000 AXNT20 KNHC 151141 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU MAY 15 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 20W/21W S OF 12N MOVING W AT 10-15 KT. AN AREA OF SHOWERS AND EMBEDDED TSTMS ARE ASSOCIATED WITH THE WAVE...BUT MOST OF THIS ACTIVITY IS W OF THE WAVE AXIS. IN ADDITION...THE MIMIC-TPW PRODUCT FROM CIMSS SHOWS THE PRESENCE OF THIS SYSTEM WITH AN AREA OF MOISTURE EXTENDING NORTHWARD TO NEAR 12N. A WEAK TROPICAL WAVE IS ALONG 64W S OF 12N MOVING W AT 10 KT. THE WAVE IS VERY ILL-DEFINED AND MOSTLY INLAND OVER CENTRAL VENEZUELA WHERE IT IS GENERATING SCATTERED MODERATE CONVECTION W OF WAVE AXIS. THE GFS MODEL GUIDANCE INDICATES LOW-LEVEL MOISTURE WILL REMAIN ACROSS N CENTRAL VENEZUELA AND ADJACENT COASTAL WATERS IN THE CARIBBEAN SEA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 6N10W 5N19W 5N23W 5N28W EQ39W EQ51W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM FROM A LINE 2N9W 3N18W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 6N-9N BETWEEN 14W-16W. SIMILAR CONVECTION IS FROM 4N-8N BETWEEN 25W-28W. CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN 90-120 NM FROM A LINE 1N23W TO 3S28W. ...DISCUSSION... GULF OF MEXICO... THE GULF OF MEXICO LIES BETWEEN A 1020 MB SURFACE HIGH OFFSHORE OF THE SOUTH CAROLINA IN THE W ATLC AND LOW PRESSURE TROUGHING OVER E TEXAS AND E MEXICO. THIS WEATHER PATTERN IS PRODUCING FAIRLY UNIFORM 15-20 KT SOUTHERLY WINDS ACROSS THE GULF. PRE-FRONTAL TROUGH EXTENDS ALONG THE TEXAS COAST WHERE SCATTERED SHOWERS AND THUNDERSTORMS ARE ONGOING IN THE NW GULF. THIS ACTIVITY WILL CONTINUE TO MOVE NE TOWARDS THE LOUISIANA/MISSISSIPPI GULF COAST BY MID-MORNING. ALOFT...A LARGE UPPER HIGH CENTERED OVER THE EASTERN YUCATAN PENINSULA EXTENDS A RIDGE ACROSS THE ENTIRE GULF WITH AXIS ALONG 85W. ITS ASSOCIATED FLOW IS TRANSPORTING ABUNDANT UPPER LEVEL MOISTURE FROM THE EPAC THROUGH MEXICO INTO SE TEXAS AND MUCH OF THE GULF. GIVEN DIFFLUENT UPPER LEVEL PATTERN ACROSS THE NW GULF INCREASED PRECIPITATION CHANCES ARE EXPECTED AHEAD OF THE NEXT COLD FRONT WHICH IS FORECAST TO ENTER THE GULF ON THURSDAY AFTERNOON. CARIBBEAN SEA... THE TAIL END OF A COLD FRONT EXTENDING FROM THE CENTRAL ATLC IS PRODUCING SOME SCATTERED SHOWER ACTIVITY ACROSS E JAMAICA AND HISPANIOLA. OTHERWISE...VERY TRANQUIL WEATHER RESIDES ACROSS THE CARIBBEAN BASIN IN LARGE PART DUE TO A LARGE MID-UPPER RIDGE CENTERED OVER THE EASTERN YUCATAN PENINSULA AND UPPER TROUGHING OVER THE E CARIBBEAN. THESE UPPER FEATURES ARE PRODUCING MODERATE TO STRONG SUBSIDENCE ACROSS THE CARIBBEAN SEA SUPPRESSING THE DEVELOPMENT OF ANY SIGNIFICANT CONVECTION. THE GFS MODEL GUIDANCE KEEPS MOISTURE FROM THE TAIL END OF THE FRONT AFFECTING HISPANIOLA AND PUERTO RICO THROUGH FRI. ATLANTIC OCEAN... A 1001 MB LOW PRESSURE SYSTEM IS WELL N OF THE AREA OVER THE N CENTRAL ATLC. THE ASSOCIATED COLD FRONT ENTERS THE FORECAST AREA NEAR 32N53W THEN CONTINUES SW CROSSING TO NE OF HISPANIOLA. LOW-LEVEL CONVERGENCE ALONG THE FRONTAL BOUNDARY COUPLED WITH UPPER DIFFLUENT FLOW IS PRODUCING A 120-150 NM WIDE BAND OF SCATTERED SHOWERS AND THUNDERSTORMS IMMEDIATELY E OF THE FRONT N OF 25N. SOUTH OF 25N TO HISPANIOLA SCATTERED SHOWERS WILL CONTINUE TO LINGER IN ASSOCIATION WITH WEAKENING FRONTAL BOUNDARY AND ARE FORECAST ACROSS THE E DOMINICAN REPUBLIC AND PUERTO RICO THURSDAY. COLD AIR STRATOCUMULUS CLOUDS ARE BEHIND THE FRONT ACROSS THE W ATLC AND IMPLY THAT A COOL AND DRIER AIR MASS HAS TAKEN HOLD ACROSS THE BAHAMAS. THE REST OF THE CENTRAL AND E ATLC IS DOMINATED BY A 1025 MB SURFACE HIGH LOCATED NEAR 31N40W. IN THE UPPER LEVELS...BROAD RIDGING SUPPORTS CENTRAL ATLC SURFACE HIGH WITH AXIS EXTENDING ALONG 40W. BROAD TROUGHING WITH BASE NEAR THE CANARY ISLANDS WILL CONTINUE TO MOVE EASTWARD AND PROVIDE ONLY MID-UPPER LEVEL CLOUDINESS ALONG THE COAST OF MOROCCO. OF NOTE...TODAY MARKS THE BEGINNING OF THE EASTERN PACIFIC HURRICANE SEASON. BASED ON LATEST AVERAGES...EVERY YEAR 15 NAMED STORMS FORM...9 OF WHICH BECOME HURRICANES AND 4 OF THOSE HURRICANES WOULD BE OF CATEGORY 3 OR GREATER IN STRENGTH ON THE SAFFIR-SIMPSON SCALE. THE ATLANTIC HURRICANE SEASON BEGINS JUNE 1ST WITH BOTH ATLANTIC AND EASTERN PACIFIC TROPICAL SEASONS ENDING NOVEMBER 30TH. $$ HUFFMAN