WPC }v niOvO 29~ī4][sPf |3/KG HxCq}x~sp~3BJ)M+&%Ӯѱ9M" \+B_kD]O=(G;TFމ$eNY#;{+U>( Qɇ{EQU;*3>m h},^z.NMDU)#>U N %M 0:S^ w4 m 0uc 1u 72i 0w 0 0 0< 0 0 0 0D 1 72N"N 1 1+ 1 19 1"K"mmm\\oz\trot0(,,,,0(0(9 Z6Times New Roman RegularX($USUS.,Ԍd.s [r.f.,aBackup3|xU Whatelese TPCmesoscale WFOsgridded NWS JTWCAWIPS IFPS TCM TCMs(;3$2#  0  .3  0  3#37=CIQYag1.a.i.(1)(a)(i)1)a) i)(O;$0  2#  a  .3  0` (#(#(b$0  0` (#(#2#   .3  0 ` (#` (#(xir$0  0` (#(#0 ` (#` (#2#(  0  )3  0 (# (#($0  0` (#(#0 ` (#` (#0 (# (#2#(  a  )3  0h(#(#(F$0  0` (#(#0 ` (#` (#0 (# (#0h(#(#2#(   )3  0h(#h(#($0  0` (#(#0 ` (#` (#0 (# (#0h(#(#0h(#h(#2#  0  )3  0(#(#({$0  0` (#(#0 ` (#` (#0 (# (#0h(#(#0h(#h(#0(#(#2#  a  )3  0p(#(#(F$0  0` (#(#0 ` (#` (#0 (# (#0h(#(#0h(#h(#0(#(#0p(#(#2#     )3  0p(#p(#  pHGaeimquy}Bullet ListBullets List2  F    hCEIMQUY]aAutoList122222222i)1)a) hCEIMQUY]aAutoList222222222i)1)a) hCEIMQUY]aAutoList322222222i)1)a) hCEIMQUY]aAutoList422222222i)1)a) h"Icgkosw{Large BulletLarge Bullet    e         !USUS.,  _r XX  $M%V(OaPTropicalCycloneWorkingGroupforPopulating r WFOGeneratedWindForecastGrids  TeamDecisions ( s#XXT#PREFACE   P *,X,` XX*Tropicalcyclonewindforecastshavesignificantimplicationsfordecisionmakersastheserelate  < totheprotectionoflife,property,andeconomicinterests.Therefore,tropicalcyclonewind  ( forecastinformationmustbecreatedandpresentedresponsiblygiventheopportunityforforecast   errorandrelatedpotentialnegativeconsequences. r Fortropicalcyclones,theTropicalPredictionCenter(TPC),theCentralPacificHurricaneCenter J  (CPHC)andtheJointTyphoonWarningCenter(JTWC),hereinreferredtoastropicalcyclone 6  centers,arecharteredtoproduceresponsible windforecastsinbothtimeandspacefortheir "  users.IfinanywaythissynopticwindforecastaffectsaWeatherForecastOffices(WFO)   countywarningarea(CWA)ormarineareaofresponsibility(MAR),itistheWFOstaskto   responsiblyaddmesoscaledetailtobetterservicetheirlocalusers.Theintentistocomplement t theTPCforecastinlocalproducts.Moreso,itisrequiredforWFOstoproducetheirwind ` forecastinformationingriddedform,whichincludestimesof(high)impactweathersuchas L tropicalstormsandhurricanes. 8 However,adeterministiconlyapproachoutto120hours(currenttrackforecastlimit)oreven  168hours(somepublicproducts)shouldnotbeconsideredasresponsibleorsatisfactory.Since n theNationalWeatherService(NWS)intendstobegindisseminatingWFOgriddedwind Z forecastsduringthemiddleofthe2003hurricaneseason(October),ateamwasassembledto F facilitateTPCandcoastalWFOsthroughthisuncomfortablyanxious,yetexciting,endeavor. 2 ThespiritofthisdocumentisalsointendedtoencompassWFOresponsibilitiesinthePacificas  theyrelatetointeractionswiththeCPHCandtheJTWC.        `     h FORWARD  !\ AftermeetingMarch5and6atNWSHeadquarters,theteamadoptedthefollowingteam "H positionstatement,methodologyforproducingWFOInteractiveForecastPreparationSystem #4 (IFPS)generatedwindforecastgridsforthisseason,andneartermsolutionstobeimplemented $   byJune1,2003.Initialdiscussionsfordevelopinglongtermsolutionswerealsoheld. ~% ! ЀXX  j&" #XX #ޗXXTEAMPOSITIONSTATEMENT T(!$ #XXޗ #   (Hp3 " 3"   3 2H3  0    Tropicalcyclonecentersaretheofficialsourceofthetropicalcycloneforecast,regardlessof R)"% itsform(e.g.textual,graphical,orgridded). 3 ݌>*#&(#(# Ќ  " 3"   3-2H3  0    WhenapplyingtropicalcyclonecentersforecaststoalocalCWAand/orMAR,theWFO ,%( willnotdepictwindinformationatagreaterimpliedskilllevelthanthatofthetextTropical -&) CycloneForecast/Advisory(TCM)productasitrelatestothedistributionofthe34,50,and -|'* (Oa ( (  64knot(kt)windradiiinbothtimeandspace.However,theWFOmayaddmesoscaledetail r asnecessary.XX  3-Z݌^(#(# Ќ  #XX#  (Hpp " 3"   32H3  0    WFOabilitytoproduceaccurateandviablegriddedwindforecasts(speedanddirection) ^  duringtropicalcycloneevents(in2003)maybeseverelyimpairedifrequirementstosupport J  fieldoperationsatboththetropicalcyclonecentersandcoastalWFOs(asstatedinthe 6  OperationalRequirementsDocumentsforboththeAdvancedWeatherInteractiveProcessing "  System[AWIPS]andInteractiveForecastPreparationSystem/GraphicalForecastEditor   [IFPS/GFE]havenotbeenapproved,developedandimplemented. 3݌ (#(# Ќ      " 3"   32H3  0    ThereisanurgentoperationalneedforWFOstoreceivetropicalcyclonecenterswind `  forecastingriddedform(e.g.TCMproduct)tobeusedastheinitialfieldwhenpopulating L  localwindforecastgrids.Meetingthisneedwillminimizepotentialconfusionforusers, 8  fosterconsistencyinthegriddedwindforecastbetweenWFOswithrespecttotheNational $  DigitalForecastDatabase,andrelievetheoverwhelmingworkloadfortheWFOswhomight   otherwisebeforcedtomanuallycreatewindforecastgridsfromscratch. 3!݌n (#(# Ќ  " 3"   32H3  0    TheavailabilityofgriddedTCMsforthe2003hurricaneseasonshouldbegiventhehighest F priorityintheAWIPSoperationalbuildandinterimpatchreleases. 3H݌2(#(# Ќ  " 3"   32H3  0    EffortsshouldbeexpeditedtofacilitatethegenerationofgriddedTCMs,tofacilitatethe   disseminationofgriddedTCMstoWFOsviaproperAWIPScommunicationavenues,andto  facilitatetheingest,display,andmanipulationofgriddedTCMswithintheAWIPS/D2D p environmentandtheGFE. 3݌\(#(# Ќ     H " 3"   32H3  0    Theexplicitdepictionofexactwindspeedvaluesrepresentsonlyoneformofdeterministic 4 typeinformation.Deterministictypeinformationcanalsobecategoricalinnature.This   pointshouldbeexploitedforthesafetyofourusers.Categoricaltypewindinformationmost ~  likelycanbeproducedinIFPSfortropicalcyclones(in2003)aslongasGFEsmarttoolsare j  rapidlydevelopedtomeetthischallenge. 3݌V!(#(# Ќ  " 3"   3h2H3  0    Explicitwindforecastinformationisappropriatewithinthefirst24hourssincethistime .# periodmatchesupwellwiththeissuanceoftropicalcyclonewarnings;however,thevalueof $  deterministiconlywindinformation,especiallyinexplicitform,decreasesrapidlybeyond 3h݌%!(#(# Ќ    24hours. %" " 3"   3!2H3  0    Whenpresentingdeterministiconlywindforecastgrids(eitherexplicitlyorcategorically) 'X!$ duringtropicalcycloneevents,thereisthedangerofusersfocusingongridlocations (D"% associatedwiththemoreextremewindspeedswhilenotallowingfortrackerrorforthose )0#& gridlocationswithlesserspeeds.Althoughnearbygridlocationsmayhavelowervalues *$' associatedwiththem,theystillwarrantcloseattention;thisproblemincreaseswithincreasing z+%( timewithintheforecast.Theoutcomecouldbeanoverreactionforinterestsatgridlocations f,%) whichdepictthemoreextremevaluesandanunwarrantedsenseofsafetyforthosedepicted R-&* P Fr   withlowerwindspeeds.Categoricalwindspeedswithtimehelpsconveythisuncertainty F withintheforecasted34ktwindradii,butdoesnotconveyanyuncertaintyforwindspeeds 2 outsideofthe34ktradii. 3!!݌(#(# Ќ  " 3"   3&2H3  0    Inaddition,giventheaverageforecasterrorofatropicalcyclonestrackand/orintensity,  therecouldbesignificantproblemsassociatedwithotherwinddependentelementssuchas   seaheightandstormsurge.Forexamplewhendeterministiconlyinformationisprovided,   errorsinthewinddirectionforecast(e.g.onshoreversusoffshore)couldresultinusers  t incorrectlyassumingthelocationandcorrespondingmagnitudeofthemaximumstormsurge,  ` especiallyinlaterforecastperiods. 3&&݌ L (#(# Ќ  " 3"   3)2H3  0    Fortheshortterm(2003season),theteamrecommends: 3))݌j$ (#(# Ќ    (x p  " 3 "     3+223  0    nonewrequirements(e.g.windgustgrids)belevieduntilallappropriate 3+H+݌B (#(# Ќ  ݀resourcesareinplace. .    (x x  " 3 "     3,223  0    nonewrequirementsbeleviedduringthe2003tropicalcycloneseason. 3, -݌ (#(# Ќ  " 3 "     3-223  0    thepostingofdisclaimersbemandatorywithgriddedwindforecastdataandanyrelated  graphicalproducts(e.g.WFOwebpages).Recommenddisclaimerprovided. 3-.݌(#(# Ќ  " 3 "     3Q/223  0    appropriateNWSformatterswhichproducetextualproducts(publiczoneforecasts,  coastalwatersforecast,etc.)beconfiguredtocorrectlyhandlebothexplicitand  categoricaldeterministictypewindinformationandremaininaccordancewithagency p directives. 3Q//݌\(#(# Ќ  " 3 "     3T1223  0    atropicalcycloneinterpolationtoolbeprovidedonGFE. 3T11݌H(#(# Ќ  " 3"     3O2223  0    thatGFEbeconfiguredtoaccommodatethedepictionof >34kt, >50kt,and >64 z4 ktwindgridsbothduringcreationandinpostprocessing(forgraphics). 3O22݌f (#(# Ќ  " 3"     33223  0    thegriddedTCMissuebeamongthehighestprioritiesinfutureAWIPSoperationalbuild R  releasesuntilsatisfactorilyimplementedintooperations. 33#4݌>(#(# Ќ    ! !  (Hpx " 3"   362H3  0    Forthelongterm(beyondthe2003season),theteamhighlyrecommends: 36.6݌(#(# Ќ  ";"  ;60  2H23  0(#(#  developmentworkforprobabilistictropicalcyclonewindgridsbesupportedandthe   agencysoperationalsupportstructurebegintomakepreparationsforitsusage.;6,7݌!(#(# Ќ    (Hpp  METHODOLOGY  $X"  Thesolutionsreachedwereconsensusdecisionsandbaseduponthefollowingpremises: %D # " 3"   392H3  0    WFOswillnotproducewindgridsinanymoredetailthanthesynopticguidanceprovidedby b'"% thetropicalcyclonecenters.ThispromotesconsistencybetweenWFOsandtheirrespective N(#& tropicalcyclonecenter.WFOswillnotbemodifyingtheTCMforecastotherthantoaddress :)#' localmesoscalefeatures. 399݌&*$((#(# Ќ  " 3"   3;2H3  0    WFOswillusethe34,50and64ktwindradiifromtheTCMproductasguidance. 3;;݌+&*(#(# Ќ  " 3"   3<2H3  0    IfagriddedTCMisnotavailable,WFOsshoulduseacceptedtropicalcyclonesoftware -(, products(Hurrevac,Hurtrak,etc)fordisplayofTCMwindradiiandmanual .|)- %V %F %  populating/interpolationofIFPSwindgrids. 3<<݌(#(# Ќ  " 3"   3>2H3  0    ForWFOs,anexplicitgriddedwindforecastisreasonablewithinthefirst24hoursand  supportstropicalcyclonewarnings. 3>>݌t(#(# Ќ  ݀" 3"   3@2H3  0    ForWFOs,a griddedwindforecastuptoandincludingacapof64kts(hurricaneforce) L  winds2436hoursinadvancesupportstropicalcyclonewatches. 3@@@݌8 (#(# Ќ  " 3"   3{A2H3  0    Sinceforecastsofhurricaneforcewindradiibeyond36hoursarenotavailableintheTCM,  ` WFOswillfocusuponthe50ktwindradiifrom3772hours.Thiswillallowforthe  L  identificationofatropicalcyclonetobeatleastasintenseasastrongtropicalstorm(if  8  necessary). 3{AA݌$ (#(# Ќ  " 3"   3C2H3  0    Beyond72hours,windradiiinformationarenotavailableintheTCM;onlycenterlocation   andmaximumsustainedwindsareprovided.Ifcenterlocationsareprovided,thentheWFO   willfocusupondistributingwindscappedat34ktsinanorganizedcyclonicfield. 3CC݌ (#(# Ќ  " 3"   3uE2H3  0    Beyond120hours,notropicalcycloneforecastinformationisavailableintheTCM. \ Therefore,WFOswillnotforecasttropicalstormsandhurricanes(thatis,winds>34kt H associatedwithanorganizedsystemoftropicaloriginhavingconvectivecloudsand 4 precipitationaboutaclosedlowlevelcycloniccirculation).However,fortendencypurposes  p intheextendedforecastanduponWFOdiscretion,the121168hourforecastcandepict  \ windsupto30kts.>"HThechoicefor30ktsavoidspotentialconfusionwhichcanresultfrom H theautomatedroundingof33ktsto35ktswhengeneratinggraphicalwindbarbs,andwith 4 associatedtextualformatterswhichconvertktstomilesperhour(thenroundtothenearest5   mph).> 3uEE݌ (#(# Ќ  I" 3"   3J2H3  0    Categoricalwindspeedswhicharethresholdcappedaccordingtotheforecastperiodwill  avoidoveralarmingusers,maintainconsistencywithtropicalcyclonecenters,accountfor  decreasingskillinextendedperiods,andprovidesomeindicationofthepresenceofa l tropicalcycloneanditsassociatedhazards. 3J3J݌X (#(# Ќ  " 3 "   36L2H3  0    ExceptionsmaybepermittedforthePacificRegionastheJTWCissues100ktwindradii 0"  andWFOGuamissueswatches48hoursinadvance. 36LcL݌#l!(#(# Ќ  ޗXXNEARTERMSOLUTIONS#XXޗM#ԀFOR2003     p      x  %0!$  " 3 "   3oN2H3  0    WindSpeedValuesWithinthe34ktWindRadii_N  3oNN݌'#&(#(# Ќ  024hours  )$( UsewindforecastfromtheTCM(griddedifavailable)asguidanceforlocatingthe34,50and *%) 64ktwindradiitomaintainsynopticconsistency.Applylocalknowledgeandmesoscale z+&* expertisetoproduceexplicit/deterministicwindspeedforecastsforallCWA/MARgridsusinga f,'+ fullcontinuumofvaluesuptothemaximumsustainedwindvalueprovidedbytropicalcyclone R-(, $M $e $  centersvO.Q    R 2536hours   UsewindforecastfromtheTCM(griddedifavailable)asguidanceforlocatingthe34,50and t 64ktwindradiitomaintainsynopticconsistency.Applylocalknowledgeandmesoscale ` expertisetoproduceexplicit/deterministicwindspeedforecastsforallCWA/MARgridsusinga L  fullcontinuumofwindspeedsupto64kts.For64ktsandaboveusethecappedvalueof64kts 8  forgridpointsinsidethe64ktwindradii. $ t   3772hours   L  UsewindforecastfromtheTCM(griddedifavailable)asguidanceforlocatingthe34ktand50  8  ktwindradiitomaintainsynopticconsistency.Applylocalknowledgetoproduceexplicit/ $  deterministicwindspeedforecastsforallCWA/MARgridsusingafullcontinuumofwind   speedsupto50kts.For50ktsandaboveusethecappedvalueof50ktsforgridpointsinside   the50ktwindradii.IR    73120hours  p UseforecastfromtheTCMasguidanceforlocatingthecenterpositionstomaintainsynoptic ` consistency.DuringHurricaneHotlineConferenceCallcoordinatethebestmeansof L determiningthe34ktradii(extrapolationof34ktradiifrom72hour,modelguidance, 8 coordinationconsensus,etc.).Applylocalknowledgetoproduceexplicit/deterministicwind $t speedforecastsforallCWA/MARgridsusingafullcontinuumofwindspeedsupto34kts.For ` 34ktsandaboveusethecappedvalueof34ktsforgridpointsinsidethe34ktwindradii.V L  121168hours     h      $ UsetraditionalguidanceandWFOdiscretiontoproduceexplicit/deterministicwindspeed  forecastsforallCWA/MARgridsusingafullcontinuumofwindspeedsupto30kts.The  choicefor30ktsavoidspotentialconfusionwhichcanresultfromtheautomatedroundingof33  ktsto35ktswhengeneratinggraphicalwindbarbs,andwithassociatedtextualformatterswhich  convertktstomilesperhour(thenroundtothenearest5mph).Y p " 3 "   3c\2H3  0    WindSpeedValues Outsidethe34ktWindRadii  3c\\݌H!(#(# Ќ  0168hours  `  $#t! Usedeterministicwindspeedvalues. $`"   " 3 "   3]2H3  0    WindDirectionValuesInsideorOutsidethe34ktWindRadii  3]^݌%8!$(#(# Ќ  0168hours  '#& Usedeterministicwinddirectionvalues. (#'   " 3 "   3A_2H3  0    WindGustValuesInsideorOutsidethe34ktWindRadii  3A_q_݌*%)(#(# Ќ  Atthistimethereisnorequirementtoproduceagustgridthisyearoverthemarinezones.Asan \,'+ option,ifaWFOdesirestoproduceagustgriditwillhavetobecreated withlittleorno H-(, guidance.=\ 4.)- Ї  (Hpp " 3"   3a2H3  0    Disclaimer 3a b݌(#(# Ќ     (Hpp _a Windsinandneartropicalcyclonesshouldbeusedwithcautionduetouncertaintyinforecast  track,size,andintensity.