000 AGXX40 KNHC 131836 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 300 PM EDT SUN JUL 13 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. TROPICAL STORM BERTHA IS FORECAST TO SLOWLY MEANDER NORTH OVER THE NEXT TWO DAYS BEFORE TAKING A MORE EASTERLY TURN AS IT ENCOUNTERS A WEAKENED MID LEVEL TROUGH CURRENTLY OVER THE UPPER MISSISSIPPI VALLEY. AT THE SAME TIME...THE MID TO UPPER LEVEL RIDGE TO ITS E IS EXPECTED TO WEAKEN SIGNIFICANTLY AS AN UPPER LOW FROM THE N CENTRAL ATLC...NEAR 40N 42W...DRIFTS SW. BERTHA COULD CONTINUE TO INFLUENCE THE FAR NE PORTION OF THE FORECAST REGION THROUGH FRI. SEE THE OFFICIAL NHC FORECAST FOR DETAILS ON BERTHA. A WEAK MID LEVEL TROUGH CURRENT JUST E OF FL SHOULD SLOWLY MIGRATE W ACROSS THE PENINSULA THROUGH THU AND INTO THE WESTERN GULF OF MEXICO ON FRI. THE SURFACE REFLECTION...A WEAK TROUGH OVER THE NORTHERN GULF OF MEXICO AND EXTENDING OFF THE N FL COAST...IS EXPECTED TO LINGER THROUGH THU BEFORE SHIFTING W AS WELL. LOOK FOR THE SURFACE RIDGE TO BUILD TO THE S OF BERTHA AND SLOWLY BUILD W INTO THE GULF OF MEXICO. A TROPICAL WAVE CURRENTLY ALONG 89W SHOULD PASS W THRU THE YUCATAN AND THE BAY OF CAMPECHE MON THROUGH WED. IN THE CARIBBEAN...EXPECT MAINLY E FLOW ALONG THE S EDGE OF THE SURFACE RIDGE AXIS TO DOMINATE THE PATTERN. A TROPICAL WAVE ALONG 58W S OF 20N SHOULD PASS W AT 15 TO 20 KT ALONG THE SOUTHERN PERIPHERY OF THE RIDGE PUTTING THE WAVE THROUGH THE ISLANDS BY MON MORNING...ACROSS 70W BY WED...AND APPROACHING THE E COAST OF NICARAGUA BY FRI. ANOTHER TROPICAL WAVE...THIS ONE ALONG 37W AND MOVING W AT 10 TO 15 KT...IS EXPECTED TO CROSS 55W INTO THE FORECAST AREA ON THU AND APPROACH THE ISLANDS BY THE END OF THE PD. A REGION OF UPPER LEVEL DIFFLUENCE...ON THE S EDGE OF THE UPPER LOW EXPECTED TO APPROACH TROPICAL STORM BERTHA....IS FORECAST TO TRACK W WITH THIS WAVE AND POTENTIALLY ENHANCE CONVECTION WITH THE SYSTEM THROUGH THE PERIOD. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. .FORECASTER SCHAUER CLARK. TROPICAL PREDICTION CENTER.