000 AXNT20 KNHC 140005 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON AUG 13 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 2330 UTC. ...SPECIAL FEATURE... TROPICAL DEPRESSION FOUR WAS NEAR 11.9N 32.3W AT 13/2100 UTC MOVING WEST 17 KT. MINIMUM CENTRAL PRESSURE IS 1005 MB WITH MAXIMUM SUSTAINED WINDS 30 KT GUSTING TO 40 KT. THE ASSOCIATED DEEP CONVECTION REMAINS DISPLACED TO THE W OF THE CENTER DUE TO EASTERLY SHEAR OVER THE SYSTEM. SCATTERED MODERATE IS FROM 10N-13N BETWEEN 33W-37W. A CONTINUED BRISK AND GENERALLY WESTWARD MOTION SHOULD CONTINUE DURING THE NEXT COUPLE OF DAYS WHILE THE CYCLONE MOVES ALONG THE SOUTHERN PERIPHERY OF A DEEP LAYER RIDGE. SOME STRENGTHENING IS FORECAST...AND THE DEPRESSION COULD BECOME A TROPICAL STORM TONIGHT OR ON TUESDAY. PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. A 1009 MB LOW IS NEAR 22N87W...OR JUST N OF THE NE TIP OF THE YUCATAN PENINSULA. THE SYSTEM IS INTERACTING WITH AN UPPER LOW MOVING INTO THE WRN GULF TO PRODUCE WIDESPREAD CLOUDINESS AND DISORGANIZED SHOWERS ESPECIALLY OVER THE SE GULF...S OF 27N E OF 92W. UPPER-LEVEL WINDS ARE GRADUALLY BECOMING MORE FAVORABLE FOR DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL DEPRESSION COULD FORM TONIGHT OR TOMORROW AS THE LOW MOVES TO THE WEST-NORTHWEST AT 10 TO 15 MPH. INTERESTS IN THE WESTERN GULF OF MEXICO SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE RECONNASSIANCE PLANE IS SCHEDULED TO INVESTIGATE THIS SYSTEM TOMORROW AFTERNOON...IF NECESSARY. ...TROPICAL WAVES... A TROPICAL WAVE WAS ADDED ALONG 19/20W ESTIMATED TO BE MOVING W NEAR 15 KT. A 1009 MB LOW IS ALONG THE WAVE NEAR 15N...WHICH SHOWED UP WELL IN A RECENT QUIKSCAT PASS. THE WAVE PASSAGE WAS VERY EVIDENT IN THE DAKAR SOUNDING DATA FROM LAST NIGHT TO THIS MORNING. DEEP CONVECTION IS MINIMAL THOUGH THE ASSOCIATED CLOUDINESS IS BEGINNING TO SPREAD THROUGH THE CAPE VERDE ISLANDS. TROPICAL WAVE IS ALONG 45/46W S OF 15N MOVING W NEAR 10 KT. CYCLONIC TURNING IS EVIDENT IN THE SURROUNDING LOW TO MID LEVEL CLOUDS...AND THE WAVE SHOWS UP AS A LOW AMPLITUDE SURGE OF MOISTURE IN THE UW-CIMSS TPW PRODUCT. REGARDLESS...DEEP CONVECTION IS MINIMAL WITH ASSOCIATED SHOWER ACTIVITY MOSTLY EMBEDDED IN THE ITCZ. A TROPICAL WAVE WAS ADDED ON THE INTERMEDIATE 13/1500 UTC ANALYSIS ALONG THE SPECIAL FEATURE IN THE SRN GULF. SEE DETAILS ABOVE. ...THE ITCZ... AXIS CENTERED ALONG 15N23W 14N29W 11N37W 11N43W 9N48W 8N61W. OUTSIDE OF THE CONVECTION OUTLINED ABOVE TO THE W OF TROPICAL DEPRESSION 4...VERY LITTLE DEEP CONVECTION IS NOTED NEAR THE ITCZ THIS EVENING. DISCUSSION... THE GULF OF MEXICO... THE HIGHLIGHT CONTINUES TO BE THE SPECIAL FEATURE JUST N OF THE YUCATAN AS DESCRIBED ABOVE. A MID TO UPPER LOW IS SPINNING NEAR 25N92W. UPPER DIFFLUENCE BETWEEN THIS FEATURE AND AN UPPER ANTICYCLONE CENTERED NEAR THE COLORADO/KANSAS BORDER IS SUPPORTING SCATTERED SHOWERS/ISOLATED TSTMS WITHIN 60NM EITHER SIDE OF A TAMPICO TO LAKE CHARLES LINE. A SFC TROUGH REMAINS ANALYZED TO THE W OF THE SPECIAL FEATURE EXTENDING N FROM CENTRAL BAY OF CAMPECHE TO NEAR THE LOUISIANA COAST. THIS FEATURE SEEMS TO BE LESS PRONOUNCED THAN IT WAS...AND IS HARD TO FIND WITH THE FLOW AROUND THE SPECIAL FEATURE TAKING OVER. THUS...THE TROUGH WILL LIKELY BE REMOVED FROM THE 14/0000 UTC MAP. THE CARIBBEAN SEA... WIDESPREAD CLOUDINESS...SCATTERED SHOWERS AND ISOLATED TSTMS COVER MUCH OF THE WRN CARIB MAINLY W OF 78W. IN ADDITION A FEW CLUSTERS OF MODERATE CONVECTION ARE OFF THE COAST OF COLOMBIA/PANAMA S OF 14N BETWEEN 72W-78W. THIS WEATHER IS IN RESPONSE TO THE SPECIAL FEATURE MOVING N OF THE YUCATAN INTO THE GULF...A SFC TROUGH NOW ANALYZED IN THE SW CARIB ALONG 15N82W 19N79W...AND WIDELY UPPER DIFFLUENT FLOW BETWEEN THE RIDGING IN THE NW CARIB AND AN UPPER LOW JUST S OF PUERTO RICO. THE REMAINDER OF THE CENTRAL AND ERN CARIB IS MOSTLY QUIET WITH FAIRLY DRY/STABLE MID TO UPPER AIR IN PLACE. MODERATE TRADES E OF 80W BEND MORE SE IN THE NW CARIB AHEAD OF THE SPECIAL FEATURE. THE ATLANTIC OCEAN... A LINGERING FRONTAL BOUNDARY IS MOSTLY N OF THE WRN ATLC AREA EXTENDING THROUGH BERMUDA W TO ABOUT 250 NM OFF THE GEORGIA/NORTH FLORIDA COAST. LIFT AHEAD OF THIS BOUNDARY CONTINUES TO PRODUCE BROKEN TO OVERCAST MULTILAYERED CLOUDINESS...SCATTERED SHOWERS AND ISOLATED TSTMS MAINLY N OF 26N BETWEEN 60W-75W. THIS ACTIVITY ALSO BEING SUPPORTING BY UPPER DIFFLUENT FLOW BETWEEN TROUGHING OFF THE SOUTHEAST U.S. COAST AND AND UPPER RIDGING THAT EXTENDS ENE FROM THE NRN BAHAMAS TO NEAR 32N60W. AN UPPER LOW IS NEAR 30N49W BUT IS NOT GENERATING ANY SENSIBLE WEATHER AS IT IS SURROUNDED BY FAIRLY DRY AIR. A LARGE MID TO UPPER HIGH IS NEAR 22N40W. THE ELY FLOW S OF THIS HIGH IS PRODUCING SHEAR OVER TROPICAL DEPRESSION 4. ANOTHER UPPER LOW IS IN THE NE PART OF THE AREA NEAR 30N19W...THAT IS PRODUCING MAINLY HIGH CLOUDS N OF 29N BETWEEN 22W-26W. THE REMAINDER OF THE SFC PATTERN IS DOMINATED BY A 1024 MB HIGH NEAR 33N33W. THIS HAS AN ELONGATED RIDGE STRETCHING SW TO NEAR THE CENTRAL BAHAMAS. OVERALL MOSTLY FAIR WEATHER AND MODERATE TRADES RULE N OF 15N E OF 45W. $$ MW/MT 000 AXNT20 KNHC 140005 RRA TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON AUG 13 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 2330 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION FOUR WAS NEAR 11.9N 32.3W AT 13/2100 UTC MOVING WEST 17 KT. MINIMUM CENTRAL PRESSURE IS 1005 MB WITH MAXIMUM SUSTAINED WINDS 30 KT GUSTING TO 40 KT. THE ASSOCIATED DEEP CONVECTION REMAINS DISPLACED TO THE W OF THE CENTER DUE TO EASTERLY SHEAR OVER THE SYSTEM. SCATTERED MODERATE IS FROM 10N-13N BETWEEN 33W-37W. A CONTINUED BRISK AND GENERALLY WESTWARD MOTION SHOULD CONTINUE DURING THE NEXT COUPLE OF DAYS WHILE THE CYCLONE MOVES ALONG THE SOUTHERN PERIPHERY OF A DEEP LAYER RIDGE. SOME STRENGTHENING IS FORECAST...AND THE DEPRESSION COULD BECOME A TROPICAL STORM TONIGHT OR ON TUESDAY. PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. A 1009 MB LOW IS NEAR 22N87W...OR JUST N OF THE NE TIP OF THE YUCATAN PENINSULA. THE SYSTEM IS INTERACTING WITH AN UPPER LOW MOVING INTO THE WRN GULF TO PRODUCE WIDESPREAD CLOUDINESS AND DISORGANIZED SHOWERS ESPECIALLY OVER THE SE GULF...S OF 27N E OF 92W. UPPER-LEVEL WINDS ARE GRADUALLY BECOMING MORE FAVORABLE FOR DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL DEPRESSION COULD FORM TONIGHT OR TOMORROW AS THE LOW MOVES TO THE WEST-NORTHWEST AT 10 TO 15 MPH. INTERESTS IN THE WESTERN GULF OF MEXICO SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE RECONNASSIANCE PLANE IS SCHEDULED TO INVESTIGATE THIS SYSTEM TOMORROW AFTERNOON...IF NECESSARY. ...TROPICAL WAVES... A TROPICAL WAVE WAS ADDED ALONG 19/20W ESTIMATED TO BE MOVING W NEAR 15 KT. A 1009 MB LOW IS ALONG THE WAVE NEAR 15N...WHICH SHOWED UP WELL IN A RECENT QUIKSCAT PASS. THE WAVE PASSAGE WAS VERY EVIDENT IN THE DAKAR SOUNDING DATA FROM LAST NIGHT TO THIS MORNING. DEEP CONVECTION IS MINIMAL THOUGH THE ASSOCIATED CLOUDINESS IS BEGINNING TO SPREAD THROUGH THE CAPE VERDE ISLANDS. TROPICAL WAVE IS ALONG 45/46W S OF 15N MOVING W NEAR 10 KT. CYCLONIC TURNING IS EVIDENT IN THE SURROUNDING LOW TO MID LEVEL CLOUDS...AND THE WAVE SHOWS UP AS A LOW AMPLITUDE SURGE OF MOISTURE IN THE UW-CIMSS TPW PRODUCT. REGARDLESS...DEEP CONVECTION IS MINIMAL WITH ASSOCIATED SHOWER ACTIVITY MOSTLY EMBEDDED IN THE ITCZ. A TROPICAL WAVE WAS ADDED ON THE INTERMEDIATE 13/1500 UTC ANALYSIS ALONG THE SPECIAL FEATURE IN THE SRN GULF. SEE DETAILS ABOVE. ...THE ITCZ... AXIS CENTERED ALONG 15N23W 14N29W 11N37W 11N43W 9N48W 8N61W. OUTSIDE OF THE CONVECTION OUTLINED ABOVE TO THE W OF TROPICAL DEPRESSION 4...VERY LITTLE DEEP CONVECTION IS NOTED NEAR THE ITCZ THIS EVENING. DISCUSSION... THE GULF OF MEXICO... THE HIGHLIGHT CONTINUES TO BE THE SPECIAL FEATURE JUST N OF THE YUCATAN AS DESCRIBED ABOVE. A MID TO UPPER LOW IS SPINNING NEAR 25N92W. UPPER DIFFLUENCE BETWEEN THIS FEATURE AND AN UPPER ANTICYCLONE CENTERED NEAR THE COLORADO/KANSAS BORDER IS SUPPORTING SCATTERED SHOWERS/ISOLATED TSTMS WITHIN 60NM EITHER SIDE OF A TAMPICO TO LAKE CHARLES LINE. A SFC TROUGH REMAINS ANALYZED TO THE W OF THE SPECIAL FEATURE EXTENDING N FROM CENTRAL BAY OF CAMPECHE TO NEAR THE LOUISIANA COAST. THIS FEATURE SEEMS TO BE LESS PRONOUNCED THAN IT WAS...AND IS HARD TO FIND WITH THE FLOW AROUND THE SPECIAL FEATURE TAKING OVER. THUS...THE TROUGH WILL LIKELY BE REMOVED FROM THE 14/0000 UTC MAP. THE CARIBBEAN SEA... WIDESPREAD CLOUDINESS...SCATTERED SHOWERS AND ISOLATED TSTMS COVER MUCH OF THE WRN CARIB MAINLY W OF 78W. IN ADDITION A FEW CLUSTERS OF MODERATE CONVECTION ARE OFF THE COAST OF COLOMBIA/PANAMA S OF 14N BETWEEN 72W-78W. THIS WEATHER IS IN RESPONSE TO THE SPECIAL FEATURE MOVING N OF THE YUCATAN INTO THE GULF...A SFC TROUGH NOW ANALYZED IN THE SW CARIB ALONG 15N82W 19N79W...AND WIDELY UPPER DIFFLUENT FLOW BETWEEN THE RIDGING IN THE NW CARIB AND AN UPPER LOW JUST S OF PUERTO RICO. THE REMAINDER OF THE CENTRAL AND ERN CARIB IS MOSTLY QUIET WITH FAIRLY DRY/STABLE MID TO UPPER AIR IN PLACE. MODERATE TRADES E OF 80W BEND MORE SE IN THE NW CARIB AHEAD OF THE SPECIAL FEATURE. THE ATLANTIC OCEAN... A LINGERING FRONTAL BOUNDARY IS MOSTLY N OF THE WRN ATLC AREA EXTENDING THROUGH BERMUDA W TO ABOUT 250 NM OFF THE GEORGIA/NORTH FLORIDA COAST. LIFT AHEAD OF THIS BOUNDARY CONTINUES TO PRODUCE BROKEN TO OVERCAST MULTILAYERED CLOUDINESS...SCATTERED SHOWERS AND ISOLATED TSTMS MAINLY N OF 26N BETWEEN 60W-75W. THIS ACTIVITY ALSO BEING SUPPORTING BY UPPER DIFFLUENT FLOW BETWEEN TROUGHING OFF THE SOUTHEAST U.S. COAST AND AND UPPER RIDGING THAT EXTENDS ENE FROM THE NRN BAHAMAS TO NEAR 32N60W. AN UPPER LOW IS NEAR 30N49W BUT IS NOT GENERATING ANY SENSIBLE WEATHER AS IT IS SURROUNDED BY FAIRLY DRY AIR. A LARGE MID TO UPPER HIGH IS NEAR 22N40W. THE ELY FLOW S OF THIS HIGH IS PRODUCING SHEAR OVER TROPICAL DEPRESSION 4. ANOTHER UPPER LOW IS IN THE NE PART OF THE AREA NEAR 30N19W...THAT IS PRODUCING MAINLY HIGH CLOUDS N OF 29N BETWEEN 22W-26W. THE REMAINDER OF THE SFC PATTERN IS DOMINATED BY A 1024 MB HIGH NEAR 33N33W. THIS HAS AN ELONGATED RIDGE STRETCHING SW TO NEAR THE CENTRAL BAHAMAS. OVERALL MOSTLY FAIR WEATHER AND MODERATE TRADES RULE N OF 15N E OF 45W. $$ MW/MT