287  
AGNT40 KWNM 241242  
MIMATN  
 
MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN  
NWS OCEAN PREDICTION CENTER WASHINGTON DC  
842 AM EDT MON APR 24 2017  
   
FORECAST DISCUSSION
 
MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT  
.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.  
 
NO MAJOR CHANGES TO THE PREVIOUS AND ONGOING OPC FORECAST APPEARS  
NECESSARY FROM THE MORNING UPDATE. THE 06Z GFS IS VERY SIMILAR TO  
THE 00Z VERSION WHICH WAS USED FOR THE FORECAST OVER THE NEXT FEW  
DAYS.  
 
LOW PRESSURE OVER SOUTHERN SOUTH CAROLINA AND ANOTHER LOW  
LIFTING NORTH FROM THE NORTHERN BAHAMAS WILL COMBINE NEAR THE  
SOUTH CAROLINA COAST LATER TODAY OR EARLY TONIGHT, WITH THE LOW  
LIFTING NORTH AND NORTHEAST THEREAFTER. WIDESPREAD GALES WILL  
ACCOMPANY THIS LOW PRESSURE SYSTEM AS IT CROSSES THE REGION  
LATER THIS MORNING INTO WEDNESDAY NIGHT. NO CHANGES TO THE  
PREVIOUS HEADLINES WILL BE MADE FOR THE MORNING UPDATE. RAIN,  
SHOWERS, AND STRONG THUNDERSTORMS WILL ALSO ACCOMPANY THE LOW AS  
IT CROSSES THE WATERS DURING THE NEXT FEW DAYS. CURRENTLY, THE  
LATEST RADAR, SATELLITE AND LIGHTNING DATA INDICATES SHOWERS AND  
LOCALLY HEAVY THUNDERSTORMS OVER MOST OF THE SOUTHERN AND  
CENTRAL NT2 WATERS MOVING OFF TO THE NORTH. WIND GUSTS EXCEEDING  
GALE FORCE AND VERY ROUGH SEAS CAN BE EXPECTED IN OR NEAR THE  
STRONGER THUNDERSTORMS THROUGHOUT TODAY, TONIGHT AND INTO THE  
MIDDLE OF THE WEEK. ONLY MINOR ADJUSTMENTS TO THE PREVIOUS GRIDS  
AND FORECAST WILL BE MADE FOR THE MORNING UPDATE.  
 
SEAS...AGAIN, NO MAJOR CHANGES APPEAR NECESSARY FOR THE MORNING  
UPDATE. WE WILL ADJUST GRIDS AND THE FORECAST SLIGHTLY TO FIT  
INITIAL CONDITIONS AND NEARBY WFO AND TAFB FORECASTS. CURRENTLY,  
SEA HEIGHTS RANGE FROM 3 TO 5 FEET OVER NT1 OFFSHORE WATERS, OR  
OFF THE NEW ENGLAND COAST TO 5 TO 8 FEET FROM AROUND THE  
DELMARVA SOUTHWARD.  
 
-----------------------------------------------------------------  
PREVIOUS DISCUSSION...  
 
OVER THE SHORT TERM, AS ONE WOULD HOPE AS THE EVENT DRAWS NEARER  
THE NEW 00Z MODELS ARE NOW OVERALL IN GOOD AGREEMENT IN REGARDS  
TO BOTH THEIR FORECAST TRACKS OF A SIGNIFICANT SURFACE LOW  
TRACKING NNE NEAR THE E COAST TONIGHT THROUGH WED AND ITS  
ASSOCIATED FORECAST GRADIENTS. IN RESPONSE TO A CLOSED UPPER LOW  
FORECAST TO MOVE TOWARDS THE SE COAST, THE 00Z MODELS REMAIN  
CONSISTENT IN FORECASTING A SURFACE LOW TO LIFT N INTO THE FAR SW  
NT2 WATERS AND MERGE WITH ANOTHER LOW NEAR THE S CAROLINA COAST  
BY LATE TODAY WITH ASSOCIATED ESE GALES OVERSPREADING THE SRN NT2  
WATERS. THEN TONIGHT INTO WED THE MODELS AGREE THAT THE SURFACE  
LOW WILL BECOME VERTICALLY STACKED WITH THE UPPER LOW AND TRACK  
SLOWLY NE TO OFF THE MID ATLANTIC COAST WITH THE ASSOCIATED GALES  
SPREADING NE ACROSS THE NT2 WATERS. IN REGARDS TO THE FORECAST  
TRACK OF THIS LOW, WOULD FAVOR THE MORE CONSISTENT 00Z GFS  
SOLUTION, WHICH IS SUPPORTED BEST BY THE 00Z UKMET/GEFS MEAN. IN  
REGARDS TO THE ASSOCIATED FORECAST GRADIENTS, BELIEVE THE 00Z GFS  
SOLUTION LOOKS REPRESENTATIVE. THEREFORE, PLAN ON POPULATING OUR  
FORECAST WIND GRIDS WITH OUR SMART TOOL THAT WILL PLACE STRONGER  
00Z GFS FIRST SIGMA LEVEL WINDS IN UNSTABLE AREAS AND WEAKER 00Z  
GFS 10M WINDS IN STABLE AREAS (WHICH WILL BE PRIMARILY FROM THE  
GULF STREAM NWD) FOR TODAY THROUGH WED WITH SOME ADDITIONAL MINOR  
EDITS IN DEFERENCE TO THE 00Z UKMET/ECMWF. SO PER THESE WINDS DO  
NOT ANTICIPATE MAKING ANY SIGNIFICANT TIMING AND/OR AREAL  
COVERAGE CHANGES TO THE PREVIOUSLY FORECASTED HIGH CONFIDENCE  
GALE WARNINGS.  
 
IN THE LONG RANGE, AS THE 00Z MODELS FORECAST THE UPPER LOW TO  
WEAKEN, TO VARYING DEGREES THEY ALL FORECAST THE ASSOCIATED  
SURFACE LOW TO ALSO WEAKEN AS IT TRACKS TO JUST S OF LONG ISLAND  
WED NIGHT (WITH ITS ASSOCIATED WINDS BECOMING SUBGALE), THEN  
DISSIPATE THU. OVERALL, WOULD FAVOR THE SOMEWHAT FASTER  
DISSIPATION FORECAST BY THE 00Z GFS/ECMWF. THEREFORE AFTER  
CONTINUING TO POPULATE WITH 00Z GFS FIRST SIGMA/10M WINDS WED  
NIGHT, AS A COMPROMISE WILL POPULATE WITH A 50/50 BLEND OF 00Z  
GFS 10M AND 00Z ECMWF BOUNDARY LAYER WINDS ON THU/THU NIGHT. THEN  
LATE FRI/FRI NIGHT, WITH THE 00Z GEFS MEAN INDICATING THAT THE  
00Z GFS IS TOO PROGRESSIVE, WILL FAVOR THE WEAKER AND LESS  
PROGRESSIVE 00Z ECMWF SOLUTION FOR A WEAK COLD FRONT TO APPROACH  
THE NEW ENGLAND COAST. SO WILL TRANSITION TO POPULATING WITH ALL  
00Z ECMWF BL WINDS ON FRI/FRI NIGHT.  
 
SEAS...OVERALL, THE 00Z WAVEWATCH HAS INITIALIZED THE CURRENT  
SEAS SLIGHTLY BETTER THAN THE 00Z ECMWF WAM. WITH THIS IN MIND,  
AND SINCE THE 00Z GFS WILL BE FAVORED, WILL POPULATE OUR FORECAST  
WAVE GRIDS WITH THE 00Z WAVEWATCH III FOR TODAY THROUGH WED  
NIGHT. THEN SINCE A BLENDED 00Z GFS/ECMWF SOLUTION WILL BECOME  
FAVORED, WILL TRANSITION TO POPULATING WITH A 50/50 BLEND OF THE  
TWO WAVE MODELS ON THU/THU NIGHT. THEN FRI/FRI NIGHT, SINCE THE  
00Z ECMWF WILL BECOME FAVORED, WILL POPULATE WITH ALL 00Z ECMWF  
WAM SEAS.  
   
EXTRATROPICAL STORM SURGE GUIDANCE
 
AS THE STRONG ELY GRADIENT  
IS FORECAST DEVELOP N OF THE LOW PRESSURE CENTER LATE TODAY AND  
THEN SHIFT NWD UP THE MID ATLANTIC COAST TONIGHT INTO TUE NIGHT,  
THE 00Z ESTOFS CONTINUES TO FORECAST A MORE SIGNIFICANT SURGE TO  
DEVELOP ON THE COAST THAN FORECAST BY THE 00Z ETSS. OVERALL,  
WOULD FAVOR THE HIGHER 00Z ESTOFS SOLUTION.  
   
WARNINGS
 
PRELIMINARY.  
   
NT1 NEW ENGLAND WATERS
 
 
NONE.  
   
NT2 MID-ATLANTIC WATERS
 
   
ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL
 
 
GALE TUESDAY INTO TUESDAY NIGHT.  
GALE POSSIBLE WEDNESDAY.   
ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N
 
 
GALE TUESDAY NIGHT.  
GALE POSSIBLE WEDNESDAY INTO WEDNESDAY NIGHT.    
ANZ825...INNER WATERS FROM BALTIMORE CANYON TO CAPE CHARLES LIGHT
 
 
GALE TUESDAY.   
ANZ828
 
INNER WATERS FROM CAPE CHARLES LIGHT TO CURRITUCK BEACH LIGHT...  
GALE TONIGHT INTO TUESDAY.    
ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS CANYON
 
 
GALE TONIGHT INTO TUESDAY NIGHT.  
GALE POSSIBLE WEDNESDAY.   
ANZ830...INNER WATERS FROM CURRITUCK BEACH LIGHT TO CAPE HATTERAS
 
 
GALE TONIGHT INTO TUESDAY.    
ANZ833...INNER WATERS FROM CAPE HATTERAS TO CAPE FEAR
 
 
GALE TODAY INTO TUESDAY.    
ANZ930...OUTER WATERS FROM HATTERAS CANYON TO CAPE FEAR
 
 
GALE TODAY INTO TUESDAY.    
ANZ835...INNER WATERS FROM CAPE FEAR TO 31N
 
 
GALE TODAY INTO TONIGHT.    
ANZ935...OUTER WATERS FROM CAPE FEAR TO 31N
 
 
GALE TODAY INTO TONIGHT.  
 

 
 
.FORECASTER MILLS/VUKITS. OCEAN PREDICTION CENTER.  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page