Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 180324
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
824 PM PDT WED SEP 17 2014

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.

THE LTST IR SAT IMG SHOW CONV CLDS OVR THE NRN WTRS BUT WITH SOME
LIGHTNG. THE RADAR SHOW TSTMS CELLS OVR THE ERN PARTS OF THE NRN
WTRS. AT 18/00Z AREA OF LOW PRES WITH ONE CNTR 998 MB JUST W OF
THE CNTRL WTRS HAS A FRNT STRCHNG NE ACRS THE NW PORTIONS OF WASH
WTRS. ASERIES OF LOWS XTEND SE INTO CAL STATE.THE PRES GRDNT IS
NOT ALL THAT TIGHT AND THE MAX OBS WINDS ARE 25 KT OVR THE CNTRL
REGION. THE LAST ASCAY PASS AT 1848Z HAD WINDS TO 30 KT OVR THE
CNTRL REGION. THE SEAS ARE HGHST WITH 14 FT PEAKS OVR THE WRN
PARTS OF THE CNTRL CA. THE GLB MDLS ARE IN GUD AGRMNT OVR THE
SHORT TERM. WIL STAY WITH GFS. LOW PRES WILL PERSIST OVR THE CNTR
REGION BUT WILL WEAKEN AS HGH PRES APPROACHES FRM THE W. NO WRNGS
IN THE FCST


-----------------------------------------------------------------
PREVIOUS DISCUSSION...

OVER THE SHORT TERM...OVERALL THE NEW 12Z MDLS ARE IN RNSBLY GOOD
AGRMT IN REGARDS TO THEIR FCST TRACKS FOR A SLOWLY WKNG SFC LOW
DRIFTING E ACRS THE NRN PZ6 WTRS TONITE...TURNING SWD THU...THEN
DISSIPATING THU NITE. A FCST TRACK CLOSEST TO THE 12Z GFS/ECMWF
LOOKS MOST REPRESENTATIVE. IN REGARDS TO THE FCST GRADIENTS ASCD
WITH THIS SYSTEM...A COMPROMISE BTWN THE STRONGER 12Z NAM/GFS/GEM
VS THE WEAKER 12Z NAVGEM/UKMET/ECMWF LOOKS RSNBL. PER THIS
COMPROMISE EXPECT MAX WINDS GNRLY IN THE 20-25 RANGE INVOF THE SFC
LOW. THEN BY LATE FRI/FRI NITE THE 12Z MDLS REMAIN CONSISTENT IN
FCSTG A STRENGTHENING NNWLY GRADIENT TO DVLP ACRS THE NRN PZ6 AND
SE PZ5 WTRS BTWN A HIGH PRES RIDGE FCST TO BLD ACRS THE PZ5 WTRS
AND A SFC TROF FCST TO STRENGTHEN AND EXPAND NW NEAR THE
CALIFORNIA COAST. THE 12Z NAM/GFS/GEM CONT TO FCST A SMWHT
STRONGER GRADIENT (WITH THE 12Z GFS BRIEFLY FCSTG GALE FORCE 30M
BL WINDS NR PT ST GEORGE FRI NITE) THAN THE WEAKER 12Z
NAVGEM/UKMET/ECMWF. AGAIN A COMPROMISE BTWN THESE MDL CAMPS FOR
THIS GRADIENT LOOKS RSNBL. AS A RESULT OF THIS COMPROMISE WL FCST
MAX WINDS GNRLY IN THE 20-30 KT RANGE. SO TO REPRESENT THESE SHORT
TERM COMPROMISES...SMLR TO THE PREV OFSHR FCSTS...PLAN ON
POPULATING OUR SHORT TERM FCST WIND GRIDS WITH A 50/50 BLEND OF
THE 12Z GFS 30M AND 12Z ECMWF BL WINDS FOR TONITE THRU FRI NITE.

IN THE LONG RANGE...BY LATE SAT INTO SUN THE 12Z GLOBAL MDLS
GNRLY AGREE THAT THE NNWLY GRADIENT WL WKN AS THE HIGH PRES RIDGE
WKNS AND A WEAK SFC LOW FORMS ON THE SFC TROF NR THE NRN
CALIFORNIA COAST SAT...DRIFTS NW INTO THE PZ5 WTRS SAT NITE...THEN
DISSIPATES SUN. A SOLUTION CLOSEST TO THE 12Z GFS/ECMWF LOOKS
RSNBL FOR SAT INTO SUN. THEN SUN NITE INTO MON NITE TO VARYING
DEGREES THE 12Z MDLS FCST A WEAKENING COLD FRONT TO DRIFT E INTO
THE PZ5 AND NRN PZ6 WTRS WITH WEAK ASCD GRADIENTS. THEREFORE FOR
OUR LONG RANGE WIND GRIDS WL CONT TO POPULATE WITH A 50/50 BLEND
OF THE 12Z GFS 30M AND 12Z ECMWF BL WINDS FOR SAT/SAT NITE...THEN
WL TRANSITION TO ALL 12Z ECMWF BL WINDS SUN/SUN NITE WITH SM
FURTHER EDITS IN DEFERENCE TO THE 12Z GFS 10M BL WINDS. SO NO
MAJOR LONG RANGE CHNGS ARE PLANNED FOR THE NEXT OFSHR FCST
PACKAGE.

SEAS...SMLR TO THEIR PREV RESPECTIVE RUNS...THE 12Z WAVEWATCH III
AND 12Z ECMWF WAM FCST RMRKBLY SMLR SEAS THAT NEVER DIFFER BY MR
THAN 1-2 FT THRUT THE FCST PERIOD. THEREFORE AS WAS DONE
PREVLY...WILL USE A 50/50 BLEND OF THE TWO MDLS THRU SUN NITE.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.


.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
     NONE.

.PZ6 CALIFORNIA WATERS...
     NONE.

$$

.FORECASTER MUSONDA/VUKITS. OCEAN PREDICTION CENTER.


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