000 AXNT20 KNHC 031800 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON SEP 03 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... HURRICANE FELIX HAS WEAKENED BUT IS STILL EXTREMELY DANGEROUS AND COULD RESTRENGTHEN. FELIX IS CENTERED NEAR 14.2N 78.7W AT 03/1800 UTC OR ABOUT 265 NM EAST OF CABO GRACIAS A DIOS ON THE NICARAGUA/HONDURAS BORDER...MOVING W AT 18 KT. THE MINIMUM CENTRAL PRESSURE ESTIMATED FROM AIR FORCE HURRICANE HUNTER AIRCRAFT DATA IS 950 MB. MAXIMUM SUSTAINED WIND SPEED IS 125 KT WITH GUSTS TO 155 KT. THIS MAKES FELIX A CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSON SCALE. 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 INCLUDING THE LATEST WATCH AND WARNING INFORMATION. FELIX CONTINUES ON A RATHER QUICK WNW PATH STEERED BY A STRONG RIDGE TO ITS N. IR SATELLITE IMAGES DEPICT SOME STRUCTURAL CHANGES TO THE SHAPE AND SIZE OF THE CONVECTIVE PATTERN OVER TIME WITH THE EYEWALL NOT QUITE AS SYMMETRIC AS EARLIER. NUMEROUS MODERATE TO STRONG IS WITHIN 90 NM E AND 45 NM W SEMICIRCLES. A VERY STRONG BAND...CONTAINING SIMILAR CONVECTION...IS IN THE NW SEMICIRCLE WITHIN 175 NM OF THE CENTER. AN AREA OF LOW PRES...ANALYZED 1012 MB...IS CENTERED NEAR 11N40W. THIS LOW PRES SYSTEM HAS BEEN ON A VERY SLOW SW DRIFT OVER THE PAST FEW DAYS AND HAS GENERALLY CHANGED LITTLE. THE LOW LEVEL CIRCULATION REMAINS WELL DEFINED BUT SHOWER ACTIVITY IS DISORGANIZED. DESPITE THE LACK OF IMPROVEMENT IN STRUCTURE THERE STILL IS SOME POTENTIAL FOR THIS SYSTEM TO BECOME A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF DAYS. A LOW PRES AREA IS OFF THE GEORGIA COASTLINE CENTERED NEAR 31N79W...ESTIMATED TO BE 1013 MB. VISIBLE SATELLITE IMAGERY SHOWS SOME IMPROVEMENT IN ORGANIZATION WITH LOW-LEVEL TURNING EASILY APPARENT. AT THE MOMENT...THIS LOW IS STILL SOMEWHAT FRONTAL IN NATURE WITH A SHIELD OF LOW CLOUDS LINEARLY SHAPED TO THE E OF THE CIRCULATION. HOWEVER...THERE IS SOME POTENTIAL FOR SLOW TROPICAL DEVELOPMENT AS IT DRIFTS EASTWARD DURING THE NEXT COUPLE OF DAYS. DISORGANIZED SHOWERS AND TSTMS ARE WITHIN 180 NM MOSTLY TO THE E OF THE LOW-LEVEL CENTER. ...TROPICAL WAVES... LARGE TROPICAL WAVE IS ALONG 25W/26W S OF 22N MOVING W 15 KT. THIS WAVE IS EMBEDDED WITHIN A STRETCHED GYRE COVERING CLOSE TO A 15 DEG E-W AREA. A FEW SURROUNDING SHIP/BUOY OBSERVATIONS AND A PARTIAL QSCAT PASS SUGGEST THAT THIS CYCLONIC TURNING IS AT THE SFC. THE LATEST VISIBLE IMAGES SHOW ROTATION CONCENTRATED ALONG THE WAVE AXIS NEAR 14N...AND A LOW WILL LIKELY BE ADDED TO THE NEXT SYNOPTIC MAP TO REFLECT THIS. EVEN THOUGH THE WAVE STRUCTURE HAS IMPROVED A BIT...SHOWER ACTIVITY REMAINS VERY LIMITED LIKELY SUPPRESSED BY THE STABLE LOW TO MID LEVEL AIR SURROUNDING THIS FEATURE. TROPICAL WAVE IS ALONG 56W S OF 22N MOVING W 10 KT. SATELLITE IMAGERY SHOWS A CLASSIC INVERTED V-SHAPE TO THE LOW CLOUD FIELD. SFC OBSERVATIONS MATCH THE SATELLITE SIGNATURE WITH LOWER PRESSURES CLOSER TO THE WAVE AXIS AND WINDS TURNING CYCLONICALLY. SHOWER ACTIVITY REMAINS MINIMAL AND CONFINED TO THE INTERSECTION OF THE ITCZ FROM 10N-12N BETWEEN 54W-58W...SUPPRESSED BY SINKING AIR PRODUCED BY AN UPPER TROUGH. TROPICAL WAVE IS OVER PORTIONS OF CENTRAL AMERICA ALONG 87W/88W MOVING W 10-15 KT. THIS ONCE ACTIVE WAVE IS NO LONGER EASILY DISCERNIBLE IN ANY OF THE AVAILABLE DATA...THEREFORE THE CURRENT POSITION IS BASED ON FORWARD EXTRAPOLATION. SHOWERS AND TSTMS ARE ISOLATED AT BEST IN THE REGION. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 16N17W 12N27W 10N42W 12N52W 10N63W. SCATTERED SHOWERS AND TSTMS COVER A LARGE AREA ROUGHLY FROM 6N-10N E OF 38W ASSOCIATED WITH CROSS EQUATORIAL SWLY FLOW. DISCUSSION... GULF OF MEXICO... THE WRN CORNER OF THE GULF...ROUGHLY W OF 96W...IS EXPERIENCING SCATTERED SHOWERS AND TSTMS. THIS ACTIVITY IS PRIMARILY ASSOCIATED WITH UPPER DIFFLUENCE BETWEEN AN ELONGATED UPPER RIDGE OVER THE SE STATES AND AN UPPER LOW OVER SW TEXAS AND N MEXICO. SEA LEVEL PRES ANALYSIS DOES SHOW DECENT TROUGHING...SO THE COMBINATION BETWEEN SELY LOW-LEVEL RETURN FLOW AND SOME CONVERGENCE IS LIKELY A CONTRIBUTING FACTOR TO THIS PERSISTENT AREA OF UNSETTLED WEATHER. THE TAIL END OF A SFC BOUNDARY EXTENDS ACROSS N CENTRAL FL TO 28N85W. THIS TROUGH IS ASSOCIATED WITH A BROAD LOW PRES LOCATED OFF THE GEORGIA COAST. DOPPLER RADAR IS DETECTING ISOLATED SHOWERS NEAR THE BOUNDARY BUT NOT MUCH TO TALK ABOUT. MUCH OF THE REMAINDER OF THE GULF IS RELATIVELY QUIET WITH A 1020 MB HIGH PARKED ACROSS THE MIDDLE GULF NEAR 27N89W. THIS IS ALLOWING WINDS TO BE VERY LIGHT ACROSS THE E AND CENTRAL GULF. CARIBBEAN SEA... EXTREMELY DANGEROUS HURRICANE FELIX IS THE FOCUS AS IT MOVES ACROSS THE WESTERN CARIBBEAN. FELIX IS EXPECTED TO PRODUCE 5 TO 8 INCHES ACROSS NORTHERN HONDURAS AND NORTHEASTERN NICARAGUA ...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 12 INCHES. THESE RAINS COULD PRODUCE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. SEVERAL WATCHES AND WARNINGS ARE IN EFFECT. FOR DETAILS AND REFERENCES SEE SPECIAL FEATURE SECTION ABOVE. SINKING AIR DRAWN S FROM THE ATLC AND PARTIALLY ENHANCED BY THE STRONG CIRCULATION OF FELIX LIES ACROSS MUCH OF THE AREA E OF 70W ...PRODUCING A FAIR WEATHER DAY ACROSS THIS AREA. WINDS AND SEAS HAVE ALSO DECREASED HERE WITH THE HURRICANE NOW WELL TO THE W. ATLANTIC OCEAN... A STALLED FRONT LIES ACROSS OUR NRN BORDER EXTENDING FROM 29N69W TO A LOW PRES SYSTEM CENTERED OFF THE GEORGIA COAST NEAR 31N79W. A SFC TROUGH HANGS SW FROM THE LOW TO CENTRAL FLORIDA. SCATTERED SHOWERS AND TSTMS ARE MOST CONCENTRATED WITHIN 180 NM OF THE LOW AND WITHIN 60 NM OF THE TROUGH AXIS N OF 28N. ISOLATED SHOWERS AND TSTMS ARE ELSEWHERE WITHIN 120 NM OF THE FRONT. FOR MORE DETAILS REFER TO THE SPECIAL FEATURE SECTION ABOVE. HIGH LEVEL CLOUDINESS ORIGINATING FROM THIS ACTIVITY SPREADS MUCH FARTHER S DRIVEN BY STRONG NLY FLOW BETWEEN AN UPPER HIGH CENTERED NEAR 24N68W AND AN UPPER LOW NEAR 25N53W. BOTH OF THESE UPPER FEATURES HAVE BEEN SLOW TO MOVE OVER THE PAST COUPLE OF DAYS. A WEAK SFC TROUGH...LIKELY LINKED TO A MID LEVEL LOW...IS OVER THE BAHAMAS GENERATING A FEW SHOWERS. ANOTHER WEAK AREA OF LOW PRES IS CENTERED FARTHER E NEAR 30N57W. THIS WEAK LOW IS ATTACHED TO A COLD FRONT WHICH EXTENDS VERY FAR N. ELSEWHERE AT THE SFC...A 1020 MB HIGH IS NEAR 25N69W...WHILE MODERATE RIDGING DOMINATES THE E ATLC S OF A 1030 MB HIGH NEAR 47N20W. THIS PATTERN HAS ALLOWED TRADES TO REMAIN LIGHT TO MODERATE ACROSS MOST OF THE AREA. IN THE E ATLC...A DOMINATING UPPER HIGH REMAINS PARKED ACROSS THE AREA CENTERED NEAR 24N20W. ABUNDANT DRY AIR ALOFT IS EMBEDDED WITHIN THIS RIDGE. STRONG E TO SELY FLOW NEAR THE SW PERIPHERY OF THIS HIGH IS SHEARING THE SPECIAL FEATURE NEAR 11N40W. $$ CANGIALOSI