000 AXNT20 KNHC 301049 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT MON JUL 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURE... SURFACE TROUGH IS ALONG 35N74W 32N70W 28N67W. SYSTEM REMAINS POORLY ORGANIZED WITH SEVERAL LOW LEVEL CIRCULATIONS ALONG THE TROUGH. THIS TROUGH STILL HAS SOME POTENTIAL FOR TROPICAL OR SUBTROPICAL DEVELOPMENT OVER THE NEXT COUPLE OF DAYS AS IT MOVES NORTH-NORTHEASTWARD AT 10-15 KT. CLUSTERS OF SCATTERED MODERATE ISOLATED STRONG CONVECTION WERE NOTED WITHIN 90 NM E OF THE SURFACE TROUGH AXIS AND ARE SPREADING OVER BERMUDA AND SHOULD IMPACT THE WEATHER OVER THE ISLAND FOR THE NEXT 6 HOURS OR SO. ...TROPICAL WAVES... TROPICAL WAVE OVER THE E ATLC ALONG 27W EXTENDS FROM 4N TO 19N AND IS MOVING W AT 10 KT. A 1009 MB SURFACE LOW WAS NOTED ALONG THE WAVE AXIS NEAR 11N. SCATTERED MODERATE ISOLATED STRONG CONVECTION REMAINED CONFINED TO THE INTERSECTION OF THE WAVE AXIS AND THE ITCZ BETWEEN 27W AND 35W. TROPICAL WAVE IS OVER THE CENTRAL ATLC EARLIER ALONG 50W WAS RELOCATED TO THE EAST ALONG 48W/49W BASED ON FORWARD EXTRAPOLATION OF SATELLITE HOVMOELLER ANALYSES. AN EXPANDING AREA OF SCATTERED MODERATE TO STRONG CONVECTION WAS OCCURRING AT THE BASE OF THE WAVE FROM 8N TO 11N BETWEEN 44W AND 50W. RATHER WELL DEFINED LOW TO MID LEVEL TURNING WAS NOTED NEAR 9N45W AROUND WHAT MAY BE A POSSIBLE AREA OF LOW PRESSURE. TROPICAL WAVE IS OVER THE FAR EASTERN CARIBBEAN TILTED FROM 22N63W TO 10N65W INLAND OVER SOUTH AMERICA NEAR 4N66W MOVING W NEAR 15-20 KT. BROAD LOW TO MID LEVEL TURNING NOTED ALONG THE NORTHERN PORTION WAVE AXIS JUST N OF THE LESSER ANTILLES FROM 60W-65W. SCATTERED SHOWERS ARE MOVING ACROSS THE LESSER ANTILLES WITH ISOLATED THUNDERSTORMS DEVELOPING AT THE NORTHERN END OF THE WAVE AXIS. FAR NORTHERN EXTENT OF TROPICAL WAVE IS OVER THE BAY OF CAMPECHE ACROSS MEXICO INTO THE E PACIFIC REGION ALONG 95W MOVING W NEAR 15 KT. WELL DEFINED LOW LEVEL CYCLONIC CIRCULATION IS NOTED OVER THE EAST PACIFIC WELL SOUTH OF THE GULF OF TEHUANTEPEC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 15N17W 12N26W 8N34W 11N43W 9N55W 10N61W. EXCEPT AS NOTED ABOVE IN ASSOCIATION WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS WITHIN 60-90 NM OF THE AXIS BETWEEN 35W AND 44W...AND ALONG THE COAST OF SURINAME AND FRENCH GUINEA. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL RIDGE AXIS EXTENDS FROM NE MEXICO ALONG THE TEXAS COAST THEN EWD ACROSS THE GULF COAST FROM SW LOUISIANA TO THE FLORIDA PANHANDLE WITH EMBEDDED ANTICYCLONES OVER SE TEXAS AND SOUTHERN MISSISSIPPI. A FRACTURING UPPER TROUGH EXTENDS OFF THE SE COAST AND CUTS ACROSS EXTREME SOUTH FLORIDA TO SMALL MID/UPPER LEVEL CYCLONIC CIRCULATIONS NEAR 25N89W AND 25N93W. THE CYCLONIC CIRCULATIONS WERE UNDERCUTTING THE RIDGE AS THEY MOVED W 10-15 KT. DESPITE THE PRESENCE OF THE FEATURES UPPER FLOW WAS NELY OVER MOST OF THE GULF...BECOMING INCREASINGLY DIFFLUENT OVER THE NE GULF TOWARD THE FLORIDA PANHANDLE. THE GULF WAS VIRTUALLY FREE OF CONVECTION ALTHOUGH WIDELY SCATTERED TSTMS EMBEDDED WITHIN MID LEVEL CLOUD DEBRIS WERE NOTED OVER THE EXTREME NE GULF S OF THE FLORIDA PANHANDLE. AT THE SURFACE...WEAK RIDGE EXTENDS FROM THE W ATLC ACROSS THE FLORIDA STRAITS THEN NORTHWESTWARD TO THE UPPER TEXAS COAST. CARIBBEAN... A WEAK SHEAR AXIS SLICED ACROSS THE EXTREME NW PORTION OF THE CARIBBEAN EXTENDING FROM A TINY CIRCULATION OVER ERN CUBA NEAR THE WINDWARD PASSAGE WESTWARD ALONG 20N. NELY UPPER FLOW WAS N OF THE AXIS AND WAS ADVECTING MID LEVEL CLOUD DEBRIS OVER THE FAR NW CORNER OF THE CARIBBEAN. A SMALL UPPER LEVEL RIDGE EXTENDS FROM COLOMBIA NEAR 10N75W NW TO 17N83W ESSENTIALLY DOMINATING THE FLOW OVER THE REMAINDER OF THE W CARIBBEAN W OF 75W. MID TO UPPER LEVEL EASTERLY FLOW AMIDST STRONG SUBSIDENCE COVERS THE REMAINDER OF THE CARIBBEAN. SUBSIDENCE REGION WAS SUPPRESSING CONVECTIVE DEVELOPMENT ALONG THE TROPICAL WAVE ENTERING THE FAR E CARIBBEAN. ITCZ EXTENDS FROM COLOMBIA ACROSS PANAMA AND COSTA RICA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER NW COLOMBIA AND PANAMA. ATLANTIC... REFER TO THE SPECIAL FEATURES SECTION ABOVE FOR THE SURFACE TROUGH LOCATED OVER THE NW ATLANTIC. AT THE UPPER LEVELS A NEGATIVELY TILTED TROUGH EXTENDS FROM THE MID-ATLANTIC STATES SE THROUGH 32N72W THEN TURNS SWWD ALONG 30N74W AND FRACTURING THROUGH THE BAHAMAS ACROSS S FLORIDA. FURTHER E...UPPER LEVEL ANTICYCLONES NEAR 24N65W AND 20N56W DOMINATE THE FLOW REGIME OVER THE ATLANTIC W OF 50W. A WEAK SHEAR AXIS WAS NOTED BETWEEN THE TWO ANTICYCLONES ALONG 31N55W 21N61W. ANOTHER MORE PRONOUNCED TROUGH EXTENDS FROM A CYCLONIC CIRCULATION NEAR 30N46W SWD TO 20N48W. AN EXTENSIVE UPPER LEVEL ANTICYCLONE OVER SOUTHERN MOROCCO NEAR 29N8W AND COVERED THE AREA E OF 30W WITH MODERATE ELY FLOW. LATEST CIMSS SAL ANALYSIS INDICATES AFRICAN DUST COVERS THE ATLC E OF 40W AND IS BEING DRAWN INTO THE CIRCULATION ASSOCIATED WITH THE TROPICAL WAVE ALONG 27W THEREBY SUPPRESSING DEEP CONVECTION ALONG THE WAVE AXIS ITSELF. AT THE SURFACE...A SURFACE RIDGE E OF 70W ANCHORED BY A 1023 MB HIGH NEAR 35N55W DOMINATE THE ATLANTIC WITH ONLY SCATTERED TO BROKEN STABLE STRATOCUMULUS. $$ COBB