Storm Force wind events of October and December 2010 - PowerPoint Presentation

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Storm Force wind events of October and December 2010

Kevin Birk, Mike Bardou and Mark RatzerWFO ChicagoSlide2

Review of Two Storm Force Wind Events across Lake MI

October 26th “Bomb”December 12th Winter StormBoth events produced Storm force winds (48+ knots).

However, the strength and the tracks of the two lows were quite different.Slide3

MotivationIncrease the forecast accuracy for the onset of high impact winds across Lake Michigan.

-> Gain a better understanding of the main processes that govern the onset and maintenance of storm force winds across the lake .Slide4

Central pressure dropped from 980 mb at 00UTC on the 26

th to 955 mb at 00UTC on the 27th as the surface low tracked across MN.

Lake MI remained in the warm sector through the morning of the 26th .

Occluded front pushed across the lake late morning on the 26

th

.

Following this, the system filled as the low became vertically stacked.

The October 26

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BombSlide5

12 UTC Oct 26

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00 UTC Oct 27

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300 MB Jet and Surface

300 MB Jet and Surface Slide6

12 UTC Oct 27

th 00 UTC Oct 28th

300 MB Jet and Surface

300 MB Jet and Surface Slide7

12 UTC October 26th Slide8

15 UTC October 26

th Slide9

18 UTC October 26

th Slide10

21 UTC October 26

th Slide11

00 UTC October 27

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Adiabatic Lapse RateSlide12

Forecasts For Oct 26th Event

Headlines for Gale/Storm watch first issued at 3:42 AM Sun 10/24Gale watch from Monday PM – Tuesday AM.Storm watch from Tuesday PM – Wed evening.Headlines upgraded to Storm Warning at 4:01 AM Mon 10/25. Warning from 4 AM Tue -7 PM Wed. Later forecasts shifted times slightly. Slide13

North Half Verification

Winds remained below Gale force Until about 10 AM Tue 26th as the cold front passed.Gusts remained below Storm force at the north buoy (peaked at 47 knots Tue PM). Port Inland, MI peaked at 56 knots Wed AM.

Frontal Passage

Frontal PassageSlide14

South Half Verification

Winds remained below Gale force Until about 7 AM Tue 26th as the cold front passed.Gusts remained below Storm force at the south buoy (peaked at 45 knots Tue PM). Chicago Harrison Crib peaked at 65 knots Tues AM.

Frontal PassageSlide15

December 12th Winter Storm

Surface Low tracked across Northern IL/Southern Lake MI during predawn hours on the 12th .The low deepened to 988 mb during the afternoon on the 12th as the low moved across western New York. Farther Northwest, Canadian high pressure of 1038 mb moved across eastern Dakotas.Slide16

12 UTC Dec 12

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300 MB Jet and Surface

300 MB Jet and Surface

00 UTC Dec 13

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12 UTC December 12

th Slide18

15 UTC December 12

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21 UTC December 12

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03 UTC December 13

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03 UTC December 13

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Super Adiabatic Lapse RateSlide22

Forecasts For Dec 12th Event

Headlines for Gale/Storm watch first issued at 8:50 AM December 10th. Late Saturday the 11th through Monday morning the 13th. Winds to 55 knots on Sunday/Sunday Night the 12th .

Headlines upgraded to Storm Warning at 2:27 PM on the 11th .

Late Saturday the 11

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through Monday morning the 13

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.

Winds to 55 knots on Sunday/Sunday Night the 12th .Slide23

Verification

North Half

Winds increased to Gales around 04 UTC and to Storm by 10 UTC.

Storm force winds ended around 11 UTC on the 13

th

(25 hours of storm).

South Half

Winds increased to Gales/Storm around 14 UTC.

Storm force winds ended around 05 UTC on the 13

th

(15 hours of storm).Slide24

ConsiderationsStability over the lake

Boundary layer lapse rates.Near adiabatic -> gusts = boundary layer winds.Super adiabatic -> gusts = the max wind in the boundary layer.The track of the low and time of year. Strength of cold air advection.Dynamics Isallobaric wind component.

Synoptic scale descent following the passage of a mid level vorticity max and dry slot. Slide25

Questions?