000 AXNT20 KNHC 211043 CCA TWDAT TROPICAL WEATHER DISCUSSION...COR NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1040 UTC... ...THE ITCZ... THE ITCZ IS ANALYZED FROM THE COAST OF LIBERIA NEAR 6N10W...WESTWARD ALONG 3N20W 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 35W. ISOLATED PATCHES OF MODERATE TO STRONG CONVECTION ARE WITHIN 80 NM ON EITHER SIDE OF THE AXIS EAST OF 35W. ...DISCUSSION... THE GULF OF MEXICO... AN UPPER LEVEL SHORTWAVE HAS JUST CROSSED THE FLORIDA PENINSULA LEAVING A DRY AND STABLE AIRMASS ACROSS THE REGION WEST OF 85W. HOWEVER...WEAK TO MODERATE CONVECTION LINGERS OVER THE STATE OF FLORIDA AND WITHIN 110 NM WEST OF THE WESTERN COAST OF THE STATE. THE CONVECTION ASSOCIATED WITH THIS TROUGH IS BETTER DEPICTED FROM DOPPLER RADAR IMAGERY INDICATING SCATTERED MODERATE TO HEAVY SHOWERS AND POSSIBLE THUNDERSTORMS FROM 24N TO 32N BETWEEN 80W AND 84W. 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. FURTHERMORE...THE SOUTHERN TIP OF A SURFACE TROUGH ENTERS THE FAR NORTHEAST BASIN NEAR 30N84W CONTINUING SOUTHWEST CROSSING THE FLORIDA PANHANDLE TO NEAR 28N85W. SCATTERED WEAK TO MODERATE SHOWERS ARE WITHIN 50 NM ON EITHER SIDE OF THE TROUGH. 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 SURFACE TROUGH THAT ENTERS THE DISCUSSION ARE THROUGH THE MONA PASSAGE NEAR 18N68W EXTENDING TO NEAR 14N72W. 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 SLOWLY MOVE EASTWARD WITH CONVECTION AFFECTING MOSTLY THE EASTERN 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 OVER THE FAR WESTERN ATLANTIC FROM A SURFACE TROUGH ALONG 80W FROM 25N TO 32N. THIS TROUGH IS SUPPORTED BY AN UPPER LEVEL SHORTWAVE ALIGNED WITH THE SURFACE TROUGH. FARTHER EAST...AN UPPER LEVEL SHORTWAVE IS MOVING ACROSS THE CENTRAL ATLANTIC SUPPORTING A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N45W CONTINUING SOUTHWEST ALONG 28N50W 25N58W 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 25N30W DOMINATING THE EASTERN AND PART OF THE CENTRAL ATLANTIC NORTH OF 18N BETWEEN 20W AND 45W. THIS SURFACE HIGH IS SUPPORTED BY A BROAD UPPER LEVEL RIDGE THAT COVERS THE EAST/CENTRAL ATLANTIC FROM 20W TO 50W. A SHEAR AXIS/REMNANT CLOUD LINE CONTINUES TO GENERATE SCATTERED WEAK TO MODERATE SHOWERS FROM 14N40W TO 17N52W. COMPUTER MODELS HINT THIS 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 70W AS THE UPPER LEVEL SHORTWAVE PUSHES THE SURFACE TROUGH ACROSS THIS REGION. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA