000 AGXX40 KNHC 071756 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 200 PM EDT TUE JUN 07 2011 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. AFTERNOON UPDATE... THERE IS ONLY ONE SIGNIFICANT CHANGE TO THE EARLIER THINKING...AND THAT IS WITH THE BROAD AREA OF LOW PRES IN THE NW CARIBBEAN. THIS SYSTEM IS BECOMING LESS ORGANIZED UNDER WESTERLY SHEAR. OBSERVATIONS NEAR THE LOW DO NOT SUGGEST AS EXTENSIVE AN AREA OF 20 KT WINDS AS SEEN LAST NIGHT...SO THE AREA WAS SHRUNK TO WITHIN 180 NM OF THE LOW IN THE SHORT RANGE. THE LOW WILL BE SLOW TO MOVE AWAY FROM ITS CURRENT POSITION NEAR 18N82W...BUT SHOULD FINALLY LIFT N THU AS UPPER TROUGHING OVER THE GULF OF MEXICO AMPLIFIES AND PICKS THE SYSTEM UP INTO ITS EASTERN EDGE. THE NHC-HPC MEDR CONFERENCE CALL AGREED ON A SOLUTION THAT CARRIES THE LOW INTO THE STRAITS OF FL FRI AND WEAKENS THE SYSTEM OVER THE SOUTHERN FL PENINSULA SAT. CONFIDENCE IS STILL LOW IN THE MODELS...ESPECIALLY AS THE 12Z GFS WAS DEEMED A WESTERN OUTLIER WITH THE TRACK ON THE CONFERENCE CALL. ------------------------------------------------------------- PREV DISCUSSION... GULF OF MEXICO... A WEAK 1015 MB HIGH CENTER IS ANALYZED NEAR 27N88W AT 0600 UTC. LATEST OBSERVATIONAL REPORTS FROM BUOYS THROUGHOUT INDICATE LIGHT WINDS AND LOW SEAS THROUGHOUT. THE EXCEPTION IS IN THE FAR SOUTHERN PORTIONS OF THE MIDDLE AND EASTERN ZONES WHERE A SLIGHTLY TIGHTER PRES GRADIENT THERE DUE TO THE COMBINATION OF BROAD LOW PRES IN THE WESTERN CARIBBEAN AND THE HIGH IS RESULTING IN NE-E 15 TO 20 KT WINDS. BUOY REPORTS SHOW SEA HEIGHTS IN THE RANGES OF 1-3 FT...EXCEPT IN THE FAR SOUTHERN PORTIONS OF THE MIDDLE AND EASTERN ZONES WHERE SEAS ARE MAXING UP TO 6 FT. WAVEWATCH GUIDANCE LOOKS REASONABLE FOR THE GULF...AND WILL LEAN TOWARDS THE GUIDANCE FOR THIS FORECAST PERIOD. MODELS DEPICT THE HIGH TO LIFT NW THROUGH THE NEXT 24 HOURS AS THE BROAD LOW PRES AREA IN THE CARIBBEAN SLOWLY MOVES IN A NLY DIRECTION OVER THE NEXT COUPLE OF DAYS. UNCERTAINTY STILLS REMAINS HIGH AS TO FUTURE IMPLICATIONS OF THIS LOW PRES AREA ON THE THE AREA/S WINDS AND SEAS AS FORECAST TRACK REMAINS QUITE OPEN AS TO WHERE EXACTLY THE LOW PRES WILL TRACK ONCE IT APPROACHES CUBA OR THE YUCATAN PENINSULA IN ABOUT 48 HOURS. EARLIER IT WAS THOUGHT THAT THE 15-20 KT WINDS AS STATED ABOVE WOULD DECREASE TODAY...BUT WITH THE SYNOPTIC SETUP OF LOW PRES TO THE S AND HIGH PRES ACROSS THE GULF REMAINING THROUGH THE NEXT FEW DAYS WILL CONTINUE TO MENTION 15-20 KT WINDS THROUGH FRI IN FAR SOUTHERN EASTERN GULF...AND THROUGH SAT IN THE FAR SOUTHERN MIDDLE GULF. THERE IS A VERY GOOD POSSIBILITY THAT THESE WINDS MAY HAVE TO BE ADJUSTED BASED ON TIMING AND EVOLUTION...IF ANY...OF THE LOW PRES IN THE CARIBBEAN AS IT APPROACHES THE GENERAL VICINITY OF WESTERN CUBA AND GULF AS GLOBAL MODELS SUGGEST THROUGH THE END OF WEEK. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE MAIN FEATURE CONTINUES TO BE THE BROAD AREA OF LOW PRES OVER THE NORTHWESTERN CARIBBEAN SEA WITH A MEAN LOW CENTER OF 1007 MB CENTERED NEAR 18N8.5W...OR ABOUT 100 NM SSW OF GRAND CAYMAN AT 0600 UTC THIS MORNING. A TROUGH EXTENDS FROM THE LOW SW TO INLAND NORTHEASTERN HONDURAS. LATEST SATELLITE IMAGERY SHOWS AMPLE DEEP MOISTURE COVERING JUST ABOUT THE ENTIRE CARIBBEAN SEA N OF 12N...AND ALSO THE NORTHERN AND CENTRAL SECTIONS OF THE TROPICAL N ATLC. THE MOISTURE IS RESULTING IN SCATTERED CLUSTERS OF SHOWERS AND TSTMS...WITH THE STRONGEST OF THE TSTM ACTIVITY BETWEEN JAMAICA AND EASTERN CUBA...AND N OF 15N E OF 70W. THE SHOWER AND TSTM ACTIVITY ACROSS THE CARIBBEAN AND NORTHERN TROPICAL N ATLC DURING THE PERIOD WILL BE ACCOMPANIED BY VERY LOW VISIBILITIES AND GUSTY WINDS. A BROAD UPPER LEVEL TROUGH OVER MUCH OF THE WESTERN AND CENTRAL GULF OF MEXICO HAS BEGUN TO HAMPER THE UPPER LEVEL ENVIRONMENT OVER THE FAR SE GULF AND NW CARIBBEAN SEA AS A JET STREAM BRANCH MARKED BY STRONG SW WINDS IS PRODUCING SW SHEAR OVER THOSE AREAS. THE SAME SYNOPTIC AS MENTION ABOVE UNDER GULF OF MEXICO WITH HIGH PRES OVER THE GULF N OF THE LOW IS RESULTING IN A TIGHT PRES GRADIENT N AND NE OF THE LOW WITH NE-E MOSTLY 20 KT WIND...ALTHOUGH AT TIMES WINDS REACH UP TO 25 KT. SEAS WITHIN THESE AREAS OF WINDS ARE 5-7 FT...BUT SOMETIMES MAY RISE TO 8 FT. A TROPICAL WAVE IN THE TROPICAL N ATLC ZONE ALONG A POSITION FROM 16N56W TO 10N60W MOVING NW AT 10-15 KT. THE WAVE WILL MOVE THROUGH THE REMAINDER OF THE TROPICAL N ATLC TODAY... AND MOVE INTO THE EASTERN CARIBBEAN LATE THIS AFTERNOON AND EARLY EVENING...WITH LITTLE IMPACTS TO WIND AND SEAS WITH JUST PERHAPS BRIEF INSTANCES OF GUSTY WINDS WITH ASSOCIATED PASSING SHOWERS AND SCATTERED TSTMS. THE WAVE WILL THEN LIFT NW AND MERGE WITH AN E TO W TROUGH OVER THE FAR NORTHERN WATERS THROUGH WED NIGHT. THE PRES GRADIENT WILL BE RELATIVELY WEAK ELSEWHERE ASIDE FROM CONDITIONS DESCRIBED WITH THE LOW AND OUTSIDE CONVECTION ALLOWING FOR LIGHT WIND CONDITIONS AND LOW SEAS TO BE IN STORE THROUGH FRI. SW N ATLC... FRESH NE TO E WINDS ARE NOW CONFINED TO THE SW WATERS AND MUCH OF THE STRAITS OF FLORIDA...BETWEEN WEAK HIGH PRES OVER THE WESTERN PORTION AND THE BROAD LOW PRES AREA IN THE NORTHWESTERN CARIBBEAN SEA. A WEAKENING FRONTAL TROUGH IS ALONG 31N BETWEEN 67W-78W. MAXIMUM SEAS OBSERVED ARE ABOUT 5 FT W OF THE BAHAMAS AND OVER THE STRAITS OF FLORIDA. GLOBAL MODELS FORECAST THE AREA OF HIGH PRES TO SLIDE SE THROUGH LATE THU AS WEAK LOW PRES FORMS OVER THE SE WATERS. ALL MODELS...WITH THE EXCEPTION OF THE GFS FORECAST A LOW TO FORM JUST OR ALONG THE FLORIDA E COAST BY THE END OF THE WEEK AND TRACK IT NNE. FOR NOW WILL DESCRIBE AND ANALYZE THIS FEATURE AS A TROUGH ON NEXT ISSUED FORECAST. THE MAIN EMPHASIS WILL BE THE INCREASING GRADIENT OVER THE SOUTHERN WATERS AS THE WEAK LOW FORMS THERE THROUGH THE NEXT 24 TO 36 HOURS WITH S-SW WINDS TO THE SE OF THE LOW INCREASING TO 20 KT OR MAYBE TO 25 KT. WARNINGS... ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE/SCHAUER