000 AXNT20 KNHC 222343 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED JUL 22 2015 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 2330 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS IN THE EASTERN TROPICAL ATLANTIC WITH AXIS EXTENDING ALONG 30W FROM 10N-19N AND MOVING W NEAR 15 KT OVER THE PAST 24 HOURS. THE POSITION OF THIS WAVE WAS IDENTIFIED USING 700 MB STREAMLINE ANALYSIS AND THE GFS-BASED TROUGH DIAGNOSTICS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS N OF SIGNIFICANT MOISTURE WHERE ISOLATED CONVECTION IS EVIDENT...S OF 10N. THE WAVE IS EMBEDDED IN A DUSTY SAHARAN AIR LAYER THEREFORE NO SIGNIFICANT CONVECTION IS PRESENT AT THIS TIME. A TROPICAL WAVE IS MOVING OVER PUERTO RICO AND THE E CARIBBEAN WITH AXIS EXTENDING ALONG 67W FROM 08N-20N...MOVING W NEAR 20 KT OVER THE PAST 24 HOURS. A LARGE PLUME OF MOIST AIR IS DEPICTED ON TPW IMAGERY MAINLY E OF THE WAVE AXIS EXTENDING ACROSS PUERTO RICO AND THE LESSER ANTILLES. AN UPPER-LEVEL LOW CENTERED OVER THE SOUTHERN ATLANTIC WATERS N OF PUERTO RICO IS INTERACTING WITH THIS WAVE GENERATING CLOUDINESS AND ISOLATED CONVECTION MAINLY N OF 66N AND E OF 69W. THIS WAVE WILL CONTINUE MOVING W ACROSS THE CARIBBEAN INCREASING THE MOISTURE AND HENCE SUPPORTING CONVECTION ACROSS THE GREATER ANTILLES AND ADJACENT CARIBBEAN WATERS. A TROPICAL WAVE IS MOVING OVER THE W CARIBBEAN WITH AXIS EXTENDING ALONG 81W FROM 08N-21N...MOVING W NEAR 20 KT OVER THE PAST 24 HOURS. THE WAVE HAS A NEGLIGIBLE SURFACE COMPONENT...BUT IT IS OBSERVABLE VIA THE TOTAL PRECIPITABLE WATER IMAGERY AND CARIBBEAN RAWINDSONDES. SCATTERED MODERATE CONVECTION IS CURRENTLY IN THE SOUTHERN PORTION OF THE WAVE S OF 10N MOSTLY RELATED TO UPPER-LEVEL DIVERGENCE PREVAILING ACROSS CENTRAL AMERICA AND EPAC AND ALSO THE PROXIMITY OF THE MONSOON TROUGH AXIS. THE TROPICAL WAVE PREVIOUSLY ANALYZED OVER NICARAGUA AND THE W CARIBBEAN HAS LOST ITS DEFINITION AND NO EVIDENCE OF ITS EXISTENCE CAN BE FOUND. THEREFORE...IT IS BELIEVED THAT THIS WAVE HAS DISSIPATED. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE EASTERN TROPICAL ATLANTIC NEAR 13N17W TO NEAR 10N28W. THE ITCZ BEGINS W OF A TROPICAL WAVE NEAR 09N32W TO THE COAST OF SOUTH AMERICA AT 05N53W. SCATTERED MODERATE CONVECTION IS LOCATED FROM 05N-09N BETWEEN 20W-42W. ...DISCUSSION... GULF OF MEXICO... A SURFACE RIDGE EXTENDS W FROM THE ATLANTIC INTO THE GULF WATERS ANCHORED BY A WEAK 1017 MB HIGH CENTERED NEAR 25N86W. UPPER- LEVEL DIFFLUENCE AND DAYTIME HEATING COMBINED TO GENERATE SCATTERED MODERATE CONVECTION ACROSS THE FLORIDA PENINSULA AFFECTING THE FAR E GULF WATERS E OF 83W. THE REMAINDER OF THE BASIN REMAINS CONVECTION-FREE. SCATTEROMETER DATA DEPICTS A LIGHT ANTICYCLONIC FLOW PREVAILING ACROSS THE BASIN. LITTLE CHANGE IS EXPECTED DURING THE NEXT TWO DAYS. CARIBBEAN SEA... TWO TROPICAL WAVES ARE MOVING ACROSS THE BASIN. FOR MORE DETAILS PLEASE REFER TO THE SECTION ABOVE. A MODERATE PRESSURE GRADIENT PRODUCED BY THE SURFACE HIGH OVER THE SUBTROPICAL ATLANTIC AND LOWER PRESSURES PREVAILING OVER CENTRAL AND SOUTH AMERICA IS SUPPORTING GENTLE TO MODERATE TRADES ACROSS THE CENTRAL CARIBBEAN BETWEEN 70W-80W. LIGHT TO GENTLE TRADES PREVAIL ELSEWHERE. ASIDE FROM THE CONVECTION IN THE VICINITY OF THE TROPICAL WAVES...FAIR WEATHER PREVAILS OVER THE REMAINDER OF THE CARIBBEAN. THE PRESSURE GRADIENT WILL TIGHTEN OVER THE NEXT TWO DAYS INDUCING AN INCREASE IN WIND SPEEDS ACROSS THE CENTRAL CARIBBEAN. ...HISPANIOLA... SCATTERED MODERATE CONVECTION IS OBSERVED ACROSS THE ISLAND AS THE TROPICAL WAVE CURRENTLY OVER PUERTO RICO APPROACHES INCREASING MOISTURE AND INSTABILITY. THIS WAVE IS INTERACTING WITH AN UPPER-LEVEL LOW CENTERED OVER THE ATLANTIC WATERS N OF PUERTO RICO NEAR 21N66W. SIMILAR ACTIVITY IS EXPECTED THROUGH THURSDAY. OVER THE NEXT 48 HOURS...THE TROPICAL WAVE ITS ASSOCIATED MOISTURE SHOULD BE WEST OF HISPANIOLA...REDUCING PRECIPITATION POTENTIAL THEN. ATLANTIC OCEAN... A TROPICAL WAVE IS OVER THE TROPICAL ATLANTIC. REFER TO THE SECTION ABOVE FOR MORE DETAILS. A 1023 MB BERMUDA HIGH CENTERED NEAR 29N47W AND A 1024 MB AZORES HIGH CENTERED NEAR 34N27W ARE DOMINATING THE SUBTROPICAL ATLANTIC. A SURFACE TROUGH IS BETWEEN THESE HIGH CENTERS EXTENDING FROM 30N41W TO 23N40W. ISOLATED CONVECTION IS OBSERVED ALONG THIS BOUNDARY. SCATTEROMETER DATA DEPICTS A LIGHT TO GENTLE ANTICYCLONIC FLOW ACROSS THE BASIN. NO SIGNIFICANT CHANGES ARE EXPECTED DURING THE NEXT TWO DAYS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ ERA