Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 280023
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
823 PM EDT THU AUG 27 2015

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.

NO MAJOR CHANGES ARE PLANNED FOR THE EVENING UPDATE. THE MAIN FCST
CONCERN CONTINUES TO BE TOWARD THE VERY END OF THE FCST PERIOD
WITH TROPICAL STORM ERIKA. THE 18Z GFS WAS CLOSE TO THE PREVIOUS
12Z GFS WITH THE TRACK...THOUGH WAS A TAD SLOWER THAN THE 12Z RUN
TUE AND TUE NIGHT. THE ONLY CHANGES PLANNED WILL BE OVER THE FAR
SRN NT2 WATERS PENDING THE NEW ADVISORY FROM NHC.
OTHERWISE...CURRENT FCST LOOKS ON TRACK. THE LATEST SEA STATE
ANALYSIS INDICATED THAT OBSERVED SEAS MATCHED UP WELL WITH THE
MWW3 FCST VALUES.

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

ASCAT OVRPASS AFTR 15Z RETURNED GREAT CVRG ACRS MOST OF THE OFSHR
ZNS. MOST NOTABLE FEATURE IS THE CLEARLY DEFINED WIND SHIFT ASCD
WITH A STNRY BNDRY THAT IS DRAPED NE TO SW ACRS THE SRN ZNS TO A
LOPRES CENTERED ALONG THE CST NR SAVANNAH GA. NW OF THE FRONT
INVOF THE OUTER BANKS...E TO NE 15-25 KT WINDS WERE DETECTED WHICH
WERE CONFIRMED IN THE GROUND TRUTH OF BUOY AND SHIP OBS IN THE
AREA. S OF THE BNDRY S TO SE WINDS MOSTLY IN THE 10-15 KT RANGE
WERE DETECTED...BUT WITH LOCALLY HIER VALUES TO 30 KT EMBEDDED
WITHIN ONGOING CONVECTION. THE LTST VSBL IMGRY AND LTNG DETECTION
DATA SHOW WDSPRD SHRA/TSTMS CONTG ACRS THE SRN HALF OF THE
WTRS...AND AS THE LOW OR OTHER NEW FRONTAL WVS FORM/LIFT NE ALONG
THE STALLED FRONT XPCT CONTD ROUNDS OF SHRA AND TSTMS ACRS THE SRN
HALF OF THE WTRS THRUT THE FIRST FEW PRDS OF THE PKG.

WL BE USING THE 12Z GFS 10M WINDS TO POPULATE THE GRIDS AND TEXT
THIS AFTN. THRU THE END OF THE WKND SUN A STNRY FRONT WL RMN ACRS
THE SRN WTRS AND A LOW OR SERIES OF FRONTAL WVS FORM AND RIDE NE
ALNG THE BNDRY. TO THE N AFTER A LOPRES TROF CROSSES THE NRN WTRS
TNGT A HIGH PRES WILL SPREAD OVR THE RGN. BY MON INTO TUE GUIDANCE
SUGGEST THE SRN PORTION STNRY FRONT SHUD FINALLY WASH OUT AND
HIGH PRES WL BUILD ACRS ALL OF THE OFSHR WTRS.

ASIDE FROM ALL OF THE ABV...THE MAIN FOCUS THIS AFTN CONTS TO BE
THE HIGHLY PROBLEMATIC AND HIGHLY UNCERTAIN FCST PERTAINING TO
TROPICAL STORM ERIKA. BASED ON THE LTST NHC GUID ERIKA FCST TO BE
JUST S OF THE SRN OFSHR ZNS BY D5/TUE 12Z. THIS FCST IS LIKELY TO
EVOLVE WITH FUTURE UPDATES.

.SEAS...IN SMLR FASHION TO THE WIND GRIDS WL BE USING THE LTST
12Z/WNA TO POP SIG WVHTS. WL INCRS VALUES SLIGHTLY AT THE VERY
INITIAL PERIODS TO BETTER MATCH ONGOING OBS...MORE TWDS THE
12Z/WAM...WHICH WL YIELD VALUES HIER BY ABT A FOOT IN AREAS OF 25
KT WINDS OFF THE MID ATLC CST. SHUD ALSO BE NOTED THAT THAT
LOCALLY HIER SIG WVHTS CUD BE PRESENT WITHIN THE NE-LY COUNTER
FLOW TO THE GLF STRM IN THE WTRS ADJACENT TO THE NC CST.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
.ANZ835...INNER WATERS FROM CAPE FEAR TO 31N...
     TROPICAL STORM POSSIBLE TUE.

$$

.FORECASTER KOSIER/COLLINS. OCEAN PREDICTION CENTER.



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