Typhoon News | Central Weather Bureau

PTA represents a domain that a typhoon/tropical storm center will likely moves in ... As a typhoon approaches Taiwan, the WSP and the WSP-6h usually will be ... Gotomaincontent ::: Warnings Typhoon TyphoonNews TyphoonNews Overall PotentialTrackArea WindRadiiProbability Play Download  Looping RelatedLinks FAQforTyphoon TyphoonNews(©OpenStreetMap) WorkandClassStatusduringNaturalDisasters Download  Chooseone All Region Submit ForecastLength 120h 72h Play Whatdoestyphoonpotentialtrackarea(hereafterPTA)mean? PTArepresentsadomainthatatyphoon/tropicalstormcenterwilllikelymovesinataspecifictime,whichimpliestrackforecastuncertainties.Theseyellowshadedareasdonotrefertothetyphoon/tropicalstormradius,rather,acircleof70%probabilitythatthestormcenterisenteringwithin. WhenwilltheCentralWeatherBureau(CWB)issuePTAproducts? TheCWBwillissuePTAproductsonceatyphoon/tropicalstormexistsoverthewesternNorthPacificortheSouthChinaSea.Thisproductwillbeupdatedevery6hoursuntilthetyphoondissipates. WhatarethecharacteristicsofthePTA? The70%probabilitycircleisobtainedbasedontheCWBofficialtrackforecasterrorstatisticsintherecent5years.TheradiusofPTAcircleincreasesbecausethetrackforecasterrorincreaseswithforecastperiod. WhatarethemajorfactorsaffectingthesizeofthePTA? SizeofthePTAcircleisprimarilyrelatedtotheforecastperiod.However,itisalsoaffectedbythestormmovingspeedanddirection.ThePTAcircleisusuallylargerifatyphoon/tropicalstormisexpectedtomovefastorhaverecurvature. RelatedLinks FAQforTyphoon TyphoonNews(©OpenStreetMap) WorkandClassStatusduringNaturalDisasters Download  Chooseone All Region Submit Play 6-hourlyProbabilities Probabilitiesat6-hourintervalsthattheprobabilitiesthattherangeofwindspeedatthelevel7oftheBeaufortscalewillpassthemajorlocationsinTaiwanduringtheforecastperiod.ThesereferencelocationsareselectedfromtheweatherstationsofCentralWeatherBureau. Region Submit Whatarethetyphoon/tropicalstorm30-ktwindspeedprobabilities(hereafterWSP)andthe6-hourlytyphoon/tropicalstorm34-ktwindspeedprobabilities(hereafterWSP-6h)usedfor? TheWSPandWSP-6harecalculatedbasedontheCWBtrackforecastofthetargetedtyphoonandtheerrorstatisticsoftyphooncenterpositionforecastofrecentyears. CWBWSPproductsprovideinformationaboutprobabilitiesthatthestormradiusofwindspeedofatleast30kt(scalenumberseven(7)oftheBeaufortScale)willpassthroughaspecificlocationinTaiwanareaduringthe120-hourforecastperiod. CWBWSP-6hproductsindicateprobabilitiesthatthestormradiusofwindspeedofatleast34kt(scalenumberseven(7)oftheBeaufortScale)willpassthroughaspecificlocationinTaiwanareaat6-hourtimeintervalsduringthe120-hourforecastperiod. WhatisthedifferencebetweentheWSP-6handtheWSP? Accordingtotheprobabilitytheory,theindividual6-hourprobabilitieswillnotexceedthe120-hourprobabilities,andthecumulative6-hourprobabilitiesfor120hourswillnotbeequaltothesingle120-hourprobabilities;justlikethat,forexample,iftheprobabilityofprecipitation(POP)forthedaytimeis60%andthenighttime70%,thePOPforthewholedaycannotbe130%. WhenwilltheCentralWeatherBureau(CWB)issuetheWSPandtheWSP-6hproduct? Alongwiththetyphoonpotentialtrackareaproduct,theCWBwillalsoissuetheWSPandtheWSP-6hwhenatyphoon/tropicalstormexistsoverthewesternNorthPacificortheSouthChinaSea. Whatdoestheprobabilityindicate? Theprobabilityisameasureofhowlikelyitisthatacertaineventwilloccur.Forexample,WSP80%indicatesthat80timesoutof100forecaststhatthestormradiusof30ktwindspassesthroughagivenlocation,80%fortheWSP-6hindicatesthat80timesoutof100forecaststhatthestormradiusof34ktwindspassesthroughagivenlocationduringanindividualtimeperiod. Whyarethereuncertaintiesintyphoontrackforecast? Uncertaintiesanderrorsexistintyphoonforecastsduetolackingenoughobservationsovertheoceans,andalsolimitedknowledgeonthephysicalprocessesoftyphoonmovementandstructuralchanges. Howtousethisprobabilityproduct? Sincethereareuncertaintiesanderrorsintyphoonforecasts,WSPandWSP-6hproductsalonecannotberegardedasanaidfordecisionmakingduringtyphoonperiod.Duetodifferentriskmanagementconsiderations,thethresholdfordifferentsectorstotakeaproperactionshouldbedeterminedbythedecisionmakerthemselves.PleasealsonotethattheWSPandtheWSP-6hproductdoesnotrepresent,infer,orimplythefollowingcontents:theprobabilityoftyphoonlandfall,thescaleandprobabilityoftyphoon-induceddisasters,andthetimingofCWBtyphoonwarningissuance. DoesthehigherWSPorWSP-6hindicatethestrongerwindsandheavyrainfallmayhappen? AsatyphoonapproachesTaiwan,theWSPandtheWSP-6husuallywillbegettinghigher,andthetyphoon-inducedwindsandrainfallarealsoexpectedtobegreater.However,thevariationofwindsandrainfallmaybesignificantlydifferentwithlocationsduetothetopography,whichshouldnotbepurelydeterminedbytheWSPortheWSP-6h.Forthoseconcernedaboutthelocalwindsandrainfallduringtyphoonwarningperiods,pleaserefertotheCWBofficialspecificforecasts. RelatedLinks FAQforTyphoon TyphoonNews(©OpenStreetMap) WorkandClassStatusduringNaturalDisasters 6-hourlyProbabilities