Explorations in Meteorology 28 Lab 7 Answer Key

ANSWER KEYPart I: Analyses of Station Model Plots

1. Youwillseeboth3-letterand4-letterstationidentifications(IDs)onweathermapsandtablesofdata.Four-letterIDsofstationsinthecontinentalU.S.beginwitha“K,”followedbythe3-letterIDsoftenseenelsewhere.The3-letter ID typically isanabbreviation for thenameofacityorairportwhere the reportingstation islocated.Forexample,KTLHistheIDforTallahassee,FL.MatchthefollowingstationIDswithitslocation(i.e.,cityandstate).

1. KPHX i a. Atlanta,GA(Hartsfield–JacksonInternationalAirport)2. KDFW g b. Miami,FLInternationalAirport3. KMIA b c. TinkerAirForceBase,OK4. KPHL j d. Minneapolis–St.Paul,MNInternationalAirport5. KMSP d e. SanFrancisco,CAInternationalAirport6. KATL a f. Chicago,IL(O’HareInternationalAirport)7. KJFK h g. Dallas–FortWorth,TXInternationalAirport8. KSFO e h. NewYorkCity,NY(JohnF.KennedyInternationalAirport)9. KORD f i. Phoenix,AZ(PhoenixSkyHarborInternationalAirport)10. KTIK c j. Philadelphia,PAInternationalAirport11. KSLC l k. Baltimore,MD–Washington,DCInternationalAirport12. KBWI k l. SaltLakeCity,UTInternationalAirport

2. Using Figure 8, draw isotherms at intervals of 5 degrees Fahrenheit. Be sure to label both ends of theisopleth.ThenumbersrepresentairtemperatureindegreesFahrenheit.Thedotsrepresentthelocationsoftheobservingsites.

Figure 8 – Student Exercise for Drawing Isopleths

Explorations in Meteorology 29 Lab 7 Answer Key

Figure 9 – Map of Decoded NWS Surface Data for 17 October 1996 at 0300 UTCfor Sea-Level Pressure Analysis

3. Usetheguidelinesforcontouringweatherdatatodrawisobarsatintervalsof4mbonFigure9.

Explorations in Meteorology 30 Lab 7 Answer Key

4. Inwhichstate(s)isthelowestpressurelocatedonFigure9?

State(s)withlowestpressureCentralKansasintonortheastNebraska

5. Whereisthestrongestpressuregradientlocated?(Hint:Lookforthelocationwiththemostrapidchangefromlowpressuretohighpressureacrossasmalldistance.)

LocationofstrongestpressuregradientCentralNebraska

6. Examinetheisobarsandthewindspeedsatthestations.Describetherelationshipbetweenthepressuregradientandwindspeed.

Strongerwindspeeds (i.e.,15kts to25kts)were locatedwhere thepressuregradientwasstronger (e.g.,SouthernNebraska,Kansas,NorthwestOklahoma).Weakerwinds(i.e.,5ktsto10kts)werelocatedwherethepressuregradientwasweaker(e.g.,Texas,SoutheastOklahoma,Arkansas,Missouri).

7. Describetherelationshipbetweenthepressuretendencyandthedirectionofmovementofthelow-pressuresystem.

Asthecenteroflowpressureapproached,relativelyhighvaluesofpressurewerebeing“replaced”bylowervaluesofpressure.Thepressurewasfallingasthelow-pressuresystemapproached.Inreality,thesurfacepressureinadvanceofthelowdecreased,causingthelowtodevelopeastward.

Explorations in Meteorology 31 Lab 7 Answer Key

Figure 10 – Map of Decoded NWS Surface Data for 17 October 1996 at 0300 UTCfor Air Temperature Analysis

8. Usetheguidelinesforcontouringweatherdatatodrawisothermsatintervalsof5°FonFigure10.

Explorations in Meteorology 32 Lab 7 Answer Key

9. Inwhichstatesarethehighestandlowesttemperatureslocated?

State(s)withlowesttemperatureSouthDakota

State(s)withhighesttemperatureTexas

10. Whereisthestrongesttemperaturegradientlocated?(Hint:Lookforthelocationwiththemostrapidchangefromwarmtocooltemperaturesacrossasmalldistance.)

Locationofstrongesttemperaturegradient–NebraskaPanhandleandnorthwestKansas,extendingnortheastwardto

Minnesota

11. Describeotherweatherchangesthatareassociatedwiththisparticulartemperaturegradient.

Northwindswerelocatednorthwestofthistemperaturegradient.Southwindswerelocatedsoutheastofthegradient.Clear skieswere locatedsouthof thegradient, andcloudyskieswithsomeprecipitationwere locatednorthof thegradient.

Part II: Decoding METARs

Thissectionisrecommendedforadvancedstudentsandmeteorologymajorsonly.DecodingMETARdatacanbeatime-consumingtask;however,METARsareusedfornumerousapplicationsintheNWS,FederalAviationAdministration(FAA),andsomeprivateforecastingcompanies.AlthoughMETARsareencoded,transmitted,anddecodedbycomputerstoday,theabilitytodecodeaMETARstillisagoodskilltolearn,especiallytoanalyzeinternationaldata.

12.(Advanced Students/Meteorology Majors)UsingTable2andtheMETARdecodingguide,decodetheMETARobservationat0019UTCfromMay.Note:KTIKisintheCentralTimezoneandobservesDaylightSavingsTime,whenappropriate.

StationTinkerAirForceBase,OK Temperature(highestprecision)21°CDate3May1999 DewPoint(highestprecision)20°CTime(localtime)7:19PMCDTVisibility1statutemilesAltimeter29.55inHgPrecipitationnotavailableWindDirection80degreesCardinalWindDirectionENEWindSpeed8knots

CurrentWeatherConditions:Largefunnelcloud;thunderstormwithrainandhail

CloudCoverageandHeights:Overcastat2000feet;cumulonimbuscloud

RemarksSection:A tornado is9statutemilessouthwestmovingnortheastward.Frequent inter-cloud,cloud-to-cloud, and cloud-to-ground lightning is occurring. There is a thunderstorm overhead that ismovingnortheastward.Thereis11/4”hail,andthepressureisdecreasingrapidly.

Explorations in Meteorology 33 Lab 7 Answer Key

13. (Advanced Students/Meteorology Majors)UsingtheMETARdecodingguide,decodethefollowingMETARobservationfromSeptember.Note:KNEWisintheCentralTimezoneandobservesDaylightSavingsTime,whenappropriate.

METAR KNEW 251353Z 06025KT 1 1/4SM +RA BR FEW001 BKN011 OVC023 24/23 A2973 RMK AO2 PK WND 06032/1338 SLP065 P0004 T02440228

StationNewOrleans,LA Temperature(highestprecision)24.4°CDate25SeptemberDewPoint(highestprecision)22.8°CTime(localtime)8:53AMCDTVisibility11/4statutemilesAltimeter29.73inHgPrecipitation0.04inchesduringlasthourWindDirection80degreesCardinalWindDirectionENEWindSpeed25knots

CurrentWeatherConditions:Heavyrainandmist

CloudCoverageandHeights:Fewat100feet;brokenat1100feet;overcastat2300feet

Whatdoes“PK WND 06032/1338”mean?Thepeakwindwasfrom60°at32knotsandoccurredat1338UTC.

RemainingRemarks:Sea-levelpressureis1006.5mb;precipitationoverthepasthourtotals0.04inches;stationisfullyautomatedwithaprecipitationdiscriminator.

14. (Advanced Students/Meteorology Majors)Completelyencodethefollowingreportin the correct order.

ASOS–augmentedobservationfromWilmington,NC(ILM)at3:26PMEDTonthe24th:Temperature23°C;dewpoint23°C;altimetersetting29.87"ofHg;skycover is3/8at800feet,5/8at2300feet,and7/8at3000feet,visibility3mileswithathunderstorm,rain,andmist.Windsfromthesouthat13knots,withguststo22knots.

METARKILM241926Z18013G22KT3SMTSRABRSCT008BKN023BKN03023/23A2987

15. (Advanced Students/Meteorology Majors)Plot theMETARreports fromTable3ontheircorrespondingcircleonFigure12.Usethestationmodel formatasshown inFigures1–5.Thesurfacestation locationsareprovidedinFigure6.Whenindicatingskycoveronthestationmodel,usethegreatestamountofcloudcover.Forexample,ifaMETARstatementdisplaysthecloudcoverasFEW021 BKN 050,theamountofskycoveredshouldbedisplayedasbrokenonthestationmodel.YoualsomaychecktoseeifyourplotsareconsistentwiththestationmodelplotsshowninFigure7.

Figure 12 – Station Models for METAR Decoding Exercise