000 AXNT20 KNHC 271105 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT APR 27 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF SIERRA LEONE NEAR 8N12W TO 4N20W. THE ITCZ BEGINS NEAR 4N20W AND CONTINUES ALONG 3N30W EQ40W 2S44W. A CLUSTER OF NUMEROUS MODERATE CONVECTION HAS MOVED OFF THE COAST OF AFRICA AND EXTENDS FROM 3N-8N BETWEEN 11W- 17W. SCATTERED SHOWERS ARE WITHIN 80 NM EITHER SIDE OF THE ITCZ AXIS. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER LEVEL RIDGING CONTINUES ACROSS THE GULF OF MEXICO SUPPORTING SURFACE RIDGING N OF 22N EXTENDING FROM A 1029 MB HIGH CENTERED NEAR 37N75W. E TO SE SURFACE WINDS OF 5-20 KT SPREAD ACROSS THE GULF AND AROUND THE RIDGE ALONG WITH MOSTLY CLEAR SKIES. A WEAK SURFACE TROUGH IS OVER THE BAY OF CAMPECHE ALONG 21N92W TO 17N93W. ISOLATED SHOWERS ARE POSSIBLE IN THE BAY OF CAMPECHE S OF 22N ASSOCIATED TO THE SURFACE TROUGH AND BEING ENHANCED BY MOISTURE ADVECTION FROM THE E PACIFIC OCEAN. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS AS SURFACE RIDGING REMAINS THE DOMINANT FEATURE. THE TAIL OF A COLD FRONT IS EXPECTED TO ENTER THE NW GULF SUNDAY MORNING. CARIBBEAN SEA... BROAD UPPER RIDGING ACROSS THE GULF OF MEXICO EXTENDS TO THE WESTERN CARIBBEAN. SCATTERED SHOWERS ARE POSSIBLE IN THE YUCATAN CHANNEL AND WITHIN 100 NM FROM THE SOUTHERN COASTLINE OF CUBA DUE TO MOISTURE ADVECTION FROM THE E PACIFIC OCEAN BY W-NW FLOW. AN UPPER LEVEL TROUGH CONTINUES POSITIONED OVER THE REMAINDER OF THE CARIBBEAN. DRY AIR IN THE MIDDLE LEVELS ASSOCIATED TO THIS TROUGH CONTINUES FAVORING MOSTLY FAIR CONDITIONS AT THE SURFACE WITH ONLY A FEW PATCHES OF POSSIBLE ISOLATED SHOWERS WITHIN 150 NM S OF LA HISPANIOLA AS WELL AS WITHIN 200 NM OF THE HONDURAS COASTLINE. ISOLATED SHOWERS ARE ALSO IN THE FAR SE CORNER OF THE BASIN. A MUCH LARGER AREA OF SCATTERED SHOWERS IS EAST OF THE WINDWARD ISLANDS ASSOCIATED WITH MOIST SOUTHWESTERLY FLOW ALOFT AROUND THE UPPER TROUGH. THIS AREA OF MOIST CONDITIONS EAST OF THE ISLANDS MAY DRIFT WEST OVER THE WEEKEND POSSIBLY BRINGING HEAVY RAINFALL TO SOME OF THE SOUTHERN LESSER ANTILLES. TRADEWIND FLOW OF 10-15 KT DOMINATES THE CENTRAL AND EASTERN CARIBBEAN WHILE WINDS UP TO 20 KT SPREAD OVER THE WESTERN AND SOUTHERN REGIONS OF THE BASIN DUE TO A TIGHTER PRESSURE GRADIENT. ATLANTIC OCEAN... A NARROW UPPER LEVEL TROUGH IN THE W ATLC EXTENDS ALONG 66W SUPPORTING A COLD FRONT N OF THE DISCUSSION AREA THAT TRANSITIONS TO A SURFACE TROUGH ENTERING THE DISCUSSION AREA ALONG 30N65W TO 28N66W. CONVECTION ASSOCIATED TO THIS FRONTAL BOUNDARY IS MOSTLY N OF THE DISCUSSION AREA...HOWEVER SCATTERED SHOWERS ARE POSSIBLE N OF 28N BETWEEN 62W AND 65W. AN INVERTED SURFACE TROUGH IS NE OF LA HISPANIOLA ALONG 26N69W 23N70W TO 20N69W. NO CONVECTIVE PRECIPITATION IS ASSOCIATED WITH THIS TROUGH. FARTHER EAST AN UPPER LEVEL LOW LOCATED NEAR 36N35W IS SUPPORTING A 1004 MB SURFACE LOW NEAR 34N33W WITH AN ASSOCIATED COLD FRONT THAT ENTERS THE DISCUSSION AREA ALONG 30N25W 24N31W TO 22N42W. SCATTERED SHOWERS IN THE VICINITY OF THE COLD FRONT ARE ASSOCIATED WITH MOIST SOUTHWESTERLY FLOW ALOFT AROUND THE E SIDE OF THE UPPER TROUGH WITH AXIS OVER THE E CARIBBEAN. THESE SHOWERS ARE BOUNDED IN AN AREA FROM 19N-27N BETWEEN 20W-47W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR