000 AXNT20 KNHC 261200 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED JUL 26 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...SPECIAL FEATURE... A 1009 MB SURFACE LOW PRESSURE CENTER IS INLAND OVER SOUTH TEXAS NEAR 28.5N 97.7W MOVING NORTHWARD ABOUT 10 KT. THIS SYSTEM IS GENERATING A LARGE AREA OF SHOWERS...THUNDERSTORMS AND GUSTY WINDS IN SQUALLS OVER PARTS OF THE WESTERN GULF OF MEXICO AND THE ADJACENT COASTAL AREAS. SCATTERED MODERATE CONVECTION EXISTS FROM 25N-30N BETWEEN 92W-98W. A FEW BUOYS IN THE NW GULF INDICATE WINDS NEAR 20-25 KT...ESPECIALLY IN CONVECTION. SINCE THE SURFACE LOW CENTER IS OVER LAND AND NOT EXPECTED TO REFORM OR EMERGE OFFSHORE...DEVELOPMENT IS NOT EXPECTED. LOCALLY HEAVY RAINFALL WILL CONTINUE TO OCCUR OVER PORTIONS OF SOUTHERN TEXAS AND SOUTHERN LOUISIANA TODAY. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 28W/29W S OF 21N MOVING WEST 15-20 KT. THIS WAVE HAS SOME LOW-MID LEVEL CURVATURE ESPECIALLY SOUTH OF 14N EVIDENT ON EARLY MORNING VISIBLE IMAGES. THE WAVE IS AN AREA OF THICK SAHARAN DUST THAT IS SUPPRESSING SIGNIFICANT CONVECTION. ISOLATED MODERATE CONVECTION IS EMBEDDED IN THE ITCZ AND WILL BE DISCUSSED IN THAT SECTION. A HIGH AMPLITUDE TROPICAL WAVE IS ALONG 57W S OF 25N MOVING WEST NEAR 15-20 KT. THE AREA OF LOW PRES THAT HAS BEEN ALONG THE WAVE OVER THE PAST FEW DAYS IS NO LONGER EVIDENT IN SATELLITE IMAGERY AND THE AVAILABLE DATA. HOWEVER...THE WAVE STILL REMAINS WELL-DEFINED WITH A TITLED INVERTED V-SHAPE EVIDENT. SHOWER ACTIVITY HAS ALSO INCREASED SLIGHTLY WITH SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 180 NM OF THE WAVE AXIS. FURTHER DEVELOPMENT IS NOT EXPECTED AT THIS TIME DUE TO UNFAVORABLE UPPER LEVEL WINDS. TROPICAL WAVE IS ALONG 77W S OF 18N MOVING WEST NEAR 15 KT. THIS WAVE REMAINS WEAK AND DIFFICULT TO IDENTITY. THE POSITION IS BASED UPON CONTINUITY OF FORWARD SPEED OVER THE PAST 12-24 HOURS. THE SOUTHERN PART OF THE WAVE INTERACTING WITH THE ITCZ IS TRIGGERING NUMEROUS MODERATE/STRONG CONVECTION OVER WRN COLOMBIA. THE NORTHERN EXTENSION OF THE WAVE IS INTERACTING WITH AN UPPER LOW NEAR CENTRAL CUBA PRODUCING SCATTERED SHOWERS AND TSTMS FROM HAITI TO THE YUCATAN CHANNEL. TROPICAL WAVE IS ALONG 89W S OF 17N MOVING WEST NEAR 15 KT. THIS WAVE SHOWS FAIR CURVATURE SOUTH OF 12N. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS. ...ITCZ... ITCZ IS CENTERED ALONG 11N14W 12N30W 8N45W TO INLAND OVER SOUTH AMERICA NEAR 11N61W TO PANAMA NEAR 9N80W. SMALL PATCHES OF SCATTERED MODERATE CONVECTION IS WITHIN 180 NM MAINLY TO THE SOUTH OF THE AXIS E OF 52W. CLUSTERS OF SCATTERED MODERATE CONVECTION IS OVER E VENEZUELA FROM 4N-8N BETWEEN 60W-64W. NUMEROUS MODERATE/STRONG CONVECTION IS OVER WRN COLOMBIA FROM 3N-10N BETWEEN 74W-80W. ...DISCUSSION... GULF OF MEXICO... THE MOST ACTIVE WEATHER IN THE REGION IS IN THE WEST GULF ASSOCIATED WITH A 1009 MB LOW JUST INLAND OVER SOUTH TEXAS. LOW LEVEL CONVERGENCE AND UPPER DIFFLUENCE IS PRODUCING SCATTERED MODERATE CONVECTION FROM 25N-30N BETWEEN 92W-98W. FOR MORE DETAILS SEE THE SPECIAL FEATURE SECTION ABOVE. AN ELONGATED UPPER LEVEL HIGH IS CENTERED IN THE EASTERN GULF NEAR 27N87W. DEBRIS MOISTURE IS STREAMING ANTICYCLONICALLY AROUND THE UPPER HIGH FROM THE CONVECTION IN THE W GULF ACROSS THE SE U.S. AND THEN SOUTHWARD ACROSS THE W ATLC AND FLORIDA. EARLIER THIS MORNING...PATCHES OF SCATTERED SHOWERS AND TSTMS DEVELOPED IN THE SE GULF ON THE SOUTHWARD BRANCH OF THE ANTICYCLONE. CURRENTLY MUCH OF THE ACTIVITY HAS MOVED SOUTHWARD INTO THE CARIBBEAN AND BLOSSOMED AS UPPER DIFFLUENCE IS STRONGER IN THAT REGION. AT THE SURFACE...HIGH PRES RIDGING HAS BUILT FROM THE CENTRAL ATLC ACROSS FLORIDA TO A 1019 MB HIGH IN THE E GULF NEAR 28N85W. A WEDGE OF DRY UPPER LEVEL AIR IS IN THE CENTRAL GULF BETWEEN 85W-90W KEEPING SKIES MAINLY FAIR. SURFACE WINDS ARE FAIRLY LIGHT E OF 88W. W OF 88W...WINDS ARE STRONGER WITH A FEW BUOYS REPORTING 20-25 KT IN THE NW GULF ESPECIALLY IN AREAS OF CONVECTION. THE HEAVY RAIN IN THE NW GULF WILL SLOWLY DRIFT NWD WITH THE SFC LOW THROUGHOUT THE DAY...ELSEWHERE LITTLE CHANGE IS EXPECTED. CARIBBEAN SEA... TWO WEAK ILL-DEFINED TROPICAL WAVES ARE IN THE CARIBBEAN. THE WESTERN-MOST WAVE IS RATHER BENIGN ONLY ENHANCING SHOWER ACTIVITY IN THE ITCZ. UPPER DIFFLUENCE BETWEEN AN UPPER HIGH IN THE E GULF AND AN UPPER LOW JUST SOUTH OF CENTRAL CUBA INTERACTING WITH A TROPICAL WAVE ALONG 77W IS GENERATING PATCHES OF SHOWERS AND TSTMS FROM HAITI TO THE YUCATAN CHANNEL FROM 18N-21N BETWEEN 74W-88W. THESE SHOWERS HAVE BECOME MUCH MORE WIDESPREAD OVER THE LAST FEW HOURS. A WEAK UPPER RIDGE COVERS THE AREA E OF 70W WITH PLENTY OF SUBSIDENCE. A WELL-DEFINED TROPICAL WAVE IS APPROACHING THE AREA ALREADY ENHANCING SCATTERED SHOWERS AND TSTMS ACROSS THE WINDWARD ISLANDS. THIS WAVE WILL BE MOVING INTO THE LESSER ANTILLES LATER TODAY AND TO PUERTO RICO AND HISPANIOLA ON THU INCREASING THE CHANCE OF RAIN AS IT APPROACHES. TRADE WINDS HAVE DECREASED FROM GALE FORCE EARLIER THIS WEEK TO MORE MODERATE THIS MORNING AND THESE WINDS WILL LIKELY REMAIN THAT WAY FOR THE NEXT DAY OR TWO. ATLANTIC OCEAN... THE MAIN SURFACE FEATURE IN THE ATLC IS A DOMINATING BERMUDA-AZORES RIDGE WITH A PAIR OF 1027 MB HIGHS CENTERS...ONE NEAR 37N53W AND THE OTHER NEAR 37N44W. THIS RIDGE IS CONTAMINATED BY A WEAK BENIGN 1019 MB LOW JUST N OF THE DISCUSSION AREA NEAR 34N28W. MODERATE E-ENE WINDS AND PATCHES OF LOW-MID LEVEL MOISTURE ARE ON THE SOUTH SIDE OF THE ESTABLISHED RIDGE. THE TIGHTEST PRES GRAD IS NEAR THE TROPICAL WAVE ALONG 57W. BESIDES FOR THE TROPICAL WAVES...THERE ARE ONLY A FEW AREAS OF SOME WEATHER IN THE ATLC MAINLY CONTRIBUTED TO UPPER LEVEL FEATURES. ISOLATED SHOWERS AND TSTMS ARE IN THE W ATLC...N OF 29N W OF 75W...MOVING AROUND THE PERIPHERY OF AN UPPER RIDGE IN THE E GULF. THIS ACTIVITY HAS BEEN FALLING APART THIS MORNING. TWO UPPER LOW'S ONE NEAR 29N64W AND THE OTHER NEAR 29N55W ARE RATHER DRY FEATURES ONLY PRODUCING BROKEN CLOUDS AND ISOLATED SHOWERS ON THE S AND E SIDE OF THEIR CIRCULATION. THE REMAINDER OF THE AREA IS ON THE SOUTH SIDE OF AN AMPLIFIED UPPER RIDGE/TROUGH PATTERN WITH THE RIDGE AXIS ALONG 45W AND THE BASE OF THE UPPER TROUGH DIGGING TO NEAR 30N19W. THE UW-CIMSS SAHARAN AIR LAYER ANALYSIS FROM 09 UTC DEPICTS THAT THE LEADING EDGE OF THICK DUST IS BEHIND THE WELL DEFINED TROPICAL WAVE APPROACHING THE CARIBBEAN...E OF 57W FROM 10N-30N. SCATTERED LESS DENSE DUST HAS SPREAD ACROSS THE ENTIRE CARIBBEAN. $$ CANGIALOSI