Explorations in Meteorology 61 Lab 13 Answer Key

ANSWER KEY1. RecordthetrackofHurricaneIsabelbyplottingthelatitude/longitudepairslistedinTable2for0300UTCon

14September2003to1500UTCon17September.Plotthelocationsonthevisiblesatelliteimage(Figure3).NotethatthelatitudeandlongitudegridlinesonFigure3are1°by1°,soyouwillneedtointerpolatethepositionstoproduceanaccuratetrack.

Figure 3 – Visible Satellite Image of Hurricane Isabel from1525 UTC on 15 September 2003 with Latitude and Longitude Gridlines

(Courtesy of the Naval Research Laboratory)

Explorations in Meteorology 62 Lab 13 Answer Key

2. TheNationalHurricaneCenterexpressesvarioushurricaneparametersintermsofaradiusfromthehurricanecenter.Forexample,theNHCmightstatethat50–knotwindsextend60milesnorthwestofthecenter.Toplottheparametersonastandardmapusingalatitude/longitudegrid,itisnecessarytoconvertdistancesinmiles(mi)todegreeslatitudeanddegreeslongitude.Inthetropics,onedegreeoflatitudeorlongitudeequals~70statutemiles.Athigherlatitudes,thespatialextentofonedegreeoflongitudedecreases.Thespatialextentofonedegreelatitudeisconsistenteverywhere.Forthepurposesofthislab,however,use1deglat/lon=70miles.

50mi=0.714deglat/lon 180mi=2.57deglat/lon

100mi=1.43deglat/lon 225mi=3.21deglat/lon

140mi=2deglat/lon 575mi=8.21deglat/lon

150mi=2.14deglat/lon

3. OnFigure4,plotthecenterofHurricaneIsabelusingthelatitudeandlongitudeofthe“current”hurricanepositionlistedinTable2.UseyouranswersaboveandTable3toplottheradiiofthe64-knot(witharedpencil),50-knot(withagreenpencil),and34-knot(withapurplepencil)windsonFigure4.

Figure 4 – Visible Satellite Image of Hurricane Isabel from1525 UTC on 15 September 2003 with Latitude and Longitude Gridlines

(Courtesy of the Naval Research Laboratory)

Explorations in Meteorology 63 Lab 13 Answer Key

4. ExaminetheradiiyoudrewonFigure4.Are thesewinds symmetricorasymmetricabout thecenterofIsabel?

Symmetric

5. Dotheradiiof34-knotwinds(Figure4)extendbeyondthecloudcovernotedintheimage?

Justbarelyonthewesternhalf

6. UseTable3toplottheradiiofthe12-footseas(withabluepencil)onFigure4fromthe“current”hurricanepositionlistedinTable3.

Figure 5 – Visible Satellite Image of Hurricane Isabel from1525 UTC on 15 September 2003 with Latitude and Longitude Gridlines

(Courtesy of the Naval Research Laboratory)

Explorations in Meteorology 64 Lab 13 Answer Key

7. Explainwhytheradiiofthe12-footseasarenotsymmetricabouttheeyeofthehurricane.

Largewavesonthesearesultfrombothstrongtomoderatewindspeedsjustabovethewatersurfaceandthelengthoftimethewatersurfaceexperiencesthesemoderatetostrongwinds.Becausetheradiiofthe12-footseasdonotalignwiththe34kt(orhigher)windsinFigure4,thentheremustbeapressuregradientfieldtothenorthwestofthehurricanethatallowsformoderatewindstooccurforasignificantlengthoftimeacrossthisarea.Mostlikely,thereisahighpressuresystemovertheU.S.coastlinethatinteractswiththelowpressureofthehurricanetogenerateastrongpressuregradienttothenorthwestofthecenterofthehurricane.

8. UsingFigure4,dotheradiiofthe12-footseasextendbeyondthecloudcovernotedintheimage?

Yes

9. OnFigure5,plotthecenterofHurricaneIsabelusingthelatitudeandlongitudeofthe48-hourforecastofhurricanepositionlistedinTable2.UseTable4andFigure5toplottheradiiofthe48-hourforecastpositionofthe64-knot(witharedpencil),50-knot(withagreenpencil),and34-knot(withapurplepencil)winds.

Figure 6 – Visible Satellite Image of Hurricane Isabel from1525 UTC on 15 September 2003 with Latitude and Longitude Gridlines

(Courtesy of the Naval Research Laboratory)

Explorations in Meteorology 65 Lab 13 Answer Key

10. Examine the radii you drew on Figure 5. Are these winds symmetric or asymmetric about the center ofIsabel?

Asymmetric

11. WhatfactorsmightexplainthechangeinsymmetrybetweenthewindradiiyouplottedinFigures4and5?

Thehurricaneismovingintothemid-latitudesanditsspeed,direction,andsymmetrywillbeaffectedbythehigh-andlow-pressurepatternsacrossthisregion.Thesymmetryalsomaybeaffectedbygradientsinwatertemperature(e.g.,GulfStream).

12. TheGeophysicalFluidDynamicsLaboratory inPrinceton,NJ,developedahurricane forecastmodel thatprovidesa forecastofpositionand intensityofahurricaneor tropicalstormupto84hours (3.5days) inadvance. Figure 6displays thismodel’s 84-hour forecast valid for 8:00PMEDTon18September 2003(0000UTCon19September2003).ThemodelplacedthecenterofTropicalStormIsabel(downgradedfromhurricanestatus)oversouthernVirginia.UseFigure6toanswerthefollowingscenario:

It is Monday, September 15, 2003. You are the emergency manager for the CityofBlacksburg,VA (locatedat theblackdotonFigure6).TheVirginiaTech–TexasA&M football game in Blacksburg will be televised nationally on Thursday night,September18.Asell-outcrowdof65,115isexpectedinthestadium.Kickoffissetfor7:00PMEDT.YouarehandedFigure6.Whatmeteorologicalandsocietalfactorsmustyouconsiderwhendecidingtopossiblycancel,reschedule,ormovethegame?Whatdecisionwouldyoumakeregardingthefootballgame?

Answerswillvary regarding thedecision tocancel, reschedule,ormove thegame.Factors thatmaybeconsideredincludethefollowing:(1)pastexperiences(goodorbad)withthismodel,(2)consistencyofthesemodelresultswiththosefromothermodels,(3)amountofrainforecast,(4)knowledgeofwhatamountofrainleadstolocalizedflooding(especiallyflashfloodingthroughmountainousterrain),(5)availabilityofshelterinthestadiumfordownpours/lightning/wind,(6)experiencewithinformationdisseminationmechanisms(e.g.,media)togetthewordoutaboutanychangesingametime(i.e.,youmightbeabletodelaythedecisionanother24hours),and(7)normalairportflighttimes/patternstobringinvisitorstothegame(i.e.,willtheweatherkeepvisitorsfromarrivinginthefirstplace?).