Marine Interpretation Message
Issued by NWS

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000 AGNT40 KWNM 240057 MIMATN MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN NWS OCEAN PREDICTION CENTER WASHINGTON DC 900 PM EDT WED 23 JUL 2014 .FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT .WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N. COLD FRONT IS APPROACHING NEW ENGL AND NRN MID ATLC COASTS THIS EVENING AND AHEAD OF IT IS A FEW LINES OF TSTMS. RADAR AND LIGHTNING DENSITY PRODUCT INDICATE LINE APPROACHING COASTAL ME IS WEAKENING WITH STRONGER LINES OVER WRN MA AND NWRN CT WILL BE MOVING OFFSHR BETWEEN 01Z-02Z. ANOTHER LINE WILL BE MOVING OFF NJ COAST WITHIN THE HOUR. 23Z RAP AS WELL AS 15Z SREF BASED SVR TSTM PROBABILITIES ALL SUGGEST THAT LINES SHOULD WEAKEN AS THE ENCOUNTER MORE STABLE MARINE ENVIRONMENT AND RELATIVELY FEW REPORTS OF DAMAGING WINDS WILL LIKELY NOT INCLUDE ANY GALE FORCE GUSTS IN TSTMS IN THIS EVENINGS NT1/NT2 ISSUANCES. BUT WILL MONITOR RADAR AND LIGHTNING DENSITY PRODUCT UP UNTIL ISSUANCE TIME BEFORE MAKING FINAL DECISION. GIVEN CHARACTER OF CONVECTION AT THIS TIME WILL UNDOUBTEDLY SEE SOME EHANCED WINDS HIGHER WAVES AND LIGHTNING OFFSHORE S OF NEW ENGL ANZ915/ANZ815 WRN GEORGES BANK ANZ805 AND HUDSON TO BALT CNYNS ANZ820 THIS EVENING INTO TNGT. BEYOND THE NEAR TERM 18Z GFS/NAM DID NOT OFFER MAJOR DIFFERENCES FROM THEIR RESPECTIVE PREVIOUS RUNS. BASED ON THE 1530Z HI RES ASCAT-B OVERPASS WHICH ALREADY INDICATED SOME SW 20 TO 30 KT WINDS ALONG EDGE OF PASS OVER GULF STREAM CAPE FEAR TO 31N ANZ835 ZONE WILL UPDATE GRIDS WITH 12Z GFS BOUNDARY LAYER WINDS OVER WARMER MID ATLC WATERS THRU 12Z/25. OTHERWISE WILL NOT BE MAKING MUCH CHANGE FROM PREVIOUS GRIDS/OFFSHORE FORECASTS. 18Z MULTIGRID WAVEWATCH III APPEARS 1-2 FT TOO HIGH WITH SIG WV HGTS THIS EVENING OVER MOST NT1 AND NT2 ZONES. PREVIOUS SIG WV HGT GRIDS REDUCED THE 12Z MWW3 BY 10 TO 20 PERCENT AND THIS STILL LOOKS REASONABLE. ---------------------------------------------------------------- ...PREVIOUS DISCUSSION... COLD FRONT MVG THRU THE ERN GRT LKS RGN TDY STILL ON TRACK TO MOV OFFSHR N OF CAPE HTTRS JUST PRIOR TO 12Z TMW. GFS STILL SW WNIDS INCRSNG TO 25 KT EARLY TNGT OVR THE GULF OF MAINE. N OF 39/40N... THE PREFRNT SW FLOW IN THE GFS 10M WINDS LOOK OVER DONE BY ABOUT 5 KT COMPARED WITH LATST OBS AND SCATTEROMETER PASS FM 15Z TDY. WILL CAP WINDS AT 22 KT IN THE GRIDS...EXCEPT E OF HTRS CNYN WHERE THESE SLGTLY HGR WINDS ARE MORE LIKELY OVR THE WARMED WATRS. MODELS IN VERY GOOD AGREEMENT ON THE TIMING AND LOC OF THE FRONT AS IT SLIWLY MVS SE THE NRN AND CNTRL WATESR THU THRU FRI NGT. MODELS AGREE ON WK FRONT TO HANG UP NR CAPE HTTRS FRI NGT... THEN DRIFT N TO NE INTO SAT NGT WHILE DSPTNG. MODEL DIAGREEMENT BGN TO APPEAR OVR THE WEEKEND WITH SFC LOW... OR LOWS FCST TO MOV THRU THE GRT LKS SUN AND PASS NR THE NR WATERS MON...THOUGH LESS SO WITH THE ASSD COLD FRONT. UPR LOW NOW OFF THE PAC COAST WL MOV OVR WRN CONUS RDG THEN SE ACRS THE GRT LKS RGN SUN...WHERE THE MODESL BGN TO WKN AND LOW AND DISAGREE N TIMING. THE UKMET S THE FASTEST...WHILE THE GFS/ECMWF HOLD MORE OF THE ENERGY BACK. BY 12Z MON...GFS/ECMWF AGREE ON A SLOWER MVMNT OF THE SFC LOW..BUT THEN THE GFS TAKES THE LOW NE ABOUT 200-300 NM E OF THE SLOWER ECMWF. QUITE REMARKABLY...THE MODELS ARE IN EXCELLENT AGREEMNET ON THE TIMING OF THE COLD FRONT TIMING OF THE ASSD COLD FRONT. BY 12Z TUE...GFS/ECMWF/UKMET ONLY ABOUT 60 NM OR LESS APART ON FRONT XTNDG FM ERN LONG ISLAND SW TO THE VA CAPES. SW WINDS WL BGN INCRSNG SUN AHD OF THE FRONT. BY 12Z...THE GFS BL WINDS NICRS TO 20 TO 30 KT OVR A GOOD PART OF THE OFFSHR WATERS. THE ECMWF IS ABOUT 5 TO OCCNLY 10 KT LESS. SO WL BLEND TO TWO MODELS FOR NOW. .SEAS...THE 12Z MULTIGRID WAVEWATCH INITLD SEAS AT OR ABOUT A FT TOO HIGH N OF THE GULF STREAM...AS HAS BN THE CASE. WL SHAVE 10 TO 15 PCT OFF THE WAVEWATCH FCST OVR THE COLDER WATERS FOR TNGT INTO THU NGT...THEN 10 TO 20 PCT LWR FOR SUN AND MON. .EXTRATROPICAL STORM SURGE GUIDANCE...N/A. .WARNINGS...PRELIMINARY. .NT1 NEW ENGLAND WATERS... NONE. .NT2 MID ATLC WATERS... NONE. $$ .FORECASTER CLARK/PROSISE. OCEAN PREDICTION CENTER.

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