000 AXNT20 KNHC 082339 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED AUG 08 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... WEAK LOW AMPLITUDE TROPICAL WAVE IS ALONG 34W S OF 14N MOVING W 10-15 KT. THIS WAVE REMAINS DIFFICULT TO LOCATE DUE TO MULTIPLE LOW LEVEL SWIRLS IN THE VICINITY EMBEDDED WITHIN THE ITCZ. THE OVERALL LOW-LEVEL FLOW IS UNIFORM NELY N OF THE ITCZ AND THE UW-CIMSS TPW PRODUCT SHOWS ALMOST NO MOISTURE PERTURBATION IN THE AREA...THUS CURRENT PSN IS BASED MOSTLY ON FORWARD EXTRAPOLATION. ISOLATED SHOWERS AND TSTMS ARE CONFINED TO THE ITCZ. TROPICAL WAVE IS ALONG 53W/54W S OF 23N MOVING W 15-20 KT. THIS HIGH AMPLITUDE WAVE CONTINUES TO BE CLEARLY DEFINED ON THE UW-CIMSS TPW PRODUCT...ALTHOUGH IT'S CONSIDERABLY LESS MOIST THAN THE PREVIOUS FEW DAYS. A LOW-LEVEL CIRCULATION HAS BECOME EVIDENT ALONG THE AXIS...WITHIN THE ITCZ...NEAR 12N. THE REMAINDER OF THE WAVE HAS A SURGE-LIKE STRUCTURE WITH MINIMAL CONVECTION. TROPICAL WAVE IS ALONG 62W S OF 17N MOVING W 15-20 KT. DECIDED TO ADJUST THIS WAVE SLIGHTLY TO THE W BASED ON A SHIFT TO THE SE IN THE FLOW ACROSS THE SRN WINDWARDS. SCATTERED MODERATE CONVECTION HAS FLARED UP A BIT OVER THE PAST COUPLE OF HOURS TO THE E OF THE WAVE AXIS...SHEARED BY UPPER WLY WINDS...ACROSS THE ERN ISLANDS FROM 8N-14N BETWEEN 58W-62W. TROPICAL WAVE IS ALONG 81W S OF 19N MOVING W NEAR 15 KT. EXACT WAVE PSN REMAINS DIFFICULT TO LOCATE WITH CONVENTIONAL SATELLITE IMAGERY OR SFC OBS. THE TROUGHING FURTHER E MOVING THROUGH THE CENTRAL CARIB AND SW ATLC IS A MORE SIGNIFICANT FEATURE AT THE MOMENT. THERE CONTINUES TO BE SOME DEBATE ON WHETHER OR NOT THIS FEATURE IS A TROPICAL WAVE BUT HAVE MAINTAINED CONTINUITY ANALYZING IT AS A SFC TROUGH...AS IT IS DIFFICULT TO TELL IF THIS FEATURE ORIGINATED OVER AFRICA. THIS ANALYZED TROUGH...IS LIKELY A COMBINATION OF SFC TROUGHING ASSOCIATED WITH AN UPPER LOW...A PIECE/BRANCH OF A TROPICAL WAVE AND AN EASTERLY SURGE. MORE ON THIS FEATURE IN THE DISCUSSION SECTION BELOW. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 14N17W 11N33W 14N48W 12N61W. THE AXIS REMAINS VERY QUIET ACROSS THE ITCZ THIS EVENING WITH NO SIGNIFICANT CONVECTION ALONG THE AXIS OUTSIDE OF THE AREAS ASSOCIATED WITH THE TROPICAL WAVES. DISCUSSION... GULF OF MEXICO... FAIRLY QUIET WEATHER CONTINUES ACROSS THE GULF OF MEXICO AS A LARGE STRONG UPPER HIGH REMAINS PARKED OVER THE SOUTHEAST U.S. THIS SPRAWLING RIDGE HAS CONTRIBUTED TO THE VERY HOT WEATHER ACROSS THE SE/MID-ATLANTIC STATES. STRONG ELY UPPER FLOW...ON THE S SIDE OF THIS RIDGE...COVERS THE NRN PORTION OF THE GULF TRANSPORTING A MID-HIGH LEVEL CLOUD DECK ACROSS THE AREA E OF 87W. THE ATMOSPHERE DRIES OUT W OF THERE AS THE FLOW BECOMES CONFLUENT IN RESPONSE TO INVERTED TROUGHING OVER THE SW GULF. AT THE SFC...A 1018 MB HIGH HAS BEEN QUASI-STATIONARY S OF TEX/LA BORDER NEAR 28N93W. THIS CONTINUES TO PRODUCE FAIRLY LIGHT WINDS/LOW SEAS FOR THE GULF WHICH IS GENERALLY EXPECTED TO PERSIST OVER THE NEXT COUPLE OF DAYS. CARIBBEAN SEA... SCATTERED SHOWERS AND TSTMS ARE AFFECTING A GOOD PORTION OF THE CENTRAL AND E CARIB...ROUGHLY E OF 72W. THIS UNSETTLED WEATHER IS ASSOCIATED WITH A COMPLEX TROUGH OF LOW PRES...A TROPICAL WAVE MOVING THRU THE LESSER ANTILLES AND ELONGATED UPPER TROUGHING MOSTLY N OF THE AREA. THE SFC TROUGH AXIS IS ANALYZED ACROSS HAITI TO NRN VENEZUELA ALONG 20N72W 10N70W. SFC OBS AND EARLIER QSCAT AND ASCAT PASSES SUGGESTS CONSIDERABLY STRONGER WINDS E OF THIS AXIS. ALTHOUGH FURTHER DEVELOPMENT IS NOT EXPECTED...MODEL GUIDANCE SHOWS A FAIR AMOUNT OF MOISTURE SPREADING WWD ACROSS THE CARIB OVER THE NEXT COUPLE OF DAYS. FURTHER W...CLOUDINESS AND SCATTERED SHOWERS COVER MUCH OF THE AREA S OF 14N W OF 72W ASSOCIATED WITH DIFFLUENCE ALOFT AND THE ITCZ. CONDITIONS ARE TRANQUIL ACROSS THE NW CARIB...BESIDES FOR TYPICAL AFTERNOON LAND ACTIVITY AND DEBRIS SHOWERS OVER THE SEA. ATLANTIC OCEAN... THE REGION W OF 72W IS PRETTY QUIET UNDER STRONG NELY UPPER FLOW ON THE SE SIDE OF A SPRAWLING UPPER RIDGE OVER THE SE STATES. MORE ACTIVE WEATHER COVERS THE REGION BETWEEN 62W AND 72W ASSOCIATED WITH THE NRN PART OF THE CARIBBEAN INVERTED SFC TROUGH...WHICH EXTENDS N OF HAITI ALONG 20N72W 28N68W. IN ADDITION TO THE SFC SUPPORT AN ELONGATED UPPER TROUGH EXTENDS SW FROM 30N65W TO CENTRAL CUBA NEAR 22N80W. A FEW EMBEDDED WEAK UPPER LOWS ARE ALSO NOTED IN THIS EVENINGS WV IMAGERY. ALL OF THIS TROUGHINESS IS PLAYING A PART IN PRODUCING THE DISORGANIZED ACTIVITY LOCATED WITHIN 300 NM E OF THE SFC TROUGH AXIS. ELSEWHERE...UPPER RIDGING AND DRY STABLE AIR ALOFT GENERALLY DOMINATES THE MAJORITY OF THE PATTERN IN THE E ATLC EXCEPT FOR A WELL DEFINED UPPER LOW NEAR MADEIRA ISLAND. SW FLOW AHEAD OF THIS SYSTEM IS SHEARING A TROPICAL WAVE APPROACHING THE AFRICAN COAST SPREADING MOISTURE NEWD ACROSS THE NW PART OF THE CONTINENT. THE REMAINDER OF THE SFC PATTERN IS DOMINATED BY A 1028 MB HIGH NEAR 38N35W. THIS IS PRODUCING WIDESPREAD FAIR WEATHER AND MODERATE TRADES N OF 15N E OF 45W. NE WINDS REMAIN A LITTLE STRONGER ALONG THE COAST OF NW AFRICA WHERE THE HIGH INTERACTS WITH THERMAL TROUGHING OVER AFRICA...BUT THESE WINDS ARE NOT AS STRONG AS IT HAS BEEN OVER THE LAST COUPLE OF DAYS. $$ CANGIALOSI