000 AXNT20 KNHC 211801 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED JUL 21 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURES... AN AREA OF DISTURBED WEATHER REMAINS OVER AND N OF HISPANIOLA AND PUERTO RICO. A SURFACE TROUGH EXTENDS 25N67W SW ACROSS THE CENTRAL DOMINICAN REPUBLIC TO NEAR 18N70W. UNFAVORABLE UPPER- LEVEL WINDS AND THE EFFECTS OF THE HIGH TERRAIN OF HISPANIOLA HAVE DISRUPTED THE STRUCTURE OF THE DISTURBANCE THIS MORNING. THE AXIS OF THE DISTURBANCE IS APPROACHING THE SOUTHEASTERN BAHAMAS WITH MOST OF THE CLOUDINESS...SHOWERS AND GUSTY WINDS EXTENDING EASTWARD FOR SEVERAL HUNDRED MILES. THIS ACTIVITY WILL LIKELY SPREAD OVER THE BAHAMAS DURING THE NEXT DAY OR TWO AS THE DISTURBANCE MOVES GENERALLY WESTWARD AT 10-15 MPH. ALTHOUGH THE DISTURBANCE IS CURRENTLY DISORGANIZED AND DEVELOPMENT IS NOT ANTICIPATED TODAY...UPPER-LEVEL WINDS COULD BECOME A LITTLE MORE FAVORABLE ON THURSDAY. THERE IS A MEDIUM CHANCE...50 PERCENT ...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THE HEAVY RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES IN MOUNTAINOUS AREAS. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE TROPICAL ATLANTIC EXTENDING FROM 15N37W TO 5N34W MOVING W AT 8-10 KT. SCATTERED SHOWERS AND TSTMS ARE OCCURRING WITHIN 210 NM EITHER SIDE OF THE WAVE. THE WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM WHICH IS EVIDENT ON TOTAL PRECIPITABLE WATER IMAGERY. A TROPICAL WAVE IS OVER THE W CARIBBEAN EXTENDING FROM EASTERN CUBA TO NW COLOMBIA ALONG 76W/77W MOVING W AT 10-12 KT. SCATTERED MODERATE TO STRONG CONVECTION IS CONCENTRATED IN THE SW CARIBBEAN SEA NEAR THE SOUTHERN PORTION OF THE WAVE FROM THE COAST OF PANAMA-11N WITHIN 180 NM W OF THE WAVE AXIS. ELSEWHERE SCATTERED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE WAVE AXIS WITH ISOLATED TSTMS OCCURRING N OF 17N OVER JAMAICA AND SW OF HAITI. A TROPICAL WAVE THAT WAS IN THE W GULF OF MEXICO HAS DEGENERATED INTO A SURFACE TROUGH AS DESCRIBED BELOW IN THE GULF OF MEXICO SECTION. ...ITCZ... ITCZ AXIS IS ALONG 11N15W 9N18W 11N27W 09N34W 07N47W 10N61W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FROM 2N-9N BETWEEN 27W-33W AND FROM 10N-14N BETWEEN 56W-62W. ...DISCUSSION... GULF OF MEXICO... A TROPICAL WAVE THAT WAS PREVIOUSLY OVER THE W GULF OF MEXICO IS NOW A SURFACE TROUGH. NUMEROUS SHOWERS AND TSTMS ARE OCCURRING MAINLY W OF THE TROUGH AXIS EXTENDING ACROSS THE AREA FROM S OF SW LOUISIANA TO THE S CENTRAL BAY OF CAMPECHE. THE SURFACE TROUGH WILL MOVE W INTO EASTERN TEXAS AND MEXICO TONIGHT INTO EARLY THU. ADDITIONAL SCATTERED SHOWERS AND TSTMS ARE OCCURRING OVER THE MIDDLE AND E GULF N OF 25N MAINLY DUE UPPER LEVEL DIFFLUENCE E AND S OF AN UPPER LEVEL LOW POSITIONED IN THE NW GULF. EASTERLY 15-20 KT WINDS ARE IN THE SE GULF WITH PRIMARILY 10-15 KT ELSEWHERE. CARIBBEAN SEA... A TROPICAL WAVE IS IN THE W CARIBBEAN...SEE TROPICAL WAVE SECTION ABOVE. OTHERWISE SCATTERED SHOWERS AND TSTMS ARE OCCURRING IN THE NW CARIBBEAN AND GULF OF HONDURAS DUE TO AN UPPER LEVEL DISTURBANCE. NUMEROUS SHOWERS AND SCATTERED TSTMS ARE IN THE E CARIBBEAN WITH THE HEAVIEST ACTIVITY OVER THE LEEWARD ISLANDS WHERE VERY HEAVY RAINFALL IS OCCURRING. THIS PRECIPITATION IS BEING GENERATED BY AN UPPER LEVEL LOW POSITIONED NEAR 25N71W WITH AN UPPER LEVEL TROUGH EXTENDING OVER THE LEEWARD ISLANDS. EASTERLY WINDS OF 10-15 KT DOMINATE THE MAJORITY OF THE BASIN ALTHOUGH WILL INCREASE TO 15-20 KT OVER THE E CARIBBEAN LATE IN THE WEEK AS THE PRES GRADIENT WILL TIGHTEN. ATLANTIC OCEAN... AN AREA OF DISTURBED WEATHER IS N OF HISPANIOLA AND PUERTO RICO...SEE SPECIAL FEATURE SECTION ABOVE. OTHERWISE A SURFACE RIDGE IS CENTERED JUST N OF 31N STEMMING FROM 1025 MB HIGH PRES CENTERED NEAR 32N62W WITH EASTERLY WINDS OF 10-15 KT OVER THE NORTHERN PORTION OF THE ATLANTIC. A TIGHT PRES GRADIENT EXISTS N OF THE WINDWARD ISLANDS AND S OF 27N BETWEEN THE RIDGE AND THE AREA OF DISTURBED WEATHER WITH 20-30 KT WINDS AND SEAS OF 8-13 FT E OF THE BAHAMAS TO 64W. A TROUGH IS IN THE CENTRAL ATLANTIC EXTENDING FROM 30N41W TO 17N40W. THIS TROUGH FRACTURED OFF OF A TROPICAL WAVE THAT IS LOCATED SE-S OF THE TROUGH. SCATTERED SHOWERS ARE OCCURRING WITHIN 300 NM EITHER SIDE OF THE TROUGH AXIS. THIS FEATURE WILL WEAKEN DURING THE NEXT FEW DAYS AS IT ENCOUNTERS BUILDING HIGH PRES TO THE W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LEWITSKY