000 AXNT20 KNHC 211716 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON MAY 21 2007 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1630 UTC. ...TROPICAL WAVES... TROPICAL WAVE PREVIOUSLY LOCATED NEAR 21W/22W HAS BEEN REMOVED FROM THE 12Z SURFACE ANALYSIS. VISIBLE SATELLITE IMAGERY HAS INDICATED NO LOW-LEVEL CIRCULATION PRESENT IN THE REGION. INSTEAD...NORTH FLOW IS PREDOMINATE IN THE LOWER LEVELS. IN ADDITION...COMPUTER MODELS...SATELLITE DERIVED VORTICITY...AND RECENT BUOY OBSERVATIONS ARE NOT SUPPORTIVE OF THE EXISTENCE OF A TROPICAL WAVE. THE REGION WILL CONTINUE TO BE MONITORED FOR MORE CONCLUSIVE DATA. ...ITCZ... ITCZ AXIS IS CENTERED ALONG THE EQUATOR BETWEEN 9E-3W TO 2N10W 4N20W 4N40W AND INTO SOUTH AMERICA NEAR 2N51W. CLUSTERS OF MODERATE TO STRONG CONVECTION ARE ALONG A SPEED GRADIENT BOUNDARY FROM THE EQ-4N E OF 9W. ISOLATED MODERATE CONVECTION IS WITHIN 100 NM NORTH OF THE BOUNDARY BETWEEN 17W-20W AND ALSO BETWEEN 28W-31W. ...DISCUSSION... GULF OF MEXICO... FAIR WEATHER IS DOMINATE ACROSS THE GULF UNDER NEARLY ZONAL FLOW ALOFT. A SFC HIGH PRES RIDGE RUNNING E-W ALONG 30N/31N REMAINS IN CONTROL. LIGHT TO MODERATE E-SE WINDS SPAN THE GULF EXCEPT IN THE STRAIGHTS OF FLORIDA WHERE A TIGHTENED GRADIENT BETWEEN THE HIGH PRESSURE RIDGE AND A PERSISTENT TROUGH IN THE WESTERN CARIBBEAN HAVE INCREASED THE WINDS TO 20 KT. THIS STRONG NE WIND AND SOME INFLUENCE FROM AN OLD FRONTAL BOUNDARY IS PRODUCING SCATTERED SHOWERS MOVING FROM THE W ATLC ACROSS THE FL STRAITS AND INTO THE SE GULF. UPPER AIR DIFFLUENCE IS AIDING IN CONVECTION OVER TEXAS WITH THE ZONAL FLOW TRANSPORTING THE OUTFLOW/HIGH CLOUDS OVER THE FAR NW GULF. CARIBBEAN SEA... SURFACE OBSERVATIONS AND VISIBLE IMAGERY CONTINUE TO INDICATE THE EXISTENCE OF A SURFACE TROUGH STRETCHING ACROSS THE CARIBBEAN FROM CENTRAL CUBA NEAR 22N80W TO PANAMA NEAR 9N82W WITH AN ASSOCIATED LOW PRESSURE NEAR 11N80W. THE TROUGH IS NO LONGER DRIFTING WESTWARD BUT INSTEAD HAS BECOME NEARLY STATIONARY ALONG 82W. MODERATE TO STRONG E-SE WINDS COVER THE CARIBBEAN E OF THE TROUGH WHEREAS LIGHT TO MODERATE NE WINDS EXIST TO THE WEST. THE NORTHERN HALF OF THE CARIBBEAN REMAINS FAIRLY TRANQUIL UNDER WLY UPPER FLOW...EXCEPT FOR PATCHES OF LOW-TOPPED SHOWERS AND TSTMS BETWEEN JAMAICA AND CUBA AND FURTHER NE IN THE SE BAHAMAS. THIS ACTIVITY IS ASSOCIATED WITH THE TAIL END OF A W ATLC TROUGH. THE SOUTH CARIBBEAN IS MARKED BY A CLUSTER OF MODERATE TO STRONG CONVECTION EMBEDDED WITH ISOLATED TSTMS SOUTH OF 14N BETWEEN 75W AND CENTRAL AMERICA. THIS CONVECTION IS BEING SUPPORTED BY THE EASTERN EXTENSION OF THE E PACIFIC ITCZ AND IS ENHANCED BY DIVERGENCE ALOFT. ATLANTIC OCEAN... A COLD FRONT EXTENDING FROM A SURFACE LOW WELL NORTH OF THE AREA CONNECTS TO A TROUGH NEAR 31N62W. THE TROUGH EXTENDS SW ALONG 37N65W 25N69W INTO HAITI NEAR 20N73W. LOW-LEVEL LIFT ALONG THE BOUNDARY ALONG WITH UPPER DIFFLUENCE BETWEEN THE TROUGH AND A RIDGE TO THE E IS PRODUCING SCATTERED SHOWERS AND POSSIBLE TSTMS WITHIN 200 NM AHEAD OF THE TROUGH AXIS. THE SFC FLOW IS QUITE BRISK IN THIS REGION AS A TIGHTENED PRES GRADIENT HAS SET UP BETWEEN THE TROUGH AND A 1021 MB HIGH PRES NEAR THE SE CONUS. THIS STRONG FLOW IS ADVECTING SCATTERED SHOWERS ACROSS THE W ATLC WATERS TO THE BAHAMAS AND STRAIGHTS OF FLORIDA. A STRONG 1036 MB SURFACE HIGH DOMINATES THE CENTRAL AND EAST ATLC RESULTING IN FAIR WEATHER CUMULUS ACROSS THE REGION. THE LEADING EDGE OF AN UPPER TROUGH OVER THE CENTRAL ATLC IS ADVECTING UPPER CLOUDS/MOISTURE ACROSS THE EASTERN ATLC SOUTH OF 24N. $$ WADDINGTON