000 AXNT20 KNHC 170557 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT AUG 17 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. ...SPECIAL FEATURES... TROPICAL STORM ERIN IS CENTERED NEAR 18.5N 34.5W AT 17/0300 UTC OR ABOUT 620 NM W-NW OF THE CAPE VERDE ISLANDS MOVING NW AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUST TO 45 KT. PLEASE SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 18N-22N BETWEEN 31W- 36W. THE SYSTEM IN THE GULF OF MEXICO AT 17/0300 UTC CONSISTS OF A SURFACE TROUGH THAT EXTENDS FROM 26N90W THROUGH A WEAK 101 MB LOW NEAR 21N92W TO S MEXICO NEAR 18N94W. A MID/UPPER LOW IS TO THE NE NEAR 23N90W. AN UPPER RIDGE EXTENDS FROM THE NW CARIBBEAN E OF THE LOWS THROUGH THE YUCATAN CHANNEL TO ACROSS CENTRAL FLORIDA DRAWING THE MOISTURE AND SHOWER/THUNDERSTORM ACTIVITY NE OF THE LOW SYSTEM. A BROAD AREA OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 150/175 NM OF LINE FROM OVER THE YUCATAN PENINSULA NEAR 21N88W TO OVER FLORIDA NEAR CEDAR KEY COVERING MOST OF THE E CARIBBEAN. THIS SYSTEM REMAINS POORLY ORGANIZED. ENVIRONMENTAL CONDITIONS COULD BECOME SOMEWHAT MORE FAVORABLE FOR DEVELOPMENT WHILE THE LOW GENERALLY MOVES TOWARD THE WEST-NORTHWEST OR NORTHWEST OVER THE NEXT COUPLE OF DAYS. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...TROPICAL WAVES... TROPICAL WAVE IN THE CENTRAL TROPICAL WAVE EXTENDS FROM 22N54W TO 10N54W MOVING W 15-20 KT. WAVE REMAINS EMBEDDED WITHIN AN AREA OF MODERATE MOISTURE AS DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY. NO ASSOCIATED SHOWERS OR DEEP CONVECTION. TROPICAL WAVE IS MOVING ACROSS THE CARIBBEAN EXTENDS FROM 22N68W TO 12N70W MOVING W NEAR 20 KT. PORTION OF THE WAVE N OF 16N IS EMBEDDED WITHIN AN AREA OF DEEP MOISTURE COVERING THE AREA FROM PUERTO RICO TO THE DOMINICAN REPUBLIC AS DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS DOT THE AREA FROM 15N-22N BETWEEN 60W-70W INCLUDING THE LEEWARD/VIRGIN ISLANDS...PUERTO RICO...AND HISPANIOLA. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 11N15W TO 10N19W THEN RESUMES W OF T.S. ERIN NEAR 14N36W AND CONTINUES THROUGH A WEAK 1012 MB LOW NEAR 11N45W TO 10N52W WHERE THE ITCZ BEGINS AND CONTINUES TO NEAR 8N59W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 75/90 NM OF LINE FROM 6N18W TO JUST INLAND OVER GUINEA NEAR 10N13W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 8N-13N BETWEEN 40W-53W. ...DISCUSSION... GULF OF MEXICO... THE ACTIVITY OVER E GULF IS ASSOCIATED WITH THE LOW/SURFACE TROUGH IN THE NW CARIBBEAN. SEE SPECIAL FEATURES ABOVE. AN UPPER TROUGH COVERS THE E CONUS EXTENDING FROM AN UPPER LOW OVER THE MIDDLE MISSISSIPPI VALLEY TO TEXAS AND SUPPORTING A STATIONARY BOUNDARY THAT MEANDERS ALONG THE GULF COAST FROM SW GEORGIA INTO THE GULF NEAR PANAMA CITY TO A WEAK 1014 MB LOW NEAR NEW ORLEANS THEN RE-EMERGING INTO THE GULF OVER ATCHAFALAYA BAY LOUISIANA TO NEAR GALVESTON TEXAS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60/75 NM S OF THE FRONT AND WITHIN 60 NM ALONG THE COAST OF TEXAS TO BETWEEN BROWNSVILLE AND CORPUS CHRISTI. A WEAK UPPER RIDGE IS ANCHORED OVER SW MEXICO COVERING THE SW GULF S OF 24N W OF 94W. AN UPPER RIDGE ANCHORED IN THE NW CARIBBEAN EXTENDS AN AXIS THROUGH THE YUCATAN CHANNEL OVER THE E GULF TO ACROSS CENTRAL FLORIDA INTO THE W ATLC DRAWING MOISTURE AND SUBSEQUENT SHOWERS/THUNDERSTORMS OVER THE SE GULF ASSOCIATED WITH THE SYSTEM IN THE SPECIAL FEATURES ABOVE. WEAK SURFACE RIDGE EXTENDS FROM THE W ATLC ACROSS CENTRAL FLORIDA TO OVER THE E GULF. LOW PRESSURE SYSTEM IN SPECIAL FEATURES IS FORECAST TO BEGIN TO MOVE NW TONIGHT MOVING TO THE W/CENTRAL GULF LATE SUN THEN MOVING INLAND OVER EXTREME SE TEXAS COAST LATE MON...WITH THE POSSIBILITY OF TROPICAL CYCLONE FORMATION THROUGH MON. SURFACE RIDGE WILL DOMINATE THE REMAINDER OF THE GULF THROUGH WED. CARIBBEAN SEA... AN UPPER RIDGE COVERS THE W CARIBBEAN ANCHORED NEAR 19N86W AND EXTENDS INTO THE GULF OF MEXICO WHILE A SECOND UPPER RIDGE COVERS THE E CARIBBEAN ANCHORED IN THE IN THE W TROPICAL ATLC. THIS IS INDUCING AN INVERTED UPPER TROUGH OVER THE CENTRAL CARIBBEAN EXTENDING FROM W PANAMA ACROSS JAMAICA AND THROUGH THE WINDWARD PASSAGE. CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 17N-21N BETWEEN 72W-80W. THE MONSOON TROUGH EXTENDS ACROSS THE PANAMA AND COSTA RICA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 13N W OF 77W TO INLAND OVER PANAMA TO NICARAGUA. THE SHOWER ACTIVITY IN THE NE CARIBBEAN IS ASSOCIATED WITH THE TROPICAL WAVE. THE REMAINDER OF THE CARIBBEAN IS UNDER FAIR CONDITIONS AGAIN TONIGHT. CARIBBEAN TROPICAL WAVE WILL CONTINUE W THROUGH THE CENTRAL CARIBBEAN TONIGHT AND SAT BECOMING DIFFUSE OVER THE W CARIBBEAN ON SUN. A SECOND TROPICAL WAVE WILL MOVE ACROSS THE E CARIBBEAN ON SUN AND MON AND THROUGH THE CENTRAL CARIBBEAN TUE AND WED. HISPANIOLA... SCATTERED SHOWERS ARE POSSIBLE ACROSS THE ISLAND TONIGHT WITH AN ISOLATED THUNDERSTORM ALONG THE COAST OF HAITI IN THE GULF OF GONAVE. THE TROPICAL WAVE WILL CONTINUE ACROSS THE HISPANIOLA TONIGHT AND SAT BRINGING THESE SHOWERS AND POSSIBLE MORE ISOLATED THUNDERSTORMS THROUGH THE NIGHT AND AGAIN ON SAT. ANOTHER WAVE WILL MOVE ACROSS THE ISLAND LATE SUN THROUGH TUE INCREASING THE POSSIBILITY OF HEAVIER SHOWERS/THUNDERSTORMS. ATLANTIC OCEAN... THE UPPER RIDGE OVER THE W CARIBBEAN EXTENDS ACROSS THE GULF OF MEXICO INTO THE W ATLC NEAR MELBOURNE FLORIDA TO BEYOND 32N74W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE FROM 24N-30N BETWEEN 75W-78W PORTIONS OF THE BAHAMAS. THE UPPER TROUGH OVER THE E CONUS AND THE ASSOCIATED STATIONARY FRONT IS N OF THE DISCUSSION AREA WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 30N W OF 76W. A BROAD SURFACE RIDGE DOMINATES THE REMAINDER OF THE ATLC INTO THE GULF OF MEXICO ANCHORED BY A 1028 MB N OF THE DISCUSSION AREA. SURFACE RIDGE EXTENDING INTO THE GULF OF MEXICO WILL LIFT IN N TO NEAR 31N ON SAT AND SUN AND SHIFT N OF THE AREA NEXT WEEK. THE N PORTION OF CARIBBEAN TROPICAL WAVE WILL MOVE ACROSS THE FAR SW ATLC THROUGH SUN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW