Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
000
FXPQ60 PGUM 222131
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
731 AM CHST THU OCT 23 2014

.UPDATE...
A WEAK DISTURBANCE PASSING OVER THE MARIANAS WILL BRING SCATTERED
SHOWERS AND POSSIBLE THUNDERSTORMS TO GUAM AND ROTA WATERS THIS
MORNING.

&&

.PREV DISCUSSION... /ISSUED 652 AM CHST THU OCT 23 2014/

MARIANAS SYNOPSIS...
RADAR SHOWS WIDELY SCATTERED SHOWERS JUST EAST AND SOUTHEAST OF THE
GUAM MARINE ZONE AND ISOLATED SHOWERS ELSEWHERE. SATELLITE SHOWS A
FEW HEAVIER SHOWERS FARTHER SOUTHEAST OF GUAM NEAR 13N147E...AND A
WEAK CIRCULATION IS APPARENTLY NEAR 12N146E. VAD GRADIENT WINDS ARE
NE ABOUT 10 KT. SAIPAN BUOY STILL SHOWS A NNE SWELL OF 6 TO 7 FEET.

DISCUSSION...
CLOUDINESS HAS INCREASED ACROSS THE AREA AND A FEW MORE SHOWERS
COULD ALSO RESULT IF THE SHOWERS TO OUR SOUTHEAST MOVE INTO THE
FORECAST ZONES. LIGHT EAST TO SOUTHEAST WINDS ARE EXPECTED FOR THE
MARIANA ISLANDS WHILE THE WEATHER PATTERN SEEMS TO BE SHIFTING INTO
A MORE ACTIVE MODE ACROSS MICRONESIA. MODELS INDICATE MORE ACTIVE
WEATHER ACROSS THE SOUTHERN PARTS OF THE REGION AS THE CIRCULATION
NOW JUST SE OF GUAM MOVES ROUGHLY TOWARD THE WEST EVEN WHILE A
CIRCULATION OVER EASTERN MICRONESIA ALSO FOLLOWS WESTWARD.

MARINE...
HIGH SURF ADVISORY REMAINS IN EFFECT WHILE LONG-PERIOD NNE TO NE
SWELL CONTINUES FOR THE NEXT FEW DAYS. MARINE GRIDS WERE ADJUSTED
FOR INITIAL CONDITIONS AND WW3 GUIDANCE. WIND GRIDS WERE REFRESHED
WITH LATEST GFS75 DATA.

EASTERN MICRONESIA...
A SURFACE TROUGH EXTENDS SOUTHEASTWARD FROM A WEAK CIRCULATION JUST
SOUTH OF GUAM AT 12N146E TO ANOTHER CIRCULATION CENTERED WEST OF
KOSRAE AT 5N163E. MODEST SURFACE CONVERGENCE ALONG THE NORTHERN
PERIPHERY OF THE CIRCULATION NEAR KOSRAE WILL KEEP ISOLATED
CONVECTION OVER POHNPEI UNTIL FRIDAY. AFTER THE PASSAGE OF THIS
CIRCULATION TO THE SOUTH OF POHNPEI BY FRIDAY EVENING...A BRIEF
PERIOD OF FAIR WEATHER IS POSSIBLE. FARTHER EAST...ANOTHER SURFACE
TROUGH CAN BE SEEN ON THE LATEST IR SATELLITE IMAGERY STRETCHING
NORTHEASTWARD FROM NEAR TARAWA ATOLL AT 1N170E TO BEYOND 180 AT 11N.
WIDELY SCATTERED SHOWERS AHEAD OF THIS TROUGH ARE ALREADY VISIBLE
NEAR 167E EAST OF KOSRAE...AND SHOULD REACH THAT ISLAND BY
TONIGHT. THE BULK OF WET WEATHER RELATED TO THIS SAME TROUGH WILL
ALSO ARRIVE AT MAJURO BY LATE THIS AFTERNOON AS WELL. AS THIS
TROUGH PUSHES FARTHER WESTWARD ON SATURDAY...IT WILL PROLONG
SHOWERY CONDITIONS NEAR KOSRAE THRU SATURDAY NIGHT AND SPREAD THEM
TO POHNPEI BY SATURDAY EVENING. A SURFACE RIDGE FOLLOWING BEHIND
THE TROUGH MIGHT BRING IN DRIER WEATHER FOR MAJURO BY
SATURDAY...AND THEN FOR KOSRAE AND POHNPEI ON SUNDAY.

A STRONG LOW PRESSURE SYSTEM IS DRIFTING EASTWARD FROM WELL NORTH OF
WAKE ISLAND AT 34N170E. LONG-PERIOD NNE SWELLS GENERATED BY NEAR
GALE WINDS WEST OF ITS CENTER ARE EXPECTED TO MIGRATE ACROSS CHUUK
AND POHNPEI STATES FROM FRIDAY EVENING TO SUNDAY. THIS COULD CREATE
HAZARDOUS SURF FOR BOTH STATES WHICH NEEDS TO BE MONITORED CLOSELY.
AS THIS SAME LOW PRESSURE SYSTEM CROSSES THE DATE LINE ON FRIDAY...
MODERATE NNE SWELLS WILL ALSO APPROACH THE MARSHALL ISLANDS. EVEN
THOUGH THESE NNE SWELLS WILL NOT BE HIGH ENOUGH TO CAUSE HAZARDOUS
SURF...THEY COULD COMBINE WITH SPRING HIGH TIDES TO CAUSE COASTAL
INUNDATIONS ACROSS THE MARSHALLS FROM SATURDAY TO MONDAY. THIS
SITUATION WILL ALSO NEED TO BE WATCHED VERY CLOSELY AND ISSUE A
SPECIAL WEATHER STATEMENT IF NECESSARY.

WESTERN MICRONESIA...
A SURFACE RIDGE OVER CHUUK SHOULD BE ABLE TO PROVIDE ONE MORE DAY OF
PARTLY SUNNY SKIES TODAY. CONVERGING WINDS BETWEEN THIS RIDGE AND A
CIRCULATION NEAR KOSRAE ARE ALREADY SPARKING DEEP CONVECTION EAST OF
WENO ISLAND. ANTICIPATE THIS CONVECTION TO IMPACT CHUUK LAGOON BY
LATER THIS EVENING. WEATHER MIGHT IMPROVE SLIGHTLY AS THE CIRCULATION
PASSES SOUTH OF CHUUK LAGOON ON SATURDAY. FOR EARLY NEXT WEEK...
WEAKER SOUTHEASTERLY TRADES IN THE WAKE OF THE CIRCULATION COULD
PROMOTE QUIETER WEATHER. REFER TO THE SECOND PARAGRAPH UNDER EASTERN
MICRONESIA DISCUSSION ABOVE FOR POSSIBLE HAZARDOUS SURF CONDITIONS
BY FRIDAY.

BASED ON LATEST IR SATELLITE LOOP THIS MORNING...ANOTHER SURFACE
TROUGH MEANDERS EASTWARD FROM SOUTHERN PHILIPPINES TO NEAR KOROR
INTO A CIRCULATION CENTERED SOUTH OF YAP NEAR 6N140E. DESPITE
MAINLY GENTLE WINDS ASSOCIATED WITH THESE FEATURES...THE DIVERGENT
UPPER WINDS NEAR THE SOUTHWESTERN QUADRANT OF A HIGH SOUTHEAST OF
YAP ARE ENHANCING CONVECTION SOUTH OF KOROR. THIS TREND WILL
CONTINUE THRU FRIDAY...AND A FEW THUNDERSTORMS COULD SPILL
NORTHWARD INTO KOROR WATERS TODAY. AS THE HIGH GRADUALLY SHIFTS
WESTWARD TONIGHT AND FRIDAY...CONVECTION SHOULD STAY FARTHER SOUTH.
WITH THIS IN MIND...WEATHER NEAR BOTH LOCATIONS SHOULD STAY MAINLY
DRY THRU SATURDAY. BY EARLY NEXT WEEK...THE SURFACE TROUGH AND
CIRCULATION WILL FINALLY LIFT NORTHWEST OF THE REGION AND SUSTAIN
PARTLY CLOUDY SKIES.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL 4 PM CHST SUNDAY FOR GUZ001>004.

MARIANAS WATERS...NONE.
&&

$$

WILLIAMS/SIMPSON/CHAN





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.