000 AXNT20 KNHC 160552 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT MAR 16 2013 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 3N13W 2N26W 1N34W 2S41W. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE FROM THE EQUATOR TO 5N BETWEEN 20W AND 40W. SIMILAR CONVECTION IS WITHIN 150 NM OFF THE COAST OF LIBERIA. ISOLATED MODERATE CONVECTION IS FROM 1N-4N W OF 40W TO THE NORTHERN COAST OF BRAZIL. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES FAIRLY DRY AIR ALOFT N OF 25N W OF 90W AND N OF 23N E OF 90W RESULT OF CONFLUENT UPPER LEVEL FLOW ALONG 28N AND MIDDLE LEVEL NORTHWESTERLY FLOW. THIS OVERALL ATMOSPHERIC REGIME ALOFT IS CONTINUING TO SUPPORT A BROAD SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED IN THE NE GULF NEAR 27N83W. IN TERMS OF WINDS...SOUTHERLY-SOUTHEASTERLY FLOW IN THE RANGE OF 10-15 KT SPREADS N 26N W OF 84W AS WELL AS N OF 20N W OF 94W. EASTERLY FLOW IN THE SAME MAGNITUDE RANGE DOMINATES THE CENTRAL GULF FROM 21N-25N BETWEEN 81W AND 93W. HOWEVER IN THE SW GULF S OF 20N NORTHEASTERLY FLOW IS OBSERVED. BROKEN TO OVERCAST SKIES COVER THE SW GULF S OF 25N W OF 88W SUPPORTED BY MOISTURE ADVECTION FROM THE E PACIFIC BY SOUTHWESTERLY FLOW. LIGHT FOG AND HAZE HAS BEEN REPORTED ALONG THE SOUTHERN GULF COASTLINE FROM TUXPAN TO CAMPECHE AND THE GOES IR IMAGERY ENHANCEMENT AS WELL AS THE TOTAL PRECIPITABLE WATER INDICATE POSSIBLE ISOLATED SHOWERS OVER THIS REGION. OVER THE COURSE OF 24 HOURS...RETURN FLOW WILL BUILD OVER THE BASIN WHILE THE HIGH PRESURE DRIFT EASTWARD TO THE WEST ATLC. CARIBBEAN SEA... SOUTHWESTERLY FLOW IN THE MIDDLE TO UPPER LEVELS FROM A BROAD RIDGE WITH AXIS OVER THE CENTRAL ATLC IS ADVECTING MOISTURE ACROSS MOST OF THE BASIN EARLY THIS MORNING. THIS MOISTURE IS SUPPORTING LOW LEVEL CLOUDINESS AND ISOLATED SHOWERS ACROSS THE CARIBBEAN WATERS. THE MAIN FEATURE IMPACTING THE BASIN THIS MORNING CONTINUES TO BE A SHEAR LINE ANALYZED ACROSS THE NORTHERN HISPANIOLA NEAR 19N72W TO EASTERN JAMAICA NEAR 17N77W TO 14N81W. EASTERLY TO NORTHEASTERLY FLOW SPREADS OVER THE ENTIRE REGION WITH THE MAXIMUM OBSERVED WINDS BEING 25 KT WEST OF THE SHEARLINE AND ALONG THE COAST OF COLOMBIA. THE SHEAR LINE IS EXPECTED TO BECOME DIFFUSE OVER THE NEXT 12 TO 24 HOURS AS A BROAD SURFACE RIDGE CURRENTLY OVER THE EASTERN GULF OF MEXICO BUILDS EASTWARD INTO THE SW NORTH ATLC. AS THE PRESSURE GRADIENT TIGHTENS BETWEEN 69W AND 76W DURING SATURDAY...AN AREA OF 20 TO 25 KT TRADE WINDS IS EXPECTED ACROSS PORTIONS OF THE CENTRAL CARIBBEAN. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH OVER THE NW NORTH ATLC WITH AXIS NEAR 60W EXTENDING SOUTHWESTWARD TO 27N65W IS SUPPORTING A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 30N51W CONTINUES ALONG 26N56W 21N65W TO THE NORTHERN HISPANIOLA WHERE IT TRANSITIONS TO A SHEARLINE. SCATTERED SHOWERS ARE WITHIN 260 NM WEST OF THE FRONT N OF 24N AS WELL AS 220 NM EAST OF THE COLD FRONT. IN THE EASTERN ATLC...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 37N24W AND CONTINUES TO SUPPORT A 995 MB SURFACE LOW CENTERED SOUTH-SE OF THE AZORES NEAR 35N26W. THE ASSOCIATED COLD FRONT ENTERS THE DISCUSSION AREA AS A DISSIPATING COLD FRONT THAT EXTENDS ALONG 30N19W 25N22W TO 22N27W. A SECONDARY WAVE OF ENERGY IS ALSO NOTED AS A SURFACE TROUGH AXIS FROM 30N26W TO 25N31W. LITTLE PRECIPITATION ASSOCIATED WITH THESE FEATURES LIES N OF 28N BETWEEN 23W AND 25W. WITHIN THE COURSE OF 24 HOURS...THE COLD FRONT IS EXPECTED TO DISSIPATE WHILE THE HIGH PRESSURE OVER THE EASTERN GULF DRIFTS TOWARD THE WEST ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ RAMOS