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000
FXPQ60 PGUM 240602
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
402 PM CHST FRI MAY 24 2013

.SYNOPSIS...
A SURFACE TROUGH NORTH OF THE MARIANAS CONTINUES TO GENERATE A
SW-NE ORIENTED BAND OF SHOWERS AND POSSIBLE THUNDERSTORMS ACROSS
THE FAR NORTHERN MARIANAS ISLANDS. FARTHER SOUTH...SATELLITE
IMAGERY SHOWS VERY DRY CONDITIONS ACROSS GUAM AND THE CNMI WITH
VIRTUALLY NO CLOUDS OBSERVED.

&&

.DISCUSSION...
SHOWER ACTIVITY ASSOCIATED WITH THE SURFACE TROUGH NORTH THE CNMI
WILL PROGRESS WESTWARD AND WILL NOT AFFECT THE MARIANAS REGION.
GENTLE TRADE WINDS AND ISOLATED SHOWERS ARE EXPECTED TO CONTINUE
THROUGH AT LEAST EARLY NEXT WEEK AS MODELS SHOW A PERSISTENT QUIET
WEATHER PATTERN DOMINATING A LARGE PART OF THE WESTERN PACIFIC
NORTH OF 10N. MODELS HINT AT INCREASING MOISTURE FROM THE
SOUTHEAST BY LATER NEXT WEEK.

&&

.EASTERN MICRONESIA...
A SERIES OF WEAK SURFACE TROUGHS ARE EMBEDDED WITHIN THE ZONE OF
TRADE-WIND CONVECTION SPANNING EASTERN MICRONESIA. BIGGEST CHANGE TO
THE FORECAST PACKAGE INVOLVED THE FIRST PERIOD FORECAST FOR MAJURO.
A WEAK SURFACE TROUGH JUST TO THE WEST OF MAJURO IS SERVING TO FOCUS
CONVECTION NEAR AND EAST OF MAJURO. GFS BEST CAPTURES THIS SETUP SO
WENT WITH THE GFS SOLUTION AND ADDED SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS TO FIRST PERIOD FORECAST FOR MAJURO. AWIPS DISTANCE
SPEED TOOL INDICATED CONVECTIVE BOUNDARIES MOVING WESTWARD AT
AROUND 15 KT BETWEEN KOSRAE AND POHNPEI...SO INCREASED WINDS FIRST
TWO PERIODS FOR THESE LOCATIONS. OTHERWISE...FORECAST CLOSELY
FOLLOWS PERSISTENCE. MODEL GUIDANCE CONSENSUS CALLS FOR BAND OF
TRADE-WIND CONVECTION TO DIMINISH AS THE TRADE-WIND SURGE CROSSES
INTO WESTERN MICRONESIA EARLY NEXT WEEK.

&&

.WESTERN MICRONESIA...
SYNOPTIC SETUP INVOLVES NOT VERY MUCH TO WRITE HOME ABOUT. DEEP-
LAYER RIDGING REMAINS IN CONTROL. A VERY WEAK INVERTED SURFACE
TROUGH IS PASSING SOUTH OF YAP. A NEAR-EQUATORIAL TROUGH LIES WELL
TO THE WEST OF KOROR NEAR MINDANAO. MODEL SOLUTIONS SUGGEST A
TRADE-WIND SURGE WILL BRING MORE UNSETTLED CONDITIONS TO CHUUK ON
SUNDAY. A PERIOD OF SCATTERED SHOWERS WILL BE POSSIBLE FOR CHUUK
FROM MONDAY UNTIL AT LEAST WEDNESDAY. SURGE PETERS OUT AS IT
TRANSLATES WESTWARD TOWARD YAP AND KOROR AS RIDGING REMAINS IN
CONTROL. GFS HINTS AT A WEAK NEAR-EQUATORIAL TROUGH FORMING NEAR
KOROR AND TO THE SOUTH OF YAP BY THE MIDDLE OF NEXT WEEK. WILL
MAINTAIN A DRY BIAS FOR THESE FORECAST POINTS UNLESS LATER MODEL
SOLUTIONS CONVERGE TOWARD THIS NEW FORECAST SCENARIO.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...NONE.
&&

$$

WILLIAMS/MCELROY