241  
FXPQ60 PGUM 260750  
AFDPQ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TIYAN GU  
555 PM CHST WED JUL 26 2017  
   
MARIANAS SYNOPSIS
 
 
ISLAND SHOWERS TRIGGERED BY LIGHT WINDS AND ISLAND HEATING BROUGHT  
LOCALLY HEAVY RAINFALL TO PARTS OF CENTRAL AND NORTHERN GUAM AND  
EVEN TO SAIPAN LATE THIS MORNING AND THIS AFTERNOON. AS OF LATE THIS  
AFTERNOON, SHOWERS ARE DYING OUT AS LATE-DAY COOLING SETS IN. OUT  
OVER THE COASTAL WATERS, ONLY ISOLATED SHOWERS ARE SEEN ON RADAR.  
WINDS ARE VERY LIGHT AT ABOUT 5 KT FROM THE SSW, AND SEAS ARE RUNNING  
3-4 FEET AT THE BUOYS.  
 

 
   
DISCUSSION
 
 
WITH SIMILAR WIND AND MOISTURE CONDITIONS EXPECTED ON THURSDAY,  
ISLAND SHOWERS ARE A GOOD POSSIBILITY AGAIN. THE MODELS HAVE LIGHT  
WINDS FROM THE SOUTH ON THURSDAY, WHICH IS SLIGHTLY LESS FAVORABLE  
GIVEN THE SSW-NNE ORIENTATION OF GUAM AND THE TINIAN-SAIPAN ISLAND  
PAIR. IN FACT, TINIAN AND SAIPAN MAY ESCAPE ISLAND SHOWERS IF THE  
WIND IS FROM DUE SOUTH, KEEPING TINIAN-HEATED AIR FROM CROSSING  
SAIPAN. FOR NOW, HAVE SCATTERED AFTERNOON SHOWERS FOR GUAM ONLY, AND  
THE NIGHT SHIFT CAN ADD SAIPAN IF IT APPEARS WINDS WILL BE SSW AGAIN.  
THE REST OF THE FORECAST IS UNCHANGED, AS UNSEASONABLY DRY CONDITIONS  
SHOULD PERSIST FOR AT LEAST THE NEXT WEEK.  
 

 
   
MARINE
 
 
ONLY MINOR ADJUSTMENTS WERE MADE TO MARINE GRIDS, KEEPING SOUTHWEST  
TO WEST SWELL SOMEWHAT HIGHER THIS WEEKEND. HAVE KEPT SURF AT 4 FT  
OR LESS FOR THURSDAY WITH SW SWELL OF 3 TO 5 FEET, DUE TO THE  
RELATIVELY SHORT PERIOD. BUT EXPECT THE PERIOD TO INCREASE BY FRIDAY  
WITH A MORE WESTERLY SWELL, NUDGING SURF UP TO 5 FEET AT TIMES ALONG  
WEST FACING REEFS WITH A MODERATE RISK OF RIP CURRENTS. ALONG NORTH  
FACING REEFS, THE NORTHEAST SWELL WILL BE MORE NORTHERLY FRIDAY,  
AGAIN BRINGING THE RIP RISK TO MODERATE.  
 

 
   
EASTERN MICRONESIA
 
 
THERE ARE TWO MAIN FEATURES OVER EASTERN MICRONESIA. THE FIRST IS  
AN AREA OF TRADE WIND CONVERGENCE WHICH IS BRINGING SHOWERS AND  
ISOLATED THUNDERSTORMS TO MAJURO AND THE MARSHALL ISLANDS. THIS  
AREA WILL MOVE WESTWARD OVER THE NEXT FEW DAYS AND BRING DRIER  
WEATHER TO THE MARSHALLS OVER THE WEEKEND.  
 
THE SECOND FEATURE IS A TROPICAL DISTURBANCE WEST OF CHUUK WHICH  
IS BRINGING WET WEATHER. OTHERWISE, MORE ISOLATED SHOWERS AND  
THUNDERSTORMS ARE IMPACTING POHNPEI AND KOSRAE. HOWEVER, AS THE  
CONVERGENCE TO THE EAST APPROACHES, THESE LOCATIONS WILL SEE AN  
INCREASE IN SHOWERS.  
 

 
   
WESTERN MICRONESIA
 
 
TROPICAL DEPRESSION 11W IS NORTH AND WEST OF KOROR AND YAP AND  
MOVING NORTHWARD AND EVENTUALLY WESTWARD. MEANWHILE, A TROPICAL  
DISTURBANCE WEST OF CHUUK WILL APPROACH YAP AND KOROR THURSDAY  
BRINGING ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS. BEYOND  
THAT, SHOWERS ARE EXPECTED TO BECOME MORE ISOLATED, EXCEPT FOR  
SOME ISLAND THUNDERSTORMS AT KOROR WITH LIGHT WIND THROUGH  
SATURDAY.  
 

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

 
 

 
 
MIDDLEBROOKE/NIERENBERG  
 
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