000 AXNT20 KNHC 251750 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI JUL 25 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND 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 STRONG TROPICAL WAVE IS ALONG 40W/41W S OF 23N. SHOWER ACTIVITY HAS INCREASED SINCE YESTERDAY JUST NORTH THE 1012 SFC LOW THAT REMAINS ASSOCIATED WITH THE WAVE NEAR 17N. ALTHOUGH UPPER-LEVEL WINDS ARE CURRENTLY NOT FAVORABLE FOR DEVELOPMENT... THE WAVE MAY MOVE INTO AN ENVIRONMENT MORE CONDUCIVE FOR ORGANIZATION IN A COUPLE OF DAYS. THE SYSTEM IS EXPECTED TO MOVE TO THE WEST-NORTHWEST OR NORTHWEST AT 15 TO 20 MPH DURING THE NEXT DAY OR TWO. TIGHT PRESSURE GRADIENT BETWEEN THE LOW AND THE ATLC SURFACE HIGH WILL PRODUCE AN INCREASE IN WINDS ACROSS THE CENTRAL ATLC THROUGH THE WEEKEND. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 120 NM NW OF THE LOW CENTER. A TROPICAL WAVE IS MOVING WWW NEAR 15 KT ACROSS THE E CARIBBEAN SEA. ITS AXIS IS ALONG 64W AND EXTENDS FROM THE N LEEWARD ISLANDS TO NE VENEZUELA. THE WAVE IS BENEATH STRONG TO MODERATE SUBSIDENCE/DRY AIR ALOFT WITH SCATTERED MODERATE CONVECTION ACROSS NWRN GUYANA AND NERN VENEZUELA. MAINLY LOW TOPPED SHOWERS ARE RELATED TO THE WAVE THAT SHOWS A WEAK INVERTED-V LOW LEVEL SIGNATURE. A TROPICAL WAVE IS OVER CENTRAL AMERICA ALONG 89W S OF 17N MOVING W NEAR 10 KT. THIS SYSTEM IS GENERATING SOME SHOWER ACTIVITY OVER BELIZE AND NORTHERN GUATEMALA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N17W 9N24W 12N35W 10N45W 7N58W. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE BETWEEN 11N-15N E OF 20W TO THE AFRICAN COAST. THIS CONVECTIVE ACTIVITY SEEMS TO BE ASSOCIATED WITH A TROPICAL WAVE CURRENTLY EMERGING FROM WEST AFRICA. LATEST OBSERVATIONS FROM DAKAR WITH SOUTH WINDS SUGGEST THAT THE WAVE HAS JUST CROSSED THE AREA. THIS WAVE WILL BE ADDED TO THE 18Z SFC MAP. IN ADDITION...THE HOVMOLLER DIAGRAM HAS DEPICTED THE WESTWARD MOVEMENT OF THESE SHOWER/TSTM ACTIVITY OVER THE PAST COUPLE OF DAYS. SCATTERED SHOWERS ARE WHERE THE TROPICAL WAVE ALONG 41W MEETS THE ITCZ. SCATTRED MODERATE CONVECTION IS ALONG THE COAST AND N PORTION OF GUYANA. I ...DISCUSSION... GULF OF MEXICO... TROPICAL DEPRESSION DOLLY IS STILL GENERATING LOCALLY HEAVY RAIN OVER PORTIONS OF SOUTH TEXAS AND NE MEXICO. AT 24/1500 UTC...IT WAS LOCATED NEAR THE TEXAS/MEXICO BORDER...JUST TO THE SOUTH OF THE TEXAS BIG BEND NEAR LATITUDE 29.2 NORTH...LONGITUDE 104.4 WEST. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WINDS ARE 25 KT WITH GUSTS TO 35 KT. THE DEPRESSION IS MOVING WEST-NORTHWEST AT 12 MPH AND IS FORECAST TO DEGENERATE INTO A SURFACE TROUGH LATER TODAY. SO FAR...THE STORM TOTAL RAINFALL AMOUNTS ARE BETWEEN 6 AND 12 INCHES. THE GULF IN UNDER THE INFLUENCE OF A SURFACE RIDGE WITH A 1020 MB HIGH LOCATED OVER THE NE CORNER OF THE ARE NEAR 28N86W. MODERATE TO FRESH SE WINDS ARE NOW BLOWING ACROSS THE WRN GULF BUT WILL DIMINISH TONIGHT AS HIGH PRES BUILDS W ACROSS NRN GULF WATERS. MAINLY LIGHT AND VARIABLE WINDS DOMINATES THE EASTERN GULF. ALOFT...AN UPPER ANTICYCLONE ANCHORED OVER E TEXAS IS PRODUCING NE TO E WINDS OVER THE N GULF WATERS. THIS IS AIDING IN GENERATING SCATTERED SHOWERS WITH EMBEDDED TSTMS ACROSS THE NE PORTION OF THE GULF. AN UPPER-LEVEL LOW CURRENTLY SPINNING OVER SOUTH FLORIDA IS GENERATING SCATTRED SHOWERS AND TSTMS. THIS ACTIVITY IS ALSO AFFECTING THE STRAITS OF FLORIDA AND THE KEYS. CARIBBEAN SEA... AN UPPER-LEVEL TROUGH EXTENDS FROM SOUTH FLORIDA ACROSS W CUBA AND THE YUCATAN PENINSULA. AN UPPER LOW IS EMBEDDED IN THIS TROUGH GENERATING SCATTERED SHOWERS AND TSTMS OVER SOUTH FLORIDA...THE NW BAHAMAS AND WESTERN CUBA. AN UPPER-LEVEL HIGH SITUATED JUST SOUTH OF HAITI DOMINATES THE REMAINDER OF THE BASIN WITH MODERATE TO STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS. S-SW FLOW BETWEEN THE ABOVE MENTIONED UPPER LEVEL FEATURES IS DRAWING SUFFICIENT UPPER LEVEL MOISTURE FROM THE E PACIFIC REGION INTO THE W CARIBBEAN SEA ACROSS E-CENTRAL CUBA AND THE BAHAMA ISLANDS. A TROPICAL WAVE IS MOVING WESTWARD ACROSS THE E CARIBBEAN. SEE TROPICAL WAVE SECTION. MODERATE TO STRONG TRADE WINDS OF 20 TO 30 KT ARE NOTED ACROSS THE SOUTH-CENTRAL CARIBBEAN. AN EARLIER QSCAT PASS CONFIRMED THESE WINDS. ATLANTIC OCEAN... A 1029 MB HIGH LOCATED NEAR 38N57W DOMINATES ALMOST THE ENTIRE FORECAST AREA. THIS SURFACE RIDGE WILL REMAIN IN PLACE DURING THE NEXT FEW DAYS PRODUCING MODERATE TO STRONG TRADE WINDS ACROSS THE TROPICS. AS PREVIOUSLY MENTIONED...AN UPPER-LEVEL LOW IS OVER SOUTH FLORIDA WITH A TROUGH EXTENDING SW INTO THE NE CARIBBEAN AND THE YUCATAN PENINSULA. A SECOND UPPER-LEVEL LOW IS NEAR 25N62W PRODUCING ISOLATED SHOWERS AND TSTMS FROM 21N-28N BETWEEN 59W-63W. A THIRD UPPER-LEVEL LOW IS NEAR 24N42W ANS HAS A TROUGH EXTENDING S OVER THE DEEP TROPICS. SWLY WINDS AHEAD OF THIS TROUGH ARE PRODUCING MODERATE SHEAR OVER THE TROPICAL WAVE/LOW IN THE ATLC ALONG 41W. STRONG SUBSIDENCE AND A DRY STABLE ATMOSPHERE ARE IN PLACE OVER THE CENTRAL ATLC...MAINLY BETWEEN 45W-60W WITH AN UPPER ANTICYCLONE LOCATED NEAR 19N52W. $$ GR