000 AXNT20 KNHC 150003 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED JUL 14 2010 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC... ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 30W FROM 5N TO 20N MOVING W 15-20 KT. SATELLITE IMAGERY INDICATES A BROAD AREA OF CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. A SURGE OF MOISTURE NEAR THE WAVE AXIS IS ALSO PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 5N-13N BETWEEN 23W-33W. TROPICAL WAVE IS ALONG 44W FROM 4N TO 14N MOVING W 15-20 KT. THIS WAVE IS MOSTLY EMBEDDED IN THE ITCZ AHEAD OF A MAXIMUM IN DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. WEAK CYCLONIC FLOW IS ALSO ABOUT THE WAVE AXIS EVIDENT IN SATELLITE DERIVED WINDS. A LARGE AREA OF DRY SAHARAN AIR AND DUST ENCOMPASSES THE WAVE AXIS RESTRICTING CONVECTION TO NEAR THE ITCZ. ISOLATED MODERATE CONVECTION IS FROM 5N-12N BETWEEN 40W-45W. TROPICAL WAVE IS OVER THE LESSER ANTILLES ALONG 61W S OF 15N INTO INLAND PORTIONS OF EASTERN VENEZUELA MOVING W AT ABOUT 10-15 KT. THIS WAVE EMBEDDED IN MODERATE VALUES OF MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 100 NM ON EITHER SIDE OF THE WAVE AXIS. ...ITCZ... THE ITCZ AXIS IS ANALYZED FROM THE WESTERN AFRICAN COAST OF GUINEA-BISSAU NEAR 12N16W WESTWARD ALONG 10N20W 7N30W 10N40W 8N50W 10N60W. BESIDES THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION...WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 150 NM OFF THE COAST OF LIBERIA...SIERRA LEONE...GUINEA...AND GUINEA-BISSAU. SCATTERED MODERATE CONVECTION IS ELSEWHERE WITHIN 100 NM ON EITHER SIDE OF THE ITCZ AXIS. ...DISCUSSION... GULF OF MEXICO... MOST OF THE GULF OF MEXICO IS UNDER RELATIVELY DRY AND STABLE AIR ALOFT W OF 85W...WHICH IS KEEPING CONDITIONS IN THIS REGION MOSTLY FAIR THIS EVENING. HOWEVER...WATER VAPOR IMAGERY INDICATES A SHARP GRADIENT BETWEEN DRY/STABLE AIR ALOFT AND MOIST/UNSTABLE AIR ALOFT COVERING MOST OF THE FLORIDA PENINSULA REACHING DOWN SW TO THE YUCATAN CHANNEL. SURFACE OBS ACROSS FLORIDA SHOW STRONG SURFACE CONVERGENCE...SUPPORTED BY THE UPPER LEVEL FEATURE. IN ADDITION...COMPUTER MODEL DATA INDICATES STRONG DIFFLUENCE FLOW ALOFT IN THIS REGION AS WELL. THE SCENARIO LEADS TO A SURFACE TROUGH ANALYZED ACROSS FLORIDA... WESTERN CUBA...AND THE YUCATAN PENINSULA ALONG 30N81W 26N81W 22N82W 21N85W. SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS ARE WITHIN 100 NM ON EITHER SIDE OF THE SURFACE TROUGH. CARIBBEAN SEA... WATER VAPOR IMAGERY INDICATES A MID/UPPER LEVEL LOW MOVING W ACROSS THE SOUTHERN BAHAMAS. THIS FEATURE IS PRODUCING SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS OVER THE N CARIBBEAN N OF 17N...INCLUDING INLAND PORTIONS OF CUBA...JAMAICA... HISPANIOLA...AND PUERTO RICO. THE SAME WEATHER ACTIVITY IS OCCURRING OVER THE E CARIBBEAN E OF 70W DUE TO THE PASSAGE OF A TROPICAL WAVE CURRENTLY OVER THE LESSER ANTILLES S OF 15N. PART OF THE ITCZ CROSSES OVER CENTRAL AMERICA S OF 11N INCLUDING COSTA RICA AND PANAMA. IN ADDITION...A SURFACE 1008 MB LOW IS OVER NORTHERN COLOMBIA. THE COMBINATION OF THESE TWO FEATURES SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS OVER THE SW CARIBBEAN S OF 13N W OF 75W. ATLANTIC OCEAN... SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS ARE OVER THE FAR W ATLANTIC W OF 70W INCLUDING THE BAHAMAS...RELATED TO A SURFACE TROUGH ANALYZED OVER THE FLORIDA PENINSULA...SEE GULF OF MEXICO DISCUSSION ABOVE. FURTHERMORE...WATER VAPOR IMAGERY INDICATES A MID/UPPER LEVEL LOW MOVING W ACROSS THE SOUTHERN BAHAMAS NEAR 22N75W. THIS FEATURE IS PRODUCING SCATTERED SHOWERS AND THUNDERSTORMS OVER THE S BAHAMAS AND WITHIN 90 NM OFF THE N COAST OF HISPANIOLA AND FAR NE CUBA. STRONGER CONVECTION ASSOCIATED TO THIS MID/UPPER LEVEL LOW IS CURRENTLY OVER THE N CARIBBEAN...SEE CARIBBEAN SEA DISCUSSION ABOVE. ELSEWHERE ACROSS THE ATLANTIC E OF 70W N OF 20N...BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE COVERS THE REGION SUPPORTING A PAIR OF SURFACE 1028 MB HIGHS NEAR 34N58W AND 38N38W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA