Area Forecast Discussion
Issued by NWS Pago Pago

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FXZS60 NSTU 250124 CCA

Area Forecast Discussion...CORRECTED
National Weather Service Pago Pago  AS
224 PM SST Thu May 24 2018

.Short term...
.TONIGHT THROUGH SATURDAY NIGHT...Dry subsidence air will linger
to the north of Swains through tonight. Moderate easterlies
combined with strong upper-level winds will provide scattered
mid-morning to afternoon showers through the end of the week.
Currently, a mid-level ridge near Manu`a and Tutuila will drift
southward tonight before retracting north and across the area
through Saturday night. Thus, warm overnight temperatures are
expected through short term.

.Long term...
.SUNDAY THROUGH THURSDAY...The main concern here will be the
rainfall coverage on Sunday night through Monday as an expected
surface trough from the WSW moves across the region. GFS brings
increasing moisture over the main Samoan Islands as a reflection
of the expected surface trough axis. Interestingly, a mid-level
ridge hanging to the north of the main Samoan Islands will either
impact the location or movement of the expected trough unless it
dissipates. For now, will monitor this situation before making new


.Marine...A series of expected large southwest swells with long
periods up to 17 seconds will arrive on Friday, then increasing
to near 18 to 20 seconds by Saturday night. This situation will
cause seas and surf heights to exceed advisory thresholds, and
this event will require issuance of advisories for high surfs and
small crafts through the weekend into early next week.





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