000WTNT43 KNHC 190255TCDAT3TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER 1NWS NATIONAL HURRICANE CENTER MIAMI FL AL0820111100 PM EDT THU AUG 18 2011SATELLITE IMAGES DURING THE LAST FEW HOURS BEFORE SUNSET INDICATEDTHAT THE LOW-LEVEL CIRCULATION OF THE WAVE OVER THE WESTERNCARIBBEAN SEA WAS BECOMING BETTER DEFINED WITH LOW CLOUDS MOVINGWITHIN NORTHWESTERLY FLOW OFFSHORE OF THE COAST OF NORTHEASTERNHONDURAS. MICROWAVE DATA FROM THE PAST SEVERAL HOURS CONFIRM THATTHE SYSTEM HAS A LOW-LEVEL CIRCULATION AND A RECENT 0134Z SSMISPASS EVEN HAS A WEAK RING FEATURE IN THE 37 GHZ CHANNEL.SIGNIFICANT 24H PRESSURE FALLS OF 3 TO 4 MB HAVE ALSO BEEN OBSERVEDAT BUOY 42057...WHICH HAVE LONG BEEN A HALLMARK OF TROPICAL CYCLONEFORMATION. DVORAK ESTIMATES OF T2.0 FROM BOTH TAFB AND SAB...INADDITION TO THE ABOVE DATA...SUPPORT ADVISORIES BEING INITIATED ONA TROPICAL DEPRESSION. A PEAK 1-MIN WIND OF 27 KT FROM THE BUOYAND EARLIER ASCAT DATA SUGGEST AN INITIAL INTENSITY OF ABOUT 30 KT. THE DEPRESSION DOES NOT HAVE MUCH TIME TO STRENGTHEN BEFORETHE CIRCULATION INTERACTS WITH THE NORTHERN COAST OF HONDURAS.ONLY MODEST STRENGTHENING IS FORECAST...WHICH IS IN GOOD AGREEMENTWITH THE MODEL CONSENSUS. GIVEN HOW CLOSE THE SYSTEM IS TOLAND...IT IS ALSO QUITE POSSIBLE THE DEPRESSION MAY NOT STRENGTHENAT ALL AND WEAKEN OVER THE HIGHER TERRAIN OF HONDURAS.THE INITIAL MOTION ESTIMATE IS 270/10. A MID-LEVEL RIDGE OVER THEGULF OF MEXICO SHOULD GENERALLY STEER THE SYSTEM TO THE WEST OVERTHE NEXT SEVERAL DAYS. THIS SCENARIO IS SUPPORTED BY MOST OF THEGLOBAL MODELS...WITH THE GFDL FORECAST OF THE DEPRESSION MOVINGINTO THE SOUTHERN BAY OF CAMPECHE BEING CONSIDERED AN UNLIKELYSOLUTION. THE NHC FORECAST LIES BETWEEN THE DYNAMICAL MODELCONSENSUS AND THE ECMWF MODEL.FORECAST POSITIONS AND MAX WINDSINIT 19/0300Z 15.4N 82.1W 30 KT 35 MPH 12H 19/1200Z 15.5N 83.4W 30 KT 35 MPH 24H 20/0000Z 15.7N 84.9W 35 KT 40 MPH...INLAND 36H 20/1200Z 15.9N 86.6W 35 KT 40 MPH...OVER WATER 48H 21/0000Z 16.2N 88.5W 35 KT 40 MPH 72H 22/0000Z 17.0N 93.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 23/0000Z...DISSIPATED$$FORECASTER BLAKE/BROWN
000WTNT43 KNHC 192043TCDAT3TROPICAL STORM HARVEY DISCUSSION NUMBER 4NWS NATIONAL HURRICANE CENTER MIAMI FL AL082011500 PM EDT FRI AUG 19 2011EARLIER REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFTINDICATED THAT TROPICAL DEPRESSION EIGHT WAS ON THE VERGE OFBECOMING A TROPICAL STORM. SINCE THAT TIME...THE CONVECTIVEBANDING HAS BECOME MORE PRONOUNCED AND SATELLITE ESTIMATES FROM SABAND TAFB HAVE INCREASED TO 45 KT. BASED ON THESE DATA...THEDEPRESSION WAS UPGRADED TO TROPICAL STORM HARVEY AT 1800 UTC AND ISNOW ESTIMATED TO HAVE WINDS OF 40 KT. THE NEXT AIRCRAFT ISSCHEDULED TO REACH THE STORM NEAR 00Z.THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 280/10. THERE IS NOCHANGE IN THE SYNOPTIC REASONING FOR THE TRACK FORECAST. ALOW/MID-LEVEL RIDGE OVER THE GULF OF MEXICO AND THE NORTHERN GULFCOAST IS EXPECTED TO GRADUALLY STRENGTHEN DURING THE NEXT 48-72HOURS...AND THIS SHOULD STEER THE CYCLONE GENERALLY WESTWARD TOWEST- NORTHWESTWARD THROUGH ITS LIFETIME. ONE CHANGE SINCE THE LASTADVISORY IS THAT THE GUIDANCE ENVELOPE AND THE FORECAST TRACK HAVESHIFTED A LITTLE TO THE NORTH...BRINGING THE CENTER BRIEFLY OVERTHE BAY OF CAMPECHE BETWEEN 48-72 HOURS. THE NEW FORECAST TRACK ISIN THE CENTER OF THE GUIDANCE ENVELOPE NEAR THE VARIOUS CONSENSUSMODELS.CURRENT CONVECTIVE TRENDS AND GOOD CIRRUS OUTFLOW IN THENORTHWESTERN SEMICIRCLE SUGGEST HARVEY SHOULD CONTINUE TOSTRENGTHEN UNTIL LANDFALL IN BELIZE. THE NEW INTENSITY FORECASTCALLS FOR A PEAK INTENSITY OF 55 KT NEAR LANDFALL IN BEST AGREEMENTWITH THE SHIPS AND LGEM MODELS. THEREAFTER...HARVEY SHOULD SLOWLYWEAKEN AND EVENTUALLY DISSIPATE OVER SOUTHEASTERN MEXICO. THEREARE TWO NOTES ABOUT THE INTENSITY FORECAST. FIRST...THE RAPIDINTENSIFICATION INDEX OF THE SHIPS MODEL SHOWS A 40 PERCENT CHANCEOF 25 KT OF INTENSIFICATION DURING THE NEXT 24 HOURS...AND THEINTENSITY PROBABILITIES TABLE SHOWS A 13 PERCENT CHANCE OF HARVEYBEING A HURRICANE IN 24 HOURS. SECOND...THE INTENSITIES LATER INTHE FORECAST PERIOD COULD REQUIRE ADJUSTMENT IF THE CENTER MOVESFARTHER OUT INTO THE BAY OF CAMPECHE THAN CURRENTLY FORECAST.FORECAST POSITIONS AND MAX WINDSINIT 19/2100Z 16.5N 84.7W 40 KT 45 MPH 12H 20/0600Z 16.7N 86.1W 45 KT 50 MPH 24H 20/1800Z 17.1N 87.9W 55 KT 65 MPH 36H 21/0600Z 17.6N 89.9W 40 KT 45 MPH...INLAND 48H 21/1800Z 18.0N 91.9W 30 KT 35 MPH...INLAND 72H 22/1800Z 18.5N 96.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 23/1800Z...DISSIPATED$$FORECASTER BEVEN
00WTNT43 KNHC 200253TCDAT3TROPICAL STORM HARVEY DISCUSSION NUMBER 5NWS NATIONAL HURRICANE CENTER MIAMI FL AL0820111100 PM EDT FRI AUG 19 2011DATA FROM THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT THISEVENING INDICATE THAT THE CENTER OF HARVEY WAS LOCATED JUST NORTHOF THE COAST OF HONDURAS. THIS WAS A LITTLE SOUTH AND EAST OF THEEARLIER ESTIMATES AND REQUIRED A RELOCATION ON THE 0000 UTCINTERMEDIATE ADVISORY. THE AIRCRAFT ALSO REPORTED A MAXIMUM 700 MBFLIGHT-LEVEL WIND OF 53 KT AND BELIEVABLE SFMR WINDS OF 45-50 KT. ADROPSONDE THAT JUST MISSED THE CENTER MEASURED A MINIMUM PRESSUREOF 997 MB WITH 32 KT AT THE SURFACE. THIS SUGGESTS THAT THE MINIMUMPRESSURE IS AROUND 994 MB... A DROP OF ABOUT 11 MB SINCE THISMORNING. THESE DATA SUPPORT AN INITIAL INTENSITY OF 50 KT. ENVIRONMENTAL CONDITIONS ALONG THE FORECAST TRACK ARE CONDUCIVE FORADDITIONAL STRENGTHENING. HARVEY WILL BE TRAVERSING VERY WARMWATER AND SHEAR IS EXPECTED TO REMAIN LIGHT. THE ONLY INHIBITINGFACTOR IS ITS CLOSE PROXIMITY TO LAND. THE OFFICIAL FORECASTASSUMES THAT HARVEY WILL MOVE A LITTLE NORTH OF DUE WEST ANDBE FAR ENOUGH OFFSHORE TO TAKE ADVANTAGE OF THE FAVORABLEENVIRONMENT. THE NEW INTENSITY FORECAST IS NEAR THE UPPER END OFTHE GUIDANCE...IN CLOSEST AGREEMENT WITH THE STATISTICAL SHIPS ANDLGEM MODELS. THE NEW FORECAST NOW CALLS FOR HARVEY TO BECOME AHURRICANE BEFORE REACHING THE COAST OF BELIZE IN ABOUT 24 HOURS.AFTER LANDFALL...STEADY WEAKENING IS PREDICTED AND HARVEY IS LIKELYTO BECOME A REMNANT LOW OVER SOUTHERN MEXICO IN 2-3 DAYS.BASED ON THE AIRCRAFT FIXES THE INITIAL MOTION IS 275/8...A LITTLESLOWER THAN PREVIOUSLY ESTIMATED. HARVEY SHOULD CONTINUE MOVINGWESTWARD TO WEST-NORTHWESTWARD TO THE SOUTH OF A LOW- TO MID-LEVELRIDGE ALONG THE NORTHERN COAST OF THE GULF OF MEXICO. THE TRACKMODELS ARE IN FAIRLY GOOD AGREEMENT ON THIS SCENARIO. HOWEVER...THE 0000 UTC GUIDANCE SHIFTED A LITTLE SOUTHWARD...PRIMARILY DUE TOTHE SOUTHEASTWARD RELOCATION OF THE CENTER. THIS REQUIRED A SOUTHWARD ADJUSTMENT OF THE NHC TRACK AND THE NEW OFFICIAL FORECASTREMAINS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE.FORECAST POSITIONS AND MAX WINDSINIT 20/0300Z 16.2N 85.2W 50 KT 60 MPH 12H 20/1200Z 16.4N 86.6W 55 KT 65 MPH 24H 21/0000Z 16.8N 88.5W 65 KT 75 MPH...INLAND 36H 21/1200Z 17.3N 90.7W 40 KT 45 MPH...INLAND 48H 22/0000Z 17.7N 93.0W 25 KT 30 MPH...INLAND 72H 23/0000Z 18.5N 96.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 24/0000Z...DISSIPATED$$FORECASTER BROWN/BLAKE
000WTNT43 KNHC 212044TCDAT3TROPICAL DEPRESSION HARVEY DISCUSSION NUMBER 12NWS NATIONAL HURRICANE CENTER MIAMI FL AL082011400 PM CDT SUN AUG 21 2011VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT THELOW-LEVEL CENTER OF HARVEY HAS EMERGED OVER THE EXTREME SOUTHERNBAY OF CAMPECHE...FARTHER NORTH THAN PREVIOUSLY ESTIMATED. THEINITIAL INTENSITY OF 25 KT IS UNCHANGED FROM THE PREVIOUS ADVISORYAND IS BASED PRIMARILY ON CONTINUITY. NOW THAT THE CENTER IS BACKOVER VERY WARM WATERS AND IN A RELATIVELY LOW SHEAR ENVIRONMENT...THERE IS SOME POTENTIAL FOR STRENGTHENING...ESPECIALLY SINCE THELOW-LEVEL CIRCULATION REMAINS FAIRLY WELL DEFINED. THEREFORE...THENEW OFFICIAL FORECAST SHOWS HARVEY STRENGTHENING BACK TO A TROPICALSTORM BEFORE IT MOVES INLAND OVER MEXICO.THE INITIAL MOTION ESTIMATE IS 290/12. HARVEY IS EXPECTED TO MOVEGENERALLY WEST-NORTHWESTWARD IN THE VERY SHORT TERM. THE TRACKSHOULD BEND A BIT MORE TO LEFT BEFORE REACHING THE SOUTHEASTERNCOAST OF MEXICO AS HARVEY MOVES UNDERNEATH A DEEP-LAYER RIDGECENTERED OVER THE SOUTHERN PLAINS. THE OFFICIAL NHC TRACK FORECASTHAS BEEN ADJUSTED NORTHWARD PRIMARILY DUE TO THE CENTER RELOCATIONAND REMAINS ON THE NORTHERN SIDE OF THE GUIDANCE ENVELOPE IN BESTAGREEMENT WITH THE ECMWF AND GFS MODEL SOLUTIONS.THIS FORECAST NECESSITATES THE ISSUANCE OF A TROPICAL STORM WARNINGFOR A SMALL PORTION OF MEXICAN COAST BORDERING THE SOUTHWESTERNGULF OF MEXICO. FORECAST POSITIONS AND MAX WINDSINIT 21/2100Z 18.6N 93.8W 25 KT 30 MPH 12H 22/0600Z 19.0N 95.4W 35 KT 40 MPH 24H 22/1800Z 19.3N 97.3W 25 KT 30 MPH...INLAND 36H 23/0600Z 19.5N 99.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 23/1800Z...DISSIPATED$$FORECASTER KIMBERLAIN/BRENNAN