Area Forecast Discussion
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FXPQ60 PGUM 210618
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
418 PM CHST TUE OCT 21 2014

.MARIANAS SYNOPSIS...
A SHEAR LINE WITH ATTENDANT SHOWERS AND THUNDERSTORMS IS SITUATED
NORTH OF THE CNMI OVER THE FAR NORTHERN MARIANAS. SHOWERS
ASSOCIATED WITH AN ELONGATED CIRCULATION ARE OCCURRING SOUTH OF
GUAM. OTHERWISE...ONLY A FEW LIGHT ISLAND SHOWERS ARE PRESENT
OVER AND TO THE SOUTHWEST OF THE LARGER ISLANDS.

&&

.DISCUSSION...
LITTLE CHANGE IN THE FORECAST PHILOSOPHY. A SLIGHTLY DRIER AND
MORE STABLE AIR MASS WILL FILTER IN OVER THE MARIANAS TONIGHT AND
TOMORROW WHICH SHOULD LIMIT ISLAND CONVECTION TOMORROW. MODELS
BRING THE WEAK CIRCULATION SOUTH OF GUAM WEST OVER THE NEXT
COUPLE OF DAYS AND SHOULD NOT AFFECT WEATHER ACROSS THE MARIANAS.
HOWEVER...A SURFACE TROUGH EXTENDING TO THE NORTHEAST OF THE
CIRCULATION MAY BRING INCREASED CLOUD COVER AND INCREASED SHOWERS
TO THE ISLANDS FRIDAY AND SATURDAY. ECMWF IS MOST AGGRESSIVE IN
THIS SCENARIO WITH SHOWERS LASTING THROUGH THE WEEKEND. WILL WAIT
A COUPLE OF MORE MODEL RUNS FOR A BETTER CONSENSUS BETWEEN
MODELS. OPTED FOR THE DRIER GFS AND NAVGEM SOLUTIONS FOR NOW.
OVERALL...A RELATIVELY DRY PATTERN IS EXPECTED TO CONTINUE THIS
WEEK ACCOMPANIED BY LIGHT EAST WINDS.

&&

.MARINE...
NORTH SWELL GENERATED BY A STRONG NORTH PACIFIC LOW PRESSURE
SYSTEM WILL INCREASE TONIGHT AND WEDNESDAY ACROSS THE MARIANAS.
ADJUSTED SWELL GRIDS TO INCLUDE A 4 TO 6 FT N-NE SWELL ACROSS THE
REGION. LATEST BUOY DATA FROM TANAPAG HAS NOT INDICATED A
INCREASE IN NORTH SWELL BUT IS EXPECTED TO COMMENCE LATER
TONIGHT. THE NORTH SWELL WILL BE THE MAIN COMPONENT THE
CALCULATION OF COMBINED SEAS WITH WINDS WAVES AND EAST SWELL LESS
THAN 2 FT.

&&

.EASTERN MICRONESIA...
A WEAK CIRCULATION WAS LOCATED JUST TO THE NORTHEAST OF KOSRAE
THIS AFTERNOON. LOW-LEVEL CONVERGENCE ASSOCIATED WITH THE
CIRCULATION GENERATED SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS NOT TOO FAR FROM KOSRAE THIS AFTERNOON. MODELS
PREDICT THE CIRCULATION WILL DRIFT AROUND THE AREA NEAR KOSRAE
THEN MOVE SOUTH BEFORE WASHING OUT LATE WEDNESDAY. EXPECT MOSTLY
CLOUDY SKIES AND A SLIGHT CHANCE OF THUNDERSTORMS TONIGHT AT
KOSRAE. AS THE CIRCULATION WEAKENS...SKIES WILL BE PARTLY CLOUDY
AT KOSRAE WEDNESDAY THROUGH THURSDAY NIGHT.

A RIDGE OVER POHNPEI STATE WILL KEEP WINDS LIGHT AND VARIABLE
OVER POHNPEI TONIGHT AND WEDNESDAY. AS THE CIRCULATION DECAYS SO
WILL THE RIDGE. EXPECT PARTLY CLOUDY SKIES AND ISOLATED SHOWERS
AT POHNPEI TONIGHT AND WEDNESDAY. A WEAK SURFACE TROUGH WILL
DEVELOP NEAR POHNPEI AND KOSRAE BY WEDNESDAY NIGHT.THIS WILL
ALLOW NORTH WINDS TO DEVELOP ACROSS POHNPEI WEDNESDAY NIGHT.

LOW-LEVEL CONVERGENCE WILL BRING MOSTLY CLOUDY SKIES AND A SLIGHT
CHANCE OF THUNDERSTORMS TO MAJURO TONIGHT. A WEAK RIDGE OF HIGH
PRESSURE WILL BUILD ACROSS THE MARSHALLS BRIEFLY DECREASING THE
CHANCE OF SHOWERS WEDNESDAY AND WEDNESDAY NIGHT. A SURFACE TROUGH
WILL CROSS THE DATELINE AND BRING AN INCREASED CHANCE OF SHOWERS
THURSDAY AND THURSDAY NIGHT. LOW-LEVEL CONVERGENCE IN THE WAKE OF
THE TROUGH WILL KEEP SKIES MOSTLY CLOUDY AND GENERATE A SLIGHT
CHANCE OF THUNDERSTORMS THROUGH SATURDAY. DRIER WEATHER IS
EXPECTED SUNDAY.

THE MAJURO SURFACE TROUGH WILL MOVE WEST AND COMBINE WITH THE OTHER
TROUGH NEAR KOSRAE TO PROLONG CLOUDS AND SHOWERS ACROSS POHNPEI
THROUGH FRIDAY. LOW-LEVEL CONVERGENCE WILL KEEP SKIES MOSTLY CLOUDY
THROUGH THE WEEKEND AT POHNPEI AND KOSRAE.

&&

.WESTERN MICRONESIA...
A SURFACE TROUGH STRETCHED ACROSS THE WESTERN HALF OF MICRONESIA
FROM JUST SOUTH OF GUAM WESTWARD JUST NORTH OF 10N. NORTHWEST WINDS
WILL PREVAIL AT PALAU AND NORTH WINDS AT YAP TONIGHT THROUGH
WEDNESDAY NIGHT.

A WEAK CIRCULATION WILL FORM ALONG THE TROUGH SOUTH OF GUAM. THIS
CIRCULATION WILL MOVE WEST ALLOWING EAST TRADE-WINDS TO RETURN
BEHIND IT. EAST WINDS WILL RETURN TO YAP THURSDAY AND TO PALAU
FRIDAY NIGHT. THE CIRCULATION WILL REMAIN WEAK AND EXPECT ONLY A
FEW CLOUDS AT PALAU THURSDAY AND THURSDAY NIGHT AS CONVERGENCE
AHEAD OF THE CIRCULATION WILL MOVE ACROSS THAT AREA.

SOUTHWEST WINDS ARE EXPECTED TONIGHT THROUGH WEDNESDAY NIGHT AT
CHUUK. NORTHEAST TRADE-WINDS WILL RETURN THERE THURSDAY NIGHT. DEEP
LAYER MOISTURE WILL REMAIN LIMITED SO EXPECT ONLY A FEW PERIODS OF
MOSTLY CLOUDY SKIES AT THURSDAY THROUGH SUNDAY.

&&

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

$$

WILLIAMS/ZIOBRO





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