000 AXNT20 KNHC 182313 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE SEP 18 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 2245 UTC. ...SPECIAL FEATURES... LARGE AREA OF LOW PRESSURE IN THE W ATLC BETWEEN THE N BAHAMA ISLANDS AND THE E COAST OF FLORIDA ANALYZED BY A 1012 MB LOW NEAR 26N79W. SURFACE PRESSURES ARE GRADUALLY FALLING IN THE AREA AND CONDITIONS APPEAR TO BE FAVORABLE FOR A SUBTROPICAL OR A TROPICAL CYCLONE TO FORM OVER THE NEXT DAY OR TWO...AS THE SYSTEM MOVES WESTWARD INTO THE GULF OF MEXICO. REGARDLESS OF DEVELOPMENT...THIS SYSTEM WILL LIKELY BRING SHOWERS...SQUALLS AND LOCALLY HEAVY RAIN OVER PORTION OF FLORIDA DURING THE NEXT DAY OR TWO. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 26W S OF 16N MOVING W 10-15 KT. MID LEVEL INVERTED-V CURVATURE AT A LOW ALTITUDE. SCATTERED SHOWERS/ THUNDERSTORMS ARE FROM 3N-12N BETWEEN 22W-33W. TROPICAL WAVE IS ALONG 50W/51W S OF 20N MOVING W NEAR 15 KT. BROAD MID LEVEL INVERTED-V CURVATURE COVERING THE AREA FROM 44W-55W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 15N-20N BETWEEN 45W-51W AND SCATTERED MODERATE CONVECTION IS FROM 12N-15N BETWEEN 50W-54W. TROPICAL WAVE IS ALONG 80W/81W S OF 21W MOVING W 10-15 KT. LOW LEVEL INVERTED-V CURVATURE IS OBSERVED OVER THE CENTRAL CARIBBEAN. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE FROM 11N-21N BETWEEN 79W-84W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N15W 11N24W 5N32W 10N52W 9N62W. SCATTERED/NUMEROUS STRONG COVINGTON IS INLAND OVER W AFRICA MOVING W ALONG THE IMMEDIATE COASTAL WATERS WITHIN 120 NM OF THE ITCZ AXIS. DISCUSSION... GULF OF MEXICO... LARGE UPPER LOW IS INLAND OVER CENTRAL MEXICO AND COVERS THE GULF S OF 27N W OF 92W. A SECOND LARGE UPPER LOW IS CENTERED ALONG THE W COAST OF FLORIDA NEAR TAMPA COVERING THE GULF E OF 88W THUS INDUCING AN UPPER RIDGE ACROSS THE CENTRAL GULF FROM THE YUCATAN PENINSULA TO THE COAST NEAR THE LOUISIANA/TEXAS BORDER. DIFFLUENCE BETWEEN ALL OF THESE UPPER LEVEL FEATURES IS GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM OF LINE FROM 25N85W TO THE SW LOUISIANA COAST NEAR 30N93W AND A BAND OF SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60 NM OF LINE FROM 23N90W TO THE TEXAS COAST NEAR CORPUS CHRISTI. SCATTERED SCATTERED THUNDERSTORMS ARE MOVING OFF THE W FLORIDA COAST E OF 84W FROM TAMPA ACROSS THE FLORIDA KEYS INTO THE FLORIDA STRAITS. CARIBBEAN SEA... AN UPPER HIGH IS IN THE SW CARIBBEAN NEAR 12N81W AND COVERS THE W CARIBBEAN W OF 78W ENHANCING ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE ALONG 80W/81W. A WEAK SURFACE TROUGH IS BENEATH THIS UPPER RIDGE EXTENDING ALONG THE E COAST OF THE YUCATAN PENINSULA FROM BELIZE THROUGH THE YUCATAN CHANNEL TO 23N86W GENERATING SCATTERED SHOWERS/THUNDERSTORMS INLAND AND WITHIN 90/120 NM ALONG THE COAST OF THE YUCATAN. A SECOND UPPER HIGH IS IN THE SE CARIBBEAN NEAR 12N64W COVERING THE REMAINDER OF THE AREA INDUCING AN UPPER TROUGH ACROSS THE CENTRAL CARIBBEAN FROM HAITI TO E PANAMA. A SURFACE TROUGH EXTENDS FROM THE REMNANTS OF INGRID IN THE SW ATLC ALONG 62W/63W ACROSS THE LEEWARD ISLANDS TO NEAR 14N GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS E OF 64W ACROSS THE LEEWARD AND VIRGIN ISLANDS. THE AREA OF THE CARIBBEAN S OF 17N FROM 64W-76W REMAINS CLEAR THIS EVENING. ATLANTIC OCEAN... THE UPPER LOW ALONG THE W COAST OF FLORIDA EXTENDS ACROSS THE FLORIDA PENINSULA TO 78W. AN UPPER HIGH IS TO THE E NEAR 23N73W WITH THE RIDGE AXIS EXTENDING N TO BEYOND 32N69W. DIFFLUENCE BETWEEN THESE UPPER LEVEL FEATURES IS GENERATING RAIN AND THUNDERSTORMS OVER MOST OF THE W ATLC FROM 23N-30N W OF 72W. AN UPPER TROUGH IS IN THE W/CENTRAL ATLC EXTENDING THROUGH 32N53W TO AN UPPER LOW NEAR 26N62W TO NEAR 21N68W. A SURFACE TROUGH ASSOCIATED WITH THIS UPPER TROUGH EXTENDS FROM 30N50W TO NEAR 26N58W. DENSE CLOUDS WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE E OF THE SURFACE TROUGH WITHIN 150 NM OF LINE FROM 22N60W TO BEYOND 32N46W. THE REMNANTS OF INGRID IS A 1012 MB SURFACE LOW JUST N OF THE LEEWARD ISLANDS NEAR 20N63W WITH A SURFACE TROUGH EXTENDING ALONG 62W/63W S OF 25N INTO THE E CARIBBEAN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 18N-22N BETWEEN 60W-64W. A TYPICAL E/W UPPER RIDGE COVERING THE REMAINDER OF THE TROPICAL ATLC WITH THE RIDGE AXIS ALONG 16N E OF 35W. $$ WALLACE