Jesse’s June 17, 2010 Minnesota Tornado Intercepts

Posted on 24. Jun, 2010 by Jesse in Jesse's Chase Logs, Uncategorized

Video Series: Part I

Video Series: Part II

I teamed up with Brandon Sullivan of Wicked Wind Media and Aaron Shaffer from KGAN in Cedar Rapids, IA for what looked to be a favorable chase day in northern Iowa on Thursday, June 17, 2010.  As a quick overview, a shortwave was moving out of the upper high plains as a strong mid level jet streak was nosing into far western Minnesota by early Thursday afternoon (see below).

Note: For some of the following images, I’ve provided environmental RUC mesoanalysis graphics from either 21z or 00z, which provides the reader a glimpse of the environment early in the evolution of the event (21z- 06/17), or a representation the environment at maximum tornadogenesis (00z  – 06/18).

SFC analysis – 21z 20100617

500 mb hght/temp/wind at 21z 20100617

A very warm, unstable air mass was being ushered in, courtesy of stout 850 mb flow, ahead of an attendant cold front that was draped across east central South Dakota, which allowed for considerable atmospheric destabilization, with MUCAPE values peaking AOA 4,000 J/KG across the entire region by 21z.  Note the strength of the 850 mb LLJ by 00z FRI in the second crossover image.

850 mb hght/temp/dewp at 21z 20100617

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850 mb (Red) and 500 mb (Blue) wind crossover at 00z – 20100618

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MUCAPE and Lifted Parcel Level at 21z 20100617

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Note (below) that MLCAPE across the region was already >2500 J/kg and CIN < 50 J/kg, indicating an environment that was conducive for supercells at 00z.

MLCAPE – 00z 20100618

As the first storms in our region fired well ahead of the surface cold front, a cell in central Kossuth County, IA quickly reached severe levels as it lifted ENE into an environment primed for supercells with ambient 0-1 km and deep layer vertical shear profiles, as indicated below.  Notice the increase to over 40 kts by 00z (second graphic), with a discernible bubble of highest SFC-1km vertical shear right in the area where the supercell was dropping multiple tornadoes WSW of Albert Lea.

21z SFC-1km Shear Vector – 20100617

Notice the change from app. 20 kts (above) to 40 kts (below) in a time span of 4 hours.  SFC-1km Vertical Shear >15-20 kts is generally considered favorable for supercell tornadoes.

00z SFC-1KM Vertical Shear  – 20100618

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SFC to 6 km shear values were > 40 kts in a small pocket near the region in south central Minnesota where this supercell storm was traveling in an ENE pattern.

SFC – 6 km shear values – 00z 20100618

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Very ambient 0-1 km SRH values >= 200 m2/s2 (first image) at 21z had increased to a value >= 300 m2/s2 by 00z (second image).

0-1 KM SRH 21z – 20100617

0-1km SRH – 00z 20100618

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As storms began to fire by 21z, 0-1km EHI values were already >= 4.0 across far northern Iowa and south central Minnesota, indicating strong support for significant supercell tornadoes, when combined with the favorable BL-6 km shear values >40 kts, LCL heights <1250 ~ 1000 m (see below), CIN <50 J/kg, and LFC heights <1500-2000m.

0-1km EHI 21z – 20100617

The  Storm Prediction Center had the entire area outlined in a Moderate Risk for severe weather, and storms were beginning to fire by 21z across both northern Iowa and NW Minnesota per the radar image below.  They were entering and environment where the LCL height had already reached 1250 m, lending a moderate support for tornadoes by 21z (see the second image below).

Day 1 SPC Outlook and Warnings in Effect at 21z – 20100617

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21z LCL Height – 20100617

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INL Observed Sounding – 20100618 00z

We initially targeted Spencer, Iowa, but then blasted east on Hwy 9 to intercept a cell that had went SVR warned near Swea City, IA. Shortly after we intercepted the cell, it produced a beautiful funnel just south of Swea City.

As the cell moved to the ENE, it started producing tornadoes as it inched closer to the Minnesota state line. We followed the cell as it continued hosting quite an incredible show, calling the chase near Albert Lea as the tornado became more obscured by rain and darkness was approaching.  The cell continued to cycle, producing an incredible tornado show, with everything from small, stovepipe tornadoes to wedge-shaped tornadoes, as viewed in the second part of my video series.  Besides the embedded Youtube videos, a few screen grab photos are included below.

Visible Satellite at 2115z at storms beging to explode in north central IA and southern MN

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Visible Satellite Image at 2345z – 20100617

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NWS Chanhassen Doppler Reflectivity 1:45 pm-6:25 pm

NWS Chanhassen Doppler Reflectivity 6:25 pm-8:00 pm

A complete case analysis of this tornado outbreak, including the Faribault and Freeborn County, MN tornadoes can be found on the MPX webpage here.

A few screen grabs from the video footage are shown below.