000 AXNT20 KNHC 202346 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE MAY 20 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 18W/19W S OF 12N MOVING W 15 KT. SATELLITE IMAGERY SHOWS BROAD LOW-MID LEVEL CYCLONIC TURNING FOCUSED ALONG THE AXIS NEAR 7N. SCATTERED SHOWERS ARE WITHIN 120 NM W OF THE AXIS FROM 8N-11N EMBEDDED WITHIN THE ITCZ. ALSO MIMIC TPW ANIMATION FROM CIMSS SHOWS NORTHERN MOISTURE SURGE COMING OFF THE W AFRICAN COAST DURING THE PREVIOUS 12 HOURS. TROPICAL WAVE IS ALONG 49W S OF 11N MOVING W 10-15 KT. SCATTERED SHOWERS AND TSTMS COVER A FAIRLY LARGE 420 NM AREA EITHER SIDE OF THE AXIS FROM 2N-7N...ENHANCED BY A LARGE AMPLITUDE UPPER TROUGH. THE GFS MODEL GUIDANCE CONTINUES TO SHOW VERY SLIGHT LOWER LEVEL CYCLONIC CURVATURE WITH MOST PRECIPITATION EMBEDDED WITHIN THE ITCZ. TROPICAL WAVE IS ALONG 74W S OF 13N ESTIMATED TO BE MOVING W 10-15 KT. POSITION IS BASED ON A WESTWARD MOISTURE SURGE EVIDENT ON THE MIMIC TPW ANIMATION AND FITS WELL WITH LONG TERM CONTINUITY. REGARDLESS OF THE EXACT LOCATION... THE WAVE REMAINS WEAK AND IS ENHANCING SCATTERED MODERATE/ISOLATED STRONG CONVECTION ACROSS CENTRAL COLOMBIA AND PORTIONS OF COASTAL N COLOMBIA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N10W 7N17W 6N20W 1N35W 4N46W AND INTO NE BRAZIL NEAR 4N52W. SCATTERED MODERATE CONVECTION IS FROM 5N-8N BETWEEN 10W-15W. SIMILAR CONVECTION IS WITHIN 120-150 NM ON EITHER SIDE OF THE AXIS BETWEEN 39W-52W. ...DISCUSSION... GULF OF MEXICO... STRONG SW TO W FLOW ALOFT LIES OVER THE REGION MOISTENING THE MID AND UPPER LEVELS. THIS UPPER REGIME IN COMBINATION WITH A LINGERING SURFACE TROUGH FROM N FLORIDA TO 25N88W IS TRIGGERING SCATTERED SHOWERS AND TSTMS FROM VERO BEACH FLORIDA TO N OF FORT MYERS AND INTO THE E GULF NEAR 26N84W. ELSEWHERE ACROSS THE GULF AS THE AFOREMENTIONED SURFACE TROUGH CONTINUES TO WEAKEN DURING THE NEXT 12 TO 24 HOURS...SOUTHERLY SURFACE FLOW IS EXPECTED TO RETURN OVER MUCH OF THE GULF. CARIBBEAN SEA... A 1010 MB SURFACE LOW PRESSURE IS CENTERED NEAR 9N81W OFFSHORE OF W PANAMA. MUCH OF THE AFTERNOON CONVECTION ASSOCIATED WITH THE LOW IN THE SW CARIBBEAN SEA HAS DISSIPATED WITH ONLY SCATTERED SHOWERS AND TSTMS REMAINING ACROSS INLAND COSTA RICA AND NICARAGUA. A SUBSIDENT ENVIRONMENT IS IN PLACE ACROSS MUCH OF THE REMAINDER OF THE CARIBBEAN SEA WITH A VERY BROAD MID-UPPER LEVEL RIDGE CENTERED NEAR 15N71W...ALLOWING FAIR WEATHER TO DOMINATE. EASTERLY TRADES OF 10-15 KT ARE BLOWING OVER THE BASIN AND THIS IS EXPECTED TO CHANGE LITTLE DURING THE NEXT 24 HOURS. ATLANTIC OCEAN... BROAD UPPER TROUGH COVERS THE E US AND NW ATLC WITH THE ASSOCIATED FRONT WELL NORTH OF THE AREA. BROAD UPPER RIDGE COVERS THE W ATLC INTO THE CENTRAL ATLC W OF 45W ANCHORED IN THE CARIBBEAN WITH THE AXIS EXTENDING ACROSS E CUBA TO BEYOND 32N45W. BROAD UPPER TROUGH COVERS THE REMAINDER OF THE CENTRAL ATLC TO THE E ATLC N OF 10N BETWEEN 23W-45W. A SURFACE RIDGE DOMINATES THE ATLC N OF 15N E OF 73W ANCHORED BY A 1021 MB HIGH CENTERED NEAR 27N53W AND A SIMILAR HIGH CENTERED S OF THE AZORES NEAR 33N27W. ONLY SIGNIFICANT PRECIPITATION TO NOTE IS WITH WEAKENING SURFACE TROUGH ACROSS CENTRAL FLORIDA THAT IS PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS OFFSHORE OF CENTRAL FLORIDA AND N OF THE BAHAMAS IN THE W ATLC. $$ HUFFMAN/WALTON