Area Forecast Discussion
Issued by NWS Pago Pago

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000
FXZS60 NSTU 220050
AFDPPG

AREA FORECAST DISCUSSION FOR AMERICAN SAMOA AND INDEPENDENT SAMOA
NATIONAL WEATHER SERVICE PAGO PAGO AS
150 PM SST SUN MAY 21 2017

.SHORT TERM...
TONIGHT THROUGH TUESDAY NIGHT...LATEST SATELLITE IMAGERY SHOWS A
CLUSTER OF SHOWERY CLOUDS CONCENTRATED SOUTH OF THE SAMOAN
ISLANDS. MODEL OUTPUT SHOWS THESE CLOUDS MARKING A SURFACE TROUGH
THAT WILL SLOWLY MERGING WITH A DEEPENING LOW NEAR FIJI ISLANDS BY
MONDAY. WHILE ALL THE MOISTURE IS CONVERGING TOWARD THIS LOW...A
SURFACE RIDGE BUILDS CLOSE TO THE TERRITORY...BRINGING LESS
RAINFALL ACROSS THE FORECAST AREA WITH MODERATE TO FRESH
EASTERLIES TONIGHT THROUGH MONDAY NIGHT. BY TUESDAY
MORNING...GENTLE TO MODERATE WINDS ARE EXPECTED TO BECOME MORE
NORTHERLY AS BOTH THE AFOREMENTIONED LOW AND THE RIDGE MOVE EASTWARD.

.LONG TERM...
WEDNESDAY THROUGH SUNDAY...CURRENT MODEL DATA SHOW THE
AFOREMENTIONED LOW STARTING A SOUTHEASTWARD MOVEMENT IN THE LONG
TERM...WHILE THE AFOREMENTIONED RIDGE CONTINUES TO MOVE EASTWARD.
LIGHT AND VARIABLE WINDS ARE EXPECTED TO PREVAIL AS PRESSURE
GRADIENTS ARE MORE RELAXED. PERIODS OF SHOWERS ARE STILL POSSIBLE
ACROSS THE ISLAND CHAIN AS A SURFACE TROUGH LINGERS CLOSE TO THE
ISLANDS.

&&

.MARINE...
CURRENT WAVE BUOY OBSERVATIONS SHOW HEIGHTS STILL STRADDLING
ADVISORY CRITERIA TODAY. THIS IS WHY THE ADVISORIES FOR SMALL
CRAFTS AND HIGH SURFS WERE NOT CANCELLED THIS MORNING.
ADDITIONALLY...SINCE THE TREND IN HEIGHTS ARE UPWARD TONIGHT AS A
SOUTHERLY SWELL REACHES COASTAL WATERS...DID NOT WANT TO CONFUSE
THE PUBLIC BY THE QUICK CANCELLATION AND REISSUANCE OF THESE
ADVISORIES. LATEST WAVE WATCH III SOLUTIONS SHOW THE SOUTHERLY
SWELL PEAKING MONDAY NIGHT THROUGH TUESDAY NIGHT AT 9 TO 12 FEET.
SOME MODELS SHOW THE PERIOD EXCEEDING 16 SECONDS...WHICH WILL
LIKELY EXCEED WARNING THRESHOLDS. WILL CONTINUE TO MONITOR AUNUU
WAVE BUOY OBSERVATIONS MONDAY MORNING...AND IF OBSERVATIONS EXCEED
MODEL HEIGHTS AS WAS THE CASE IN THE PAST...WILL UPGRADE THE
ADVISORY FOR HIGH SURFS TO A WARNING. UNTIL THEN...THE ADVISORIES
FOR SMALL CRAFTS AND HIGH SURFS REMAIN THROUGH AT LEAST THURSDAY.

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY REMAINS IN EFFECT
SMALL CRAFT ADVISORY REMAINS IN EFFECT

&&

$$

LUTU-MCMOORE





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