000
AGXX40 KNHC 050659
MIMATS

MARINE WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
300 AM EDT SAT SEP 05 2009

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA
AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W.

GULF OF MEXICO...SPLIT FLOW OVER THE CENTRAL CONUS WITH A BROAD 
MID TO UPPER LEVEL TROUGH OVER THE MISSISSIPPI VALLEY IS 
SUPPORTING A SURFACE TROUGH THROUGH CENTRAL FL AND THE GULF OF 
MEXICO ALONG 27N TO 28N E OF 90W. SURFACE TROUGH WILL CONTINUE 
TO DRIFT N INTO NORTHERN GULF WATERS THROUGH EARLY NEXT WEEK. 
MODELS SHOW THE WEAK TROUGH MEANDERING OVER THE N GULF COAST TUE 
AND WED. MOST OF THE MODELS CARRY SOME OF THE MID LEVEL ENERGY 
ASSOCIATED WITH THE REMAINS OF ERIKA THROUGH THE STRAITS OF FL 
INTO THE SE GULF ON TUE...WITH THE NOTABLE EXCEPTION OF THE GFS 
WHOSE SOLUTION WITH THE REMNANT OF ERIKA IS NOT PREFERRED. SEE 
SECTION BELOW FOR DETAILS. THE FORECAST CALLS FOR TROUGHING TO 
BUILD OVER THE EASTERN GULF TUE AND WED AS THE REMNANTS OF ERIKA 
APPROACH THE AREA WITH THE ECMWF AND CMC SOLUTIONS RECOMMENDED 
BY THE HPC PMDHMD PRODUCT. IN ANY EVENT...WINDS 5 TO 10 KT AND 
SEAS 1 TO 3 FT THROUGH PERIOD.

SW N ATLC...A WEAK LOW LEVEL TROUGH WILL PERSIST OVER THE NW 
PORTION THROUGH THE FORECAST PERIOD WITH LIGHT NORTHEASTERLY 
WINDS W OF THE TROUGH. UNCERTAINTY LIES WITH THE FORECAST FOR 
THE REMNANTS OF ERIKA. CONFIDENCE IS LOW IN THE NORTHEASTERLY 
AND STRONG GFS AND NOGAPS FORECASTS...ALLOWING THE MID LEVEL 
REMNANTS OF ERIKA TO MOVE INTO THE SE SIDE OF AN UPPER LOW 
CURRENTLY CENTERED NEAR 26N63W. SOUTHWESTERLY FLOW BETWEEN THIS 
LOW AND AN UPPER-LEVEL ANTICYCLONE NEAR 18N55W HAS INDUCED 
SIGNIFICANT SHEAR OVER WHAT REMAINS OF THE SYSTEM WHICH SHOULD 
INHIBIT ANY DEVELOPMENT OVER THE NEXT FEW DAYS. LOW LEVEL 
STEERING FLOW AROUND THE SUBTROPICAL HIGH SHOULD MOVE THE 
REMNANT SURFACE TROUGH W-NW THROUGH THE GREATER ANTILLES AND 
BAHAMAS WITH THE HPC PREFERRED ECMWF AND CMC MODELS SUGGESTING 
THAT SOME OF THE ENERGY WILL MOVE AHEAD OF THE MAIN SURFACE 
TROUGH INTO THE SE GULF OF MEXICO BY TUE. FOR NOW...A BLEND OF 
THE ECMWF AND CMC IS PREFERRED.
  
TROPICAL ATLC AND CARIBBEAN...AS REMNANTS OF ERIKA MOVE 
NORTHWESTERLY...THE GRADIENT ALONG COAST OF COLOMBIA HAS RELAXED 
WITH WINDS CURRENTLY LESS THAN 20 KT ACCORDING TO THE 0148 UTC 
ASCAT PASS AND BECOMING 15-20 KT OVER THE E CARIBBEAN THROUGH 
LATE SUN. TRADES THEN RESUME THROUGH MID WEEK. FURTHER E...WEAK 
LOW PRES ALONG A TROPICAL WAVE AT 14N38W HAS BEEN MOVING W AT 10 
TO 15 KT SINCE YESTERDAY....BUT SHOULD MOVE LITTLE FASTER 
REACHING ALONG 55W TUE NIGHT...MODELS DO NOT SEEM TO FAVOR 
DEVELOPMENT BUT LIKELY A NE TO SE WIND SHIFT. FURTHER 
E...ANOTHER WAVE NEAR 28W IS CURRENTLY MOVING W AT 10 KT. TWDAT 
FORECASTS CONTINUED DEVELOPMENT OF THIS SYSTEM...POSSIBLY INTO A 
TROPICAL CYCLONE...OVER THE NEXT TWO DAYS. THE MODELS DISAGREE 
ON THE SPEED OF THE SYSTEM AS IT MOVES W TOWARD THE TROPICAL N 
ATLC ZONE...WITH THE GFS THE FASTEST SOLUTION. DESPITE THE MODEL 
DIFFERENCES...THE SYSTEM IS NOT EXPECTED TO REACH FORECAST 
WATERS DURING THE FORECAST PERIOD.


WARNINGS

ATLC...
.NONE.

CARIBBEAN...
.NONE.

GULF OF MEXICO...
.NONE

$$
FORECASTER SCHAUER CLARK