000 AXNT20 KNHC 160509 TWDAT TROPICAL WEATHER DISCUSSION... NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED APR 16 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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 0430 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 6N9W 4N20W 1N30W CROSSING THE EQUATOR NEAR 37W TO 1S48W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM N OF THE AXIS BETWEEN 16W-19W AND WITHIN 130 NM N OF THE AXIS BETWEEN 20W-29W. SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 2N BETWEEN 44W AND THE NE COAST OF BRAZIL. ...DISCUSSION... GULF OF MEXICO... SATELLITE IMAGERY CONTINUES TO DISPLAY STRATOCUMULUS CLOUDS SCATTERED ACROSS THE GULF S OF 29N AND E OF 91W. THIS IS INDICATIVE OF THE UNUSUALLY COLD AND STABLE AIRMASS THAT IS LEFT OVER FROM THE PASSAGE OF TWO COLD FRONTS EARLIER THIS WEEK. AS OF 03Z...A 1025 MB SFC HIGH WAS CENTERED IN THE NW GULF NEAR 27N93W. E TO SE RETURN FLOW AROUND THE WEAK SFC RIDGE HAS BEGUN TO MODIFY THE AIRMASS IN THE WRN WATERS. ALOFT...CONFLUENCE AT THE BASE OF AN AMPLIFIED TROUGH OVER THE E CONUS/W ATLC IS CREATING STRONG SUBSIDENCE AND A VERY DRY AIRMASS OVER THE GULF NE OF A LINE FROM HOUSTON TO THE FLORIDA STRAIGHTS. NEAR ZONAL FLOW TO THE SOUTH IS ADVECTING UPPER-LEVEL MOISTURE ACROSS THE SW GULF. CARIBBEAN SEA... THE WEATHER PATTERN IN THE NW CARIBBEAN CONTINUES TO BE DICTATED BY THE PRESENCE OF TWO COLD FRONTS. AS OF 03Z...THE LEADING...AND WEAKER...FRONT EXTENDS FROM THE WINDWARD PASSAGE ACROSS THE SE TIP OF JAMAICA TO THE NICARAGUA/HONDURAS BORDER. THIS FRONT IS EXPECTED TO BE TAKEN OVER BY THE SECONDARY SURGE...WHICH CURRENTLY EXTENDS FROM CUBA NEAR 21N78W TO BELIZE NEAR 17N88W...LATER TODAY. BOTH OF THESE BOUNDARIES ARE DRY IN NATURE WITH ONLY SCATTERED CLOUDS ALONG THEM. THE SFC TROUGH THAT HAS BEEN TRAVERSING THE CARIBBEAN HAS MADE ITS WAY TO THE SW PORTION AND...AS OF 03Z...IS DEPICTED ALONG 79W FROM THE COAST OF PANAMA TO 14N. SCATTERED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE TROUGH. EASTERLY TRADES DOMINATE THE REMAINDER OF THE CARIBBEAN USHERING IN PATCHY CLOUDS AND ISOLATED LOW-TOPPED SHOWERS. ALOFT...A WEAK UPPER HIGH IS SITUATED OFF THE E COAST OF NICARAGUA WHILE TROUGHING LIES OVER THE ERN CARIBBEAN INDUCED BY AN UPPER LOW NEAR 20N56W. THIS PATTERN IS CREATING A MODESTLY DRY ENVIRONMENT. ATLANTIC OCEAN... A COMPLEX SFC LOW PRESSURE SYSTEM DOMINATES THE W ATLC. AS OF 03Z...THE 1006 MB LOW PRESSURE CENTER WAS LOCATED NEAR 29N77W. SFC TROUGHING ENTERS THE REGION NEAR 31N74W AND CONTINUES THROUGH THE LOW CENTER TO THE CENTRAL FLORIDA COAST NEAR MELBOURNE. NUMEROUS SHOWERS AND THUNDERSTORMS SURROUND THE LOW N OF 26N W OF 72W. THE TIGHT PRESSURE GRADIENT BETWEEN THE LOW AND HIGH PRES OVER THE SRN CONUS IS PRODUCING NLY GALE FORCE WINDS WITHIN 210 NM OF THE LOW. THIS LOW IS EXPECTED TO TRACK N OF THE AREA...ALLOWING THE GALE CONDITIONS TO END IN ABOUT 12 HOURS. TO THE EAST...TWO COLD FRONTS REMAIN. AS OF 03Z...THE LEADING BOUNDARY ENTERS THE W ATLC NEAR 31N63W AND EXTENDS SW ALONG 22N70W TO NEAR 20N73W. A THIN BAND OF LOW LEVEL CLOUDS EXTENDS ALONG THE BOUNDARY WITH SCATTERED SHOWERS AND THUNDERSTORMS N OF 22N. THE SECOND BOUNDARY EXTENDS FROM 31N66W ALONG 36N70W TO 21N76W. LITTLE THUNDERSTORM ACTIVITY IS ASSOCIATED WITH THIS SECOND BOUNDARY...HOWEVER LOW LEVEL CLOUDS AND SCATTERED SHOWERS COVER THE AREA BETWEEN THE TWO FRONTS. THE LEADING FRONT IS SLOW MOVING AND IS EXPECTED TO MERGE WITH THE SECONDARY SURGE LATER TODAY. SCATTERED SHOWERS AND THUNDERSTORMS ARE DEVELOPING OFF THE NORTHERN COAST OF HISPANIOLA AS THE LEADING FRONT APPROACHES THE TERRAIN. THE CENTRAL AND E ATLC IS RATHER TRANQUIL DUE TO A BROAD DEEP LAYER HIGH PRES SYSTEM CENTERED NEAR 31N41W. THE 1029 MB SFC HIGH PRES IS PRODUCING N TO NE 20-25 KT WINDS NEAR THE COAST OF AFRICA N OF 17N AND 15-20 KT WINDS ACROSS THE REMAINDER OF THE TROPICS. STRONG WLY UPPER FLOW BETWEEN AN ELONGATED UPPER TROUGH OVER W AFRICA AND A FLAT UPPER RIDGE OVER THE TROPICS IS SPREADING A PLUME OF HIGH LEVEL CLOUDINESS S OF 17N. $$ WADDINGTON