.
MARINE
TODAY'S MARINE OBSERVATIONS FROM AUNU'U BUOY INDICATE WAVE
HEIGHTS OF AROUND 7 TO 8 FEET DRIVEN BY THE MODERATE TO FRESH
SOUTHEASTERLY BREEZE. THIS MAY MAKE MARINE NAVIGATION DIFFICULT,
ESPECIALLY FOR INEXPERIENCED MARINERS OPERATING SMALLER VESSELS.
SEAS SHOULD SLOWLY SUBSIDE TO BELOW ADVISORY LEVELS BY SATURDAY
NIGHT INTO SUNDAY AS TRADE WINDS GRADUALLY WEAKEN.
FAVORABLE SEA CONDITIONS ARE EXPECTED LATE THIS WEEKEND THROUGH
EARLY TUESDAY. AS STRONG SOUTHEASTERLIES BUILD BY LATE TUESDAY,
SEAS WILL BEGIN BUILDING AGAIN. SEAS AND SURFS ARE FORECAST TO
BUILD TO HAZARDOUS LEVELS BY WEDNESDAY WITH HIGH SURF WARNING
ISSUANCE BEING POSSIBLE BY MID TO LATE WEEK.
PPG WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY REMAINS IN EFFECT
BARTON
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