Area Forecast Discussion
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449
FXPQ60 PGUM 092100
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
700 AM CHST WED FEB 10 2016

.SYNOPSIS...
A FRONTAL BOUNDARY IS TRANSITIONING INTO A SHEAR LINE AS IT
PUSHES SOUTHWARD THROUGH THE FAR NORTHERN CNMI. CLOUDINESS AND
SHOWERS ASSOCIATED WITH AN OLD SHEAR LINE STRETCHES EASTWARD FROM
EAST OF THE MARIANAS NEAR 15N150E TO BEYOND THE DATE LINE. PARTLY
CLOUDY SKIES AND A FEW SPRINKLES WERE EVIDENT OVER THE FORECAST
ZONES.

&&

.DISCUSSION...
NO CHANGES TO FORECAST PHILOSOPHY OR GRIDS. STILL EXPECT
CLOUDINESS AND SHOWER COVERAGE WILL FLUCTUATE DURING THE NEXT FEW
DAYS AS FRAGMENTS OF THE OLD SHEAR LINE PASS THROUGH. ARRIVAL OF
THE SHEAR LINE FROM THE NORTH WILL BRING BETTER LOW-LEVEL FORCING
FOR CLOUDS AND SHOWERS ON FRIDAY AND SATURDAY...BUT ONLY LIMITED
MOISTURE IS AVAILABLE...SO KEPT SHOWER COVERAGE ISOLATED. DRIER
WEATHER FROM BEHIND THE SHEAR LINE APPEARS TO BE ON TAP FOR NEXT
WEEK.

&&

.MARINE...
IPAN BUOY INITIALIZES COMBINED SEAS BETWEEN 7 AND 8 FEET...IN
GOOD AGREEMENT WITH THE MARINE GRIDS. WINDS AND SEAS WILL BEGIN TO
BUILD AS THE SHEAR LINE APPROACHES. A SMALL CRAFT ADVISORY APPEARS
TO BE IN THE OFFING BEGINNING ON FRIDAY.

&&

.FIRE WEATHER...
DAY SHIFT MAY NEED TO CONSIDER A FIRE WEATHER WATCH FOR THURSDAY
AND FRIDAY...BUT CLOUDINESS AND SHOWERS ASSOCIATED WITH THE OLD
SHEAR LINE AND NEWER/APPROACHING SHEAR LINE COULD ADD MOISTURE TO
FUELS AND MITIGATE THE FIRE THREAT.

&&

.EASTERN MICRONESIA...
THE RIDGE OF HIGH PRESSURE HUGGING 25N FROM 160E TO NEAR 180 HAS
BEEN WEAKENED BY A COMPLEX FRONTAL SYSTEM PUSHING EASTWARD FROM
NEAR MINAMI TORI SHIMA. IN RESPONSE...TRADE WINDS ACROSS
MICRONESIA FROM CHUUK STATE EASTWARD TO THE MARSHALL ISLANDS HAVE
DECREASED. LATEST MODEL GUIDANCE IS INITIALIZED WELL BY BOTH THE
NAVGEM AND UKMET. THE GUIDANCE SUGGESTS THIS COMPLEX FRONTAL
SYSTEM WILL CONSOLIDATE INTO A STRONG MID-LATITUDE LOW NORTH OF
WAKE ISLAND BY THURSDAY. FLOW AROUND THE DEVELOPING LOW WILL
ENHANCE AN EXISTING COLD FRONT AND SHEAR LINE EXTENDING
SOUTHWESTWARD FROM THIS LOW TO THE PHILIPPINE SEA. THE SHEAR LINE
IS EXPECTED TO ADVANCE SOUTHEASTWARD THRU THE MARIANA ISLANDS LATE
THURSDAY AND FRIDAY...THEN REACH CHUUK AND POHNPEI ON SATURDAY. IF
THE SHEAR LINE INTERACTS WITH TRADE-WIND DISTURBANCES SOUTH OF
10N...A WET REGIME COULD FINALLY MATERIALIZE OVER THESE TWO PLACES.
AS THE SHEAR LINE DRIFTS EASTWARD FROM CHUUK AND POHNPEI...WET
WEATHER SHOULD ALSO ARRIVE ON KOSRAE AND MAJURO BY SUNDAY.

DECREASING TRADE WINDS WILL ALLOW WIND WAVES AND SWELL TO SUBSIDE
NEAR KOSRAE AND THE MARSHALL ISLANDS TODAY AND TONIGHT. THIS WILL
ALLOW SURF TO DROP BELOW HAZARDOUS LEVELS AT BOTH LOCATIONS ON
THURSDAY. HOWEVER...SEAS WILL REMAIN HIGH ENOUGH NEAR MAJURO TO
MAINTAIN CONDITIONS HAZARDOUS FOR SMALL CRAFT THRU FRIDAY. THE
SHEAR LINE MIGRATING EASTWARD FROM CHUUK WILL INCREASE WINDS
ACROSS THE REGION AGAIN. THIS WILL CAUSE WAVES AND SWELL TO RISE
FROM WEST TO EAST...WHICH COULD LEAD TO HAZARDOUS SURF AND SMALL
CRAFT ADVISORY CONDITIONS BY THE WEEKEND.

&&

.WESTERN MICRONESIA...
CHUUK FORECAST DISCUSSION CAN BE FOUND IN THE EASTERN MICRONESIA
SECTION AS IT IS SIMILAR TO THAT FOR POHNPEI.

A WEAK TRADE-WIND DISTURBANCE WILL GENERATE SOME CLOUDS AND A FEW
SHOWERS NEAR YAP TODAY AND THEN NEAR KOROR BY LATE TONIGHT. A
SHEAR LINE IS GRADUALLY SINKING SOUTHEASTWARD ACROSS THE
PHILIPPINE SEA NEAR 13N135E. THIS FEATURE WILL MOVE OVER YAP BY
THURSDAY NIGHT AND OVER KOROR ON FRIDAY. THERE IS THE POTENTIAL
FOR THIS FEATURE TO PRODUCE SUBSTANTIAL RAINFALL ACROSS PALAU AND
YAP. DRIER WEATHER WILL RETURN ONCE THE SHEAR LINE HAS PASSED EAST
OF YAP ON SUNDAY.

SWELL GENERATED BY FRESH NORTHEAST WINDS BEHIND THE APPROACHING
SHEAR LINE WILL BEGIN ARRIVING ON PALAU AND YAP THURSDAY. WHEN
COMBINED WITH BUILDING WIND WAVES CAUSED BY FRESH WINDS NEAR THE
SHEAR LINE ITSELF...SURF AND SEAS FOR KOROR AND YAP COULD RISE TO
HAZARDOUS LEVELS BY THURSDAY NIGHT.

&&

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

$$

MCELROY/CHAN



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