Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Mon, 13 Dec 2010 14:45:05 -0600

383 
FXPQ60 PGUM 132044
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
644 AM CHST TUE DEC 14 2010

.SYNOPSIS...A WEAK TRADE-WIND DISTURBANCE PUSHED CLOUDS AND
SHOWERS ACROSS GUAM THIS MORNING. CLOUDS SHOULD REMAIN ACROSS
GUAM THROUGH TONIGHT. PARTLY CLOUDY SKIES AND ISOLATED SHOWERS
WILL PREVAIL ACROSS ROTA...TINIAN AND SAIPAN TODAY AND TONIGHT.

&&

.DISCUSSION...
TRADE-WIND DISTURBANCE WILL BRING A FEW SHOWERS AND MOSTLY CLOUDY
CONDITIONS TO GUAM TODAY AND TONIGHT. MODELS HAVE BEEN SHOWING
FOR DAYS THAT MOISTURE FROM THE DISTURBANCE WOULD PASS VERY CLOSE
TO GUAM...ALTHOUGH KEEPING IT SOUTH OF GUAM ALL THE TIME. A BIT
OF THE SHOWER AREA BUBBLED UP TO GUAM AFTER MIDNIGHT. STILL
BELIEVE THAT THE BULK OF THE SHOWERS WILL STAY SOUTH OF
GUAM...BUT CAN NOT OVERRULE REALITY SO ADDED SCATTERED SHOWERS TO
GUAM FOR THIS MORNING. SATELLITE SHOWS LOW CLOUDS EXTENDING EAST
OF GUAM TO AT LEAST 152E. FIGURE THESE CLOUDS WILL CONTINUE TO
PUSH ACROSS GUAM THROUGH TONIGHT SO ADDED MOSTLY CLOUDY TO GUAM'S
FORECAST TO REFLECT THIS. THE CLOUDS AND SHOWERS SHOULD NOT PUSH
FURTHER NORTH THAN THE ROTA CHANNEL SO LEFT MOSTLY SUNNY/PARTLY
CLOUDY AND ISOLATED SHOWERS FOR ROTA, TINIAN, AND SAIPAN. PARTLY
CLOUDY SKIES WILL RETURN TO GUAM BY WEDNESDAY. BASIC EAST TRADE-
WINDS...PARTLY CLOUDY SKIES AND ISOLATED SHOWERS SHOULD PREVAIL
THROUGH THE END OF THE FORECAST.

THE GFS IS SHOWING AN INTERESTING FEATURE NEAR THE END OF ITS RUN
AT DAY 9 AND 10. IT IS SHOWING WHAT APPEARS TO BE A COLD FRONTAL
PASSAGE ON THE 23RD. IT ACTUALLY DEPICTS WESTERLY WINDS ACROSS
THE MARIANAS ON THAT DAY AND THE 13/06Z ITERATION OF THE MODEL
SHOWED DEW POINTS IN THE UPPER 60S. THE 13/12Z RUN BACKED OFF ON
THIS BUT WHO KNOWS SINCE NEAR THE END OF THE FORECAST. SINCE THIS
IS SO FAR OUT IN TIME AND THINGS WILL MOST LIKELY CHANGE WILL
LEAVE THIS OUT OF THE FORECAST UNTIL MORE IS KNOWN.

&&

.MARINE...
NORTH SWELL WILL CONTINUE TO WEAKEN AND SURF ON NORTH AND WEST
FACING REEFS WILL DECLINE. EAST TRADE-WIND SWELL WILL PERSIST
THROUGH THE FORECAST AND BASICALLY REMAIN THE SAME WITH MINOR
CHANGES. 

&&

.EASTERN MICRONESIA...
LOW-LEVEL CONVECTION IS BEGINNING TO REDEVELOP NEAR POHNPEI AND
NORTHWEST OF KOSRAE AS A SURFACE TROUGH SLOWLY SHIFTS WESTWARD.
GFS40 AND ECMWF SEEM TO OFFER THE BEST GUIDANCE IN KEEPING
SCATTERED SHOWERS AROUND POHNPEI THROUGH TONIGHT. BEYOND
WEDNESDAY...ISOLATED SHOWERS WILL RESUME...MIRRORING CONDITIONS
AT BOTH KOSRAE AND MAJURO. MODELS PICK UP ON ANOTHER TROUGH NEAR
THE DATELINE BUT KEEP CONVECTION ON THE LIGHT SIDE. ONLY ECMWF
GREATLY INCREASES CONVECTION BY THURSDAY AND FRIDAY...BUT THEN
HAS MOST OF THE ACTIVITY TO THE EAST OF MAJURO.

&&

.WESTERN MICRONESIA...
THE SURFACE TROUGH PREVIOUSLY SOUTH OF GUAM HAS SHIFTED FARTHER
WEST TOWARD YAP AND PALAU. STEADY NORTHEAST WINDS AT YAP INDICATE
THE TROUGH AXIS IS LIKELY JUST EAST OF THE AREA. IR SAT IMAGERY
SHOWS MUCH LESS DEEP CONVECTION THAN 12 HOURS EARLIER...BUT
MODELS ANTICIPATE ADDITIONAL DEVELOPMENT TODAY LEADING TO
SCATTERED SHOWERS TODAY AT YAP AND INTO TONIGHT AT PALAU. A WEAK
CIRCULATION SOUTH OF PALAU WILL SLOWLY PUSH WESTWARD WITH NO
SIGNIFICANT DEVELOPMENT EXPECTED...BUT THE SYSTEM WILL PUSH NE
WINDS TO E THEN SE BY WED NIGHT. AT CHUUK...CONVECTION IS
BEGINNING TO DEEPEN. MODELS INDICATE SCATTERED SHOWERS WILL
DEVELOP THIS AFTERNOON AND INTO THE MIDDLE OF TONIGHT UNTIL THE
TROUGH NEAR POHNPEI PASSES THROUGH THE AREA. ISOLATED SHOWERS
SHOULD TAKE OVER FOR THE REMAINDER OF THE WEEK.

&&

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

$$

ZIOBRO/W. AYDLETT

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