Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Fri, 10 Sep 2010 03:34:04 -0500

843 
FXPQ60 PGUM 100833
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
633 PM CHST FRI SEP 10 2010

.SYNOPSIS...SHOWER ACTIVITY TO THE SOUTH AND WEST WILL PUSH ENOUGH
CLOUDS OVER THE AREA TO CREATE MOSTLY CLOUDY CONDITIONS TONIGHT.
ISOLATED SHOWERS ARE EXPECTED THE NEXT FEW DAYS.

&&

.DISCUSSION...
ONLY A FEW SMALL CHANGES TO FORECAST. WINDS ARE MORE SOUTHEAST
THAN EARLIER FORECAST INDICATED SO ADJUSTED NEW FORECAST TO FIT
CURRENT CONDITIONS. EXPECT SOUTHEAST WINDS THROUGH THE NIGHT
BECOMING MORE EASTERLY ON SATURDAY. A CONCERN WAS SHOWER ACTIVITY
TO THE SOUTH OF GUAM FRIDAY AFTERNOON. RADAR AND SATELLITE
IMAGERY DURING MID AFTERNOON INDICATED A FEW OUTFLOW BOUNDARIES
MOVING UP TOWARDS GUAM. THE CONCERN WAS THAT THIS WOULD INCREASE
SHOWER ACTIVITY ACROSS THE MARIANAS TONIGHT. WHILE THERE MIGHT BE
A BRIEF INCREASE IN SHOWERS...ESPECIALLY ACROSS GUAM...EXPECT
ISOLATED TO BE THE PREDOMINANT SHOWER COVERAGE. WITH ALL THE
SHOWER AND THUNDERSTORM ACTIVITY CLOSE TO THE AREA FIGURE THAT A
LARGE AMOUNT OF HIGH TO MID LEVEL BLOW OFF CLOUDS WILL CREATE
MOSTLY CLOUDY SKIES TONIGHT. MODELS STILL HINT AT AN INCREASE IN
SHOWER ACTIVITY ACROSS THE MARIANAS SUNDAY. UKMET...WHICH HAD
CONSISTENTLY SHOWN THIS AREA THE LAST FEW DAYS...NOW SEEMS LESS
ENTHUSIASTIC ABOUT IT. WILL KEEP ISOLATED UNTIL MORE IS KNOWN.
MODELS SEEM TO DIVERGE ON WIND DIRECTION FROM DAY 5...TUESDAY...
ONWARDS WITH ONE MODEL NORTHEAST AND ANOTHER SOUTHEAST. SO LEFT
FORECAST AS IS...WITH EAST WINDS...UNTIL THE MODELS BECOME BETTER
ADJUSTED.

&&

.MARINE...
SOUTHEAST SWELL OF ABOUT FOUR FEET IS ALL THAT IS EXPECTED THOUGH
THE WEEKEND AND THE FIRST HALF OF THE COMING WEEK. RIP CURRENT
RISK WILL BE MODERATE THE NEXT FEW DAYS.

&&

.EASTERN MICRONESIA...
A NORTHEAST-SOUTHWEST ORIENTED SURFACE TROUGH PROPAGATING THROUGH
THE MARSHALLS CONTINUES TO PROVIDE A FOCUSING MECHANISM FOR
CONVECTION OVER THE MARSHALLS THIS EVENING. ACTIVITY WILL STAY NORTH
OF WESTERN KIRIBATI AS STRONG SUBSIDENCE CONTINUES TO DOMINATE
MORE EQUATORIAL LATITUDES. WHILE THE CONVERGENCE ZONE WILL REMAIN
NEAR MAJURO THROUGH THE WEEKEND...VARIOUS NWP MODELS INDICATE THAT
THERE COULD BE LOTS OF VARIABILITY IN THE MARSHALL ISLANDS
RAINFALL. DRYING TREND HAS BEGUN AT KOSRAE AS SUBSIDENT FLOW
SETTLES OVER THE AREA FROM THE SOUTHEAST. SIMILAR CONDITIONS ARE
EXPECTED AT POHNPEI BY SATURDAY...WITH SCATTERED SHOWERS EXITING THE
AREA TONIGHT.

&&

.WESTERN MICRONESIA...
TRADE-WIND CONVERGENCE-RELATED CONVECTION IS EXPECTED TO BRING
SHOWERS TO CHUUK ON SATURDAY BEFORE DRIER CONDITIONS MOVE IN FROM THE
SOUTHEAST SATURDAY NIGHT AS SUGGESTED BY MOST OF THE MODELS. AN UPPER-
LOW CONTINUES TO ENHANCE CONVECTION JUST TO THE NORTH OF YAP AND
KOROR...BUT IS WANING IN AFFECT AS IT GRADUALLY MOVES
WESTWARD. DESPITE THE WESTWARD MOVEMENT OF THE LOW...THUNDERSTORMS
ARE STILL POSSIBLE AT YAP DUE TO THE JUXTAPOSITION OF A DIFFLUENT
WIND FIELD ALOFT. A THUNDERSTORM WAS REPORTED AT YAP DURING THE 
AFTERNOON. BOTH THE GFS AND ECMWF BRING A TROUGH OVER YAP WITH THE
LIKELIHOOD OF SCATTERED SHOWERS ABOUT SUNDAY NIGHT OR
MONDAY. NEED FURTHER CLARIFICATION FROM FUTURE MODELS AND/ OR
ANALYSES TO SEE HOW THIS FEATURE MATERIALIZES.

&&

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

$$

ZIOBRO/DEVITA/GUARD

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