000 AXNT20 KNHC 281738 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT MAY 28 2011 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 56W S OF 13N MOVING W NEAR 15 KT. WELL DEFINED CYCLONIC TURNING IN THE LOW LEVEL CLOUDS IS OBSERVED ON SATELLITE IMAGERY AND IS EMBEDDED WITHIN AN AREA OF DEEP LAYERED MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE WATER. ISOLATED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE WAVE BETWEEN 9N-13N. THIS WAVE IS APPROACHING THE WINDWARD ISLANDS AND COULD GIVE THE ISLANDS SHOWERS THIS EVENING. TROPICAL WAVE IS INLAND OVER VENEZUELA ALONG 64W/65W S OF 11N MOVING W NEAR 15 KT. THIS WAVE WILL REMAIN INLAND AND IS EMBEDDED WITHIN DRY STABLE AIR...THUS CURRENTLY IS NOT PRODUCING ANY SIGNIFICANT WEATHER. ...ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 10N12W 7N19W 5N27W 4N40W INTO SOUTH AMERICA NEAR 2N51W. CLUSTERS OF SCATTERED MODERATE/ ISOLATED STRONG CONVECTION ARE WITHIN 120/150 NM ON BOTH SIDES OF THE ITCZ BETWEEN 20W-48W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE EXTENDS FROM THE NW GULF TO OVER THE LOWER MISSISSIPPI VALLEY AND A HIGHLY AMPLIFIED UPPER TROUGH EXTENDS FROM THE NW ATLC ACROSS THE N BAHAMAS TO THE STRAITS OF FLORIDA AND THE N COAST OF CUBA NEAR HAVANA COVERING THE E GULF E OF 85W. THIS IS GIVING THE REMAINDER OF THE GULF NW WINDS ALOFT. DRY STABLE AIR REMAINS OVER MUCH OF THE GULF WHILE UPPER LEVEL MOISTURE IS BEING DRAWN S OVER THE E GULF BUT IS ONLY PRODUCING ISOLATED SHOWERS OVER FLORIDA BAY AND S FLORIDA LEAVING THE REMAINDER OF THE GULF UNDER FAIR CONDITIONS THIS AFTERNOON. A WEAK SURFACE RIDGE EXTENDS FROM THE W ATLC ACROSS THE FLORIDA PENINSULA TO 90W GIVING THE W GULF S RETURN FLOW SPREADING SMOKE FROM FIRES THAT CONTINUE OVER S MEXICO AND THE YUCATAN PENINSULA. SURFACE RIDGE IS EXPECTED TO SLOWLY STRENGTHEN AND LIFT N OF THE BASIN THROUGH MON NIGHT. CARIBBEAN SEA... THE UPPER TROUGH OVER THE W ATLC COVERING THE E GULF OF MEXICO DOES NOT EXTEND INTO THE NW CARIBBEAN BUT IS PRODUCING A WEAK JET STREAM WITH WINDS 70 TO 80 KTS FROM JUST N OF THE CAYMAN ISLANDS NEAR 20N82W ACROSS CUBA AND THE S BAHAMA ISLANDS TO 23N68W. THE UPPER FLOW FROM GULF OF MEXICO IS FORCING DRY STABLE AIR OVER THE NW CARIBBEAN W OF LINE FROM E CUBA TO THE GULF OF HONDURAS AND S BELIZE. THE REMAINDER OF THE CARIBBEAN IS DOMINATED BY AN UPPER RIDGE ANCHORED OVER W VENEZUELA. A SURFACE TROUGH IS DEVELOPING ACROSS THE SW CARIBBEAN AS INDICATED BY THE LATEST WINDSAT PASS EXTENDING FROM NEAR 13N74W TO PANAMA NEAR 9N81W AND WILL PLACED ON THE 28/1800 UTC MAP. SCATTERED/HEAVY SHOWERS WITH SCATTERED THUNDERSTORMS COVER THE AREA S OF 13N TO INLAND OVER COLOMBIA BETWEEN 72W-79W AND SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS DOT THE AREA S OF 13N BETWEEN 79W-84W. ISOLATED SHOWERS ARE POSSIBLE FROM 13N-17N BETWEEN 74W-85W LEAVING THE REMAINDER OF THE CARIBBEAN UNDER FAIR CONDITIONS THIS AFTERNOON. WINDS WILL INCREASE OVER THE CENTRAL AND E CARIBBEAN THIS AFTERNOON THROUGH WED BETWEEN DEVELOPING SURFACE TROUGH IN THE SW CARIBBEAN AND SURFACE RIDGE OVER THE W ATLC. THE TROPICAL WAVE ALONG 56W WILL MOVE ACROSS THE WINDWARD ISLANDS TONIGHT BRING SHOWERS TO THE ISLANDS THE EVENING. ATLANTIC OCEAN... A HIGHLY AMPLIFIED UPPER TROUGH EXTENDS FROM THE NW ATLC ACROSS THE N BAHAMAS TO THE STRAITS OF FLORIDA AND THE N COAST OF CUBA NEAR HAVANA COVERING THE W ATLC W OF 70W. THIS UPPER TROUGH COUPLED WITH AFTERNOON HEATING IS BEGINNING TO PRODUCE A BAND OF SCATTERED SHOWERS/THUNDERSTORMS WITHIN 75/90 NM OF LINE FROM 21N70W ACROSS THE TURKS AND CAICOS ALONG 22N75W THEN CONTINUING ALONG THE BAHAMA ISLANDS TO 27N79W THEN N TO BEYOND 32N78W. A BROAD UPPER TROUGH IS OVER THE N/CENTRAL ATLC N OF 28N BETWEEN 47W-60W SUPPORTING A PRIMARY 1015 MB SURFACE LOW NEAR 31N53W AND A SURFACE TROUGH EXTENDING SW ALONG 28N55W TO 25N58W. A SECOND 1014 MB LOW SURFACE LOW IS TO THE SW OF THE PRIMARY LOW NEAR 29N59W AND A THIRD 1013 MB LOW IS TO THE SE NEAR 24N51W. A SURFACE TROUGH..AS INDICATED BY A RECENT WINDSAT PASS...EXTENDS FROM THE 1013 MB LOW TO NEAR 21N60W. THIS SURFACE TROUGH WAS MASKED EARLIER ON THE 12 UTC MAP BY ABUNDANCE OF HIGH CLOUDS IN THE VICINITY AND WILL BE PLACED ON THE 28/1800 UTC MAP. AN UPPER RIDGE IS TO THE E OF THE ABOVE LOW PRESSURES EXTENDING FROM THE W TROPICAL NEAR 8N54W ALONG 20N41W THEN N TO BEYOND 32N42W PRODUCING DIFFLUENT ENVIRONMENT ALOFT TO GENERATING SCATTERED SHOWERS WITHIN 250/300 NM OF LINE FROM 17N50W ALONG 24N45W TO BEYOND 32N45W. A SURFACE RIDGE DOMINATES THE E ATLC N OF 17N BETWEEN 20W-45W ANCHORED BY A 1034 MB HIGH NW OF THE AZORES. AN UPPER TROUGH IS OVER THE FAR NE ATLC EXTENDING THROUGH 32N20W TO 26N27W SUPPORTING A 1014 MB LOW OFF THE COAST OF PORTUGAL WITH A SURFACE TROUGH EXTENDING TO 31N19W AND ANY SHOWER ACTIVITY N OF THE DISCUSSION AREA. THE SURFACE RIDGE OVER THE W ATLC WILL SHIFT N THROUGH SUN. NE WINDS WILL INCREASE SLIGHTLY BY MON BETWEEN THE RIDGE TO THE N AND A WEAK TROUGH OVER THE SE W ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW