000 AXNT20 KNHC 211053 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT TUE APR 21 2009 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 1015 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 5N9W 3N17W CROSSING THE EQUATOR NEAR 22W TO 3S31W TO NE BRAZIL NEAR 2S45W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM N OF THE ITCZ AXIS BETWEEN 14W-20W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF 2N BETWEEN 21W-25W. ...DISCUSSION... THE GULF OF MEXICO... A DEEP LAYER TROUGH OVER THE E CONUS CONTINUES TO DIG INTO THE REGION...WITH AN ASSOCIATED COLD FRONT EXTENDING FROM S FLORIDA TO THE YUCATAN PENINSULA AND A FASTER MOVING SECONDARY COLD FRONT EXTENDING FROM N FLORIDA TO AROUND 90 NM S OF MOBILE ALABAMA. LOW LEVEL CONVERGENCE NEAR THESE BOUNDARIES COUPLED WITH DEEP ATMOSPHERIC LIFT IN MOIST SOUTHWESTERLY FLOW ALOFT ARE SUPPORTING SCATTERED SHOWERS AND TSTMS OVER THE SE GULF INCLUDING S FLORIDA. THIS ACTIVITY IS BEING FURTHER ENHANCED BY A PREFRONTAL TROUGH THAT EXTENDS FROM THE FLORIDA KEYS TO W CUBA. THE COLD FRONTS ARE FORECAST TO HAVE CLEARED THE REGION LATER TODAY...WITH SURFACE HIGH PRESSURE TRANSLATING FROM W TO E ACROSS THE AREA THROUGH MID-WEEK. ATMOSPHERIC SUBSIDENCE NEAR THIS HIGH IS BEING SUPPORTED BY DRY NORTHWESTERLY FLOW ALOFT...AND WILL RESULT IN GENERALLY FAIR WEATHER CONDITIONS ACROSS THE ENTIRE GULF BY THIS AFTERNOON WITH RELATIVELY LIGHT SURFACE WINDS. THE SURFACE HIGH WILL MOVE E OF THE GULF BY LATE WEEK...WITH SE RETURN FLOW INCREASING. THE CARIBBEAN SEA... A LARGE AREA OF CONVECTIVE ACTIVITY IS INLAND OVER COLOMBIA TRIGGERED BY A SWLY UPPER JET AND ENHANCED BY LOCAL FLOWS AND USUAL SFC LOW PRES. EARLIER QUIKSCAT PASS REVEALED 20-25 KT NE/E WINDS BETWEEN THE COAST OF COLOMBIA AND HISPANIOLA WITH 15-20 KT TRADES ELSEWHERE E OF 80W. WINDS ARE LIGHT AND VARIABLE OVER THE W PORTION DUE TO THE PRESENCE OF A WEAK PREFRONTAL TROUGH ALONG 83W/84W. SOME MOISTURE...LIKELY CONTAINING ONLY ISOLATED SHOWERS AND TSTMS...HAS MOVED INTO THE NW CARIBBEAN AHEAD OF A COLD FRONT OVER THE E GULF. THIS FRONT IS EXPECTED TO MOVE INTO A PORTION OF THE AREA BUT SHOULD HAVE LITTLE SIGNIFICANT WEATHER IMPACTS. THE ATLANTIC OCEAN... SCATTERED SHOWERS AND TSTMS ARE WITHIN 300 NM E OF THE FLORIDA AND GEORGIA COASTS TRIGGERED BY UPPER DIFFLUENT FLOW AND A COLD FRONT EXTENDING FROM 32N77W TO S FLORIDA. SEE GULF OF MEXICO SECTION FOR MORE DETAILS. SLY WINDS HAVE INCREASED TO 20-30 KT NEAR THE N BORDER W OF 72W DUE TO THE TIGHT PRESSURE GRADIENT BETWEEN THE FRONT AND STRONG HIGH PRES E OF BERMUDA. OVER THE CENTRAL ATLC...DEEP LAYER TROUGHING REMAINS WELL DEFINED PROVIDING LIMITED SUPPORT FOR A STATIONARY FRONT FROM 32N46W TO 27N54W. A WEAK SMALL SCALE LOW LIES AT THE BASE OF THE FRONT BUT IS PRODUCING LITTLE SIGNIFICANT WEATHER. A MORE AMPLIFIED TROUGH...SUPPORTING ANOTHER FRONT...IS EXPECTED TO SWEEP SE AND ABSORB OR MERGE WITH THE WEAK LOW/FRONT OVER THE NEXT COUPLE OF DAYS. A NARROW SWATH OF SCATTERED SHOWERS AND TSTMS ARE LOCATED IN THE UPPER DIFFLUENT ZONE N OF 22N BETWEEN 35W-41W. AN UPPER JET EXTENDING NE FROM THE WINDWARD ISLANDS TO 20N40W IS LIKELY PRODUCING SCATTERED SHOWERS AND TSTMS WITHIN 300 NM E OF THE JET AXIS. OTHERWISE...THE E ATLC IS DOMINATED BY A STRONG AZORES HIGH. $$ CANGIALOSI/COHEN