000 AXNT20 KNHC 262331 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU JUL 26 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... TROPICAL WAVE TILTED ALONG 7N31W 16N27W MOVING W 10 KT. A SMALL LOW-LEVEL CYCLONIC CIRCULATION IS NOTED IN SATELLITE IMAGERY ALONG THE WAVE AXIS NEAR 14N30W...AND THIS IS THE FOCUS OF A RECENT BLOW-UP OF CONVECTION. SCATTERED MODERATE CONVECTION FROM 10N-16N BETWEEN 30W-33W. TROPICAL WAVE TILTED ALONG 5N45W 10N45W 15N42W MOVING W 10 KT. SATELLITE IMAGERY INDICATED A SMALL-SCALE SURFACE LOW ALONG THE WAVE NEAR 10N45W AND THIS WAS CONFIRMED BY A WESTERLY WIND OF 15 KT FROM SHIP A8IY6 AT 18Z JUST S OF THE LOW. SCATTERED MODERATE CONVECTION FROM 8N-13N BETWEEN 44W-49W. CENTRAL CARIBBEAN TROPICAL WAVE ALONG 73W S OF 18N MOVING W 20-25 KT. THE WAVE WAS OBSERVED IN UPPER AIR DATA PASSING SAN JUAN PUERTO RICO BETWEEN 00Z AND 12Z EARLIER TODAY...AND LIKELY PASSING CURACAO NEAR 12Z THIS MORNING. THE WAVE IS PLACED ALONG 73W BY EXTRAPOLATION AND ACCORDING TO A SMALL CLUSTER OF SCATTERED MODERATE CONVECTION S OF HAITI FROM 15N-17N BETWEEN 70W-74W. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 10N13W 9N18W 14N27W 13N40W 9N54W 10N62W. A LARGE TROPICAL WAVE MOVING THROUGH W AFRICA NEAR 10W IS PRODUCING STRONG LOW-LEVEL CONVERGENCE ALONG THE AFRICAN COAST...AND RESULTING IN SCATTERED MODERATE CONVECTION WITHIN 120 NM OF THE COAST BETWEEN THE IVORY COAST AND GUINEA-BISSAU. SCATTERED MODERATE UP TO 180 NM S OF AXIS BETWEEN 17W-22W. ISOLATED SHOWERS/TSTMS FROM 5N-14N BETWEEN 35W-42W. ...DISCUSSION... GULF OF MEXICO... WIDESPREAD SHOWERS/TSTMS CONTINUE TO DEVELOP OVER THE NW AND N/CENTRAL GULF AND MOVE N INTO SE TEXAS AND LOUISIANA. A SURFACE TROUGH HAS BECOME INCREASINGLY APPARENT IN SATELLITE AND RADAR IMAGERY AS WELL AS FROM THE COASTAL BUOYS E OF TEXAS...AND LIES OVER THE EXTREME W GULF FROM 28N95W TO 22N96W. THE UPPER LEVEL ENVIRONMENT IS FAVORABLE FOR CONTINUED CONVECTIVE DEVELOPMENT WITH DIFFLUENCE LYING BETWEEN AN UPPER LOW OVER THE RIO GRANDE VALLEY AND AN UPPER HIGH OVER THE BAY OF CAMPECHE. HOWEVER... THERE ARE NO INDICATIONS THAT THE SYSTEM WILL DEVELOP SINCE SURFACE PRESSURES ARE NOT CURRENTLY FALLING. DEEP SOUTHERLY FLOW CONTINUES TO ADVECT TROPICAL MOISTURE INLAND ACROSS E TEXAS AND LOUISIANA...WITH PRECIPITABLE WATER VALUES UP TO 2.25" ACCORDING TO MICROWAVE IMAGERY AND SOUNDINGS FROM BROWNSVILLE...CORPUS CHRISTI...AND LAKE CHARLES. THE DEPTH OF THE ONSHORE SOUTHERLY FLOW IS EXPECTED TO BECOME SHALLOWER OVER THE NEXT FEW DAYS WHICH COULD DECREASE THE AMOUNT OF CONVECTION THAT WILL AFFECT THE AREA. CARIBBEAN SEA... MOST OF THE CARIBBEAN BASIN IS UNDER A DRY REGIME WITH WATER VAPOR AND MICROWAVE IMAGERY SHOWING LOWER MOISTURE VALUES EXTENDING W ACROSS THE LESSER ANTILLES TO THE COAST OF NICARAGUA. A FAST-MOVING TROPICAL WAVE...PAIRED WITH AN INVERTED UPPER TROUGH ALONG 77W...IS PRODUCING A SMALL CLUSTER OF TSTMS S OF HAITI. ALSO...LOW-LEVEL SPEED CONVERGENCE OF THE WINDS N OF PANAMA HAVE LED TO THE DEVELOPMENT OF SCATTERED MODERATE/STRONG CONVECTION FROM 9N-12N BETWEEN 78W-83W. ELSEWHERE...A BROAD UPPER HIGH OVER THE BAY OF CAMPECHE IS ADVECTING THE LAST BIT OF DEEP MOISTURE OVER THE W CARIBBEAN WWD INTO CENTRAL AMERICA AND THE PACIFIC WITH MOST OF THE DEEP CONVECTION LOCATED OVER THE YUCATAN PENINSULA AND HONDURAS/NICARAGUA. ATLANTIC OCEAN... THE LOW-LEVEL SUBTROPICAL RIDGE IS LOCATED N OF THE AREA ALONG 35N AND IS PRODUCING MAINLY WEAK TRADES ACROSS THE TROPICAL AND SUBTROPICAL ATLC. THE RIDGE IS ESPECIALLY WEAK OVER THE W ATLC DUE TO THE CLOSED MID/UPPER LOW OVER THE GREAT LAKES AND A SECOND CLOSED LOW OVER THE CENTRAL ATLC NEAR 32N56W. A WEAK SURFACE TROUGH IS LOCATED NE OF THE BAHAMAS FROM 29N72W SW TO GRAND BAHAMA ISLAND AND UPPER DIFFLUENCE IN THE AREA HAS SPARKED SCATTERED MODERATE CONVECTION FROM 24N-28N BETWEEN 70W-75W. THE EASTERN UPPER LOW IS ALSO PRODUCING AN AREA OF SCATTERED MODERATE CONVECTION FROM 24N-32N BETWEEN 54W-61W. OVER THE E ATLC...A FAR-REACHING UPPER RIDGE AXIS EXTENDS FROM MOROCCO SW TO 23N40W THEN TO THE WINDWARD ISLANDS WITH DEEP EASTERLY FLOW LYING S OF THAT OVER THE TROPICS. MODERATE SUBSIDENCE N OF 20N E OF 50W IS KEEPING THINGS MOSTLY DRY OVER THE SUBTROPICS. IN THE TROPICS...LOW-LEVEL CROSS-EQUATORIAL SOUTHERLY FLOW HAS PUSHED THE ITCZ NWD TO BETWEEN 12N-14N FOR THE TIME BEING. HOWEVER...THE LARGE CIRCULATION OF A VIGOROUS TROPICAL WAVE OVER W AFRICA APPEARS TO BE CHANGING THIS PATTERN WITH STRONGER NORTHERLIES DEVELOPING OFF THE COAST...AND THE ITCZ IS PLUNGING S TO ABOUT 8N INTO SIERRA LEONE AND LIBERIA. $$ BERG