000 AXNT20 KNHC 181134 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST MON FEB 18 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 1115 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA ENTERING THE E TROPICAL ATLC THROUGH SOUTHERN LIBERIA TO 02N20W WHERE THE ITCZ CONTINUES TO EQ25W EQ30W EQ37W. SMALL CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 120 NM NORTH OF THE MONSOON TROUGH AXIS EAST OF 20W. SIMILAR CONVECTION IS WITHIN 200 NM NORTH OF THE ITCZ AXIS BETWEEN 21W AND 37W. SCATTERED MODERATE CONVECTION IS WEST OF THE ITCZ ALL THE WAY TO THE NORTHERN COAST OF BRAZIL S OF 3N. ...DISCUSSION... GULF OF MEXICO... A 1029 MB HIGH PRES LOCATED OVER NORTHERN FLORIDA NEAR 30N82W IS PROVIDING ANTICYCLONIC WIND IN THE RANGE OF 20-25 KT WEST OF 90W AND OF 10-15 KT EAST OF 90W. STRONG SOUTHEASTERLY AND SOUTHERLY WIND FLOW IS BANKING LOW LEVEL CLOUDS WITH ISOLATED SHOWERS ALONG THE WESTERN GULF COAST. OVERCAST SKIES WITH POSSIBLE ISOLATED SHOWERS EXTEND APPROXIMATELY 200 NM OFF THE WEST GULF COASTLINE. IN THE UPPER LEVEL WESTERLY FLOW CONTINUE MOVING OVER THE WHOLE BASIN AND DRY AIR ALOFT SUPPORTS FAIR WEATHER OVER THE REMAINDER OF THE GULF. RETURN FLOW WILL CONTINUE WITHIN THE NEXT 24 HOURS OVER THE ENTIRE REGION AS THE HIGH PRESSURE OVER FLORIDA MERGE WITH ANOTHER HIGH PRESSURE TO THE NORTH AND THEN DISPLACES TO THE WEST ATLC. A NEW FRONT ENTERS THE NW GULF WITHIN THIS TIME FRAME EXTENDING APPROXIMATELY FROM LOUISIANA SW TO SOUTHERN TEXAS. RAINSHOWERS ACTIVITY IS EXPECTED ALONG THE NORTHERN GULF COAST AND ADJACENT WATERS WEST OF 86W. CARIBBEAN SEA... AS OF 0900 UTC...THE STATIONARY FRONT IN THE WESTERN CARIBBEAN HAS VANISHED AND INSTEAD A SHEARLINE IS BEING ANALYZED ALONG 19N72W 18N75W 16N79W 13N81W 12N82W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 120 NM EITHER SIDE OF THE SHEARLINE. WEST OF THE SHEARLINE NORTHEASTERLY WINDS IN THE RANGE OF 20-25 KT DOMINATE. EASTERLY TRADEWINDS IN THE RANGE OF 15-20 KT SPREAD OVER THE REMAINDER OF THE CARIBBEAN. IN THE UPPER LEVEL...A TROUGH OVER THE W ATLC DIPS S OVER THE NW CARIBBEAN N OF 19N SUPPORTING THE AFOREMENTIONED SHEARLINE. NEAR ZONAL WESTERLY FLOW ALOFT DOMINATES THE REMAINDER OF THE CARIBBEAN SEA. WATER VAPOR SATELLITE IMAGERY CONTINUES TO SHOW VERY STRONG SUBSIDENCE AND DRY STABLE AIR ALOFT E OF 75W ACROSS THE REMAINDER OF THE BASIN. WITHIN THE NEXT 24 HOURS...THE SHEARLINE WILL SLOWLY WEAKEN. ISOLATED/SCATTERED SHOWERS ARE EXPECTED TO CONTINUE OVER THE NW CARIBBEAN WHILE WINDS OVER NW CARIBBEAN SHIFT FROM NORTHERLY FLOW TO EASTERLY FLOW. NEAR GALE FORCE WINDS ARE EXPECTED ALONG THE COAST OF COLOMBIA. ATLANTIC OCEAN... OVER THE WEST ATLC...HIGH PRESSURE CONTINUE TO BUILD. THE AFOREMENTIONED BROAD UPPER LEVEL TROUGH OVER THE WEST ATLC SUPPORTS A COLD FRONT THAT ENTERS THE DISCUSSION AREA AT 18/0600 UTC NEAR 30N56W EXTENDING SW TO 25N62W AND THEN TO 20N71W WHERE IT BECOMES A SHEARLINE. NO CONVECTIVE PRECIPITATION IS ASSOCIATED WITH THIS FRONT OVER THE W ATLC. HOWEVER ISOLATED SHOWERS ARE POSSIBLE WITHIN 165 NM WEST OF THE FRONT. E OF THE FRONT...A 1025 MB HIGH PRES IS CENTERED NEAR 29N40W WHICH IS EXPECTED TO MOVE SLIGHTLY SE OVER THE NEXT 24 HOURS. THIS SYSTEM EXTENDS A RIDGE OVER MOST OF THE E AND CENTRAL ATLC. ALOFT...AN UPPER RIDGE COVERS THE CENTRAL ATLC. A NARROW UPPER TROUGH IS OVER THE E ATLC WHICH IS SUPPORTING A DISSIPATING COLD FRONT CURRENTLY EXTENDING FROM 30N14W TO 27N16W. WITHIN THE NEXT 24 HOURS...THE SHEARLINE EXTENDING FROM THE COLD FRONT WILL VANISH AND THE FRONTAL BOUNDARY TO THE NORTH WILL CONTINUE A NORTHEASTWARD TRACK WHILE IT WEAKENS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR