000 AXNT20 KNHC 220605 TWDAT TROPICAL WEATHER DISCUSSION... NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE APR 22 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 0530 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 04N03W 04N47W 03N51W. SCATTERED MODERATE CONVECTION WITHIN 60 NM N OF AXIS BETWEEN 30W AND 33W. A SECOND ITCZ AXIS IS SOUTH OF THE EQUATOR ALONG 03S04W 03S04W 05S13W 03S39W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 90 NM OF THE SECOND AXIS BETWEEN 03W AND 18W. ...DISCUSSION... GULF OF MEXICO... A MID/UPPER LEVEL RIDGE IS MOVING EAST OVER THE LOWER MISSISSIPPI VALLEY AND NORTHERN GULF OF MEXICO...BEHIND AN UPPER LOW MOVING OFF THE CAROLINA COAST. 1016 MB SURFACE HIGH PRESSURE IS CENTERED NEAR 28N87W. A SURFACE TROUGH ASSOCIATED WITH THE UPPER LOW OFF THE CAROLINAS EXTENDS FROM ACROSS THE BAHAMAS THROUGH THE STRAITS OF FLORIDA AND TO THE SOUTH OF THE SURFACE HIGH ACROSS THE SOUTHEASTERN GULF. SHOWERS WERE ACTIVE ALONG THE TROUGH EARLIER IN THE EVENING BUT HAVE SINCE DISSIPATED. DRY SUBSIDENT AIR PREVAILS OVER THE EASTERN GULF...IN NW FLOW ALOFT BETWEEN THE MID/UPPER RIDGE AND THE UPPER LOW. SHIP AND BUOY OBSERVATIONS SHOW SEAS TO BE 2 FT OR LESS OVERALL. BUOYS OVER THE WESTERN GULF ARE REPORTING MODERATE SE WINDS ON THE WESTERN EDGE OF THE SURFACE HIGH PRES. SATELLITE IMAGERY SHOWS POSSIBLE ADVECTION FOG OR LOW STRATUS OVER THE NW GULF OFF THE TEXAS COAST THIS MORNING. LITTLE CHANGE IS EXPECTED OVER GULF WATERS THROUGH TONIGHT. WINDS WILL GRADUALLY INCREASE OVER THE WESTERN GULF TOMORROW BETWEEN THE HIGH PRES OVER THE EASTERN GULF AND AN AREA OF LOW PRES DEVELOPING OVER THE PLAINS. CARIBBEAN... A MID/UPPER LEVEL TROUGH SHOWING UP ON WATER VAPOR IMAGERY DIGGING THROUGH THE EASTERN CARIBBEAN IS BRINGING DRY SUBSIDENT ACROSS MUCH OF THE CARIBBEAN BASIN E OF 70W. SOME MID AND UPPER LEVEL CLOUDINESS IS EVIDENT IN THE WESTERLY FLOW FOLLOWING THE TROUGH. A FEW SHOWERS ARE DEVELOPING OFF THE SOUTHEAST COAST OF CUBA...THE PRODUCT OF DRAINAGE FLOW CONVERGENCE AT THE SURFACE...AND SLIGHTLY UNSTABLE MID LEVEL AIR MOVING INTO THE AREA WITH THE NW FLOW ALOFT. OTHERWISE...MODERATE TO FRESH TRADES PERSIST ACROSS THE WHOLE BASIN. ATLANTIC OCEAN... A WEAK SURFACE LOW 1012 MB IS ANALYZED OFF THE CENTRAL EAST COAST OF FLORIDA...AT THE BASE OF AN UPPER TROUGH EXTENDING FROM A VIGOROUS UPPER LOW ALONG THE CAROLINA COAST. AN ASSOCIATED SURFACE TROUGH EXTENDS FROM THE CAROLINAS TO THE SURFACE LOW...THEN ON TO THE FLORIDA KEYS. ANOTHER WEAKER SURFACE TROUGH IS SITUATED FURTHER EAST...AND EXTENDS FROM 31N74W THROUGH THE CENTRAL BAHAMAS...THEN TO CENTRAL CUBA. THESE TROUGHS WILL MAKE SLOW PROGRESS TO THE SE TODAY...BUT LOSE STEAM AS THE UPPER SUPPORT BEHIND THE UPPER TROUGH BECOMES MORE ZONAL. FURTHER EAST...ANOTHER UPPER TROUGH SHOWS UP ON WATER VAPOR AND SATELLITE DERIVED WINDS...FROM NEAR BERMUDA TO 23N52W. UPPER DIVERGENCE TO THE EAST OF THIS TROUGH IS GENERATING SCATTERED SHOWERS GENERALLY N OF 23N E OF THE TROUGH TO 50W. AN UPPER RIDGE IS CENTERED SOUTH OF THIS TROUGH NEAR 9N44W. DIVERGENCE ALOFT ON THE EAST AND SOUTH SIDES OF THE UPPER ANTICYCLONE IS STARTING TO ENHANCE CONVECTION ALONG THE ITCZ...GENERALLY W OF 25W. A 1025 MB SURFACE HIGH IS CENTERED TO THE WEST OF THE CANARY ISLANDS NEAR 30N27W. AN ASCAT PASS FROM 6 HOURS AGO SHOWED GENERALLY MODERATE TRADE WIND FLOW ACROSS THE EASTERN ATLC TO THE SOUTH OF THE SURFACE HIGH. THE EXCEPTION IS ALONG THE AFRICAN COAST TO AS FAR SOUTH AS SENEGAL WHERE SHIP AND SCATTEROMETER DATA SHOW 25 TO 30 KT NORTHERLY FLOW. LITTLE CHANGE IS EXPECTED IN THE TRADE WIND FLOW OVER THE NEXT 48 HOURS. $$ CHRISTENSEN