000 AXNT20 KNHC 011753 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT SEP 1 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. ...SPECIAL FEATURE... TROPICAL STORM FELIX IS CENTERED NEAR 12.5N 64.5W AT 01/1800 UTC OR ABOUT 365 NM SSE OF SAN JUAN PUERTO RICO AND ABOUT 465 NM SE OF SANTO DOMINGO IN THE DOMINICAN REPUBLIC MOVING W NEAR 16 KT. THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE RESERVE HURRICANE HUNTER PLANE WAS 999 MB. MAXIMUM SUSTAINED WIND SPEED HAS INCREASED TO 60 KT WITH GUSTS TO 75 KT...THIS MEANS THAT FELIX IS VERY CLOSE TO HURRICANE INTENSITY. FELIX IS ON A STRENGTHENING TREND WITH THE CIRCULATION APPEARING TIGHTER AND SPIRAL RAIN BANDS BECOMING BETTER DEFINED AS SEEN ON SATELLITE AND THE MARTINIQUE RADAR. IR IMAGES ALSO SHOW A FAIRLY TIGHT INNER CORE WITH NUMEROUS MODERATE/SCATTERED STRONG CONVECTION WITHIN 45 NM OF THE CENTER. SCATTERED MODERATE /ISOLATED STRONG CONVECTION IS ELSEWHERE WITHIN 180 NM OF THE CENTER IN RAINBANDS. THIS CONVECTION EXPANDS FURTHER W...WITHIN 240 NM...IN THE SW QUADRANT WHERE THERE IS ENHANCED CONVERGENCE. STEADY STRENGTHENING IS FORECAST OVER THE NEXT COUPLE OF DAYS AS ATMOSPHERIC AND OCEANIC CONDITIONS ARE FAVORABLE ACROSS THE CARIB SEA AND FELIX COULD BECOME A HURRICANE LATER TONIGHT OR SUNDAY. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... WELL DEFINED TROPICAL WAVE IS TILTED ALONG 19N34W 6N36W MOVING W 15 KT. A 1009 MB LOW SITS ALONG THIS WAVE AXIS NEAR 13N36W. VIS IMAGES SHOW THE LOW-LEVEL CENTER EXPOSED TO THE E OF SCATTERED MODERATE CONVECTION LOCATED WITHIN 300 NM TO THE W OF THE CENTER. THIS WAVE IS OBVIOUSLY FEELING THE EFFECTS OF ELY SHEAR PRODUCED BY A STRONG UPPER HIGH CENTERED TO THE N. FURTHER DEVELOPMENT IS POSSIBLE AS THE SYSTEM MOVES W INTO A MORE FAVORABLE ENVIRONMENT OVER THE NEXT DAY OR TWO. IT IS NOTABLE THAT THIS WAVE IS PRODUCING A LARGE PERTURBATION IN THE ITCZ ACROSS A RATHER LARGE AREA. TROPICAL WAVE HAS BEEN ADJUSTED W ALONG 77W/78W S OF 20N MOVING W 15 KT. THIS ADJUSTMENT WAS BASED MOSTLY ON THE PRESENTATION ON SATELLITE WHICH SHOWS THE ASSOCIATED CLOUD MASS DEEPENING AND EXPANDING FROM JAMAICA TOWARD THE N COAST OF COLOMBIA. SCATTERED SHOWERS AND TSTMS ARE EMBEDDED WITHIN 120 NM OF THE AXIS...MOST ORGANIZED FROM 15N-18N. RECENT VISIBLE IMAGES SHOWS A POSSIBLE VAGUE INVERTED V-SHAPE TO THE CLOUDS SUGGESTING THAT THIS WAVE COULD BE HIGHER AMPLITUDE. IN ADDITION...A CLUSTER OF SHOWERS AND TSTMS HAVE DEVELOPED OVER THE WRN BAHAMAS APPROACHING EXTREME S FLA...AT LEAST PARTIALLY RELATED TO THIS WAVE. TROPICAL WAVE IS ALONG 87W S OF 21N MOVING W 10-15 KT. THIS WAVE IS DIFFICULT TO LOCATE TODAY IN THE AVAILABLE DATA. LITTLE SHOWER ACTIVITY IS IN THE VICINITY OF THIS ANALYZED FEATURE. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N16W 14N33W 9N38W 11N58W. BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 360 NM S OF THE AXIS E OF 27W. DISCUSSION... GULF OF MEXICO... VERY WEAK SFC PRES PATTERN ACROSS THE GULF TODAY CHARACTERIZED BY A PAIR OF WEAK TROUGHS IN THE REGION. ONE TROUGH EXTENDS FROM A 1012 MB LOW OVER THE FL PANHANDLE TO 28N88W. DOPPLER RADAR DATA DEPICTS NARROW LINES OF SCATTERED SHOWERS AND TSTMS MAINLY WITHIN 90 NM W OF THE TROUGH AXIS. THIS ACTIVITY WILL LIKELY INCREASE AND EXPAND THIS AFTERNOON ESPECIALLY OVER N AND CENTRAL FLORIDA WHEN LOCAL EFFECTS CONTRIBUTE. THE OTHER TROUGH RUNS N-S NEAR THE COAST OF MEXICO ALONG 97W S OF 26N. THIS TROUGH IS MORE ACTIVE...IN TERMS OF MOISTURE...WITH SCATTERED SHOWERS AND TSTMS NOTED WITHIN 120 NM EITHER SIDE OF THE AXIS. ANOTHER AREA EXPERIENCING SOMEWHAT ORGANIZED PRECIP IS THE NW GULF NEAR THE TX AND WRN LA COAST N OF 27N W OF 93W. THIS WEATHER IS ASSOCIATED WITH A STALLED FRONT DRAPED ACROSS THE U.S. GULF COAST. THE REMAINDER OF THE AREA IS RELATIVELY TRANQUIL WITH PATCHES OF ISOLATED SHOWERS AND LIGHT AND VARIABLE WINDS. MODELS SUGGEST LITTLE CHANGE OVER THE NEXT 24 HOURS. CARIBBEAN SEA... ATTENTION REMAINS FOCUSED ON TROPICAL STORM FELIX MOVING ACROSS THE SE CARIB. A PRECIP REPORT FROM TRINIDAD SHOWS 1.5 INCHES FELL ON THE ISLAND YESTERDAY. ADDITIONAL RAINFALL OF 1-2 INCHES IS EXPECTED ACROSS THE SRN WINDWARD ISLANDS WITH TOTAL ACCUMULATIONS OF UP TO 7 IN. RAINFALL AMOUNTS OF 2-4 INCHES ARE POSSIBLE OVER THE OFFSHORE ISLANDS OF VENEZUELA AND THE NETHERLANDS ANTILLES ABC ISLANDS. FOR MORE DETAILS ON FELIX REFER TO THE SPECIAL FEATURE SECTION ABOVE. A TROPICAL WAVE HAS BECOME MORE ACTIVE S OF JAMAICA...REFER TO THAT SECTION ABOVE FOR DETAILS. BESIDES FOR ALL OF THAT...THERE A COUPLE OF SHOWERS OVER WRN CUBA AND A PORTION OF THE NW CARIB ASSOCIATED WITH MOISTURE ROTATING AROUND AN UPPER TROUGH IN THE REGION. MID TO UPPER RIDGING N OF FELIX IS EXPECTED TO EXPAND W STEERING FELIX TO THE W OR WNW OVER THE NEXT FEW DAYS ACROSS THE CARIB SEA. ATLANTIC OCEAN... SCATTERED SHOWERS AND TSTMS EXIST N OF 29N BETWEEN 60W AND 68W. THE LOW-LEVEL FEATURE HELPING TO TRIGGER THIS ACTIVITY IS A PRE-FRONTAL TROUGH WHICH CURVES INTO OUR AREA ALONG 32N68W 30N74W. UPPER WLY FLOW AND DIFFLUENCE BETWEEN AN UPPER HIGH CENTERED NEAR 28N68W AND AN UPPER LOW NEAR 29N53W IS ENHANCING THIS MOISTURE PLUME AND SPREADING DEBRIS CLOUDINESS AND ISOLATED SHOWERS FROM 23N-28N BETWEEN 50W-60W. A CLUSTER OF SHOWERS AND TSTMS HAS RECENTLY DEVELOPED OVER THE WRN BAHAMAS APPROACHING S FLA. THIS ACTIVITY APPEARS RELATED IN PART TO THE N EXTENSION OF THE CARIB WAVE. THE REMAINDER OF THE AREA IS RELATIVELY QUIET DOMINATED BY A STRONG MID TO UPPER HIGH CENTERED NEAR 23N30W. STRONG ELY FLOW ON THE S SIDE OF THIS HIGH IS SHEARING THE LARGE TROPICAL WAVE AND AREA OF LOW PRES IN THE E ATLC. ELSEWHERE AT THE SFC...TYPICAL SUBTROPICAL RIDGING IS INTERRUPTED A BIT BY THE AFOREMENTIONED TROUGHING IN THE W ATLC...NEAR BERMUDA...AND A LARGE NEARLY STATIONARY LOW PRES SYSTEM IN THE N CENTRAL ATLC. THIS HAS ALLOWED TRADES TO BE MOSTLY LIGHT TO MODERATE ACROSS THE AREA...EXCEPT FOR IN THE VICINITY OF TROPICAL STORM FELIX. $$ CANGIALOSI