000 AXNT20 KNHC 291805 RRA TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN JUN 29 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...SPECIAL FEATURES... BOTH SURFACE OBSERVATIONS AND SATELLITE WIND DATA INDICATE THE LOW PRESSURE SYSTEM LOCATED ABOUT 200 NM E OF ST AUGUSTINE FLORIDA IS GRADUALLY BECOMING BETTER DEFINED WHILE MOVING SLOWLY S-SW. EVEN THOUGH UPPER-LEVEL WINDS ARE ONLY MARGINALLY FAVORABLE...A TROPICAL DEPRESSION IS EXPECTED TO FORM THE NEXT DAY OR TWO. HOWEVER...CLOSENESS TO DRY AIR COULD INHIBIT SIGNIFICANT DEVELOPMENT UNTIL LATE TUESDAY WHEN ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME MORE FAVORABLE WHILE THE LOW MEANDERS OVER EASTERN FLORIDA COASTAL WATERS. THIS DISTURBANCE IS CURRENTLY GENERATING SCATTERED MODERATE CONVECTION AND TSTMS N OF 25N W OF 73W. PLEASE REFER TO THE ATLC TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE IS SLIGHTLY N OF THE ITCZ WITH AXIS EXTENDING FROM 15N46W TO 7N48W MOVING W-NW AT 20 KT DURING THE LAST 24 HOURS. VERY DRY AIR FROM A SAHARAN AIR LAYER OUTBREAK SPREADS OVER MOST OF THE WAVE ENVIRONMENT HINDERING DEEP CONVECTIVE ACTIVITY. SCATTERED SHOWERS ARE IN THE VICINITY OF THE ITCZ FROM 6N-10N BETWEEN 47W-50W. TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN WITH AXIS EXTENDING FROM 17N64W TO 7N65W MOVING W-NW AT 20 KT DURING THE LAST 24 HOURS. EVEN THAT THE SSMI TPW AND WATER VAPOR IMAGERY SHOW MID- UPPER LEVEL MOISTURE ASSOCIATED WITH THIS WAVE...STRONG DEEP LAYER ENVIRONMENTAL WIND SHEAR IS HINDERING THE DEVELOPMENT OF DEEP CONVECTION. A SECOND TROPICAL WAVE IS OVER THE CARIBBEAN WITH AXIS EXTENDING FROM 18N81W TO 9N82W MOVING W AT 20-25 KT DURING THE LAST 24 HOURS. SSMI TPW AND WATER VAPOR IMAGERY SHOW MID-UPPER LEVEL MOISTURE ASSOCIATED WITH THIS WAVE. SCATTERED SHOWERS AND TSTMS ARE WITHIN 100 NM EITHER SIDE OF ITS AXIS S OF 15N. TROPICAL WAVE FORMERLY MOVING ACROSS SOUTHERN MEXICO IS NO LONGER DISCERNIBLE AS IT HAS MERGED WITH AN AREA OF LOW PRESSURE E-SE OF TROPICAL DEPRESSION FOUR-E. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA NEAR 10N14W TO 7N23W TO 6N32W. THE ITCZ BEGINS NEAR 6N32W AND CONTINUES ALONG 5N45W TO 7N59W. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 4N-10N E OF 41W AND FROM 6N-10N W OF 56W. ...DISCUSSION... ...THE GULF OF MEXICO... A MIDDLE-LEVEL ANTICYCLONE CENTERED SW OF LOUISIANA CONTINUES TO SUPPORT SURFACE RIDGING ACROSS THE GULF. THE SURFACE RIDGE IS ANCHORED BY A 1022 MB HIGH OVER THE NE BASIN NEAR 28N86W AND PROVIDES RETURN FLOW OF 5-15 KT ACROSS THE BASIN...EXCEPT W OF 92W WHERE WINDS REACH UP TO 20 KT. MODERATE MOISTURE IS ACROSS THE THE EASTERN GULF...HOWEVER HIGH PRESSURE AT THE SURFACE IS SUPPRESSING CONVECTION...THUS THE DEVELOPMENT OF RAINSHOWERS. HAZY WEATHER IS ACROSS THE WESTERN GULF ASSOCIATED WITH A SAHARAN AIRMASS BEING ADVECTED INTO THE REGION FROM THE NORTHERN CARIBBEAN. DRY AIR ASSOCIATED WITH THIS AIRMASS IS KEEPING MOSTLY FAIR WEATHER...EXCEPT IN THE BAY OF CAMPECHE W OF 93W WHERE UPPER LEVEL DIFFLUENCE AND REMNANT MOISTURE FROM A SURFACE TROUGH SUPPORT SCATTERED SHOWERS. HIGH PRESSURE WILL PREVAIL ACROSS THE BASIN FOR THE NEXT COUPLE OF DAYS. ...THE CARIBBEAN SEA... TWO TROPICAL WAVES ARE MOVING ACROSS THE CARIBBEAN WATERS...ONE WEST OF THE LESSER ANTILLES AND ANOTHER EAST OF NICARAGUA. SEE THE TROPICAL WAVES SECTION ABOVE FOR MORE DETAILS. SSMI TPW IMAGERY SHOW MODERATE MOIST CONDITIONS EAST OF 83W SOUTH OF 16N WHILE A TONGUE OF SAHARAN DRY AIR MOVES WESTWARD OVER THE NORTHERN BASIN. THIS DRY AIR IS SUPPORTING MOSTLY FAIR BUT HAZY CONDITIONS IN THIS REGION OF THE CARIBBEAN. OVER THE MOIST REGION...STRONG DEEP LAYER ENVIRONMENTAL WIND SHEAR HINDERS THE DEVELOPMENT OF CONVECTION. ALOFT...A CYCLONIC CIRCULATION IS OVER THE NW CARIBBEAN WHILE A BROAD E-W ELONGATED RIDGE COVERS THE REMAINDER BASIN. AN UPPER-LEVEL LOW N OF PUERTO RICO IS GENERATING DIFFLUENCE OVER THE FAR NE CARIBBEAN WHICH IS SUPPORTING SCATTERED SHOWERS OVER THE NORTHERN LEEWARD ISLANDS. 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. THE WAVE OVER THE WESTERN BASIN WILL MOVE INLAND CENTRAL AMERICA LATER TODAY AND IS EXPECTED TO MERGE WITH AN AREA OF LOW PRESSURE IN THE EPAC WATERS TOMORROW MORNING. THE WAVE OVER THE E CARIBBEAN WILL CONTINUE TO MOVE W TOWARD THE WESTERN BASIN WHILE A NEW TROPICAL WAVE ENTERS THE E CARIBBEAN MON MORNING. ...HISPANIOLA... A DRY AIRMASS FROM THE SAHARA CONTINUE TO MOVE ACROSS THE GREATER ANTILLES AND ADJACENT WATERS...THUS SUPPORTING FAIR BUT HAZY WEATHER CONDITIONS. HOWEVER...DIFFLUENT FLOW ALOFT S-SW OF THE ISLAND IS SUPPORTING SCATTERED SHOWERS OVER SOUTHERN HAITI COASTAL WATERS AND POSSIBLE ISOLATED SHOWERS ALONG THE SOUTHERN COAST OF THE ISLAND. THE CONTINUED PRESENCE OF THE SAHARAN AIR LAYER IN THE AREA OVER THE NEXT COUPLE OF DAYS SHOULD RESULT IN DELAYED DEVELOPMENT OF AFTERNOON CONVECTION WITH GENERALLY LESS COVERAGE THAN IS TYPICALLY EXPECTED. ...THE ATLANTIC OCEAN... THE WESTERNMOST PART OF A BROAD MIDDLE-LEVEL TROUGH IS SUPPORTING A DISTURBANCE OVER THE SW N ATLC WATERS. THIS DISTURBANCE HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE SOMETIME TUESDAY. SEE THE SPECIAL FEATURES SECTION FOR MORE INFORMATION. FARTHER EAST...THE SAME MID LEVEL TROUGH SUPPORT A SURFACE TROUGH ALONG 33N57W TO 27N64W WHICH IS GENERATING HEAVY SHOWERS AND TSTMS N OF 26N BETWEEN 56W-63W. IN BETWEEN THESE TWO FEATURES...A 1021 MB HIGH SLOWLY DRIFTING SE IS NEAR 27N69W. ELSEWHERE OVER THE ATLANTIC...A BROAD SURFACE RIDGE ANCHORED BY A 1029 MB HIGH NEAR 33N41W EXTENDED A RIDGE TO 16N AND SUPPORTS GENERALLY FAIR WEATHER CONDITIONS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR