000 AXNT20 KNHC 162345 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE JUL 16 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 17N18W TO 4N18W MOVING WEST AT 15-20 KT. UPPER AIR SOUNDINGS FROM DAKAR SENEGAL INDICATE THE WAVE MOVING OFF THE COAST OF AFRICA BETWEEN 16/0000 AND 16/1200 UTC. THE WAVE ALSO COINCIDES WITH A 700 MB TROUGH AXIS AND A SURGE OF MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/STRONG CONVECTION IS FROM 6N-9N BETWEEN 17W-20W. TROPICAL WAVE EXTENDS FROM 2052W TO 11N50W MOVING W NEAR 20 KT. THE WAVE IS EMBEDDED WITHIN A LARGE SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION IS FROM 13N-18N BETWEEN 48W-54W. TROPICAL WAVE EXTENDS FROM 18N63W TO 10N61W MOVING W NEAR 15 KT. THE WAVE ALIGNS WITH A NARROW AREA OF INCREASED MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF MAURITANIA NEAR 19N16W TO 12N23W 6N34W. THE ITCZ BEGINS NEAR 6N34W AND CONTINUES TO 5N55W. ISOLATED MODERATE CONVECTION IS FROM 4N-8N BETWEEN 23W- 32W. ...DISCUSSION... GULF OF MEXICO... MOIST CONDITIONS CONTINUE THROUGHOUT MUCH OF THE GULF OF MEXICO THIS EVENING ASSOCIATED WITH SEVERAL UPPER LEVEL LOW CENTERS. A TIGHTLY SPUN UPPER LOW IS MOVING INTO NEW MEXICO WITH A TROUGH AXIS CONTINUING THROUGH TEXAS INTO THE WESTERN GULF. THIS UPPER TROUGH IS PROVIDING DIFFLUENT FLOW OVER THE NW GULF. A SECOND UPPER LOW IS CENTERED JUST WEST OF THE YUCATAN PENINSULA NEAR 22N92W PROVIDING DIFFLUENT FLOW OVER THE PENINSULA. A THIRD UPPER LOW IS OVER CENTRAL FLORIDA NEAR 27N83W PROVIDING DIFFLUENT FLOW OVER FLORIDA INCLUDING THE PANHANDLE. WEAK UPPER RIDGING IS SANDWICHED OVER THE NORTH CENTRAL GULF. THIS COMPLEX PATTERN IS PROVIDING INSTABILITY OVER SEVERAL AREAS GIVING WAY TO SHOWER/THUNDERSTORM ACTIVITY. SCATTERED SHOWERS/THUNDERSTORMS ARE MOST CONCENTRATED OVER THE NE GULF NORTH OF 27N EAST OF 86W...AND CONTINUE WESTWARD ALONG THE GULF COAST. ACTIVITY NEAR FLORIDA IS ALSO BEING ENHANCED BY A SURFACE TROUGH ALONG 28N82W TO 22N81W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO OVER THE WESTERN GULF FROM 20N-28N BETWEEN 92W-97W. THIS ACTIVITY IS ENHANCED BY A SECOND SURFACE TROUGH ALONG 27N97W TO 19N94W. WINDS AT THE SURFACE ARE PRIMARILY EAST TO SOUTHEAST RANGING FROM 10-15 KT. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. CARIBBEAN SEA... UPPER LEVEL RIDGING COVERS THE WESTERN CARIBBEAN CENTERED OVER HONDURAS. WATER VAPOR IMAGERY INDICATES RELATIVELY DRY AIR ALOFT IS OVER THE BASIN AROUND THE UPPER RIDGE...WHICH CONTINUES AROUND BROAD UPPER TROUGHING OVER THE CENTRAL CARIBBEAN...AND AROUND ANOTHER UPPER RIDGE OVER THE EASTERN CARIBBEAN. THE DRY AIR ALOFT IS HELPING MAINTAIN FAIR CONDITIONS THROUGHOUT THE CARIBBEAN WATERS EXCEPT FOR SOME ISOLATED/THUNDERSTORMS SHOWERS OVER THE NORTHWESTERN PORTIONS EMBEDDED WITHIN TRADEWIND FLOW OF 15-25 KT. HOWEVER...AFTERNOON SHOWERS/THUNDERSTORMS HAVE BUILT UP OVER SEVERAL OF THE ISLANDS INCLUDING CUBA...JAMAICA...AND HISPANIOLA. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SW CARIBBEAN SOUTH OF 13N BETWEEN 78W-83W ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS THROUGH PANAMA TO A 1005 MB LOW OVER NORTHERN COLOMBIA. A TROPICAL WAVE HAS MOVED INTO THE EASTERN CARIBBEAN NEAR 62W. HOWEVER...NO SHOWERS/THUNDERSTORMS ARE ASSOCIATED WITH THE WAVE AT THIS TIME. THE TROPICAL WAVE IS EXPECTED TO CONTINUE WESTWARD. A SECOND WAVE FARTHER EAST WILL LIKELY BRING MORE MOISTURE TO THE LESSER ANTILLES THAN THE CURRENT WAVE. THE MOISTURE COULD REACH THE ISLAND WITHIN 24 HOURS AND PROVIDE ISOLATED SHOWERS. HISPANIOLA... SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS NORTHERN HISPANIOLA FROM 19N-20N BETWEEN 69W-73W. MODERATE MOISTURE IS IN THE VICINITY ESPECIALLY NORTH OF THE ISLAND ASSOCIATED WITH AN UPPER LEVEL TROUGH IN THE FAR WEST ATLC. MOISTURE ASSOCIATED WITH A TROPICAL WAVE JUST EAST OF THE LESSER ANTILLES IS EXPECTED TO REACH HISPANIOLA WITHIN 24 HOURS AND MAY INCREASE AFTERNOON CONVECTION. A SECOND WAVE WILL BRING MORE MOISTURE LATER IN THE WEEK. ATLANTIC OCEAN... DIFFLUENT FLOW ALOFT COVERS THE WEST ATLC AROUND AN UPPER LEVEL LOW OVER FLORIDA SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS OVER MUCH OF THE BAHAMAS FROM 22N-28N BETWEEN 74W-80W. A SECOND UPPER TROUGH IS ALONG 29N71W TO 24N65W SUPPORTING A SURFACE TROUGH ALONG 31N69W TO 24N65W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN 220 NM EAST OF THE AXIS. BROAD UPPER RIDGING DOMINATES THE REMAINDER OF THE CENTRAL AND EASTERN TROPICAL ATLC CENTERED NEAR 23N28W. THIS UPPER RIDGE SUPPORTS BROAD SURFACE RIDGING ANCHORED BY A 1025 MB HIGH NEAR 28N42W. MUCH OF THE EASTERN ATLC IS ALSO COVERED BY A VERY STABLE SAHARAN AIR LAYER EXTENDING TO ALMOST 45W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON