000 AXNT20 KNHC 210546 CCA TWDAT TROPICAL WEATHER DISCUSSION...COR NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED APR 21 2010 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0540 UTC... ...THE ITCZ... THE ITCZ IS ANALYZED FROM THE COAST OF SIERRA LEONE NEAR 7N13W...WESTWARD ALONG 5N20W 1N30W CONTINUING ALONG THE EQUATOR LINE TO 52W. WIDELY SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 150 NM ON EITHER SIDE OF THE AXIS WEST OF 30W. ISOLATED PATCHES OF MODERATE TO STRONG CONVECTION ARE WITHIN 80 NM ON EITHER SIDE OF THE AXIS EAST OF 30W. ...DISCUSSION... THE GULF OF MEXICO... AN UPPER LEVEL SHORTWAVE IS OVER THE EASTERN GULF...AND IT WILL BE CROSSING THE FLORIDA PENINSULA OVER THE NEXT 6 TO 12 HOURS. STRONG LIFTING AHEAD OF THIS FEATURE IS SUPPORTING A SURFACE TROUGH ANALYZED OVER THE STATE OF FLORIDA ALONG 30N82W 27N82W 24N83W. THE CONVECTION ASSOCIATED WITH THIS TROUGH IS BETTER DEPICTED FROM DOPPLER RADAR IMAGERY INDICATING MODERATE TO HEAVY SHOWERS AND POSSIBLE THUNDERSTORMS FROM 23N TO 32N BETWEEN 80W AND 85W. THIS AREA OF CONVECTION IS EXPECTED TO MOVE OUT OF THE AREA OF DISCUSSION BY WEDNESDAY LATE MORNING. HOWEVER...EXPECT INSTABILITY IN THIS REGION WITH SHOWERS LINGERING THROUGH WEDNESDAY LATE AFTERNOON. BEHIND THIS TROUGH...ANOTHER SURFACE TROUGH ENTERS THE DISCUSSION AREA THROUGH THE WESTERN FLORIDA PANHANDLE NEAR 31N85W CONTINUING WEST-SOUTHWEST ALONG 29N87W 28N91W...JUST 30 NM SOUTH OF MORGAN CITY LOUISIANA. SCATTERED WEAK TO MODERATE SHOWERS ARE WITHIN 50 NM ON EITHER SIDE OF THE TROUGH. A STABLE AIRMASS DOMINATES ELSEWHERE ACROSS THE REGION. COMPUTER MODELS INDICATED AN UPPER LEVEL RIDGE OF HIGH PRESSURE BUILDING ACROSS THE REGION FOR THE REST OF THE WORK WEEK. THE CARIBBEAN SEA... WATER VAPOR IMAGERY SHOWS A BROAD AREA OF MID LEVEL MOISTURE MOVING NORTHEAST ACROSS THE CENTRAL AND EASTERN CARIBBEAN EAST OF 80W. BEHIND THIS AREA OF MID LEVEL MOISTURE LIES AN UPPER LEVEL SHORTWAVE THAT SUPPORTS A RATHER WEAK SURFACE TROUGH THAT EXTENDS SOUTHWEST FROM SOUTH CENTRAL HAITI EXTENDING TO NEAR 12N77W. SCATTERED ISOLATED WEAK SHOWERS ARE WITHIN 30 NM ON EITHER SIDE OF THE TROUGH...BUT RATHER AFFECTING THE ISLAND OF HISPANIOLA DUE TO TOPOGRAPHIC EFFECT. MODERATE CONVECTION IS ALSO FOUND WITHIN 110 NM OFF THE COAST OF PANAMA COLOMBIA AND VENEZUELA BETWEEN 65W AND 82W. THIS TROUGH IS EXPECTED TO CONTINUE TO MOVE EASTWARD WITH CONVECTION AFFECTING MOSTLY THE NORTHEASTERN BASIN INCLUDING HISPANIOLA...PUERTO RICO...AND THE US/UK VIRGIN ISLANDS. COMPUTER MODELS SUGGEST THIS AREA OF CONVECTION WILL LINGER THROUGH THURSDAY NIGHT. THE ATLANTIC OCEAN... WEAK TO MODERATE CONVECTION IS ALREADY ENTERING THE FAR WESTERN ATLANTIC FROM A SURFACE TROUGH CURRENTLY OVER THE FLORIDA PENINSULA. THIS TROUGH IS SUPPORTED BY AN UPPER LEVEL SHORTWAVE OVER THE EASTERN GULF OF MEXICO. FARTHER EAST...AN UPPER LEVEL SHORTWAVE IS MOVING ACROSS THE CENTRAL ATLANTIC SUPPORTING A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N49W CONTINUING SOUTHWEST ALONG 27N55W 25N65W. SHOWERS ARE POSSIBLE WITHIN 120 NM ON EITHER SIDE OF THE FRONT. TO THE EAST OF THIS FRONT LIES A SURFACE HIGH PRESSURE SYSTEM NEAR 27N35W DOMINATING THE EASTERN AND PART OF THE CENTRAL ATLANTIC NORTH OF 18N BETWEEN 20W AND 50W. THIS SURFACE HIGH IS SUPPORTED BY A BROAD UPPER LEVEL RIDGE THAT COVERS THE EAST/CENTRAL ATLANTIC FROM 20W TO 50W. A WEAKENING COLD FRONT ENTERS THE DISCUSSION AREA OVER THE FAR EASTERN ATLANTIC THROUGH 32N10W CONTINUING SOUTHWEST ALONG 20N20W 16N30W 14N40W. A SHEAR AXIS/REMNANT CLOUD LINE CONTINUES FROM 14N40W TO 17N52W. SCATTERED WEAK TO MODERATE SHOWERS ARE WITHIN 50 NM EITHER SIDE OF THE COLD. THE SHEAR AXIS IS GENERATING A BROAD AREA OF WEAK TO MODERATE SHOWERS COVERING FROM 12N TO 18N BETWEEN 40W AND 52W. AS THE EASTERN ATLANTIC COLD FRONT CONTINUES TO WEAKEN AND MOVE EASTWARD...COMPUTER MODELS HINT THE CONVECTION GENERATED BY THE SHEAR LINE MAY LINGER NEAR THE MENTIONED AREA THROUGH THURSDAY MORNING. ALSO LOOK FOR MORE CONVECTION DEVELOPING OVER THE WESTERN ATLANTIC WEST OF 72W AS THE UPPER LEVEL SHORTWAVE ENTERS THIS REGION. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA