000 AXNT20 KNHC 301728 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED MAY 30 2007 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS LOCATED ALONG 32W S OF 9N MOVING W ABOUT 15 KT. THERE IS A HINT OF LOW TO MID LEVEL SIGNATURE ASSOCIATED WITH THIS WEAK LOW-LATITUDE FEATURE THAT MOVED OFF THE AFRICAN COAST ABOUT 3 DAYS AGO. THEREFORE...THE PSN IS BASED MOSTLY ON THIS CLOUD STRUCTURE WHICH MATCHED UP WELL WITH CONTINUITY. CONVECTION IS FAIRLY LINEAR AND APPEARS MAINLY ASSOCIATED WITH THE ITCZ. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 4N22W 4N30W 5N35W 5N52W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM N OF THE AXIS BETWEEN 19W-27W...34W-41W...AND W OF 46W. SIMILAR ACTIVITY IS WITHIN 120 NM S OF THE AXIS E OF 14W. ...DISCUSSION... THE GULF OF MEXICO... PRONOUNCED UPPER TROUGHING COVERS THE MAJORITY OF THE GULF EXTENDING SWD FROM THE ROCKIES TOWARD THE YUCATAN PENINSULA. THE COMBINATION OF UPPER DIFFLUENCE TO THE E OF THE TROUGH AXIS AND LOW TO MID LEVEL CONVERGENCE NEAR A LOW LEVEL TROUGH BOUNDARY ALONG 87W S OF 23N IS FUELING SCATTERED TO NUMEROUS SHOWERS AND TSTMS S OF 25N BETWEEN 83W-88W. IR IMAGES AND LIGHTNING DATA SUGGEST THAT THE ASSOCIATED MORE ACTIVE WEATHER IS IN THE NW CARIB. RELATIVELY QUIET CONDITIONS...PATCHY MID-HIGH LEVEL CLOUDS...EXIST ELSEWHERE. AT THE SFC...A 1023 MB HIGH PRES IS CENTERED OVER NE GEORGIA. THE TIGHTENED PRES GRADIENT BETWEEN THE HIGH AND TROUGH NEAR THE YUCATAN CHANNEL IS PICKING UP ELY WINDS TO 20-25 KT IN THE FL STRAITS AND 15-20 KT ELSEWHERE IN THE E GULF. THESE WINDS LIGHTEN AND VEER TO THE S/SE IN THE W GULF ON THE W PERIPHERY OF THE RIDGE. LOOKING AHEAD A DAY OR TWO...THE MAIN FEATURE OF INTEREST IS THE LOW-LEVEL TROUGH MENTIONED. SEVERAL COMPUTER MODELS SHOW THIS FEATURE MOVING NE INCREASING WINDS AND PULLING TROPICAL MOISTURE ACROSS THE E GULF. THE CARIBBEAN SEA... SCATTERED SHOWERS AND TSTMS PERSIST ACROSS THE W CARIB NAMELY W OF 81W...WITH THE GREATEST AREA OF CONVECTION APPROACHING THE WRN TIP OF CUBA FROM THE SW. THIS MOISTURE IS ASSOCIATED WITH A LOW-LEVEL TROUGH WHICH RUNS FROM NICARAGUA TO THE YUCATAN CHANNEL CONTINUING INTO THE SE GULF. VIS IMAGES DISPLAY A BROAD ENVELOPE OF CYCLONIC TURNING IN THE LOW LEVELS...ALTHOUGH QSCAT AND SFC OBS LIKELY INDICATE THAT THE MORE SUBSTANTIAL AMPLITUDE IS OFF THE SFC. ASSOCIATED ISOLATED TSTMS EXTEND FURTHER E BETWEEN 74W AND 81W MAINLY S OF JAMAICA. FARTHER E...THE TAIL END OF AN ATLC SFC TROUGH EXTENDS JUST N OF HISPANIOLA. UPPER DIFFLUENCE TO THE E OF THIS BOUNDARY IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS S OF PUERTO RICO AND ACROSS THE VIRGIN ISLANDS AS DEPICTED ON DOPPLER RADAR FROM SAN JUAN. A WEDGE OF DRY STABLE AIR ALOFT EXTENDS ACROSS THE WINDWARD ISLANDS TO NEAR 15N71W PROVIDING FAIR WEATHER FOR THE SE PORTION OF THE CARIB SEA. LOOKING AHEAD...COMPUTER MODELS SUGGEST THAT A FAIR AMOUNT OF MOISTURE WILL REMAIN IN THE W CARIB OVER THE NEXT FEW DAYS AS THE TROUGH SLOWLY PUSHES NE. THE ATLANTIC OCEAN... A DEEP LAYER TROUGH COVERS MUCH OF THE W ATLC EXTENDING FROM BERMUDA TO THE SE BAHAMAS. PLENTY OF DRY AIR ALOFT COVERS THE REGION N OF 23N W OF 62W KEEPING THE REGION WITH ONLY SCATTERED LOW-LEVEL STRATOCUMULUS CLOUDS. THIS UPPER TROUGH IS PROVIDING SUPPORT FOR TWO SFC BOUNDARIES. ONE IS ANALYZED AS A TROUGH...LACKING THERMAL STRUCTURE...EXTENDING ALONG 32N58W 22N64W TOWARD HISPANIOLA. LIFT ALONG AND E OF THE BOUNDARY ALONG WITH DIFFLUENCE ALOFT IS PRODUCING SCATTERED SHOWERS AND TSTMS BETWEEN 53W-63W. THE OTHER SFC FEATURE IS A BACK DOOR TYPE COLD FRONT WHICH IS ANALYZED FROM BERMUDA TO THE CAROLINAS. THIS FEATURE IS MARKED BY THIN LOW CLOUDS AND A SURGE IN THE NLY FLOW. THE REMAINDER OF THE REGION IS DOMINATED BY A 1027 MB HIGH NEAR 33N31W. THIS HIGH PRES SYSTEM IS SUPPLYING FAIR WEATHER AND MODERATE TRADES ACROSS THE TROPICS. IN THE MID AND UPPER LEVELS...AN ELONGATED TROUGH/RIDGE PATTERN HAS SET UP BUT OVERALL LITTLE WEATHER IS BEING PRODUCED BY THESE UPPER FEATURES. $$ JC