000 AXNT20 KNHC 280003 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI JUN 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... ATLANTIC TROPICAL WAVE AXIS IS NEAR 15N31W TO 04N30W. WITH THE SUBTROPICAL HIGH OVER THE EASTERN ATLANTIC...THE EASTERLY JET EXTENDS WELL OFF OF AFRICA. AS A RESULT...THE WAVE IS MOVING RATHER QUICKLY WESTWARD NEAR 25 KT. THE WAVE IS MOVING THROUGH A DRY ENVIRONMENT ASSOCIATED TO SAHARAN AIR COMBINED WITH SUBSIDENT AIR ON THE EAST SIDE OF THE SUBTROPICAL HIGH BEING ADVECTED WESTWARD. WITH THE WAVE MOVING AT SUCH A FAST SPEED... CONVERGENCE ASSOCIATED WITH THE WAVE OVER THE ATLANTIC WATERS IS ATYPICALLY WEST OF THE WAVE AXIS WITH ACTIVE CONVECTION NOTED FROM 06N TO 09N BETWEEN 31W AND 39W IN THE VICINITY OF THE ITCZ. ATLANTIC TROPICAL WAVE AXIS IS NEAR 15N47W TO 08N48W...MOVING WESTWARD AT 15 KT. CONVERGENCE ASSOCIATED TO THIS WAVE IS MORE TYPICAL FOR A WAVE OVER THE ATLANTIC WATERS...OCCURRING EAST OF THE WAVE. WITH CONVERGENCE EAST OF THE WAVE...SCATTERED MODERATE CONVECTION IS NOTED FROM 09N TO 11N BETWEEN 43W AND 48W IN THE VICINITY OF THE ITCZ. FAR EASTERN CARIBBEAN TROPICAL WAVE AXIS IS NEAR ALONG 17N62W TO 07N65W...MOVING WESTWARD AT 15 TO 20 KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED OVER THE SE CARIBBEAN AS WELL AS IN THE VICINITY OF THE WAVE AXIS OVER SOUTH AMERICA. CARIBBEAN TROPICAL WAVE AXIS IS NEAR 20N82W TO 10N82W. AS IS TYPICAL FOR TROPICAL WAVES REACHING THE WESTERN CARIBBEAN...THE WESTWARD PROGRESS HAS SLOWED AND IS MOVING WESTWARD AT 10 TO 15 KNOTS. THERE IS LIMITED CONVECTION ASSOCIATED TO THIS WAVE. A RIDGE OF HIGHER TPW IS NOTED OVER THE SW CARIBBEAN ASSOCIATED TO THIS WAVE. THE PAPAGAYO JET IS STRENGTHENING DUE TO THE WAVE WHICH IS HELPING FOR LOW LEVEL GAP WIND FLOW THROUGH NICARAGUA INTO THE EASTERN NORTH PACIFIC WATERS. THIS GAP WIND FLOW WILL INCREASE OVER THE NEXT COUPLE OF DAYS AS THE WAVE MOVES INTO THE EASTERN NORTH PACIFIC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 14N17W TO 09N23W. ITCZ EXTENDS FROM 00N23W TO 06N40W TO THE COAST OF SOUTH AMERICA NEAR 04N51W. SCATTERED MODERATE CONVECTION WAS NOTED FROM 06N TO 09N BETWEEN 31W AND 48W. ...DISCUSSION... ...THE GULF OF MEXICO... A SHARP UPPER LEVEL TROUGH EXTENDS FROM THE NW UNITED STATES SE REACHING ACROSS WESTERN OKLAHOMA AND WESTERN TEXAS. A SHORT WAVE TROUGH IS MOVING ACROSS SOUTHERN LOUISIANA. UPPER LEVEL DIVERGENCE ASSOCIATED TO THIS SHORT WAVE IS HELPING TO MAINTAIN ACTIVE CONVECTION OVER THE NORTHERN GULF S OF LOUISIANA AND N OF 27N. AN UPPER LEVEL ANTICYCLONE IS EAST OF THE TROUGH OVER THE SE UNITED STATES CENTERED OVER NORTHERN FLORIDA. AT THE SURFACE...WEAK HIGH PRESSURE OF 1020 MB IS CENTERED OVER THE NE GULF OF MEXICO NEAR 29N85W WITH ASSOCIATED RIDGE EXTENDING SE ACROSS S FLORIDA. WESTERLY STEERING FLOW S OF THE RIDGE AXIS HAS HELPED DRIVE THE DIURNAL CONVECTION OVER FLORIDA OFF THE WEST COAST OF SOUTHERN HALF OF FLORIDA AND OVER THE FLORIDA KEYS. WINDS IN THE 5-10 KT RANGE WERE NOTED OVER THE NE GULF WATERS WITH 10-15 KT WINDS OVER THE GULF WATERS OVER THE SE GULF AND CENTRAL GULF...AND WINDS OVER THE WESTERN GULF ARE IN THE 15 TO 20 KT RANGE. ...THE CARIBBEAN SEA... BROAD UPPER LEVEL CYCLONIC FLOW PREVAILS ACROSS THE CARIBBEAN BASIN WITH UPPER LEVEL TROUGHING NOTED OVER THE WESTERN CARIBBEAN SEA. DRY AIR RESULTING FROM AN AIR MASS OF SAHARAN ORIGIN COVERED MOST OF THE BASIN. THIS AIRMASS IS ALSO CHARACTERIZED BY A STABLE ENVIRONMENT. AS A RESULT...ONLY SHALLOW TRADEWIND CUMULUS...WITH PERHAPS A LOW TOPPED SHOWER COVERED MUCH OF THE WATERS. ACTIVE CONVECTION WAS NOTED OVER THE SW CARIBBEAN ENHANCED BY THE INTERACTION OF THE MONSOON TROUGH WITH THE SOUTHERN EXTENT OF A TROPICAL WAVE MOVING ACROSS THE WESTERN WATERS. THIS IS ALSO AN AREA WHERE THE SAHARAN AIR MASS TYPICALLY DOES NOT REACH. ANOTHER AREA OF ACTIVE CONVECTION IS NOTED OVER THE FAR SE WATERS ASSOCIATED TO THE TROPICAL WAVE OVER THE EASTERN CARIBBEAN. THE PRESSURE GRADIENT BETWEEN A WEAK ATLANTIC RIDGE AND THE MONSOON TROUGH IS MAINTAINING TRADES IN THE 20-25 KT RANGE OVER THE CENTRAL CARIBBEAN...WITH TRADES IN THE 15 KT RANGE OVER THE EASTERN CARIBBEAN...AND TRADES IN THE 10-15 KT RANGE OVER THE WESTERN CARIBBEAN. ...HISPANIOLA... WITH THE LOSS OF DAYTIME HEATING AND ASSOCIATED INSTABILITY... CONVECTION CONTINUES TO WEAKEN OVER WESTERN HISPANIOLA. A SAHARAN AIR MASS WILL PROPAGATE OVER HISPANIOLA OVER THE NEXT COUPLE OF DAYS. AS A RESULT... THE 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 $$ AL