907
AGPN40 KWNM 280336
MIMPAC
MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
836 PM PDT TUE APR 27 2021
FORECAST DISCUSSION
MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.
RELATIVELY TRANQUIL CONDITIONS WILL CONTINUE OVER THE OFFSHORE
ZONES AS HIGH PRESSURE REMAINS OVERHEAD AND WILL CONTINUE TO
STRENGTHEN HEADING INTO WED. THE SURFACE RIDGING HAS PUSHED INTO
THE WEST COAST WITH A TROUGH IN THE CENTRAL CALIFORNIA VALLEY.
GOES-W AIR MASS RGB IMAGERY SHOWS A PRONOUNCED UPPER-LEVEL
TROUGH OVER THE DESERT SW WITH A POTENT DISTURBANCE MOVING SE
THROUGH THE NORTHERN BAJA REGION. A 500 MB RIDGE SITS W OF THE
OUTER WATERS AND EXTENDS NORTH INTO SOUTHERN BRITISH COLUMBIA.
MEANWHILE, A WARM FRONT IS SKIRTING THE NORTHERN PZ5 WATERS
TONIGHT WITH LITTLE FANFARE. IN FACT, GOES-W NIGHTTIME
MICROPHYSICS SHOWS VERY LITTLE CLOUDINESS OVER MOST OF THE PZ5
AND PZ6 ZONES.
CURRENT FORECAST LOOKS GOOD AS ASCAT SHOWS WINDS OF LESS THAN 25
KT ACROSS THE ZONES AND THE LATEST SEA STATE HAS WAVES OF 8 FT OR
LESS. NO CHANGES WILL BE MADE TO THE FORECAST THIS EVENING. FOR
ADDITIONAL FORECAST DETAILS, PLEASE SEE THE PREVIOUS DISCUSSION
BELOW.
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PREVIOUS DISCUSSION...
HIGH PRESSURE WILL REMAIN ANCHORED TO THE WEST OF THE SOUTHERN
WATERS WHILE A FEW WEAK FRONTS WILL PASS OVER THE NORTHERN AND
CENTRAL WATERS AND INLAND TROUGH ALONG CALIFORNIA COAST, WILL
REMAIN FAIRLY WEAK THROUGH THE FORECAST PERIOD. CURRENT NCEP
SYNOPTIC SURFACE WEATHER MAP HAS LOW PRESSURE 1005 MB OVER
SOUTHERN CALIFORNIA THAT EXTENDS A TROUGH NORTHWEST ALONG THE
CALIFORNIA COAST. HIGH PRESSURE 1021 MB NEAR 30N135W STILL EXTENDS
A RIDGE EAST INTO THE WATERS INTO ANOTHER WEAK HIGH CENTER 1020
MB OVER OREGON WATERS.
AT 500 MB LEVEL, GLOBAL MODELS STILL SHOW SOME ENERGY EMBEDDED
IN A SHORT WAVE OVER THE NORTH WATERS WHILE AN UPPER LEVEL RIDGE
HAS CONTINUED TO DOMINATE THE SOUTHERN HALF OF THE WATERS. MOST
OF THE ENERGY WILL SHIFT INLAND IN THE SHORT TERM. THE ENERGY
WILL THEN SLOWLY THIN OUT AND THAT WILL CONTINUE TO WEAKEN THE
TROUGH ALONG CALIFORNIA COAST IN THE EXTENDED PERIOD.
GLOBAL MODELS GFS/CMC/NOGAPS/UKMETHR/ECMWFHR HAVE REMAINED FAIRLY
CLOSE TO THE LATEST SYNOPTIC SURFACE OBSERVATIONS. MODELS ARE IN
A GOOD AGREEMENT ON MAINTAINING HIGH PRESSURE TO THE WEST AND
KEEPING A WEAKENING TROUGH ALONG THE COAST. MODELS ALSO HAVE
PERSISTENTLY SHOWN HIGH PRESSURE DOMINATING THE FORECAST WATERS
INITIALLY AND SLOWLY WEAKENING INTO THE EXTENDED PERIOD. OTHER
ARE STILL MINOR VARIATIONS AMONG THE MODELS THAT ARE MAINLY ON
THE EXTENT OF AREAL COVERAGE OF RELATIVELY HIGHER WINDS IN THE
EXTENDED PERIOD. WILL CONTINUE TO USE GFS AS IT CONTINUES TO HAVE
A SLIGHTLY LARGER AREA COVERED BY ENHANCED WINDS AND EVEN
STRONGER THAN NOGAPS AND UKMETHR WHILE ECMWFHR STILL HAS THE
WEAKEST WINDS. BOTH CMC AND GFS HAVE A BETTER AND ARE MUCH CLOSER
TO THE OBSERVATIONS AND FOR CONSISTENCY, WILL CONTINUE TO USE
GFS FOR WINDS.
SEAS
ARE STILL RELATIVELY SMALL AND FAIRLY UNIFORM ACROSS THE
WATERS AS THEY RANGE BETWEEN 4 AND 7 FT WITH RELATIVELY LARGE
SEAS OVER THE OUTER WATERS. GFSWAVE AND ECMWFWAVE MODELS STILL FIT
GENERALLY WELL THE LATEST OBSERVED SEAS AND HAVE BEEN QUITE
CONSISTENT WITH OBSERVATIONS IN PREVIOUS RUNS. BOTH WAVE MODELS
STILL AGREE ON KEEPING RELATIVELY SMALL SEAS ACROSS HE WATERS
THROUGH MOST OF THE FORECAST PERIOD. THIS IS REASONABLE AS WINDS
ARE RELATIVELY LOW ACROSS THE WATERS AND WILL CONTINUE WITH
GFSGLOBAL WAVE FOR SEAS.
EXTRATROPICAL STORM SURGE GUIDANCE
N/A
WARNINGS
PRELIMINARY.
PZ5 WASHINGTON/OREGON WATERS
NONE.
PZ6 CALIFORNIA WATERS
NONE.
.FORECASTER FOLMER/MUSONDA. OCEAN PREDICTION CENTER.
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