000
AGXX40 KNHC 201844
MIMATS

MARINE WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
330 PM EDT SAT JUN 20 2009

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

ATLC...
THE MODELS ARE IN GOOD AGREEMENT ON THE DEVELOPMENT OF A HIGHLY 
AMPLIFIED PATTERN N OF 20N WITH A SLOW MOVING CUT OFF LOW OFF 
THE NORTHEAST U.S. COAST BOOKENDED BY UPPER LEVEL RIDGING OVER 
THE CENTRAL N ATLC AND THE SOUTHERN PLAINS/LOWER MISSISSIPPI. 
THE MAJOR FEATURE OF INTEREST IS THAT WRN ATLC CUT OFF LOW. THE 
ASSOCIATED DEEPENING SURFACE LOW WILL PUSH OFF THE E COAST EARLY 
SUN...WITH A WEAKENING COLD FRONT ENTERING THE NORTHERN WATERS 
ON MON. GLOBAL MODELS AGREE ON THE EVOLUTION OF THE SYSTEM AND 
THE TIMING OF THE FRONT THROUGH SUN...WITH SOUTHWEST WINDS 
INCREASING TO 20-30 KT AHEAD OF THE FRONT LATE THIS WEEKEND AND 
EARLY NEXT WEEK. MORE CONSIDERABLE UNCERTAINTY LIES WITH THE 
TRACK AND STRENGTH OF THE SHORTWAVE ENERGY DROPPING DOWN THE 
BACKSIDE OF THE UPPER TROUGH THROUGH THE SOUTHEAST U.S. AND 
OFFSHORE ON MON. THE MODELS AGREE ON DEVELOPING A WAVE ALONG THE 
SURFACE BOUNDARY NEAR 29N72W BY MON EVENING...BUT DIFFER WITH 
THE TIMING AND STRENGTH OF THE WAVE AS IT LIFTS NORTHEASTWARD 
ALONG THE BOUNDARY...EVENTUALLY WRAPPING INTO THE LOW N OF THE 
AREA. THE SURFACE FRONT WILL WEAKEN OVER FORECAST WATERS BY 
TUE...THOUGH THE BROAD TRAILING SURFACE TROUGH WILL YIELD 
SUFFICIENTLY STRONG GRADIENT FLOW W OF A BUILDING HIGH OVER THE 
CENTRAL ATLC TO MAINTAIN 20-30 KT WINDS E OF THE TROUGH INTO 
WED. THE BUILDING SUBTROPICAL HIGH WILL SHIFT WEST ALONG 28/29N 
PAST 50W BY WED.  AS A RESULT...TRADE WINDS ARE EXPECTED TO 
INCREASE SOLIDLY ABOVE 20 KT S OF 16N. THE TROPICAL WAVE 
CURRENTLY ALONG 48W WILL CONTINUE W INTO THE TROPICAL N ATLC 
SUN/MON...REMAINING S OF 12N.

CARIBBEAN...
THE AFOREMENTIONED TROPICAL WAVE WILL MOVE INTO THE EASTERN 
CARIBBEAN TUE AND CONTINUE W ABOUT 4-5 DEGREES A DAY THROUGH 
WED. THE WAVE WILL GRADUALLY BE SLOWING AND LIFTING NORTHWARD 
NEAR THE VERY END OF THE FORECAST PERIOD AS IT ENCOUNTERS THE 
LEADING EDGE OF A BUILDING BROAD TROUGH OVER THE WESTERN 
CARIBBEAN. THE HIGHLY AMPLIFIED DEEP LAYER TROUGHING ASSOCIATED 
WITH THE CUT OFF LOW OFF THE EASTER U.S. COAST WILL WEAKEN THE 
SUBTROPICAL RIDGE OVER THE BAHAMAS AND STRAITS OF FL AND ACT TO 
SLOW THE EASTERLY STEERING FLOW THROUGH THE CARIBBEAN. 
CURRENTLY...E WINDS OF 15 TO 20 KT COVER MUCH OF THE 
CARIBBEAN...WITH THE EXCEPTION OF 20-25 KT WINDS FOUND NEAR THE 
COAST OF COLOMBIA ACCORDING TO THE 1412 ASCAT PASS. 

GULF OF MEXICO...
HIGH PRES OVER THE N CENTRAL GULF WILL CONTINUE TO WEAKEN AND 
SLIDE W THROUGH EARLY NEXT WEEK AS A WEAK COLD FRONT ASSOCIATED 
WITH THE DEEP LAYER LOW IN THE WESTERN N ATLC PUSHES SOUTH INTO 
THE EASTERN GULF MON AND DISSIPATES. EXPECT LOW LEVEL TROUGHING 
TO LINGER OVER THE SOUTHEAST U.S. AND FAR NE GULF THROUGH THE 
REMAINDER OF THE FORECAST PERIOD...INCREASING THE PRES GRADIENT 
ACROSS THE EASTERN HALF OF THE GULF AND BRINGING NW FLOW SOLIDLY 
TO 15 KT MON THROUGH WED.

WARNINGS

ATLC...
.NONE.

CARIBBEAN...
.NONE.

GULF OF MEXICO...
.NONE.

FORECASTER SCHAUER CLARK. TROPICAL PREDICTION CENTER.