000 AGXX40 KNHC 301842 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 300 PM EDT THU APR 30 2009 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... SOUTHEASTERLY FLOW WILL PREVAIL OVER THE GULF THROUGH AT LEAST MONDAY WITH THE WESTERN EDGE OF THE ATLC RIDGE STRETCHING TO THE NE GULF OF MEXICO WHILE A MEAN TROUGH LIES OVER TX AND NE MEXICO. STRONG EASTERLY FLOW IN THE STRAITS OF FLORIDA...COUNTER TO THE CURRENT...WILL DIMINISH SLIGHTLY OVER THE WEEKEND...ONLY TO INCREASE TO CONSISTENTLY ABOVE 20 KT AGAIN BY MON AS THE RIDGE AXIS IN THE ATLC SHIFTS SOUTHWARD. THE MODELS ARE IN GOOD AGREEMENT HERE...BUT DIVERGE IN THE WESTERN GULF WHERE THERE IS DISAGREEMENT WITH THE TIMING AND STRENGTH OF THE NEXT TROUGH TO MOVE INTO THE PLAINS. THE NOGAPS AND 12Z/30 ECMWF PROPOSED FASTER AND FLATTER SOLUTIONS ALOFT IN THE PLAINS THAN THE GFS AND UKMET. CONSIDERING THE STRONG ZONAL UPPER JET EXPECTED TO DEVELOP ACROSS THE NE PACIFIC BY SAT...BELIEVE A FASTER AND WEAKER SOLUTION IS MORE LIKELY AND THE FRONT WILL PROBABLY NOT MAKE IT TO THE TX COAST BEFORE RETREATING NORTHWARD NEAR THE END OF THE PERIOD. SW N ATLC... THE MODELS AGREE THAT THE 1027 MB HIGH PRES SYSTEM NEAR 30N47W THAT HAS DRIVEN THE STRONG WINDS S OF 25N IN THE SW N ATLC THE LAST FEW DAYS WILL BE OVERTAKEN BY THE 1035 MB HIGH CENTER NEAR 42N64W AS IT MOVES EASTWARD ALONG 40N. THE STATIONARY BOUNDARY ALONG 33N WILL WEAKEN AS A RESULT...WITH THE PREVAILING WINDS SOUTHEASTERLY AROUND 10 KT N OF 28N TONIGHT THROUGH SUN. IN THE BAHAMAS AND S FL...WINDS HAVE DIMINISHED SLIGHTLY IN RESPONSE TO THE SHIFTING HIGH PRESSURE...AND THE MEAN FLOW IS EXPECTED TO DROP BELOW 20 KT OVER THE WEEKEND ONLY TO RETURN ON MON. THERE IS CONSIDERABLY LARGER UNCERTAINTY IN THE FORECAST S OF 28N E OF 70W WHERE A WEAKENING DEEP LAYER TROUGH IS EXPECTED TO BREAK DOWN BY SAT AS THE UPPER LEVEL TROUGH IS SHIFTED SE BY THE ANTICYCLONE DRIFTING SE OVER SW N ATLC WATERS. MEANWHILE THE SURFACE TROUGH...CURRENTLY ALONG 61W FROM 19N TO 26N...CONTINUES WESTWARD. CONFIDENCE IS LOW...BUT THE FORECAST CALLS FOR THE SURFACE TROUGH TO DISSIPATE BY SAT. THERE IS A CONSIDERABLE AMOUNT OF DEEP LAYER MOISTURE ASSOCIATED WITH THE TROUGH AT THE MOMENT...BUT CONVECTION IS WEAK AND FOUND NE OF THE TROUGH AXIS. CARIBBEAN AND TROPICAL N ATLC... SIMILARLY TO ABOVE BASINS...THE CARIBBEAN AND TROPICAL ATLC ARE EXPERIENCING DIMINISHING EASTERLY FLOW DUE TO THE WEAKENED ATLC HIGH PRES RIDGE....WITH STRONGEST FLOW AROUND 25 KT CURRENTLY FOUND IN THE SOUTHERN CARIBBEAN NEAR THE COAST OF COLOMBIA WHERE IT IS MORE TYPICAL. SEAS ARE RESPONDING ACCORDINGLY WITH SLOWLY SUBSIDING NELY WIND SWELL AT AROUND 8 SECONDS AFFECTING THE REGION S OF 20N IN THE TROPICAL ATLC. THE DEEP LAYER TROUGH CURRENTLY AROUND 61W TO THE NE OF THE CARIBBEAN IS EXPECTED TO BREAK DOWN IN THE VERTICAL OVER THE NEXT FEW DAYS...WITH THE UPPER LEVEL TROUGH MOVING EASTWARD AND AMPLIFYING OVER THE TROPICAL CENTRAL ATLC BY SUN/MON. WHILE THE MODELS AGREE ON THIS UPPER LEVEL PATTERN...THEY DISAGREE ON THE EVOLUTION OF ANY MID LEVEL ENERGY PASSING S OF THE MEAN RIDGE THROUGH THE NORTHERN PORTION OF THE TROPICAL N ATLC ZONE....SO CONFIDENCE IN THE FORECAST BREAKS DOWN HERE BY THE WEEKEND. ATLC... .NONE.. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FORECASTER SCHAUER CLARK. TROPICAL PREDICTION CENTER.