000 AXNT20 KNHC 280603 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT JUN 28 2014 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...TROPICAL WAVES... ATLANTIC TROPICAL WAVE ALONG 35W SOUTH OF 15N IS MOVING QUICKLY WESTWARD NEAR 25 KT DUE TO EASTERLY JET SOUTH OF THE SUBTROPICAL HIGH. THE WAVE IS MOVING THROUGH A DRY ENVIRONMENT ASSOCIATED TO SAHARAN AIR COMBINED WITH SUBSIDENT AIR EAST OF THE SUBTROPICAL HIGH. CONVECTION IS WEST OF THE WAVE AXIS...WITH SHOWERS NOTED FROM 06N TO 09N BETWEEN 35W AND 42W IN THE VICINITY OF THE ITCZ. ATLANTIC TROPICAL WAVE ALONG 49W SOUTH OF 16N...MOVING WESTWARD AT 15 KT. CONVERGENCE ASSOCIATED TO THIS WAVE IS OCCURRING EAST OF THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS NOTED FROM 7N TO 9N BETWEEN 43W AND 49W IN THE VICINITY OF THE ITCZ. EASTERN CARIBBEAN TROPICAL WAVE ALONG 65W SOUTH OF 17N...MOVING WESTWARD AT 15 TO 20 KT. SCATTERED MODERATE CONVECTION IS NOTED OVER THE WINDWARD ISLANDS AS WELL AS IN THE VICINITY OF THE WAVE AXIS OVER SOUTH AMERICA. CARIBBEAN TROPICAL WAVE ALONG 83W SOUTH OF 20N. ITS WESTWARD PROGRESS HAS SLOWED AND IS MOVING AT 10 KT OR LESS. THERE IS LIMITED CONVECTION ASSOCIATED TO THIS WAVE. PAPAGAYO GAP WIND FLOW IS EXPECTED TO INCREASE DURING THE NEXT COUPLE OF DAYS AS THE WAVE REACHES THE EASTERN NORTH PACIFIC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 14N17W TO 9N23W. ITCZ EXTENDS FROM 9N23W TO 6N47W TO THE COAST OF SOUTH AMERICA NEAR 5N52W. SCATTERED MODERATE CONVECTION FROM 5N TO 9N BETWEEN 32W AND 49W. ...DISCUSSION... ...THE GULF OF MEXICO... AN UPPER LEVEL TROUGH EXTENDS ACROSS OKLAHOMA INTO WESTERN TEXAS. UPPER LEVEL DIVERGENCE ASSOCIATED WITH A SHORT WAVE TROUGH MOVING ACROSS LOUISIANA IS HELPING MAINTAIN CONVECTION IN THE NORTHERN GULF S OF LOUISIANA. AN UPPER LEVEL ANTICYCLONE IS EAST OF THE TROUGH CENTERED OVER NORTHERN FLORIDA. WEAK 1020 MB HIGH IS CENTERED OVER THE NE GULF OF MEXICO NEAR 29N84W WITH A RIDGE EXTENDING SE ACROSS FLORIDA. WESTERLY STEERING FLOW S OF THE RIDGE AXIS HAS HELPED DRIVE DIURNAL CONVECTION OVER FLORIDA AND DRIFTING OFF THE WEST COAST OF FLORIDA AND THE FLORIDA KEYS. ...THE CARIBBEAN SEA... BROAD UPPER LEVEL CYCLONIC FLOW PREVAILS ACROSS THE CARIBBEAN BASIN WITH UPPER LEVEL TROUGHING NOTED IN THE WESTERN CARIBBEAN. DRY SAHARA-SOURCE AIR MASS CONTINUES OVER THE AREA CHARACTERIZED BY A STABLE ENVIRONMENT. SHALLOW TRADE WIND CUMULUS...WITH FEW SHOWERS PREVAIL OVER MUCH OF THE WATERS. ACTIVE CONVECTION IN THE SW CARIBBEAN IS BEING ENHANCED BY INTERACTION OF THE MONSOON TROUGH WITH THE SOUTHERN EXTENT OF A TROPICAL WAVE MOVING ACROSS WESTERN WATERS OUTSIDE THE USUAL REACH OF THE SAHARAN AIR MASS. THE PRESSURE GRADIENT BETWEEN THE ATLANTIC RIDGE AND THE MONSOON TROUGH IS MAINTAINING 20-25 KT TRADES IN THE CENTRAL CARIBBEAN AND 10-20 KT WINDS IN BOTH THE WESTERN AND EASTERN CARIBBEAN. ...HISPANIOLA... THE DIURNAL CYCLE OF DAYTIME HEATING AND ASSOCIATED CONVECTION CONTINUES TO WEAKEN OVER HISPANIOLA. SAHARAN AIR MASS WILL MOVE OVER HISPANIOLA OVER THE NEXT COUPLE OF DAYS AND DEVELOPMENT OF AFTERNOON CONVECTION SHOULD BE DELAYED...WITH GENERALLY LESS COVERAGE THAN IS TYPICALLY EXPECTED DURING THE SUMMER MONTHS. ...THE ATLANTIC OCEAN... UPPER LEVEL TROUGH EXTENDS FROM AN UPPER LEVEL LOW NEAR 30.5N51.5W SOUTHWESTWARD ACROSS THE WESTERN ATLANTIC... TOWARD HISPANIOLA THEN INTO THE WEST CENTRAL CARIBBEAN. SUBSIDENCE EAST OF THIS FEATURE IS HELPING TO MAINTAIN THE EASTERN ATLANTIC SUBTROPICAL HIGH CENTERED NEAR 33N40W. A SURFACE RIDGE EXTENDS WSW OF THE SUBTROPICAL HIGH ACROSS THE WESTERN ATLANTIC ROUGHLY ALONG 27/28N. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED OVER THE BAHAMAS AND WEST OF THE BAHAMAS ISLAND CHAIN ASSOCIATED TO THE NORTHERN EXTENT OF A TROPICAL WAVE. A DRY AIRMASS PREVAILS OVER THE TROPICAL ATLANTIC WATERS AND IS ASSOCIATED TO THE COMBINATION OF SAHARAN AIR AND DRY SUBSIDENT AIR ON THE EASTERN SIDE OF THE SUBTROPICAL HIGH THAT IS BEING ADVECTED WESTWARD AROUND THE CIRCULATION OF THE HIGH. THIS IS LIMITING DEEP CONVECTION TO THE ITCZ AND SOUTHERN EXTENT OF THE TROPICAL WAVES MENTIONED ABOVE. WINDS OVER THE SW N ATLC WATERS W OF 65W ARE IN THE 5 TO 10 KT RANGE OVER MUCH OF THE AREA EXCEPT S OF 22N WHERE WINDS ARE IN THE 10-15 KT RANGE. TRADEWINDS OVER THE TROPICAL ATLANTIC WATERS ARE IN THE 15-20 KT RANGE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MUNDELL