000 AXNT20 KNHC 281820 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI SEP 28 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 1715 UTC. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM KAREN AT 28/1500 UTC IN THE ATLANTIC OCEAN WAS NEAR 15.1N 49.2W MOVING WEST-NORTHWEST 8 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE WAS 1009 MB. THE MAXIMUM SUSTAINED WIND SPEEDS WERE 35 KT WITH GUSTS TO 45 KT. PLEASE READ THE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. PERSISTENTLY STRONG SOUTHWESTERLY SHEAR IS EXPECTED TO AFFECT KAREN DURING THE NEXT 72 HOURS. THE FORECAST ALREADY FOR THE NEXT TWELVE HOURS IS FOR KAREN TO WEAKEN TO A TROPICAL DEPRESSION. IT IS POSSIBLE THAT SOME INTERMITTENT BURSTS OF DEEP CONVECTIVE PRECIPITATION MAY OCCUR DURING THE NEXT FEW DAYS. UNFAVORABLE UPPER LEVEL NORTHWESTERLY WIND FLOW IS EXPECTED TO MOVE ACROSS KAREN AND CONTINUE ITS WEAKENING TREND AFTER 72 HOURS. SATELLITE DATA FROM THIS MORNING SUGGESTED THAT THE WEAKENING CENTER OF KAREN WAS MOVING ERRATICALLY. THE WIND SPEED OF 35 KT ASSIGNED TO KAREN AT 28/1500 UTC MAY BE GENEROUS CONSIDERING ITS COMPARATIVELY-WEAKENED STATE. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM 15N TO 17N BETWEEN 48W AND 49W. TROPICAL STORM LORENZO WAS DOWNGRADED TO TROPICAL DEPRESSION LORENZO AT 28/1500 UTC. THE CENTER OF TROPICAL DEPRESSION AT 28/1500 UTC WAS INLAND NEAR 20.6N 98.4W MOVING WEST 8 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE WAS 1002 MB. THE MAXIMUM SUSTAINED WIND SPEEDS WERE 30 KT WITH GUSTS TO 40 KT. PLEASE READ THE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. ALL DATA INDICATE THAT LORENZO HAS WEAKENED TO A TROPICAL DEPRESSION AS IT CONTINUES TO MOVE MORE AND MORE INLAND IN EASTERN MEXICO. THE FORECAST TRACK IS WESTWARD FOR THE NEXT 36 HOURS AT A COMPARATIVELY SLOW PACE...AFTER WHICH TIME THE REMNANT LOW PRESSURE CENTER IS EXPECTED TO DISSIPATE. TORRENTIAL RAINS ARE STILL A STRONG POSSIBILITY WITH A SLOWLY-MOVING LORENZO AND/OR ITS REMNANT LOW PRESSURE CENTER. THE COLDEST CLOUD TOP TEMPERATURES... -69 DEGREES CELSIUS AT 47000 FEET ARE ALONG THE MEXICO GULF COAST FROM 23N TO 24N BETWEEN 97W AND 98W. SHOWERS AND THUNDERSTORMS REMAIN FROM 21N TO 25N BETWEEN 96W AND 100W. TROPICAL DEPRESSION FOURTEEN DEVELOPED IN THE EASTERN ATLANTIC OCEAN AT 28/1500 UTC NEAR 14.1N 26.5W MOVING WEST 6 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE WAS 1008 MB. THE MAXIMUM SUSTAINED WIND SPEEDS WERE 30 KT WITH GUSTS TO 40 KT. PLEASE READ THE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/ WTNT34 KNHC FOR MORE DETAILS. THIS DEPRESSION DEVELOPED IN AN AREA OF DEEP ORGANIZED CONVECTIVE PRECIPITATION NEAR THE CENTER WITH WELL ESTABLISHED UPPER LEVEL OUTFLOW. A SHIP LOCATED JUST TO THE NORTH OF THE CENTER REPORTED 29 KNOTS. THIS DEPRESSION HAS THE OPPORTUNITY TO STRENGTHEN A LITTLE DURING THE NEXT DAY OR TWO WHILE THE MIDDLE TO UPPER LEVEL SHEAR IS LOW. THE MIDDLE TO UPPER LEVEL WIND PATTERNS FOR THE NEXT TWO TO THREE DAYS SUGGEST THAT THE FUTURE TRACK OF T.D. FOURTEEN WILL BE TO THE NORTHWEST AND THEN NORTH...ENCOUNTERING HIGHER SHEAR AND COOLER SEA SURFACE TEMPERATURES AFTER 48 HOURS. STRONG SHOWERS AND THUNDERSTORMS NOW ARE FROM 13N TO 14N BETWEEN 24W AND 26W... AND FROM 14N TO 15N BETWEEN 25W AND 26W. TWO OTHER BURSTS OF SHOWERS AND THUNDERSTORMS ARE WITHIN A 15 NM RADIUS OF 16N23W AND 16N25.5W. ...TROPICAL WAVES... AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 30W/31W SOUTH OF 20N MOVING WEST 10 TO 15 KT. NO WELL DEFINED CYCLONIC FLOW IS NOTED IN THE VISIBLE CLOUD FIELD TO THE WEST OF T.D. FOURTEEN. NO DEEP CONVECTIVE PRECIPITATION ACCOMPANIES THIS WAVE. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 77W/78W SOUTH OF 21N MOVING WEST 10 TO 15 KT. THIS WAVE CUTS RIGHT THROUGH JAMAICA. AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTER IS NEAR 15N74W AND A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 19N83W. A MIDDLE LEVEL TROUGH IN THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA AND THE UPPER LEVEL ANTICYCLONIC FLOW MAY BE CREATING AN ENVIRONMENT OF DIFFLUENT FLOW AT SOME LEVELS... ENOUGH TO CREATE SCATTERED STRONG SHOWERS AND THUNDERSTORMS FROM 11N TO 14N BETWEEN 79W AND NICARAGUA. IT IS POSSIBLE THAT SOME ENERGY FROM THE WAVE MAY BE INFLUENCING THIS PRECIPITATION. SHOWERS AND THUNDERSTORMS MORE TO THE NORTH...FROM 18N TO 21N BETWEEN 75W AND 85W ARE IN AN AREA OF UPPER LEVEL DIFFLUENT FLOW AND AROUND THE MIDDLE TO UPPER LEVEL CYCLONIC CENTER. ...THE ITCZ... 7N12W 11N22W 10N33W 12N46W 11N52W 9N60W. WIDELY SCATTERED TO SCATTERED MODERATE SHOWERS/ISOLATED STRONG THUNDERSTORMS ARE FROM 8N TO 13N BETWEEN 56W AND 62W...COVERING SOME OF THE SOUTHEASTERN CARIBBEAN SEA ISLANDS. THIS AREA IS AT THE BASE OF A SYNOPTIC SCALE ATLANTIC OCEAN TROUGH AND THE WESTERN END OF THE ITCZ. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE WITHIN 75 NM ON EITHER SIDE OF 6N11W 3N17W... AND FROM 7N TO 10N BETWEEN 41W AND 44W. ISOLATED MODERATE SHOWERS ARE WITHIN 90 NM ON EITHER SIDE OF 3N20W 6N29W 5N35W AND 5N45W. DISCUSSION... THE GULF OF MEXICO... TROPICAL DEPRESSION LORENZO IS WEAKENING IN EASTERN MEXICO. RAINFALL TO THE EAST OF T.D. LORENZO IS IN THE COASTAL WATERS FROM 21N TO 25N...AND INLAND ALSO. THE SLOW MOTION OF LORENZO WILL GIVE IT SOME TIME IN ORDER TO BE ABLE TO PRODUCE TORRENTIAL RAINFALL ALONG ITS PATH FOR THE NEXT FEW DAYS. UPPER LEVEL ANTICYCLONIC OUTFLOW ON TOP OF LORENZO MAKES ITS WAY INTO THE GULF WATERS AS FAR EAST AS 88W. MIDDLE TO UPPER LEVEL CYCLONIC FLOW IS AROUND A TROUGH THAT EXTENDS FROM GEORGIA INTO CENTRAL FLORIDA TO CUBA...AND ULTIMATELY TO THE 19N83W CARIBBEAN SEA CYCLONIC CENTER. DRY AIR/SUBSIDENCE IS IN THE TROUGH AND MOVING ACROSS THE SOUTHEASTERN U.S.A.. THE CARIBBEAN SEA... MIDDLE TO UPPER LEVEL CYCLONIC FLOW CUTS ACROSS THE AREA FROM THE NORTHEASTERN CORNER TO THE SOUTHEASTERN CORNER...PASSING ON TOP OF HISPANIOLA AND PUERTO RICO AND EXITING THE AREA ACROSS ST. LUCIA...BARBADOS AND OTHER WINDWARD ISLANDS. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 77W/78W SOUTH OF 21N MOVING WEST 10 TO 15 KT. THIS WAVE CUTS RIGHT THROUGH JAMAICA. AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTER IS NEAR 15N74W AND A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 19N83W. A MIDDLE LEVEL TROUGH IN THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA AND THE UPPER LEVEL ANTICYCLONIC FLOW MAY BE CREATING AN ENVIRONMENT OF DIFFLUENT FLOW AT SOME LEVELS... ENOUGH TO CREATE SCATTERED STRONG SHOWERS AND THUNDERSTORMS FROM 11N TO 14N BETWEEN 79W AND NICARAGUA. IT IS POSSIBLE THAT SOME ENERGY FROM THE WAVE MAY BE INFLUENCING THIS PRECIPITATION. SHOWERS AND THUNDERSTORMS MORE TO THE NORTH...FROM 18N TO 21N BETWEEN 75W AND 85W ARE IN AN AREA OF UPPER LEVEL DIFFLUENT FLOW AND AROUND THE MIDDLE TO UPPER LEVEL CYCLONIC CENTER. THE ATLANTIC OCEAN... A 1014 MB LOW PRESSURE CENTER IS NEAR 29N78W EAST OF THE FLORIDA COAST. A SURFACE TROUGH PASSES THROUGH THE LOW CENTER...TO THE NORTHERN BAHAMAS AND ULTIMATELY TO CUBA NEAR 23N81W. A MIDDLE LEVEL TROUGH REMAINS UNDER AN UPPER LEVEL RIDGE IN THE WESTERN ATLANTIC OCEAN. THE RIDGE IS ALONG 20N73W 25N74W 29N73W BEYOND 31N72W. A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 27N60W. MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE SURROUNDS THIS CYCLONIC CENTER...AS FAR WEST AS 70W AND FAR EAST AS 50W. DRY AIR/SUBSIDENCE EVEN CURVES TO THE SOUTHEAST FROM 30N70W TO 20N60W. A TROUGH CONNECTS A 30N50W CYCLONIC CIRCULATION CENTER TO THE 27N60W CENTER...TO 10N60W OFF THE COASTS OF TRINIDAD AND VENEZUELA. WIDELY SCATTERED TO SCATTERED MODERATE SHOWERS/ ISOLATED STRONG THUNDERSTORMS ARE WITHIN 60 TO 75 NM ON EITHER SIDE OF 28N46W 25N55W 22N62W IN THE TROUGH. $$ MT