000 AXNT20 KNHC 111208 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT MON SEP 11 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 FEATURES... THE CENTER OF HURRICANE FLORENCE AT 11/1200 UTC WAS LOCATED NEAR 32.38N 65.8W...OR ABOUT 52 NM/95 KM WEST OF BERMUDA. FLORENCE IS MOVING TOWARD THE NORTH NEAR 10 KT. A TURN TO THE NORTH- NORTHEAST WITH AN INCREASE IN FORWARD SPEED IS EXPECTED OVER THE NEXT 24 HOURS. MINIMUM CENTRAL PRESSURE IS 975 MB. MAXIMUM SUSTAINED WINDS ARE NEAR 70 KT WITH GUSTS TO 85 KT...THIS IS A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON SCALE. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 290 MILES/415 KM. AN ELEVATED OBSERVING SITE IN BERMUDA RECENTLY REPORTED A GUST TO 79 MPH. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 24 HOURS. PLEASE READ THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC OR THE PUBLIC ADVISORY UNDER MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. NUMEROUS MODERATE TO STRONG CONVECTION EXISTS FROM 31N-35N BETWEEN 63W-67W WITH A LARGE SHIELD OF SCATTERED MODERATE CONVECTION STRETCHED OUT TO THE N BY THE UPPER TROUGH. THE BERMUDA RADAR SHOWS WELL DEFINED BANDS ESPECIALLY N OF THE CENTER. FLORENCE IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF 2 TO 4 INCHES OVER BERMUDA...WITH POSSIBLE MAXIMUM AMOUNTS OF 6 INCHES. THE CENTER OF TROPICAL DEPRESSION SEVEN WAS LOCATED NEAR 20.5N 55.1W OR ABOUT 495 MILES...800 KM...EAST-NORTHEAST OF THE LEEWARD ISLANDS AT 11/0900 UTC. THE DEPRESSION IS MOVING SLOWLY TO THE WEST-NORTHWEST NEAR 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB. MAXIMUM SUSTAINED WINDS ARE NEAR 30 KT WITH GUSTS TO 40 KT. FOR MORE DETAILS PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/ WTNT22 KNHC OR THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC. THIS TROPICAL CYCLONE...VERY MUCH UNLIKE FLORENCE...IS COMPACT. OVER THE PAST COUPLE OF DAYS THIS SYSTEM WAS FEELING THE EFFECTS OF NORTHWESTERLY WIND SHEAR EXPOSING THE LOW LEVEL CENTER TO THE NORTH. HOWEVER...THE SHEAR LET UP A LITTLE ON SUNDAY ALLOWING THE CONVECTION TO WRAP PARTIALLY AROUND THE CENTER AT TIMES. HOWEVER THE SYSTEM IS STILL OBVIOUSLY FEELING THE EFFECTS OF NORTHWESTERLY SHEAR WITH THE MOST ORGANIZED CONVECTION DOWN-SHEAR IN THE SE QUADRANT. CONVECTIVE BANDING HAS BEEN IMPROVING SOME IN ORGANIZATION THIS MORNING ESPECIALLY IN THE SE QUADRANT. SCATTERED MODERATE CONVECTION EXISTS FROM 18N-21N BETWEEN 54W-58W. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS...AND THE DEPRESSION COULD BECOME A TROPICAL STORM TODAY. ...TROPICAL WAVES... A TROPICAL WAVE IS IN THE E ATLC ALONG 30W S OF 18N MOVING W NEAR 10 KT. THE OVERALL STRUCTURE OF THIS WAVE IS MORE DISORGANIZED THAN IT WAS OVER THE PAST COUPLE OF DAYS. LOW TO MID CLOUD MOTIONS DO SHOW SOME CYCLONIC TURNING FROM 8N-14N ABOUT THE AXIS. SCATTERED SHOWERS AND TSTMS EXIST WITHIN 300 NM EITHER SIDE OF THE AXIS S OF 11N. SOME INTERACTION WITH A LARGE UPPER LOW TO THE NNW IS TRIGGERING A NARROW LINE OF SHOWERS WITHIN 180 NM AHEAD OF THE AXIS N OF 12N. A LOW AMPLITUDE TROPICAL WAVE IS ALONG 43W SOUTH OF 15N MOVING W NEAR 10 KT. THIS WAVE IS SLIGHTLY MORE DISCERNIBLE COMPARED TO YESTERDAY BASED ON SATELLITE IMAGES. SHOWER/TSTM ACTIVITY IS DISORGANIZED BUT HAS BECOME STRONGER AND EXPANDED IN COVERAGE FROM 9N-13N BETWEEN 40W-49W. HOWEVER...BECAUSE OF THE LINEAR APPEARANCE OF THE CONVECTION IT IS MORE LIKELY ASSOCIATED WITH THE ITCZ. A TROPICAL WAVE IS ALONG 56W S OF 16N MOVING W NEAR 10 KT. THIS WAVE AT LEAST IN PART SPAWNED THE DEVELOPMENT OF TROPICAL DEPRESSION SEVEN. THE WAVE APPEARED TO HAVE SPLIT...THE SOUTHERN PORTION IS PROPAGATING W WITH SLIGHT VEERING IN THE LOW LEVEL CLOUDS ABOUT THE AXIS. THIS IS THE LOW AMPLITUDE FEATURE THAT WILL BE TRACKED. ISOLATED TO SCATTERED SHOWERS ARE WITHIN 200 NM EITHER SIDE OF THE AXIS. TROPICAL WAVE ALONG 95W/96W HAS MOVED INTO THE EPAC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N14W 8N22W 10N42W 10N62W. BESIDES FOR THE CONVECTION DISCUSSED IN THE TROPICAL WAVES SECTION...SCATTERED MODERATE/STRONG IS MOVING OFF THE W COAST OF AFRICA E OF 18W FROM 10N-15N ASSOCIATED WITH A WELL DEFINED TROPICAL WAVE AND LOW PRES SYSTEM THAT WILL LIKELY MOVE OFF THE COAST LATER TODAY. SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM S OF THE AXIS BETWEEN 16W-21W. ...DISCUSSION... THE GULF OF MEXICO... A FAIR AMOUNT OF UPPER LEVEL MOISTURE LIES OVER MUCH OF THE GULF N OF 24N. THIS SEEMS MOSTLY ASSOCIATED WITH UPPER DIFFLUENCE BETWEEN AN UPPER HIGH OVER CENTRAL MEXICO NEAR 23N101W WITH RIDGING EXTENDING ACROSS THE GULF ALONG 27N AND BROAD WESTERLY FLOW OVER THE SOUTHERN U.S. HOWEVER...MOST OF THE DEEP MOISTURE OR SHOWER ACTIVITY HAS DISSIPATED DURING THE OVERNIGHT HOURS LEAVING ONLY ISOLATED SHOWERS EMBEDDED IN THE MOISTURE PLUME. A SFC TROUGH WAS ANALYZED IN REGION EARLIER...HOWEVER SFC OBS AND QUIKSCAT DATA SUGGEST THAT THE TROUGH HAS DISSIPATED. S OF 24N....MOISTURE IS HIGH LEVEL MOISTURE IS MORE SCATTERED IN NATURE. THE PATCH OF SHOWERS AND TSTMS IN THE E BAY OF CAMPECHE EARLIER THIS MORNING HAS DISSIPATED. ISOLATED SHOWERS ARE N OF CUBA MOVING TOWARDS THE KEYS. BUT OVERALL...DEEP MOISTURE IS VERY LIMITED. SFC WINDS HAVE VEERED MORE SOUTH-SOUTHEASTERLY THIS MORNING. THESE WINDS ARE LIGHT DUE TO THE WEAK PRES GRAD IN PLACE. LITTLE PATTERN CHANGE IS EXPECTED OVER THE NEXT DAY OR TWO. GFS SUGGESTS THAT A COLD FRONT MAY ENTER THE NW GULF ON WED. THE CARIBBEAN SEA... THE WEATHER IN THE CENTRAL CARIBBEAN IS VERY QUIET...THANKS TO DRY STABLE AIR ALOFT TO THE SOUTH OF AN UPPER ANTICYCLONE CENTERED JUST N OF HISPANIOLA. MODERATE SUBSIDENCE LIES BETWEEN 69W AND 81W. THERE IS A LITTLE MORE MOISTURE IN THE E CARIBBEAN WITH MAINLY MID-HIGH LEVEL CLOUDINESS AND ISOLATED SHOWERS E OF 69W ACROSS THE LESSER ANTILLES. THIS IS MAINLY ASSOCIATED WITH DEBRIS MOISTURE FROM TROPICAL DEPRESSION SEVEN. SIMILAR WEATHER EXISTS IN THE W CARIBBEAN WHERE A FAIR AMOUNT OF MOISTURE WITH EMBEDDED SCATTERED SHOWERS ARE FOUND W OF 80W. THIS ACTIVITY IS ASSOCIATED WITH AN UPPER LEVEL LOW WHICH IS SEEN SPINNING ON WATER VAPOR IMAGES MOVING OVER THE YUCATAN PENINSULA. MUCH MORE ORGANIZED SHOWERS AND TSTMS ARE OVER CENTRAL AMERICA AND S MEXICO WHERE UPPER DIFFLUENCE IS STRONGER AND THERE IS ENHANCEMENT IN THE LOW LEVELS FROM TROPICAL WAVES IN THE EPAC AND THE ITCZ. AT THE SURFACE...TRADES ARE FAIRLY LIGHT 10 TO 15 KT WITH A WEAK PRESSURE GRADIENT LEFT S OF FLORENCE. THE ATLANTIC OCEAN... HURRICANE FLORENCE AND TROPICAL DEPRESSION SEVEN ARE THE HIGHLIGHTS. FLORENCE IS ROUNDING THE SUBTROPICAL RIDGE...WHICH COVERS THE REGION FROM 43W-66W...AND HAS BEGAN ITS RECURVATURE. AN UPPER TROUGH LIES TO THE W OF THIS RIDGE OFF THE E COAST OF THE U.S. WHICH HAS CAUSED THE SIGNIFICANT BREAK IN THE RIDGE SUPPORTED THIS STEERING REGIME FOR FLORENCE. SCATTERED MODERATE CONVECTION EXISTS FROM 29N-33N BETWEEN 64W-67W. ANOTHER MORE WIDESPREAD BATCH OF CONVECTION LIES TO THE N STRETCHED OUT BY THE UPPER TROUGH. LONG PERIOD SWELL ASSOCIATED WITH FLORENCE HAS BEGUN REGISTERING ON MOST EAST COAST BUOYS...THUS DANGEROUS SURF IS EXPECTED FROM FLORIDA THROUGH NEW ENGLAND AND WILL PERSIST OVER THE NEXT COUPLE OF DAYS. SEE STATEMENTS FROM LOCAL WEATHER SERVICE OFFICES FOR DETAILS ON COASTAL CONDITIONS. ABOUT 900 NM TO THE SE OF FLORENCE LIES T.D. 7. UNLIKE FLORENCE THIS IS A SMALL SYSTEM WITH SCATTERED MODERATE CONVECTION FOUND FROM 17N-21N BETWEEN 54W-57W. FOR MORE DETAILS REFER TO THE SPECIAL FEATURE SECTION. FARTHER EAST...A MID TO UPPER LOW IS CENTERED NEAR 27N36W. ISOLATED TO SCATTERED SHOWERS/TSTMS ARE SPINNING CYCLONICALLY AROUND THE UPPER LOW FROM 25N-32N BETWEEN 28W-38W. A LARGE MID-UPPER RIDGE IS CENTERED JUST S OF THE CANARY ISLANDS WITH THE RIDGE AXIS EXTENDING SWWARD TO NEAR 11N41W. A WELL-DEFINED TROPICAL WAVE AND LOW-MID LEVEL LOW PRES SYSTEM IS MOVING OFF THE COAST OF AFRICA GENERATING SCATTERED SHOWERS AND TSTMS E OF 18W FROM 10N-15N. $$ CANGIALOSI