000 AXNT20 KNHC 220550 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT JUN 22 2013 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... TROPICAL WAVE EXTENDS FROM 05N33W TO 15N33W MOVING W AT 20 KT. THE WAVE COINCIDES WITH A WEAK 700 MB TROUGH AND A RELATIVE MAXIMUM IN DEEP LAYER MOISTURE NOTED ON TOTAL PRECIPITABLE WATER IMAGERY FROM 02N-09N BETWEEN 28W-34W. ALSO OF NOTE...THE WAVE IS LOCATED WITHIN AN AREA OF CLEARING EMBEDDED IN THE SAHARAN AIR LAYER SURROUNDING THE WAVE AXIS. WIDELY SCATTERED MODERATE CONVECTION IS FROM 06N-08N BETWEEN 29W-33W. TROPICAL WAVE EXTENDS FROM 07N46W TO 16N47W MOVING W AT 15 KT. THE WAVE LIES WITHIN A RELATIVE MAXIMUM ON TOTAL PRECIPITABLE WATER IMAGERY FROM 07N-22N BETWEEN 43W-48W. THE SAHARAN AIR LAYER AS NOTED ON GOES-R PG IMAGERY REMAINS A STRONG SIGNAL AND CONTINUES TO SURPRESS ANY SIGNIFICANT DEEP CONVECTION IN THE VICINITY OF THE WAVE...INCLUDING S OF 10N IN CLOSER PROXIMITY TO THE ITCZ AXIS. TROPICAL WAVE EXTENDS FROM 11N81W TO 19N80W MOVING W AT 15 KT. THE WAVE ALIGNS WITH WEAK 700 MB TROUGHING THAT EXTENDS FROM THE SW CARIBBEAN OVER CENTRAL CUBA AND INTO THE SW NORTH ATLC OVER THE BAHAMAS. PARTIAL ENERGY FROM THE WAVE HAS FRACTURED NORTH- NORTHWESTWARD AND REMAINS ANALYZED AS A SURFACE TROUGH PRODUCING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS THIS EVENING. AS FOR THE WAVE...IT REMAINS BENEATH UNFAVORABLE CONDITIONS ALOFT AS NORTHWEST FLOW IN THE UPPER LEVELS CONTINUES TO PROVIDE AN OVERALL STABLE ENVIRONMENT ACROSS PORTIONS OF THE CENTRAL AND WESTERN CARIBBEAN. THE WAVE IS EXPECTED TO CONTINUE WESTWARD AND BRING INCREASED CLOUDINESS AND HIGHER CHANCES FOR PRECIPITATION ACROSS CENTRAL AMERICA OVER THE NEXT 24 TO 48 HOURS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO 10N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N20W TO 07N33W TO 07N46W TO 05N53W. ISOLATED MODERATE CONVECTION IS FROM THE EQUATOR TO 07N BETWEEN 26W-38W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES AN MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE SE CONUS THAT SUPPORTS WEAK SURFACE TROUGHING EXTENDING FROM THE SW NORTH ATLC OFFSHORE OF THE CAROLINAS WEST- SOUTHWEST ACROSS EXTREME NORTHERN FLORIDA INTO EASTERN LOUISIANA. AS OF 22/0300 UTC...A SURFACE TROUGH EXTENDED FROM NEAR JACKSONVILLE FLORIDA TO NORTH OF THE TAMPA BAY AREA NEAR 28N83W THAT IS PROVIDING FOCUS FOR ISOLATED SHOWERS N OF 27N E OF 85W. OTHERWISE...THE REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1020 MB HIGH CENTERED NEAR 28N92W. EAST-SOUTHEAST WINDS IN THE RANGE OF 5 TO 15 KT ARE NOTED ON EARLIER SCATTEROMETER PASSES AND THE LATEST SHIP... BUOY...AND OIL PLATFORM OBSERVATIONS INDICATE THESE CONDITIONS SHOULD PERSIST THROUGH THE OVERNIGHT HOURS. THE RIDGING SHOULD MAINTAIN ITSELF SUNDAY AND THROUGHOUT MUCH OF THE WEEK AHEAD. CARIBBEAN SEA... THE CARIBBEAN IS LARGELY INFLUENCE BY A MIDDLE TO UPPER LEVEL LOW CENTERED NORTH OF HISPANIOLA NEAR 21N72W. THE TROUGH AXIS DIPS SOUTH-SOUTHWEST TO A BASE OVER THE SW CARIBBEAN NEAR 11N77W WITH ANOTHER WEAKER AXIS EXTENDING FROM OVER JAMAICA NEAR 18N78W TO OVER THE YUCATAN CHANNEL NEAR 22N86W. WATER VAPOR IMAGERY INDICATES THE AREAS WITHIN THE TROUGHING ARE RELATIVELY DRY AND STABLE ALOFT WHICH IS PROVIDING FOR OVERALL TRANQUIL CONDITIONS N OF 14N BETWEEN 73W-83W. A FEW ISOLATED SHOWERS AND TSTMS ARE HOWEVER OCCURRING IN THE VICINITY OF THE CAYMAN ISLANDS AND JAMAICA FROM 18N-21N BETWEEN 78W-82W. OTHERWISE ON THE SOUTHWEST PERIPHERY OF THE TROUGH...NORTH-NORTHWESTERLY FLOW ALOFT DOMINATES AND IS PROVIDING FOR SUFFICIENT UPPER LEVEL DIFFLUENCE TO SUPPORT SCATTERED SHOWERS AND TSTMS S OF 15N W OF 80W... INCLUDING INLAND PORTIONS OF NICARAGUA AND COSTA RICA. A TROPICAL WAVE ALONG 81W WILL ALSO CONTINUE TO MOVE WESTWARD OVER THE NEXT FEW DAYS AND INCREASE CLOUDINESS AND PRECIPITATION FOR CENTRAL AMERICA INTO EARLY NEXT WEEK. EAST OF THE UPPER LEVEL TROUGH AXIS...SOUTHWESTERLY FLOW ALOFT CONTINUES TO ADVECT MOISTURE FROM OVER NORTHERN SOUTH AMERICA TOWARDS THE MONA PASSAGE AND PUERTO RICO. MOST OF THIS MOISTURE REMAINS AS INCREASED CLOUD COVER ACROSS THE EASTERN CARIBBEAN...HOWEVER A FEW ISOLATED LOW-TOPPED SHOWERS ARE NOTED ON SATELLITE IMAGERY N OF 13N E OF 72W...THAT STRETCH NORTHEASTWARD INTO THE ADJACENT WATERS OF THE SW NORTH ATLC. HISPANIOLA... CURRENTLY CONDITIONS REMAIN RELATIVELY TRANQUIL FOR THE OVERNIGHT ACROSS THE ISLAND AS LATE EVENING CONVECTION HAS DIMINISHED. WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL LOW IS CENTERED NORTH OF THE ISLAND NEAR 21N72W WITH PRIMARILY MOIST SOUTHWESTERLY FLOW ALOFT LOCATED EAST OF A TROUGH AXIS WHICH BISECTS THE ISLAND ALONG 72W. GLOBAL MODEL DATA INDICATES THE LOW WILL WEAKEN OVER THE NEXT FEW DAYS AND LIFT GRADUALLY NORTHWARD WITH SOUTHWESTERLY FLOW ALOFT BECOMING DOMINANT THROUGH EARLY NEXT WEEK. AS A RESULT...THE ATMOSPHERE WILL FAVOR BECOMING MORE UNSTABLE DURING THE AFTERNOON AND EVENING HOURS WITH SCATTERED SHOWERS AND TSTMS EXPECTED WITH PEAK DAYTIME HEATING AND INSTABILITY. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL LOW CENTERED OVER THE SE CONUS NEAR 35N84W SUPPORTS A WEAK 1018 MB LOW CENTERED NEAR 33N78W AND THE ASSOCIATED FRONTAL BOUNDARY EXTENDING TO THE COAST NEAR 31N81W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER THE FAR NW PORTION OF THE SW NORTH ATLC N OF 29N W OF 78W. FARTHER SOUTHEAST... ENERGY THAT HAS FRACTURED AWAY FROM A TROPICAL WAVE MOVING ACROSS THE WESTERN CARIBBEAN SEA REMAINS ANALYZED AS A SURFACE TROUGH FROM 22N75W TO 27N73W AND IS PROVIDING FOCUS FOR WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING WITHIN 120 NM WEST OF THE SURFACE TROUGH AXIS. THIS AREA OF INCREASED MOISTURE AND PRECIPITATION IS EXPECTED TO CONTINUE AN OVERALL WEST- NORTHWEST MOVEMENT OVER THE NEXT FEW DAYS WITH CLOUDINESS AND PRECIPITATION CHANCES ELEVATED FOR THE WESTERN BAHAMAS AND FLORIDA PENINSULA OVER THE WEEKEND. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1036 MB HIGH CENTERED WEST OF THE AZORES NEAR 39N32W. A STABLE DRY AIRMASS COVERS MUCH OF THE EASTERN ATLC INDICATED BY THE LARGE AREA OF DUST THAT EXTENDS FROM THE COAST OF AFRICA TO 50W. 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