000 AXNT20 KNHC 211756 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT MAR 21 2015 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 1630 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 6N11W TO NEAR 4N21W. THE ITCZ EXTENDS FROM 0NS23W TO THE COAST OF SOUTH AMERICA NEAR 3S40W. SCATTERED MODERATE TO STRONG CONVECTION IS OCCURRING WITHIN 150 NM S OF THE AXIS E OF 20W...AND FROM 0N-6S BETWEEN 30W AND 46W. ...DISCUSSION... GULF OF MEXICO... BROAD AND PERSISTENT UPPER RIDGE DOMINATES THE BASIN...CENTERED ON AN ANTICYCLONE OVER THE GULF OF HONDURAS AND EXTENDING N ALONG 88W INTO THE OHIO VALLEY. A SOUTHERN STREAM MID TO UPPER CYCLONE WAS SHIFTING EAST NORTHEASTWARD ACROSS NRN MEXICO AND NEW MEXICO...AND IS FORECAST TO WEAKEN AS IT MOVES INTO THE LOWER MISSISSIPPI THROUGH MONDAY AND FLATTEN THE RIDGE CONSIDERABLY. TROPICAL MOISTURE FROM THE EPAC IS BEING DRAWN FROM THE TROPICS N ACROSS MEXICO AND THEN NE ACROSS THE NW HALF OF THE BASIN IN THE FORM OF HIGH CLOUDS. AT THE SURFACE...AND WEAK FRONTAL BOUNDARY MEANDERS ALONG THE N GULF COASTS AND COASTAL WATERS THIS MORNING...FROM NEAR CORPUS CHRISTI HUGGING THE COAST TO THE MOUTH OF THE MISSISSIPPI RIVER THEN E-SE TO THE FLORIDA BIG BEND. A WEAK 1019 MB HIGH WAS CENTERED S OF THIS BOUNDARY OVER THE NE GULF OF MEXICO NEAR 27N86.5W. AREAS OF DENSE FOG AND LOW STRATUS COULD BE SEEN IN SATELLITE IMAGERY EARLIER THIS MORNING N OF THE FRONT SHIFTING SLOWLY S ACROSS THE COASTAL WATERS FROM SE LOUISIANA TO THE BIG BEND AREA...AND ALSO ACROSS N FLORIDA. VSBYS HAVE BEGUN TO IMPROVE LATE THIS MORNING AS FOG AND STRATUS BEGIN TO BURN OFF. A COASTAL TROUGH WAS EVIDENT ACROSS SW PORTIONS OF THE BASIN ALONG THE MEXICAN COAST FROM NEAR LA PESCA TO COATZACOALCOS. LIGHT TO MODERATE SOUTHERLY RETURN FLOW PREVAILED ACROSS NW PORTIONS...AND WAS OVERRUNNING THE FRONT TO PROVIDE MOISTURE FOR WIDESPREAD CONVECTION ACROSS MOST OF THE TEXAS COASTAL ZONES AND INTO SW LOUISIANA. THE FRONT IS EXPECTED TO MEANDER ACROSS THE N AND NW COASTAL WATERS TODAY...AND REMAIN WEAK ACROSS NE PORTIONS...THEN SHIFT SE ACROSS W PORTIONS TONIGHT AND SUNDAY...REACHING FROM SE LOUISIANA TO TAMPICO MEXICO BY SUNDAY AFTERNOON. ACTIVE CONVECTION IS EXPECTED ALONG THE BOUNDARY TONIGHT AND SUNDAY. CARIBBEAN SEA... VERY STABLE ATMOSPHERIC CONDITIONS PERSIST ACROSS THE BASIN TODAY AS A TUTT AXIS CONTINUES FROM THE CENTRAL ATLC W-SW TO CENTRAL AMERICA ALONG 10N. THE ATLANTIC RIDGE REMAINS FAR REMOVED FROM THE BASIN...WHICH IS ALLOWING FOR ONLY LIGHT TO MODERATE TRADEWINDS ACROSS MOST OF THE BASIN...WHILE TYPICALLY STRONG TRADES ACROSS S CENTRAL PORTIONS OFFSHORE OF COLOMBIA WERE ONLY 20 KT THIS MORNING...PER RECENT SCATTEROMETER DATA. SCATTEROMETER DATA ALSO SHOWED ELY WINDS 15-20 KT ACROSS THE OUTER WATERS OF THE GULF OF HONDURAS. SMALL CLUSTERS OF BROKEN MULTI LAYERED CLOUDS AND EMBEDDED MODERATE SHOWERS WERE NOTED JUST SW OF HISPANIOLA...BETWEEN JAMAICA AND CUBA...AND ACROSS SE PORTIONS. EXPECT LITTLE CHANGE IN THESE OVERALL CONDITIONS DURING THE NEXT 24-36 HOURS. ...HISPANIOLA... THE SANTO DOMINGO UPPER AIR SOUNDING FROM THIS MORNING VERIFIES SATELLITE IMAGERY...WHERE VERY STABLE MID TO UPPER CONDITIONS PREVAIL DUE TO SUBSIDENCE ACROSS THE REGION. LIGHT TO MODERATE TRADES WERE OCCURRING SURROUNDING THE ISLAND...WITH A WEAK WAVE AGAIN DEVELOPING TO THE LEE OF THE ISLAND OVERNIGHT...YIELDING THE CLOUDS AND SHOWERS EXTENDING FROM THE BARAHONA PENINSULA W AND SW TO 16N74.5W. SCATTERED TO BROKEN CUMULUS COULD BE SEEN DEVELOPING ACROSS THE INTERIOR OF THE ISLAND SINCE 1500 UTC...AND SHOULD DEVELOP SCATTERED SHALLOW CONVECTION DURING THE AFTERNOON HOURS...THEN CLEAR UP OVERNIGHT. EXPECT SIMILAR CONDITIONS OVER THE NEXT 24 HOURS AND THIS DIURNAL CYCLE REPEATS. ATLANTIC OCEAN... TUTT AXIS PREVAILS THROUGH THE MIDDLE LEVELS EXTENDING FROM BROAD UPPER CYCLONE EXTENDING FROM FRANCE AND PORTUGAL SW TO E OF THE LESSER ANTILLES THEN WWD ALONG ABOUT 13N INTO THE CARIBBEAN. A SOUTHERN REGION SHORT WAVE WAS AMPLIFYING ALONG 56- 57W...WITH TROUGH TRAILING OFF THE SW AND REINFORCING SUBSIDENCE ACROSS THE E AND SE CARIBBEAN. THIS TROUGH SUPPORTS A STATIONARY FRONT MEANDERS FROM 31N46W TO 23N60W THEN FORMS A WARM FRONT NW TO NEAR 31N67W. THIS WARM FRONT INTERSECTS A WEAK COLD FRONT MOVING SLOWLY SE INTO NW PORTIONS NEAR 31N68W TO 29N74W THEN STATIONARY TO JUST N OF JACKSONVILLE. A PRE FRONTAL TROUGH WAS S OF THE FRONT TO THE NW BAHAMAS. AREAS OF DENSE FOG HUGGED FLORIDA E COASTAL ZONES AND COASTAL WATERS THIS MORNING FROM JACKSONVILLE TO LAKE WORTH BUT HAS SINCE BURNED OFF. ELSEWHERE THE ATLC RIDGE EXTENDED FROM THE NE ATLC SW INTO CENTRAL PORTIONS AND WAS PROMOTING MODERATE TRADEWINDS ACROSS THE BASIN E OF 55W...AS WELL AS N OF THE STALLED FRONT BETWEEN 50W AND 70W. LOOK FOR THE FRONT ACROSS NW PORTIONS TO MOVE E TODAY AND REACH FROM NEAR BERMUDA TO 29N68W TO OFFSHORE OF JACKSONVILLE BY THIS EVENING...THEN SINK SLOWLY SE ACROSS CENTRAL PORTIONS TONIGHT. MEANWHILE...WEAK LOW PRES IS FORECAST TO DEVELOP ACROSS THE N FLORIDA AND GEORGIA COASTAL WATERS TONIGHT AND SUN AND REMAIN NEARLY STATIONARY AND WILL CONTINUE TO CONTRIBUTE TO WEAKENED TRADEWIND FLOW ACROSS MOST OF THE AREA W OF 55W. A WARM FRONT MAY EVOLVE WITH THE LOW...AND SUFFICIENT PRESSURE GRADIENT IS EXPECTED N OF THE FRONT TO PRODUCE NE TO E WINDS 20-25 KT ACROSS EXTREME NW PORTIONS...WHERE CONVECTION WILL BECOME ACTIVE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ STRIPLING