DewDew PointPoint ClimatologyClimatology

ForFor SoutheastSoutheast Minnesota,Minnesota, NortheastNortheast Iowa,Iowa, andand WesternWestern WisconsinWisconsin

WFOWFO LaLa CrosseCrosse ClimatologyClimatology SeriesSeries #17#17

Mary-Beth Schreck Dan Baumgardt NWS La Crosse, WI ObjectivesObjectives

•• BecomeBecome familiarfamiliar withwith climatologicalclimatological hourlyhourly TdTd curvescurves •• UnderstandUnderstand howhow windwind directiondirection affectsaffects TdTd •• BecomeBecome awareaware ofof thethe uniqueunique characteristicscharacteristics ofof KLSEKLSE andand KRSTKRST DataData MethodologyMethodology •• 19611961--19951995 SurfaceSurface HourlyHourly ObservationsObservations – NCDC SAMSON CDROM 1960-1990 – NCDC HUSWO CDROM 1990-1995 – 1965-1972 removed due to station closures: 23 total years possible. • LSE (17) – No 62,63,80,81,85, 91. Removed June 78,82,95. • RST (20) – No 78, 80, 90 • ALO (18) – No 73,74,80,81 • EAU (19) – No 78-81 • MSN: (23) • MCW: (17) – No 73,74,78-81 DataData MethodologyMethodology

•• HourlyHourly dewpointdewpoint calculatedcalculated overover thethe periodperiod ofof recordrecord forfor everyevery dayday ofof thethe yearyear atat eacheach ofof thethe sixsix sites.sites. AlsoAlso donedone hourlyhourly forfor everyevery month.month. •• AverageAverage monthlymonthly dewpointdewpoint categorizedcategorized byby windwind directiondirection waswas calculatedcalculated forfor eacheach sitesite byby month.month. •• AA groupgroup averageaverage waswas calculatedcalculated byby averagingaveraging thethe thethe datadata fromfrom eacheach ofof thethe sixsix sites.sites. •• AA ‘‘perturbationperturbation’’ oror anomalyanomaly (Td(Td’’)) waswas createdcreated byby subtractingsubtracting thethe sitesite dewpointdewpoint (Td)(Td) fromfrom thethe groupgroup averageaverage (Td(Td aveave).). TdTd’’ == TdTd aveave -- TdTd – This perturbation, or Td’, is used to show where the dewpoint varies from the group average. – Shows local or site specific differences more clearly. SynopticSynoptic vs.vs. LocalLocal SignalsSignals

•• AllAll monthsmonths –– whenwhen therethere isis aa synopticsynoptic signal,signal, itit dominatesdominates •• WinterWinter monthsmonths –– synopticsynoptic scalescale tendstends toto havehave moremore influenceinfluence •• SummerSummer monthsmonths –– locallocal signalsignal hashas moremore influenceinfluence – Exchange between soil moisture and water vapor in air – Crop coverage vs. moisture in air – River as moisture source JanuaryJanuary -- JuneJune

Average Hourly Dewpoint - January La Crosse, Wisconsin

12 2.0

11 1.5 10 1.0 0.5 9 Average Hourly Dewpoint - February 0.0 8 La Crosse, Wisconsin -0.5 Dewpoint (F) 7 -1.0 KLSE vs.Group 17 2.0 6 -1.5 (F) Difference Dewpoint 16 1.5 5 -2.0 1.0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 15 0.5 Hour (LT) 14 Average Hourly Dewpoint - March 0.0 13 La Crosse, Wisconsin KLSE Td KLSE Td vs. Group -0.5 Dewpoint (F) Dewpoint

12 KLSE vs. Group -1.0 27 3.0 11 -1.5 Difference (F) Dewpoint 2.5 26 2.0 10 -2.0 25 1.5 123456789101112131415161718192021222324 1.0 Hour (LT) 24 0.5 0.0 23 -0.5 KLSE Td KLSE Td vs. Group

Dewpoint (F) -1.0 22 -1.5 KLSE vs. Group

21 -2.0 (F) Difference Dewpoint -2.5 Average Hourly Dewpoint - April 20 -3.0 La Crosse, Wisconsin 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT) 37 3.0 2.5 KLSE Td KLSE Td vs. Group 36 2.0 1.5 35 1.0 Average Hourly Dewpoint - May 34 0.5 0.0 La Crosse, Wisconsin 33 -0.5

Dewpoint (F) -1.0 50 3.0 32 KLSE vs.Group -1.5 2.5

31 -2.0 (F) Difference Dewpoint 49 2.0 -2.5 Average Hourly Dewpoint - June 48 1.5 30 -3.0 1.0 La Crosse, Wisconsin 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 47 0.5 0.0 Hour (LT) 46 -0.5 60 2.0

Dewpoint (F) -1.0

45 KLSE vs.Group 1.5 KLSE Td KLSE Td vs. Group -1.5 59

Dewpoint Difference (F) Difference Dewpoint 1.0 44 -2.0 58 -2.5 0.5 43 -3.0 57 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 0.0 56 Hour (LT) -0.5 Dewpoint (F)

55 KLSE vs. Group -1.0

KLSE Td KLSE Td vs. Group DifferenceDewpoint (F) 54 -1.5 53 -2.0 123456789101112131415161718192021222324 Hour (LT)

KLSE Td KLSE Td vs. Group JulyJuly -- DecemberDecember

Average Hourly Dewpoint - July La Crosse, Wisconsin

65 2.0 64 1.5 63 1.0 Average Hourly Dewpoint - August 0.5 62 La Crosse, Wisconsin 0.0 61 -0.5 64 2.0 Dewpoint (F)

60 KLSE vs. Group -1.0 63 1.5 59 -1.5 (F) Difference Dewpoint 62 1.0 58 -2.0 0.5 61 123456789101112131415161718192021222324 0.0 60 Hour (LT) -0.5 Average Hourly Dewpoint - September Dewpoint (F)

59 KLSE vs. Group La Crosse, Wisconsin KLSE Td KLSE Td vs. Group -1.0 58 -1.5 (F) Difference Dewpoint 56 2.0 57 -2.0 123456789101112131415161718192021222324 55 1.5 1.0 Hour (LT) 54 0.5 53 KLSE Td KLSE Td vs. Group 0.0 52 -0.5

Average Hourly Dewpoint - October Dewpoint (F)

51 KLSE vs.Group La Crosse, Wisconsin -1.0 50 -1.5 (F) Difference Dewpoint

43 2.0 49 -2.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 42 1.5 Hour (LT) 1.0 41 0.5 KLSE Td KLSE Td vs. Group 40 0.0 Average Hourly Dewpoint - November 39 -0.5 La Crosse, Wisconsin Dewpoint (F)

38 KLSE vs. Group -1.0

37 -1.5 Dewpoint Difference (F) 30 2.0 36 -2.0 29 1.5 123456789101112131415161718192021222324 28 1.0 Average Hourly Dewpoint - December Hour (LT) 0.5 27 La Crosse, Wisconsin 0.0 KLSE Td KLSE Td vs. Group 26 -0.5 17 2.0 Dewpoint (F)

25 KLSE vs. Group -1.0 16 1.5 24 -1.5 (F) Difference Dewpoint 1.0 15 23 -2.0 0.5 14 123456789101112131415161718192021222324 0.0 Hour (LT) 13 -0.5 Dewpoint (F)

12 KLSE vs. Group KLSE Td KLSE Td vs. Group -1.0 11 -1.5 (F) Difference Dewpoint 10 -2.0 123456789101112131415161718192021222324 Hour (LT)

KLSE Td KLSE Td vs. Group TheThe BigBig PicturePicture (All(All Sites):Sites): HourlyHourly DewDew PointsPoints

•• LargerLarger variationvariation overover 2424 hourshours duringduring thethe WinterWinter monthsmonths thanthan SummerSummer monthsmonths ExerciseExercise -- JanuaryJanuary

Average Hourly Dewpoint - January

12 2.0

11 1.5 1.0 10 0.5 9 0.0 8 -0.5 Dewpoint (F) 7 Difference (F) -1.0

6 -1.5 Site vs. Group Dewpoint 5 -2.0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT) JanuaryJanuary –– TdTd variationvariation 66ooFF

Average Hourly Dewpoint - January La Crosse, Wisconsin

12 2.0

11 1.5 ) 1.0 10 ) 0.5 9 0.0 8 -0.5 Dewpoint (F Dewpoint

7 -1.0 KLSE vs. Group

6 -1.5 Dewpoint Difference (F 5 -2.0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324

Hour (LT)

KLSE Td KLSE Td vs. Group ExerciseExercise -- JulyJuly

Average Hourly Dewpoint - July

65 2.0

64 1.5 1.0 63 0.5 62 0.0 61 -0.5 Dewpoint (F) 60 Difference (F) -1.0

59 -1.5 Site vs. Group Dewpoint 58 -2.0 123456789101112131415161718192021222324 Hour (LT) JulyJuly –– TdTd variationvariation 33oo FF

Average Hourly Dewpoint - July La Crosse, Wisconsin

65 2.0

64 1.5 )

63 1.0 ) 0.5 62 0.0 61 -0.5 Dewpoint (F

60 KLSE vs. Group -1.0

59 -1.5 (F Difference Dewpoint 58 -2.0 123456789101112131415161718192021222324

Hour (LT)

KLSE Td KLSE Td vs. Group Exercise:Exercise: LabelingLabeling

Mixing/ET battle Average Hourly Dewpoint - July ET Condensation Sunset La Crosse, Wisconsin Stable PBL Begins Sunrise ET tiny ET still occurring 65

64

63

62

61

Dewpoint (F) Dewpoint 60

59

58 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT)

KLSE Td JulyJuly –– DailyDaily CycleCycle

Average Hourly Dewpoint - July La Crosse, Wisconsin

65 2.0

64 Sunset 1.5 ) Co nd Mixing/ET battle en 1.0 63 E sa ) T t tin io T y n E 0.5 62 Stable PBL Begins ET still occurring 0.0 61 Sunrise -0.5 Dewpoint (F

60 KLSE vs. Group -1.0

59 -1.5 (F Difference Dewpoint 58 -2.0 123456789101112131415161718192021222324

Hour (LT)

KLSE Td KLSE Td vs. Group ExerciseExercise –– WetWet andand DryDry

Average Hourly Dewpoint - July La Crosse, Wisconsin

65 2.0

64 Sunset 1.5 ) Co nd Mixing/ET battle en 1.0 63 E sa ) T t tin io T y n E 0.5 62 Stable PBL Begins ET still occurring 0.0 61 Sunrise -0.5 Dewpoint (F

60 KLSE vs. Group -1.0

59 -1.5 (F Difference Dewpoint 58 -2.0 123456789101112131415161718192021222324

Hour (LT)

KLSE Td KLSE Td vs. Group Answers:Answers: WetWet andand DryDry YearsYears

Hourly Dewpoint - July - La Crosse WI

65

64

63

62

61

Dewpoint (F) Dewpoint 60

59

58 0 2 4 6 8 1012141618202224 Hour (LST) LSE July LSE Wet 1976 - Dry RealReal LifeLife ExampleExample –– JulyJuly 20042004

Hourly Dew point - July - La Crosse WI

72

67 LSE July 26 2004 Ridge

LSE July Average Td 62

LSE July 10 2004 Ridge Dewpoint (F) Dewpoint 57 After Rains

52 0 6 12 18 24 Hour (LST) ARXARX ForecastForecast TrendsTrends

Normal Diurnal cycle (condensation)

Wrong trend Southerly NW, post-frontal Moisture Advection dry air advection. 0Z 4Z Non-climo diurnal curve TheThe BigBig PicturePicture (All(All Sites):Sites): HourlyHourly DewDew PointsPoints

•• LargerLarger variationvariation overover 2424 hourshours duringduring thethe WinterWinter monthsmonths thanthan SummerSummer monthsmonths •• TdTd risesrises duringduring eveningevening hourshours fromfrom AprilApril throughthrough October;October; 99 toto 1010 pmpm peakpeak –– VegetationVegetation relatedrelated EveningEvening TdTd RisesRises

Average Hourly Dewpoint - April La Crosse, Wisconsin

37 3.0 Average Hourly Dewpoint - May 2.5 36 2.0 La Crosse, Wisconsin 1.5 35 1.0 34 0.5 50 3.0 Average Hourly Dewpoint - June 0.0 2.5 49 33 -0.5 2.0 La Crosse, Wisconsin 1.5 Dewpoint (F) -1.0 48

32 KLSE vs.Group -1.5 1.0 60 2.0 47 0.5 31 -2.0 Dewpoint Difference (F) -2.5 0.0 59 1.5 46 30 -3.0 -0.5 1.0 Dewpoint (F) Dewpoint -1.0 58

1 2 3 4 5 6 7 8 9 101112131415161718192021222324 45 KLSE vs. Group -1.5 0.5 57 Hour (LT) 44 -2.0 Difference (F) Dewpoint -2.5 0.0 56 KLSE Td KLSE Td vs. Group 43 -3.0 -0.5 Dewpoint (F)

123456789101112131415161718192021222324 55 KLSE vs.Group -1.0

Hour (LT) (F) Difference Dewpoint 54 -1.5 53 -2.0 Average Hourly Dewpoint - July KLSE Td KLSE Td vs. Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 La Crosse, Wisconsin Hour (LT)

65 2.0 KLSE Td KLSE Td vs. Group

64 1.5 )

63 1.0 ) 0.5 62 0.0 Average Hourly Dewpoint - August 61 -0.5 La Crosse, Wisconsin Dewpoint (F

60 KLSE vs. Group -1.0

59 -1.5 (F Difference Dewpoint 64 2.0 58 -2.0 63 1.5 123456789101112131415161718192021222324 62 1.0 Hour (LT) 0.5 61 Average Hourly Dewpoint - September KLSE Td KLSE Td vs. Group 0.0 60 La Crosse, Wisconsin -0.5 Dewpoint (F) 59 -1.0 KLSE vs. Group 56 2.0 58 -1.5 (F) Difference Dewpoint 55 1.5 57 -2.0 1.0 123456789101112131415161718192021222324 54 0.5 Hour (LT) 53 0.0 KLSE Td KLSE Td vs. Group 52 -0.5 Dewpoint (F)

51 KLSE vs.Group -1.0

50 -1.5 (F) Difference Dewpoint 49 -2.0 123456789101112131415161718192021222324 Hour (LT)

KLSE Td KLSE Td vs. Group TheThe BigBig PicturePicture (All(All Sites):Sites): HourlyHourly DewDew PointsPoints

•• LargerLarger variationvariation overover 2424 hourshours duringduring thethe WinterWinter monthsmonths thanthan SummerSummer monthsmonths •• TdTd risesrises duringduring eveningevening hourshours fromfrom AprilApril throughthrough October;October; 99 toto 1010 pmpm peakpeak –– VegetationVegetation relatedrelated •• TransitionTransition fromfrom 22 TdTd peakspeaks toto 11 inin OctoberOctober –– GrowingGrowing seasonseason endingending TransitionTransition fromfrom 22 peakspeaks toto 11

Average Hourly Dewpoint - September La Crosse, Wisconsin

56 2.0 55 1.5 54 1.0 0.5 53

0.0 (F) 52 -0.5 Dewpoint (F) 51 -1.0 KLSE vs. Group Dewpoint Difference 50 -1.5 49 -2.0

1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT) Average Hourly Dewpoint - October KLSE Td KLSE Td vs. Group La Crosse, Wisconsin

43 2.0

42 1.5 )

41 1.0 ) 0.5 40 0.0 39 -0.5 Dewpoint (F 38 -1.0 KLSE vs. Group

37 -1.5 (F Difference Dewpoint 36 -2.0 123456789101112131415161718192021222324

Hour (LT) Average Hourly Dewpoint - November KLSE Td KLSE Td vs. Group La Crosse, Wisconsin

30 2.0 29 1.5 28 1.0 0.5 27

0.0 (F) 26 -0.5 Dewpoint (F)

25 Group vs. KLSE -1.0 Dewpoint Difference 24 -1.5 23 -2.0

1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT)

KLSE Td KLSE Td vs. Group UniqueUnique toto KLSE:KLSE: HourlyHourly

•• TdTd isis lowerlower thanthan thethe groupgroup inin winterwinter months;months; higherhigher thanthan groupgroup inin summersummer monthsmonths –– EspeciallyEspecially atat nightnight –– ImportantImportant forfor fogfog developmentdevelopment –– HighestHighest perturbationperturbation isis inin Aug/SeptAug/Sept TdTd LowerLower ThanThan GroupGroup inin WinterWinter

Average Hourly Dewpoint - February La Crosse, Wisconsin

17 2.0 16 1.5 1.0 15 0.5 14 0.0 13 -0.5 Dewpoint (F)

12 Group KLSE vs. -1.0

11 Dewpoint Difference (F) 1.5F lower than group -1.5 10 -2.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour (LT)

KLSE Td KLSE Td vs. Group TdTd HigherHigher ThanThan GroupGroup inin SummerSummer

Average Hourly Dewpoint - August La Crosse, Wisconsin

64 2F Higher than 2.0 group overnight 63 1.5 1.0 62 0.5 61

0.0 (F) 60 -0.5 Dewpoint (F)

59 KLSE vs. Group -1.0 Dewpoint Difference 58 -1.5 57 -2.0

1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT)

KLSE Td KLSE Td vs. Group Aug.Aug. andand Sept.Sept. biggestbiggest anomalyanomaly

Average Hourly Dewpoint - September La Crosse, Wisconsin

56 2F higher than 2.0 group overnight 55 1.5 1.0 54 0.5 53

0.0 (F) 52 -0.5 Dewpoint (F)

51 KLSE vs. Group -1.0 Dewpoint Difference Difference Dewpoint 50 -1.5 49 -2.0

1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT)

KLSE Td KLSE Td vs. Group UniqueUnique toto KLSE:KLSE: HourlyHourly

•• TdTd isis lowerlower thanthan thethe groupgroup inin winterwinter months;months; higherhigher thanthan groupgroup inin summersummer monthsmonths –– EspeciallyEspecially atat nightnight –– ImportantImportant forfor fogfog developmentdevelopment –– HighestHighest perturbationperturbation isis inin Aug/SeptAug/Sept •• InIn greengreen months,months, TdTd actuallyactually decreasesdecreases duringduring afternoon,afternoon, thenthen risesrises againagain TdTd DecreasesDecreases inin AfternoonAfternoon

Average Hourly Dewpoint - June La Crosse, Wisconsin

60 2.0 59 1.5 Td increase 1.0 58 0.5 57 0.0 56 Td decrease -0.5 Dewpoint (F)

55 KLSE vs. Group -1.0

54 -1.5 (F) Difference Dewpoint 53 -2.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour (LT)

KLSE Td KLSE Td vs. Group UniqueUnique toto KRST:KRST: HourlyHourly

•• LaterLater impactimpact fromfrom growinggrowing seasonseason GrowingGrowing SeasonSeason

Average Hourly Dewpoint - May Average Hourly Dewpoint - June La Crosse, Wisconsin La Crosse, Wisconsin

50 3.0 60 2.0 2.5 Nocturnal Nocturnal BL 1.5 49 2.0 59 boundary layer forms, traps ET 1.0 48 1.5 58 forms, traps ET 1.0 0.5 47 0.5 57 0.0 0.0 46 -0.5 56 -0.5 Dewpoint (F) Dewpoint (F) Dewpoint -1.0 KLSE vs. Group 45 Group vs. KLSE 55 -1.5 -1.0 Dewpoint Difference (F) Difference Dewpoint 44 -2.0 Dewpoint Difference(F) 54 -1.5 -2.5 43 -3.0 53 -2.0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT) Hour (LT)

KLSE Td KLSE Td vs. Group KLSE Td KLSE Td vs. Group

Average Hourly Dewpoint - May Average Hourly Dewpoint - June Rochester, Minnesota Rochester, Minnesota

48 3.0 58 2.0

2.5 t 57 1.5 47 2.0 1.0 46 1.5 56 1.0 0.5 45 0.5 55 0.0 0.0 44 -0.5 54 -0.5 Dewpoint (F) Dewpoint (F) Dewpoint -1.0 Weaker BL due to mixing Weaker BL due to mixing Difference (F)

43 KRST vs. Group 53 (elev), ET mixed -1.5 (elev), ET mixed -1.0

-2.0 Dewpoint Difference(F) 42 52 KRST vs. Group Dewpoin -2.5 -1.5 41 -3.0 51 -2.0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT) Hour (LT)

KRST Td KRST Td vs. Group KRST Td KRST Td vs. Group UniqueUnique toto KRST:KRST: HourlyHourly

•• LaterLater impactimpact fromfrom growinggrowing seasonseason •• JulyJuly andand AugustAugust areare thethe onlyonly monthsmonths withwith thethe eveningevening TdTd higherhigher thanthan thethe daytimedaytime –– MixingMixing vs.vs. EvapotranspirationEvapotranspiration –– CropCrop canopycanopy coveragecoverage mostmost extensiveextensive KRSTKRST EveningEvening TdTd HigherHigher ThanThan AfternoonAfternoon

Average Hourly Dewpoint - July Rochester, Minnesota

64 2.0 63 1.5

62 1.0 0.5 61

0.0 (F) 60 -0.5 Dewpoint (F)

59 KRST vs. Group -1.0 Dewpoint Difference 58 -1.5 57 -2.0

1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT) Average Hourly Dewpoint - August

KRST Td KRST Td vs. Group Rochester, Minnesota

62 2.0 61 1.5

60 1.0 0.5 59

0.0 (F) 58 -0.5 Dewpoint (F)

57 KRST vs. Group -1.0 Dewpoint Difference Difference Dewpoint 56 -1.5 55 -2.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour (LT)

KRST Td KRST Td vs. Group UniqueUnique toto KRST:KRST: HourlyHourly

•• LaterLater impactimpact fromfrom growinggrowing seasonseason •• JulyJuly andand AugustAugust areare thethe onlyonly monthsmonths withwith thethe eveningevening TdTd higherhigher thanthan thethe daytimedaytime –– MixingMixing vs.vs. EvapotranspirationEvapotranspiration –– CropCrop canopycanopy coveragecoverage mostmost extensiveextensive •• LowerLower TdTd thanthan groupgroup inin Aug.Aug. andand Sept.Sept. –– HarderHarder toto fogfog atat KRSTKRST KRSTKRST FogFog SeasonSeason

Average Hourly Dewpoint - August Rochester, Minnesota

62 2.0

61 1.5 t

60 1.0 0.5 59 0.0 58 -0.5 Dewpoint (F) 57 (F) Difference 1.5F Lower Td than -1.0

56 KRST vs. Group Dewpoin group overnight -1.5 55 -2.0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Hour (LT) Average Hourly Dewpoint - September KRST Td KRST Td vs. Group Rochester, Minnesota

53 2.0

52 1.5 t

51 1.0 0.5 50 0.0 49 -0.5 Dewpoint (F) 48 Difference (F) -1.0 1.5 to 2F Lower Td 47 -1.5 KRST vs. Group Dewpoin than group overnight 46 -2.0 123456789101112131415161718192021222324 Hour (LT)

KRST Td KRST Td vs. Group TheThe BigBig PicturePicture (All(All Sites):Sites): TdTd vs.vs. WindWind DirectionDirection

•• WW toto NWNW directionsdirections areare driestdriest NovNov –– FebFeb •• EE windwind yieldsyields highesthighest TdTd NovNov -- FebFeb WW toto NWNW WindsWinds Driest;Driest; EE WindsWinds MostMost MoistMoist

Average Dewpoint vs. Wind Direction - January La Crosse, Wisconsin

20 6.0 18 Most Moist Flow n 16 4.0

) 14 2.0 12 10 0.0 8

Dewpoint (F -2.0 6 (F) Difference 4 -4.0 2 KLSE vs. Group Dewpoi Driest Flow 0 -6.0 0 45 90 135 180 225 270 315 360

Wind Direction

Td KLSE Td vs. Group TheThe BigBig PicturePicture (All(All Sites):Sites): TdTd vs.vs. WindWind DirectionDirection

•• WW toto NWNW directionsdirections areare driestdriest NovNov –– FebFeb •• EE windwind yieldsyields highesthighest TdTd NovNov -- FebFeb •• HighestHighest DewDew pointspoints areare confinedconfined toto SoutherlySoutherly JunJun –– AugAug HighestHighest TdTd confinedconfined toto aroundaround 180180oo

Average Dewpoint vs. Wind Direction - June La Crosse, Wisconsin

65 4.0 63

3.0 ) 61 2.0

) 59 57 1.0 55 0.0 53 -1.0 Dewpoint (F 51 -2.0 KLSE vs. Group 49 Dewpoint Difference (F 47 -3.0 45 -4.0 0 45 90 135 180 225 270 315 360

Wind Direction

Td KLSE Td vs. Group UniqueUnique toto KLSE:KLSE: TdTd vs.vs. WindWind DirectionDirection

•• MoistMoist anomalyanomaly forfor NWNW windswinds comparedcompared toto groupgroup inin Dec.Dec. andand Jan.Jan. –– LakeLake OnalaskaOnalaska andand MississippiMississippi RiverRiver influence?influence? KLSEKLSE NWNW toto NN moistmoist windwind anomalyanomaly

Average Dewpoint vs. Wind Direction - January La Crosse, Wisconsin

20 6.0 18 16 4.0 14 2.0 12 10 0.0 8

Dewpoint (F) -2.0

6 KLSE vs. Group 4

-4.0 (F) Difference Dewpoint 2 0 -6.0

0 45 90 135 180 225 270 315 360 Wind Direction

Td KLSE Td vs. Group LaLa CrosseCrosse GeographyGeography

Lake Onalaska La Crosse River Valley

KLSE UniqueUnique toto KLSE:KLSE: TdTd vs.vs. WindWind DirectionDirection

•• MoistMoist anomalyanomaly forfor NWNW windswinds comparedcompared toto groupgroup inin Dec.Dec. andand Jan.Jan. –– LakeLake OnalaskaOnalaska andand MississippiMississippi RiverRiver influence?influence? •• HigherHigher TdTd thanthan groupgroup withwith EE windswinds inin WinterWinter EE WindWind AnomalyAnomaly atat KLSEKLSE

Average Dewpoint vs. Wind Direction - December La Crosse, Wisconsin

25 6.0 23 3F Higher 4.0 21 than Group 19 2.0 17 15 0.0 13

Dewpoint (F) -2.0

11 KLSE vs. Group 9

-4.0 DifferenceDewpoint (F) 7 5 -6.0 0 45 90 135 180 225 270 315 360 Wind Direction

Td KLSE Td vs. Group UniqueUnique toto KLSE:KLSE: TdTd vs.vs. WindWind DirectionDirection •• MoistMoist anomalyanomaly forfor NWNW windswinds comparedcompared toto groupgroup inin Dec.Dec. andand Jan.Jan. –– LakeLake OnalaskaOnalaska andand MississippiMississippi RiverRiver influence?influence? •• HigherHigher TdTd thanthan groupgroup withwith EE windswinds inin WinterWinter •• VeryVery drydry anomalyanomaly atat 2020o andand 260260o (~(~ --55oF)F) inin WinterWinter –– Bluffs?Bluffs? VeryVery drydry anomalyanomaly ~~ 2020oo andand 260260oo

Average Dewpoint vs. Wind Direction - January La Crosse, Wisconsin

20 6.0 18 16 4.0 14 2.0 12 10 0.0 8

Dewpoint (F) -2.0

6 KLSE vs. Group 4

5F Dry Anomaly -4.0 (F) Difference Dewpoint 2 0 -6.0

0 45 90 135 180 225 270 315 360 Wind Direction

Td KLSE Td vs. Group UniqueUnique toto KLSE:KLSE: TdTd vs.vs. WindWind DirectionDirection •• MoistMoist anomalyanomaly forfor NWNW windswinds comparedcompared toto groupgroup inin Dec.Dec. andand Jan.Jan. – Lake Onalaska and Mississippi River influence? •• HigherHigher TdTd thanthan groupgroup withwith EE windswinds inin WinterWinter •• VeryVery drydry anomalyanomaly atat 2020o andand 260260o (~(~ --55oF)F) inin WinterWinter – Bluffs? •• SESE toto SS andand NENE toto EE TdTd moistmoist anomalyanomaly duringduring warmwarm monthsmonths – La Crosse River valley influence? NENE toto EE andand SESE toto SS WarmWarm AnomalyAnomaly

Average Dewpoint vs. Wind Direction - August La Crosse, Wisconsin

70 4.0 68 2F Higher than Group 3.0 66 2.0 64 62 1.0 60 0.0 58 -1.0 Dewpoint (F)

56 Group vs. KLSE -2.0 54 Dewpoint Difference (F) 52 -3.0 50 -4.0 0 45 90 135 180 225 270 315 360 Wind Direction

Td KLSE Td vs. Group ConclusionsConclusions -- WinterWinter •• SynopticSynoptic signalsignal typicallytypically dominatesdominates •• LargerLarger TdTd variationvariation inin 2424 hourshours thanthan inin SummerSummer (average(average ~~ 66--77 F,F, versusversus 22--3F)3F) •• WW toto NWNW windswinds areare driest;driest; EE windswinds correspondcorrespond withwith higherhigher TdTd •• KLSEKLSE –– TdTd lowerlower thanthan groupgroup inin drydry monthsmonths –– NWNW toto NN wind:wind: higherhigher Td,Td, riverriver influence?influence? –– EE windswinds eveneven higherhigher thanthan restrest ofof groupgroup ConclusionsConclusions -- SummerSummer •• MoreMore locallocal signalsignal isis seenseen •• ComplexComplex diurnaldiurnal behaviorbehavior seenseen (e.g.,(e.g., sunrise,sunrise, afternoonafternoon mixing,mixing, earlyearly eveningevening rise,rise, overnightovernight condensation).condensation). •• SmallerSmaller TdTd swingsswings overover 2424 hourshours •• TdTd decreasesdecreases slightlyslightly duringduring afternoon;afternoon; risesrises duringduring eveningevening •• KLSEKLSE – Td higher than group in summer months – Biggest nighttime moist anomaly during peak fog months (Aug. and Sept.) – Td decrease more evident during afternoon; rises during evening – SE to S and NE to E Td moist anomaly during warm months