000 AXNT20 KNHC 171800 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON SEP 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1730 UTC. ...TROPICAL WAVES... TROPICAL WAVE WAS ADDED TO THE 17/1200 UTC MAP ALONG 18W/19W S OF 16N...ESTIMATED TO BE MOVING W NEAR 10-15 KT. AS NOTED IN THE PREVIOUS DISCUSSION...THE WAVE PASSAGE WAS EVIDENT IN THE RECENT DAKAR RAOB DATA. THE FEATURE ALSO SHOWS UP WELL AS A LOW AMPLITUDE MOISTURE SURGE ON THE UW-CIMSS TPW PRODUCT. THE ASSOCIATED...DISORGANIZED SCATTERED MODERATE CONVECTION IS PUSHING AWAY FROM THE AFRICAN COAST FROM 5N-12N BETWEEN 17W-22W. TROPICAL WAVE IS GENERALLY ALONG 43W S OF 19N MOVING W 10-15 KT. A WEAK 1012 MB LOW IS ALONG THE WAVE AXIS NEAR 12.5N...BUT IS RATHER ELONGATED AS SHOWN BY A QUIKSCAT PASS EARLIER THIS MORNING...WITH WINDS GENERALLY 5-15 KT IN THE IMMEDIATE VICINITY. THE WAVE IS ASSOCIATED WITH A LARGE BUT DISORGANIZED AREA OF SHOWERS AND THUNDERSTORMS....AND ANY DEVELOPMENT OF THIS SYSTEM IS EXPECTED TO BE SLOW TO OCCUR. SCATTERED MODERATE IS WITHIN 210 NM E OF THE AXIS FROM 8N-15N...WITH ISOLATED MODERATE WITHIN 210 NM W OF THE AXIS FROM 11N-16N. TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 75W S OF 20N MOVING W 10-15 KT. THE SHOWER/TSTM ACTIVITY ASSOCIATED WITH THIS WAVE HAVE DIMINISHED QUITE A BIT OVER THE LAST SEVERAL HOURS...AND UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR DEVELOPMENT IN THIS AREA OVER THE NEXT COUPLE OF DAYS. SHOWERS/TSTMS ARE MOSTLY ISOLATED IN NATURE NOW WITHIN 180 NM EITHER SIDE OF THE AXIS. THERE APPEARS TO BE MORE LOW LEVEL CYCLONIC TURNING NEAR THE SE BAHAMAS...WHICH MAY BE THE NRN PORTION OF THIS WAVE THAT HAS FRACTURED. WILL LIKELY INTRODUCE THIS AS A TROUGH ON THE 1800 UTC MAP. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 13N16W 7N28W 13N41W 10N50W 7N60W. OUTSIDE OF THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED CLUSTERS OF MODERATE CONVECTION ARE S OF THE AXIS FROM 3N-7N BETWEEN 22W-33W. SCATTERED MODERATE ALSO WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 46W-53W. DISCUSSION... GULF OF MEXICO... A DISSIPATING FRONTAL BOUNDARY IS AFFECTING THE GULF THIS AFTERNOON...WITH THE WANING BOUNDARY EXTENDING FROM THE W COAST OF FLORIDA NEAR 27N82W TO JUST OFFSHORE S TEXAS NEAR 26N97W. ISOLATED SHOWERS/TSTMS ARE GENERALLY WITHIN 90 NM OF THE BOUNDARY...BUT HAVE DIMINISHED SOME SINCE EARLY THIS MORNING. ANOTHER CLUSTER OF MODERATE CONVECTION IS OVER THE NE GULF NEAR 28N96W WHICH ALSO APPEARS TO BE SOMEWHAT RELATED TO THE DYING FRONT...BUT CLOSER TO WHERE THE LOW LEVEL MOISTURE GRADIENT EXISTS INSTEAD OF THE WIND SHIFT. THIS ACTIVITY IS ALSO OCCURRING NEAR THE BASE OF THE DOMINATING MID TO UPPER TROUGH OVER THE EAST COAST. THE ONLY OTHER ACTIVITY NOTED ARE A FEW TSTMS IN THE BAY OF CAMPECHE S OF 20N BETWEEN 93W-96W...WHICH ARE ASSOCIATED WITH LIFT AHEAD OF THE UPPER LOW OVER MEXICO NEAR 21N98W. THE REMAINDER OF THE UPPER PATTERN IS DOMINATED BY RIDGING...EXTENDING N/NW FROM AN UPPER HIGH NEAR 22N89W THROUGH ERN TEXAS. SFC RIDGING BUILDING BEHIND THE DYING FRONT WILL TAKE OVER MUCH OF THE GULF N OF 25N THROUGH TUE...WITH WEAK TROUGHING TO THE S. SOME OF THE GLOBAL MODELS ARE SUGGESTING A SFC LOW WILL DEVELOP IN THE ERN GULF LATER IN THE WEEK...BUT THE EXACT TIMING...LOCATION...AND INTENSITY OF THIS FEATURE ARE HIGHLY UNCERTAIN AT THIS POINT. CARIBBEAN SEA... A WEAK SFC TROUGH IS OVER THE NW CARIBBEAN EXTENDING FROM THE COAST OF WRN CUBA NEAR 23N82W TO 16N83W. A BROAD REGION OF LOW LEVEL TURNING REMAINS EVIDENT NEAR THIS TROUGH...WITH WINDS REMAINING MOSTLY BELOW 15 KT. THE TROUGHING IS PRODUCING A FEW ISOLATED TSTMS N OF 15N W OF 78W. THE OTHER SFC FEATURE AFFECTING THE BASIN IS THE TROPICAL WAVE IN THE CENTRAL PORTION AS DESCRIBED ABOVE. THE REMNANT LOW ASSOCIATED WITH TROPICAL DEPRESSION INGRID IS LOCATED JUST EAST OF THE NORTHERNMOST LEEWARD ISLANDS. REDEVELOPMENT OF THIS SYSTEM IS NOT EXPECTED DURING THE NEXT COUPLE OF DAYS AS IT MOVES SLOWLY W TO WNW. A CLUSTER OF MODERATE CONVECTION IS JUST OFFSHORE NICARAGUA FROM 10N-13N BETWEEN 82W-84W...THAT IS OCCURRING AT THE BASE OF THE UPPER TROUGHING EXTENDING SW FROM WRN HAITI TO 10N84W. A SIMILAR CLUSTER OF MODERATE CONVECTION IS JUST N OF THE COLOMBIA/VENEZUELA BORDER FROM 12N-15N BETWEEN 70W-73W...WHICH SEEMS ASSOCIATED WITH UPPER DIVERGENCE BETWEEN THE AFOREMENTIONED UPPER TROUGH AND UPPER RIDGING OVER THE ERN CARIBBEAN. LIGHT TO MODERATE TRADES ARE IN PLACE AND EXPECTED TO PERSIST THROUGH MIDWEEK. ATLANTIC OCEAN... THE DOMINATING FEATURE OF THE WRN ATLC IS THE STATIONARY FRONT THAT ENTERS THE AREA NEAR 32N72W AND CONTINUES TO CENTRAL FLORIDA NEAR 28N81W. THIS...IN ADDITION TO ITS SUPPORTING MID TO UPPER TROUGH OVER THE EAST COAST...IS PRODUCING NUMEROUS SHOWERS AND TSTMS N OF 28N W OF 72W TO THE COAST OF FLORIDA. MODERATE TO FRESH NE WINDS ARE COMMON BEHIND THE FRONT WHICH HAVE USHERED IN SOME PLEASANT...FALL-LIKE WEATHER INTO THE SOUTHEAST U.S. SCATTERED SHOWERS AND TSTMS ARE OVER THE BAHAMAS AND ADJACENT WATERS S OF 26N BETWEEN 73W-79W. SOME LOW LEVEL TURNING IS NOTED IN THIS REGION WHICH WILL LIKELY BE ADDED AS A TROUGH ON THE 1800 UTC MAP. SCATTERED SHOWERS AND TSTMS ARE OVER THE CENTRAL ATLC WATERS FROM 23N-28N BETWEEN 51W-60W...PRIMARILY TIED TO THE UPPER LOW NEAR 26N61W. THERE IS ALSO A SFC TROUGH IN THE REGION ALONG 29N54W 27N62W 24N64W. A FEW SMALL CLUSTERS OF MODERATE CONVECTION ARE ALSO E OF THE REMNANT LOW ASSOCIATED WITH FORMER TROPICAL DEPRESSION INGRID...FROM 15N-21N BETWEEN 56W-60W. CLOUD TOPS OVER THE ACTIVITY CONTINUE TO BE STRETCHED TO THE E WITH PERSISTENT WLY SHEAR OVER THE AREA. ANOTHER WEAK SFC TROUGH ENTERS THE AREA NEAR 32N36W AND CONTINUES S/SW THROUGH 28N36W 26N42W. ISOLATED SHOWER ACTIVITY IS WITHIN 60NM MAINLY E OF THIS BOUNDARY. TYPICAL SFC RIDGING IS OVER THE REMAINDER OF THE E ATLC PRODUCING MODERATE NE TRADES E OF 30W...STRONGEST ALONG THE NW COAST OF AFRICA. UPPER RIDGING IS OVER THE TROPICAL ATLC WITH UPPER HIGH CENTERS ESTIMATED TO BE NEAR 13N45W AND 17N25W. EXTENSIVE WLY FLOW ALOFT IS NORTH OF THESE HIGHS E OF 58W. $$ WILLIS