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800
FXPQ60 PGUM 170806
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
606 PM CHST THU APR 17 2014

.MARIANAS SYNOPSIS...
PGUA WSR-88D SHOWS SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
BOTH TO THE NORTHWEST AND TO THE SOUTHEAST OF THE MARIANAS WATERS.
THOSE TO THE NORTHWEST ARE BEING CAUSED BY A LATE SEASON SHEAR
LINE WHILE THOSE TO THE SOUTHEAST ARE BEING CAUSED BY AN
APPROACHING TROPICAL DISTURBANCE. THE VAD WIND PROFILE REVEALS
NORTHEAST WINDS OF 10 TO 16 KNOTS THROUGH THE LOWEST 11 THOUSAND
FEET WITH STRONGER NORTHEAST WINDS ABOVE THAT THROUGH THE LOWEST
25 THOUSAND FEET.

&&

.DISCUSSION...
APPROACHING TROPICAL DISTURBANCE IS NOW CLEARLY VISIBLE ON RADAR.
GFS40 BRINGS THE SHOWERS TO OUR DOORSTEP...DISSIPATES THEM...THEN
REFORMS THEM ON THE OTHER SIDE. THIS DOES NOT SEEM PARTICULARLY
REALISTIC SO WENT AHEAD AND BROUGHT THEM IN FOR THE FORECAST. ONE
THING THAT MAY NEED TO BE WATCHED IS THAT THE DIURNAL CYCLE COULD
ALLOW THE SHOWERS TO MOVE IN AROUND MIDNIGHT. UKMET SUGGESTS
SHOWERS COULD LINGER THROUGH SUNDAY...AND THE ECMWF-HIRES SUGGESTS
THEY COULD STILL BE HERE MONDAY. FOR NOW LEFT THE FORECAST ALONE
WITH THE SHOWERS EXITING SATURDAY. ASSUMING THE SHOWERS ARRIVE...
WHICH LOOKS MORE LIKELY THAN NOT...THE ENDING TIME WILL BE THE
MAJOR FORECAST PROBLEM FOR FUTURE SHIFTS. COMBINED SEAS OF 6 TO 8
FEET TONIGHT WILL BEGIN TO DIMINISH AROUND MONDAY. NO SMALL CRAFT
OR HIGH SURF ADVISORIES ARE ANTICIPATED.

&&

.EASTERN MICRONESIA...
LITTLE CHANGE TO PRIOR FORECASTS AND DISCUSSION. THE NEAR-EQUATORIAL
TROUGH CONTINUES TO STRETCH SOUTH OF POHNPEI AND OVER KOSRAE TO END
SOUTH OF MAJURO AT THE EQUATOR. SHOWERS AND THUNDERSTORMS HAVE
INCREASED AREAL COVERAGE AND ARE NOW PRESENT ALONG AND ON BOTH SIDES
OF THE TROUGH AXIS AROUND POHNPEI AND KOSRAE. SHOWERS ARE SEEN NEAR
MAJURO AND TOWARDS THE DATE LINE BUT SHOWER COVERAGE IS LESSENING
AROUND MAJURO WITH WARMER CLOUD TOPS. A DRIER PATTERN IS DEPICTED BY
THE MODELS FOR MAJURO FOR THE WEEKEND. FOR POHNPEI AND KOSRAE...
FORECAST REMAINS UNSETTLED THE NEXT FEW DAYS. THE NEAR-EQ TROUGH
WILL REMAIN NEARLY STATIONARY UNTIL FRIDAY. MODELS SHOW THE TROUGH
STILL SHIFTING SOUTHWEST FRIDAY AND SATURDAY. THE MODELS SHOW A
CIRCULATION DEVELOPING SOUTHEAST OF KOSRAE...MOVING NORTHWEST ON
SATURDAY AND SUNDAY. FORECAST IN THE MID TO LONG RANGE HINGES ON
WHETHER THIS FEATURE DEVELOPS AND PASSES OVER THESE LOCATIONS...
BRINGING SHOWERS AND THUNDERSTORMS...OR PASSES SOUTH OR NEAR THESE
LOCATIONS.

&&

.WESTERN MICRONESIA...
SHOWERS AND THUNDERSTORMS PERSIST NEAR THE CIRCULATION CENTERED
BETWEEN GUAM AND CHUUK. A NEAR-EQUATORIAL TROUGH RUNS FROM
8N130E...ACROSS YAP...THROUGH THE CIRCULATION AND ACROSS CHUUK INTO
EASTERN MICRONESIA. MOISTURE REMAINS HIGH ON THE CHUUK SOUNDING
TODAY...WITH A PWAT OF 2.45 INCHES THIS MORNING AND A K-INDEX OF
36...SO ADDED SCATTERED SHOWERS TO TONIGHT`S FORECAST AND CONTINUED
WITH ISOLATED THUNDERSTORMS. CHUUK REPORTED 0.30 INCHES OF RAIN ON
THE LAST 6Z SYNOPTIC OBSERVATION. MODELS SHOW THE CIRCULATION
HEADING WEST-NORTHWEST THROUGH SATURDAY. AS IT DOES...CONDITIONS
WILL GRADUALLY IMPROVE AT CHUUK INTO THE WEEKEND. FORECAST AT YAP
AND PALAU MAINTAINS A DRY BIAS WITH LIGHT WINDS THROUGH MONDAY.
MODELS TRACK THE CIRCULATION JUST WEST OF CHUUK WESTWARD AND NEAR
YAP AND KOROR BY TUESDAY SO ADDED INCREASED CLOUDS AND SHOWERS AND
ISOLATED THUNDERSTORMS TO THE YAP AND KOROR TUESDAY FORECAST.

&&

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

$$

STANKO/DEVITA








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