Area Forecast Discussion
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000
FXPQ60 PGUM 260533
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
329 PM CHST MON JAN 26 2015

.SYNOPSIS...
STREAM LINE ANALYSIS SHOWS A ROBUST SHEAR LINE STILL NORTH OF
MARIANAS WATERS WITH ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...WINDS NORTH OF THE SHEAR LINE HAVE DECREASED IN THE PAST
12 HOURS INDICATING THAT THE SHEAR LINE IS WEAKENING. A TRADE-
WIND REGIME EXISTS OVER AND UPSTREAM OF THE MARIANAS WITH RADAR
SHOWING ONLY A FEW PASSING LIGHT SHOWERS.

&&

.DISCUSSION...
REPOPULATED MOST FORECAST GRIDS WITH LATEST AVAILABLE MODEL
GUIDANCE WHILE MANUALLY ADJUSTING SOME GRIDS AS REQUIRED.
HOWEVER...ONLY MINOR CHANGES WERE MADE OVERALL. THE SHEAR LINE
ACROSS THE NORTHERN MARIANAS APPEARS TO BE WEAKENING WIND-WISE
BASED ON THE MOST RECENT SCATTEROMETER PASS. A DRY TRADE-WIND
PATTERN HAS SET UP OVER THE REGION SOUTH OF THE SHEAR LINE AND IS
EXPECTED TO PERSIST FOR THE NEXT SEVERAL DAYS. BOTH THE GFS AND
ECMWF SHOW A SUBTROPICAL AIR MASS ARRIVING LATE THIS WEEK WHICH
COULD RESULT IN A SLIGHT REDUCTION IN TEMPERATURES AND LOWER
RELATIVE HUMIDITIES BY THE WEEKEND.

&&

.MARINE...
RITIDIAN BUOY INDICATED COMBINED SEAS CLIMBED TO 10 FEET
OVERNIGHT. SEAS ARE BEGINNING TO FALL BUT NORTH SWELL COMBINED
WITH NORTHEAST SWELL AND WIND WAVES GENERATED BY THE SHEAR LINE
WILL RESULT IN HAZARDOUS SURF ALONG NORTH FACING REEFS THROUGH
TUESDAY MORNING. WAVE MODEL GUIDANCE SHOWS A STEADY DECREASE IN
SEAS TONIGHT SO SURF ADVISORY MAY NEED TO BE CANCELLED SOONER IF
DATA AND GUIDANCE SUPPORTS DOING SO.

&&

.EASTERN MICRONESIA...
A NEAR-EQUATORIAL TROUGH PERSISTS JUST SOUTH OF CHUUK...POHNPEI
AND KOSRAE TODAY. MODERATE TO FRESH TRADE WINDS DOMINATE WEATHER
AT THESE FORECAST POINTS...ALSO AT MAJURO. THIS PATTERN IS
EXPECTED TO PERSIST FOR THE NEAR TERM AT LEAST...WHILE A TRADE-
WIND CONVERGENCE ZONE UPSTREAM EAST OF THE DATE LINE MOVES
WESTWARD CAUSING SOME SHOWERS AT MAJURO AND KOSRAE BY MIDWEEK...
THEN POHNPEI AND CHUUK TOWARD THE WEEKEND.

LARGE TRADE-WIND WAVES AND SWELL WILL SUSTAIN HAZARDOUS SURF ON
KOSRAE FOR THE NEXT SEVERAL DAYS. SEAS ACROSS THE MARSHALL ISLANDS
WILL BE HAZARDOUS FOR SMALL CRAFT OPERATION THRU MIDWEEK. SEAS NEAR
POHNPEI AND CHUUK WILL BEGIN TO RISE ON TUESDAY WHICH MIGHT BECOME
HAZARDOUS FOR SMALL CRAFT AS WELL.

&&

.WESTERN MICRONESIA...
DISCUSSION FOR THE CHUUK FORECAST IS INCLUDED IN THE EASTERN
MICRONESIA SECTION DUE TO A SIMILAR PATTERN.

BOTH KOROR AND YAP ARE BETWEEN SIGNIFICANT SYNOPTIC-SCALE WEATHER
FEATURES. A SHEAR LINE IS FAR TO THE NORTH AND A NEAR-EQUATORIAL
TROUGH IS FAR TO THE SOUTH. THIS DRY TRADE-WIND PATTERN IS EXPECTED
TO CONTINUE THROUGH THIS WEEK.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL 10 AM CHST TUESDAY FOR GUZ001>004.

MARIANAS WATERS...NONE.
&&

$$

WILLIAMS/SIMPSON



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