Area Forecast Discussion
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000
FXPQ60 PGUM 262151 RRA
AFDPQ

AREA FORECAST DISCUSSION...RESENT
NATIONAL WEATHER SERVICE TIYAN GU
731 AM CHST FRI FEB 27 2015

RESENT FOR POSTING ON WEBPAGE

.SYNOPSIS...EAST TRADE-WINDS AND A FEW SMALL SHOWERS PREVAIL
ACROSS THE MARIANAS THIS MORNING. RELATIVELY DRY WEATHER IS
EXPECTED THROUGH THE WEEKEND.

&&

.DISCUSSION...
LITTLE CHANGE MADE TO THE FORECAST. HIGH PRESSURE CENTERED EAST
OF JAPAN WILL KEEP WINDS BETWEEN 15 TO 20 MPH TODAY. 2 KFT WINDS
ON THE VAD WERE 25 KNOTS AND SCATTEROMETER DATA SHOWED NORTHEAST
WINDS BETWEEN 15 TO 20 KTS. THESE WIND SPEEDS ARE CONSISTENT WITH
CURRENT MODEL PREDICTIONS. WINDS WILL DECREASE SLIGHTLY TONIGHT
BEFORE ANOTHER HIGH PRESSURE AREA BUILDS OUT INTO THE NORTHWEST
PACIFIC AND ELEVATES WIND SPEEDS.

RADAR IMAGERY THIS MORNING SHOWED ONLY A FEW SMALL SHOWERS MOVING
ACROSS THE LOCAL AREA. MODEL PREDICTIONS KEEP DEEP LAYER MOISTURE
LACKING THROUGH THE FORECAST. GFS...ECMWF AND NAVGEM SHOW WEAK
CONVERGENCE ACROSS THE AREA SATURDAY AND THEY ALSO PORTRAY A WEAK
TROUGH MOVING ACROSS THE MARIANAS MONDAY THROUGH TUESDAY. WHILE
THESE FEATURES MAY PRODUCE A FEW MORE CLOUDS STILL ONLY EXPECT
ISOLATED SHOWERS TO PREVAIL BECAUSE OF THE LACK OF DEEP MOISTURE.

&&

.MARINE...
OBSERVATIONS THIS MORNING FROM THE RITIDIAN AND IPAN BUOY INDICATED
SEAS AT AROUND 7 TO 8 FEET. A NORTH AND A NORTHEAST SWELL WILL
PERSIST THROUGH THE FORECAST. GLOBAL WAVE WATCH AND EP10 SHOW THE
NORTH SWELL DECREASING SLIGHTLY SATURDAY NIGHT. THESE SWELLS WILL
KEEP A MODERATE RISK OF RIP CURRENTS ON NORTH AND EAST FACING
REEFS.

&&

.FIRE WEATHER...
A RED FLAG WARNING REMAINS IN EFFECT. WINDS SHOULD INCREASE
DURING THE DAY AND RELATIVE HUMIDITY SHOULD DECREASE ENOUGH
TO SATISFY RED FLAG WARNING CRITERIA. DRY CONDITIONS SHOULD
PERSIST AT LEAST THROUGH THE WEEKEND...SO THE FIRE WEATHER
WATCH WILL MOST LIKELY NEED TO BE EXTENDED.

&&

.EASTERN MICRONESIA...
A SHEAR LINE IS EXPECTED TO PERSIST NEAR CHUUK AND POHNPEI...AND
NORTH OF KOSRAE AND MAJURO THRU THIS EVENING. TWO TRADE-WIND
DISTURBANCES MOVING WESTWARD FROM WEST OF KOSRAE WILL CONTINUE TO
INTERACT WITH THE SHEAR LINE AND TRIGGER SPORADIC CONVECTION NEAR
POHNPEI TODAY AND CHUUK THRU THIS EVENING. AS THE SUB-TROPICAL
HIGH CURRENTLY WEST OF MIDWAY GRADUALLY WEAKENS AND DRIFTS
EASTWARD ON SATURDAY....THIS SHOULD CAUSE THE SHEAR LINE TO BECOME
MORE DIFFUSE. THEREFORE ANTICIPATE SHOWER COVERAGE TO DECREASE
NEAR BOTH LOCATIONS BY SATURDAY MORNING.

LATEST RAPIDSCAT SATELLITE IMAGERY REVEALS A CIRCULATION LINGERING
SOUTHWEST OF POHNPEI NEAR 1N154E. MODERATE TO FRESH TRADE WINDS
GENERATED BY THE AFOREMENTIONED SUB-TROPICAL HIGH ARE CONVERGING
AGAINST GENTLE TRADES EAST OF THE CIRCULATION. THIS HAS ESTABLISHED
A CONVERGENT ZONE BETWEEN THE EQUATOR AND 5N FROM 161E TO 173E.
DEEP CONVECTION ASSOCIATED WITH THIS ZONE WILL IMPACT KOSRAE THRU
THIS WEEKEND. AS THESE TRADES PUSH FARTHER WESTWARD ON SUNDAY...
THIS CONVERGENT ZONE MIGHT EXTEND INTO POHNPEI AND CHUUK AS WELL.
TOWARD MIDWEEK NEXT WEEK...DECREASING TRADE CONVERGENCE SHOULD
FINALLY ALLOW DRIER WEATHER TO RETURN TO ALL THREE LOCALES. SINCE
MAJURO WILL BE WELL TO THE NORTHEAST OF THE CONVERGENT ZONE...A
DRY TRADE REGIME WILL DOMINATE THE ATOLL MOST OF THE FORECAST
PERIOD. THE ONLY EXCEPTION WILL BE SUNDAY AND MONDAY WHICH A WEAK
TRADE DISTURBANCE FROM UPSTREAM EAST OF THE DATE LINE NEAR 170W
MIGHT SPARK OFF A FEW SHOWERS.

WAVE WATCH 3 MODEL AND SATELLITE ALTIMETRY DATA ARE BEGINNING TO
SHOW A DOWNWARD TREND ON THE NORTH-NORTHEAST SWELL ACROSS CHUUK...
POHNPEI AND KOSRAE STATES THIS MORNING. THIS SHOULD ALLOW SURF TO
DROP BELOW HAZARDOUS LEVELS ON KOSRAE BY THIS EVENING AND POHNPEI
...CHUUK ON SATURDAY. COMBINED SEAS OF 8 TO 10 FEET...HAZARDOUS
FOR SMALL CRAFT OPERATION WILL LINGER NEAR CHUUK AND POHNPEI UNTIL
THIS EVENING. THE NORTH-NORTHEAST SWELL IS EXPECTED TO PEAK NEAR
MAJURO TODAY....PRODUCING SURF HEIGHTS OF 8 TO 9 FEET. THIS WILL
CAUSE HIGHER RISK OF RIP CURRENTS BUT NO HAZARDOUS SURF IS
ANTICIPATED.

&&

.WESTERN MICRONESIA...
THE CHUUK FORECAST DISCUSSION IS INCLUDED WITH EASTERN MICRONESIA
ABOVE DUE TO A SIMILAR SYNOPTIC WEATHER PATTERN AS POHNPEI AND KOSRAE.

ACCORDING TO THE LATEST WATER VAPOR SATELLITE LOOP...THE UPPER-LEVEL
TROUGH MOVING TOWARD YAP AND KOROR FROM THE SOUTHEAST HAS WEAKENED
OVERNIGHT. AS A RESULT...NO SIGNIFICANT WEATHER IS GOING TO OCCUR
DURING THE PASSAGE OF THIS SYSTEM...MAYBE A SLIGHT CHANCE OF
THUNDERSTORMS NEAR KOROR TONIGHT. MAINLY MODERATE NORTHEASTERLY
TRADES AND ISOLATED SHOWERS WILL PREVAIL THRU THIS WEEKEND. A
DEVELOPING FRONTAL SYSTEM OVER SOUTHERN CHINA IS GOING TO TRACK
EAST- NORTHEASTWARD INTO SOUTHERN JAPAN BY EARLY NEXT WEEK. THIS
SYSTEM SHOULD WEAKEN THE SUB-TROPICAL RIDGE NEAR 22N WHICH MIGHT
ALLOW THE NEAR-EQUATORIAL TROUGH CURRENTLY NEAR 5N TO LIFT
NORTHWARD CLOSER TO KOROR AND YAP. IF SO...THE CHANCE OF SHOWERS
WILL INCREASE FOR BOTH PLACES BY MONDAY.

SATELLITE ALTIMETRY DATA FROM LATE LAST NIGHT INDICATE SEAS HAVE
DROP FURTHER TO BETWEEN 5 AND 7 FEET NEAR YAP. THIS AGREES WITH THE
WAVE WATCH 3 MODEL GUIDANCE WHICH SUGGESTS SURF HAS FALLEN BELOW
ADVISORY LEVELS THIS MORNING.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...RED FLAG WARNING UNTIL 6 PM CHST THIS EVENING FOR GUZ001.

MARIANAS WATERS...NONE.
&&

$$

ZIOBRO/CHAN



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