279  
FXPQ50 PGUM 030815  
AFDGUM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TIYAN GU  
615 PM CHST WED JUN 3 2020  
   
MARIANAS SYNOPSIS
 
 
PARTLY CLOUDY SKIES, ISOLATED SHOWERS AND MODERATE TRADE WINDS ARE  
PRESENT ACROSS THE MARIANAS. SEAS OF 2 TO 4 FEET ARE INDICATED AT THE  
BUOYS.  
 

 
   
DISCUSSION
 
 
MODELS HAVE CHANGED VERY LITTLE THE LAST COUPLE OF RUNS, AND SO THE  
FORECAST IS UNCHANGED AS WELL. GFS STILL GRAZES GUAM WITH SCATTERED  
SHOWERS ASSOCIATED WITH A TROUGH PASSING SOUTH OF GUAM ON SATURDAY,  
AND ISOLATED THUNDERSTORMS ARE STILL POSSIBLE FOR THE MARIANAS  
FRI-SAT. OTHERWISE, ONLY ISOLATED SHOWERS ARE EXPECTED OVER THE  
NEXT WEEK, WITH LITTLE CHANGE IN WINDS.  
 

 
   
MARINE
 
 
MODERATE TRADE WINDS AND 3-4 FT SEAS ARE EXPECTED TO CHANGE LITTLE  
OVER THE NEXT WEEK, WITH A MODERATE RIP RISK REMAINING FOR EAST  
FACING REEFS. AS NOTED ABOVE, ISOLATED THUNDERSTORMS ARE EXPECTED  
FRI-SAT, WITH SCATTERED SHOWERS SATURDAY FOR GUAM WATERS.  
 

 
   
EASTERN MICRONESIA AND CHUUK
 
 
GENTLE TO MODERATE TRADE WINDS ARE SEEN ACROSS THE REGION. A SURFACE  
TROUGH IS ACROSS CHUUK STATE NEAR 152E AND A TRADE-WIND DISTURBANCE  
IS APPROACHING KOSRAE FROM 165E. AT THE UPPER LEVELS, A LOW IS NEAR  
SAIPAN AT 15N148E AND A HIGH IS EAST OF POHNPEI AT 8N160E. THESE  
SYSTEMS WILL SUSTAIN DIVERGENT FLOW ACROSS CHUUK AND POHNPEI OVER THE  
NEXT FEW DAYS.  
 
THE SURFACE TROUGH WILL CONTINUE TO COUPLE WITH SOUTHERLY DIVERGENT  
FLOW ALOFT TO TRIGGER SPORADIC CONVECTION NEAR CHUUK THRU THURSDAY  
NIGHT. FARTHER EAST, THE TRADE DISTURBANCE SHOULD PROLONG PATCHY  
SHOWERS AND A FEW THUNDERSTORMS NEAR POHNPEI THRU FRIDAY, AND KOSRAE  
UNTIL THURSDAY EVENING. THIS SAME DISTURBANCE WILL ALSO SUSTAIN  
INSTABILITY NEAR CHUUK THRU FRIDAY NIGHT. AFTER THE PASSAGE OF THESE  
SYSTEMS, DRIER TRADE WINDS WILL USHER IN FAIR CONDITIONS FOR CHUUK  
AND POHNPEI BY THIS WEEKEND, AND KOSRAE BY THURSDAY EVENING. THESE  
SAME DRIER TRADES SHOULD CONTINUE TO DOMINATE MAJURO THRU SATURDAY.  
THE ONLY EXCEPTION WILL BE FROM LATER TONIGHT THRU THURSDAY NIGHT IN  
WHICH A WEAK SURFACE IMPULSE CAN SPARK A FEW SHOWERS. A BAND OF  
CONVERGENT TRADE WINDS CAN BE SEEN BETWEEN 3N AND 5N FROM NEAR TARAWA  
AND BUTARITARI ATOLLS AT 170E EASTWARD TO THE DATE LINE. THIS FEATURE  
IS EXPECTED TO GRADUALLY SHIFT NORTHWESTWARD STARTING THIS WEEKEND  
WHICH WILL BRING MORE SHOWERS TO MAJURO AND KOSRAE AROUND SUNDAY.  
 
A MODERATE TRADE-WIND SWELL WILL MAINTAIN SEAS AT 4 TO 5 FEET ACROSS  
THE ENTIRE REGION INTO EARLY NEXT WEEK.  
 

 
   
WESTERN MICRONESIA FOR YAP AND KOROR
 
 
MAINLY GENTLE WINDS ARE SEEN ACROSS FAR WESTERN MICRONESIA THIS  
AFTERNOON. A COUPLE OF WEAK IMPULSES ARE SEEN NEAR YAP AT 138E AND  
FARTHER EAST AT 144E. AN UPPER-LEVEL TROUGH EXTENDS NORTHEASTWARD  
FROM SOUTHWEST OF PALAU AT 4N130E ACROSS KOROR AND YAP TO BEYOND A  
LOW NEAR SAIPAN AT 15N148E.  
 
DESPITE THE PRESENCE OF MODEST DIVERGENCE ALOFT RELATED TO THE UPPER  
FEATURES AND WEAK SURFACE IMPULSES, MUCH DRIER AIR ABOVE 650MB SHOULD  
SUSTAIN PARTLY CLOUDY SKIES ABOVE YAP THRU THURSDAY NIGHT. FOR KOROR,  
THE LACK OF DRIER AIR WILL ALLOW PERIODIC SHOWERS AND A FEW  
THUNDERSTORMS TO FLARE UP THRU THURSDAY EVENING. MOST MODEL GUIDANCE  
IS FORMING A NEAR-EQUATORIAL TROUGH SOUTH OF KOROR AND YAP NEAR 6N  
LATE THURSDAY NIGHT AND FRIDAY, THEN GRADUALLY LIFTING NORTHWARD THRU  
THE WEEKEND. UNDER THIS SCENARIO, SHOWER COVERAGE WILL INCREASE NEAR  
KOROR STARTING THURSDAY NIGHT, AND YAP BY FRIDAY AFTERNOON. UNSTABLE  
WEATHER IS GOING TO CONTINUE AT LEAST THRU EARLY NEXT WEEK. GENTLE TO  
OCCASIONALLY MODERATE WINDS AND BENIGN SEAS ARE ANTICIPATED ACROSS  
FAR WESTERN MICRONESIA INTO NEXT WEEK.  
 

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

 
 

 
 
MIDDLEBROOKE/CHAN  
 
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