000 AXNT20 KNHC 122345 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT MAR 12 2011 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 07N12W 02N19W CROSSING THE EQUATOR NEAR 25W AND ALONG 01S41W THEN INTO NE BRAZIL NEAR 02S44W. SCATTERED MODERATE CONVECTION IS S OF 04N W OF 22W. ALONG THE WESTERN EXTENT OF THE ITCZ AXIS A SURFACE TROUGH IS ANALYZED FROM 06N49W TO 03S46W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE BOUNDARY... INCLUDING INTERIOR PORTIONS OF NE BRAZIL N OF 05S E OF 51W. ...DISCUSSION... GULF OF MEXICO... RELATIVELY DRY AIR AND UPPER LEVEL SUBSIDENCE WITHIN WEST- NORTHWESTERLY UPPER LEVEL FLOW IS EVIDENT ON WATER VAPOR IMAGERY THIS EVENING ACROSS THE GULF BASIN. THIS WIDESPREAD SUBSIDENCE CONTINUES TO SUPPORT A 1027 MB SURFACE HIGH CENTERED IN THE NE GULF NEAR 29N84W. MOSTLY CLEAR SKIES ARE NOTED ON SATELLITE IMAGERY AND THESE FAIR WEATHER CONDITIONS ARE EXPECTED TO LAST THROUGH THE OVERNIGHT HOURS INTO SUNDAY MORNING. THE HIGH IS FORECAST TO GRADUALLY SHIFT EASTWARD THROUGH MONDAY AND LOCATE OVER THE SW NORTH ATLC. INCREASED SE WINDS ARE EXPECTED OVER THE WESTERN GULF WITH THE NEXT WEAK FRONTAL BOUNDARY FORECAST TO EMERGE OFF THE TEXAS AND LOUISIANA GULF COASTS BY LATE MONDAY INTO EARLY TUESDAY. CARIBBEAN SEA... AN UPPER LEVEL RIDGE AXIS EXTENDS ACROSS THE TROPICAL ATLC ALONG 07N TO SOUTH AMERICA AND THEN W-NW TOWARDS THE NW CARIBBEAN SEA NEAR 17N78W. MOSTLY DRY AIR AND A STABLE ATMOSPHERE ALOFT ACCOMPANIES THIS UPPER LEVEL RIDGING ACROSS THE CARIBBEAN SEA BASIN THIS EVENING. EARLIER MORNING ASCAT PASSES INDICATED E-NE TRADES IN THE 10 TO 20 KT RANGE GENERALLY S OF 17N...WITH HIGHER NE WINDS IN THE 15 TO 25 KT RANGE OCCURRING OVER PORTIONS OF THE NW CARIBBEAN AND IN THE VICINITY OF THE WINDWARD PASSAGE. HIGH PRESSURE CURRENTLY LOCATED OVER THE NE GULF OF MEXICO AND A DIFFUSE COLD FRONT ANALYZED NE OF CUBA IS CREATING THE ENHANCED NE FLOW FILTERING THROUGH THE WINDWARD PASSAGE AND THE WATERS BETWEEN CUBA AND JAMAICA THIS EVENING. THE HIGH IS FORECAST TO SLIDE EASTWARD INTO THE SW NORTH ATLC BY EARLY MONDAY AND PRODUCE STRONGER EASTERLY FLOW AS THE PRESSURE GRADIENT TIGHTENS. THESE TRADES WILL PERSIST THROUGHOUT MUCH OF THE WEEK AS THE HIGH IS EXPECTED TO REMAIN NEARLY STATIONARY. ATLANTIC OCEAN... A DEEP LAYERED TROUGH CONTINUES TO SLOWLY MOVE ACROSS THE WESTERN NORTH ATLC SUPPORTING A COLD FRONT THAT ENTERS THE SW NORTH ATLC REGION NEAR 32N63W AND EXTENDS SW TO ALONG 25N68W BECOMING MORE DIFFUSE ACROSS THE SE BAHAMAS AND EASTERN CUBA. SCATTERED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE FRONT. A WEAK PRE-FRONTAL SURFACE TROUGH IS ANALYZED FROM 32N62W TO 23N63W WITH ISOLATED SHOWERS WITHIN 120 NM EITHER SIDE OF THE BOUNDARY. FARTHER EAST INTO THE CENTRAL ATLC...AN WEAK UPPER LEVEL CUT-OFF LOW IS CENTERED NEAR 25N42W THAT SUPPORTS A SURFACE TROUGH ANALYZED FROM 25N49W TO NEAR 20N35W. INDICATIONS FROM EARLIER MORNING ASCAT PASSES SHOW A STRONG SHEAR AXIS EXISTS ALONG THIS BOUNDARY WITH STRONGER E TO NE WINDS LOCATED TO THE NE OF THE BOUNDARY. LOW-LEVEL SPEED CONVERGENCE ALONG WITH THE UPPER LEVEL DIFFLUENT ENVIRONMENT PROVIDED BY THE UPPER LEVEL LOW IS GENERATING SCATTERED SHOWERS COVERING THE AREA N OF THE SURFACE TROUGH AXIS FROM 20N-28N BETWEEN 31W-50W. ELSEWHERE OVER THE EASTERN ATLC...A DIFFUSE AND DISSIPATED COLD FRONT IS ANALYZED INTO THE DISCUSSION AREA NEAR 32N22W AND EXTENDS WESTWARD ALONG 30N TO NEAR 36W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT. THIS FRONT IS SUPPORTED ALOFT BY AN UPPER LEVEL TROUGH LOCATED N OF 28N BETWEEN 15W-30W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN