000 AXNT20 KNHC 201801 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE MAR 20 2012 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO 07N16W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N16W TO 02N29W TO 01N36W TO THE EQUATOR NEAR 41W THEN TO 02S44W. NO SIGNIFICANT CONVECTION IS NOTED. ...DISCUSSION... GULF OF MEXICO... A MID/UPPER LEVEL RIDGE IS OVER THE EASTERN PART OF THE GULF ROUGHLY ALONG 84W...AND EXTENDING S TO THE NW CARIBBEAN SEA. TO THE W OF THE RIDGE...UPPER LEVEL SWLY FLOW IS EVIDENT AHEAD OF A VIGOROUS UPPER LEVEL TROUGH CURRENTLY OVER THE SOUTHERN PLAINS WITH PLENTY OF MIDDLE TO UPPER LEVEL ENERGY ASSOCIATED WITH IT. AT THE SURFACE...THE ASSOCIATED COLD FRONT IS JUST OFFSHORE THE TEXAS COAST AS OF EARLY THIS AFTERNOON. A PRE-FRONTAL SQUALL LINE IS VIVIDLY NOTED ON BOTH NWS RADAR DISPLAYS AND ON SATELLITE IMAGERY TO EXTEND FROM NE TEXAS SSW TO WITHIN 40-50 NM SE OF THE FAR SOUTHERN TEXAS COAST. VERY STRONG SE-S FLOW MARKING THE LOW LEVEL JET SHOOTING NW FROM THE SW GULF INTO THE NW GULF AHEAD OF THE SQUALL LINE CONSISTS OF 25-30 KT WINDS AS NOTED ON RECENT AND EARLIER BUOY...AND OFFSHORE OIL PLATFORM OBSERVATIONS. STRONG TSTM ACTIVITY WITH GUSTY WINDS ALONG THE SQUALL WILL CONTINUE TO TRACK NE THROUGH WED EVENING AS THE COLD FRONT BEHIND IT SLOWLY MOVES EASTWARD. THE FRONT IS FORECAST TO GRADUALLY WEAKEN AND DISSIPATE OVER THE MIDDLE GULF SECTION WED NIGHT AND THU AS THE UPPER LEVEL SUPPORT DIMINISHES. E TO SE WINDS OF 15-20 KT ARE EXPECTED E OF THE FRONT WED DIMINISHING TO 10 KT THU...AND NW-N DIMINISHING TO 10 KT BEHIND IT WED AND THU AS WEAK HIGH PRES SETTLES IN OVER THE NE GULF. CARIBBEAN SEA... CONFLUENT WESTERLY UPPER LEVEL FLOW IS OBSERVED ACROSS MUCH OF THE WESTERN CARIBBEAN ON THE WESTERN PERIPHERY OF WEAK UPPER LEVEL TROUGHING EXTENDING INTO THE NORTH-CENTRAL CARIBBEAN FROM THE SW N ATLC. THE TAIL END OF THE TROUGH STRETCHES SW TO NW COLOMBIA. RESULTANT MODERATE SUBSIDENCE FROM THE CONFLUENT FLOW IS PRESENT E OF A LINE FROM HAITI TO SE HONDURAS AND E TO LINE FROM MARTINIQUE TO NW VENEZUELA. STABLE ATMOSPHERIC CONDITIONS ASSOCIATED WITH THE MODERATE SUBSIDENCE LAYER ARE ALLOWING FOR ONLY ISOLATED SHOWERS IN THE THE LIGHT ELY SURFACE TO LOW-LEVEL FLOW TO PREVAIL. OVER THE NW PORTION...SCATTERED TO BROKEN HIGH CLOUDS ORIGINATING FROM THE EASTERN PACIFIC ARE STREAMING EASTWARD N OF 15N W OF 76W WHICH IS WHERE THE SRN PORTION OF THE GULF MID/UPPER LEVEL IS LOCATED. VERY NARROW LINES OF ISOLATED SHOWERS MOVING QUICKLY NW ARE NOTED WITHIN THIS AREA OF SCATTERED TO BROKEN HIGH CLOUDS. BROKEN HIGH CLOUDS STREAMING NEWD ARE TO THE SE OF THE MARTINIQUE TO NW VENEZUELA LINE. THE LOW TO MID LEVELS OF THE ATMOSPHERE WITHIN THIS SAME AREA REMAIN RATHER STABLE. THE HIGH CLOUDS SE OF THE MARTINIQUE TO NW VENEZUELA ARE SPREADING NE AND E ACROSS THE ATLC AS DESCRIBED BELOW. WITH RESPECT TO MAINLY MARINE INTERESTS...NE TO E 20-25 KT WINDS ARE CONFINED TO S OF 13N BETWEEN 73W AND 77W UNDER TIGHT PRES GRADIENT BETWEEN THE 1006 MB COLOMBIAN LOW AND STRONG ATLC HIGH PRES RIDGING TO THE N OF THE CARIBBEAN. THESE WINDS ARE FORECAST TO SLACKEN TO 15-20 KT BY THU AS ATLC HIGH PRES CENTERED N OF 32N DROPS S AND WEAKENS. ATLANTIC OCEAN... WATER VAPOR IMAGERY INDICATES BROAD UPPER LEVEL TROUGHING OVER MUCH OF THE SW N ATLC BETWEEN 74W AND 56W WITH ITS MEAN AXIS EXTENDING INTO THE DISCUSSION AREA THROUGH 32N55W...AND CONTINUING SW TO 26N65W TO DOMINICAN REPUBLIC AND INTO THE NORTH/CENTRAL CARIBBEAN SEA. THE NORTHEASTERN PORTION OF THIS TROUGH AXIS SUPPORTS A SURFACE TROUGH ANALYZED FROM 32N38W TO 26N45W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 60-90 NM OF THE TROUGH. MOSTLY MODERATE SUBSIDENCE SUPPRESSING DEEP CONVECTION FROM DEVELOPING IS PRESENT WITHIN THE AREA OF THE TROUGH EXCEPT N OF 26N W OF 70W WHERE UPPER LEVEL MOISTURE IS SEEN ADVECTING SSE IN MODERATE TO STRONG UPPER NW FLOW IN THE WAKE OF THE TROUGH. THE OTHER EXCEPTION IS A 75 NM WIDE LINE OF SCATTERED SHOWERS AND A FEW TSTMS THAT LIES ALONG 22N61W 22N70W. THIS ACTIVITY IS MAINLY ATTRIBUTED TO LOW-LEVEL WIND SPEED CONVERGENCE AS TIGHT PRES GRADIENT EXISTS ALONG THE SRN PERIPHERY OF A STRONG SURFACE ATLC RIDGE OVER THE WRN PORTION OF THE ATLC ANCHORED BY 1029 HIGH CENTER N OF THE AREA NEAR 36N65W. OVER THE EASTERN PORTION OF THE ATLC...THE NOTABLE FEATURE IS A RATHER STRONG SURFACE NE TO SW RIDGE EXTENDING FROM 32N25W TO 25N34W. BROAD UPPER LEVEL RIDGING IS SEEN IN THE UPPER LEVELS OF THE ATMOSPHERE OVER THIS AREA OF THE ATLC WITH THE EXCEPTION OF THE FAR SE PORTION WHERE A MID/UPPER LEVEL TROUGH EXTENDS FROM EASTERN LIBERIA AFRICA SW TO NEAR 01N14W. CLUSTERS OF SCATTERED STRONG CONVECTION ARE LOCATED WITHIN 120 NM SE OF THE TROUGH. SCATTEROMETER DATA FROM THIS MORNING SHOWED WHAT APPEARS TO BE A POSSIBLE RE-ALIGNMENT OF THE ITCZ AXIS ALONG THE LOCATION OF THIS CONVECTIVE ACTIVITY. VISIBLE SATELLITE IMAGERY SHOWS A LARGE AREA OF AFRICAN DUST COVERING THE AREA FROM 02N TO 23N E OF ABOUT 49W. VERY STRONG CONFLUENT TYPE SW FLOW UPPER FLOW BETWEEN THE UPPER LEVEL RIDGING AND A RATHER VIGOROUS DEEP LAYER TROUGH PRESSING SEWD N OF THE RIDGE IS ADVECTING AMPLE MOISTURE IN THE MID AND UPPER LEVELS OF THE ATMOSPHERE IN THE FORM OF BROKEN MOSTLY UPPER LEVEL CLOUDS NEWD FROM NORTHERN S AMERICA TO NEAR 40W FROM 21N TO 32N...AND SEWD IN THE FORM OF SCATTERED HIGH LEVEL CLOUDS E OF 40W TOWARDS WESTERN AFRICA FROM 16N TO 22N. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ AGUIRRE