Severe Storms and Gustnadoes: June 14, 2008
Plenty of sunshine was the rule during the day on Saturday, June 14 over much of central Minnesota. The ground had ample time to heat up and encouraged development of strong thunderstorms over west central Minnesota by evening. The thunderstorms turned severe and moved swiftly across the state, making the journey from Alexandria to the Twin Cities in about two hours. A strong gust front developed out ahead of the storms and produced "gustnadoes" or tornado look-a-like formations. This lead to many false tornado reports that day. There were pockets of damage due to the winds. Trees and branches were blown down due to the strong winds, and sent many people who were enjoying the day scurrying for cover.
The National Weather Service in Chanhassen commented on the gustnadoes associated with this event. Below is a recap that was posted on their Web site.
What was with all those Tornado Reports Saturday evening? Saturday evening saw a rash of severe weather across central Minnesota, as a powerful squall line raced down I-94 through western Minnesota and into the Twin Cities. Trained spotters and law enforcement agencies provided many valuable reports of hail as large as nickels, measured wind speeds as high as 65 mph, and downed trees, tree limbs, and structural damage from the high winds. However, those are not the only reports received at the NWS in Chanhassen on Saturday evening. There were also many independent reports of tornadoes, as the line of storms swept southeastward across central Minnesota. The first reports came from the Alexandria and Long Prairie vicinities, with the emergency dispatch centers from Douglas, Pope, and Todd counties calling to notify us of reported tornadoes in their respective counties. Not long after these reports were received, calls began pouring in from Kandiyohi, Meeker, and Stearns counties, including a report near New London, where two law enforcement officers and two trained spotters independently reported a tornado. As these calls flooded the NWS office, the meteorologists watching and warning for the storms were a bit surprised. The radar data showed no rotation conducive to even a small tornado spin-up, and the very dry atmosphere made the environment unfavorable for tornado development. As the reports were coming into the office, personnel concluded that these were likely "gustnadoes" on the gust front boundary emanating from the squall line, and these thoughts were relayed to the various law enforcement agencies and other spotters in the area. Photos and video of several of these tornado reports have been received and reviewed, confirming the initial thoughts that these were harmless "gustnadoes". Some of you may be asking... What is a gustnado? Is it a tornado? Is it dangerous? A gustnado is a rotating column of air that forms as a result of turbulence along a thunderstorm gust front boundary. Gustnadoes are associated with shelf clouds, a cloud structure that is often confused with a wall cloud, which is sometimes a tornadic cloud feature. A gustnado is not a tornado, and it is not dangerous. On Saturday evening, the gust front boundary was clearly evident in radar data from the Chanhassen Doppler radar, and often, many of the reports occurred several miles ahead of the main area of precipitation with the squall line, which is where the gust front was located. As the shelf cloud associated with the squall line moved over the NWS office in Chanhassen, meteorologists observed the turbulence within it, seeing how it could be confused with a more dangerous wall cloud feature and consequently, result in the volume of tornado reports. We very much appreciate all of the valuable reports from the volunteers that we receive during active weather in Minnesota and Wisconsin, and we would like to thank you all for the service that you provide for us and the safety of the communities you live in.
Listed below are Local Storm Reports from the National Weather Service.
PRELIMINARY LOCAL STORM REPORT...SUMMARY NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 830 PM CDT SUN JUN 15 2008 ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 0713 PM HAIL ALEXANDRIA 45.87N 95.38W 06/14/2008 E0.75 INCH DOUGLAS MN TRAINED SPOTTER WIND GUST OF 56 MPH MEASURED AT ALEXANDRIA AIRPORT. 0808 PM HAIL MELROSE 45.68N 94.81W 06/14/2008 M0.88 INCH STEARNS MN AMATEUR RADIO 0818 PM HAIL 4 W ATWATER 45.14N 94.86W 06/14/2008 M0.25 INCH KANDIYOHI MN TRAINED SPOTTER 0834 PM HAIL ST CLOUD 45.55N 94.17W 06/14/2008 M0.88 INCH STEARNS MN TRAINED SPOTTER 0838 PM TSTM WND GST 7 S HILLMAN 45.91N 93.89W 06/14/2008 M60.00 MPH MORRISON MN TRAINED SPOTTER 0844 PM HAIL 4 N SPICER 45.29N 94.94W 06/14/2008 M0.75 INCH KANDIYOHI MN TRAINED SPOTTER 0848 PM HAIL ATWATER 45.14N 94.78W 06/14/2008 M0.88 INCH KANDIYOHI MN TRAINED SPOTTER COUNTY RD 2 AND 28 0855 PM TSTM WND GST MONTICELLO 45.30N 93.80W 06/14/2008 M63.70 MPH WRIGHT MN TRAINED SPOTTER 0858 PM TSTM WND GST CLEARWATER 45.41N 94.04W 06/14/2008 M53.00 MPH WRIGHT MN MESONET 0900 PM HAIL GROVE CITY 45.15N 94.68W 06/14/2008 M0.75 INCH MEEKER MN TRAINED SPOTTER 0900 PM TSTM WND DMG MONTICELLO 45.30N 93.80W 06/14/2008 WRIGHT MN TRAINED SPOTTER 11 INCH BRANCHES DOWN 0900 PM TSTM WND GST MILACA 45.76N 93.65W 06/14/2008 M57.00 MPH MILLE LACS MN MESONET 0908 PM TSTM WND GST LESTER PRAIRIE 44.88N 94.04W 06/14/2008 M66.00 MPH MCLEOD MN MESONET 0910 PM TSTM WND DMG BIG LAKE 45.34N 93.75W 06/14/2008 SHERBURNE MN TRAINED SPOTTER 8 INCH TREE DOWN 4.6 MILES NORTH OF HWY 10 ON COUNTY ROAD 5 0910 PM TSTM WND DMG MAPLE GROVE 45.11N 93.46W 06/14/2008 HENNEPIN MN BROADCAST MEDIA SIX TO TEN INCH DIAMETER TREE DOWN 0912 PM TSTM WND GST WINSTED 44.97N 94.05W 06/14/2008 E60.00 MPH MCLEOD MN TRAINED SPOTTER 0912 PM TSTM WND DMG WAYZATA 44.97N 93.51W 06/14/2008 HENNEPIN MN TRAINED SPOTTER 60 FOOT TREE DOWN ACROSS POWER LINES WITH POWER OUTAGE IN AREA 0915 PM TSTM WND DMG ST LOUIS PARK 44.95N 93.36W 06/14/2008 HENNEPIN MN TRAINED SPOTTER ONE FOOT DIAMETER TREE DOWN WITH STRUCTURE DAMAGE TO ROD IRON RAILING 0915 PM TSTM WND GST MAPLE PLAIN 45.01N 93.66W 06/14/2008 E60.00 MPH HENNEPIN MN TRAINED SPOTTER 0917 PM TSTM WND DMG WACONIA 44.85N 93.79W 06/14/2008 CARVER MN NWS EMPLOYEE 3-FOOT DIAMETER TREE SNAPPED OFF TWO TO THREE FEET ABOVE GROUND 0917 PM TSTM WND DMG WACONIA 44.85N 93.79W 06/14/2008 CARVER MN LAW ENFORCEMENT LARGE TREES DOWN 0919 PM HAIL DASSEL 45.08N 94.31W 06/14/2008 M0.75 INCH MEEKER MN TRAINED SPOTTER 0920 PM TSTM WND DMG CHASKA 44.82N 93.61W 06/14/2008 CARVER MN PUBLIC SHINGLES TORN OFF ROOFS AT THE UNIVERSITY OF MINNESOTA ARBORETUM. 0925 PM TSTM WND DMG ANOKA 45.21N 93.39W 06/14/2008 ANOKA MN AMATEUR RADIO 4 INCH DIAMETER BRANCHES DOWN 0926 PM TSTM WND GST FRIDLEY 45.08N 93.26W 06/14/2008 M60.00 MPH ANOKA MN AMATEUR RADIO AT INTERSTATE 694 AND HWY 65 0928 PM TSTM WND DMG EDINA 44.89N 93.36W 06/14/2008 HENNEPIN MN TRAINED SPOTTER SEVERAL TREE BRANCHES 3-4 INCHES IN DIAMETER FELLED. 0928 PM TSTM WND DMG EDINA 44.89N 93.36W 06/14/2008 HENNEPIN MN TRAINED SPOTTER THREE INCH BRANCH DOWN AT HWY 62 AND TRACY AVENUE 0930 PM TSTM WND DMG 3 NNW BLOOMINGTON 44.87N 93.34W 06/14/2008 HENNEPIN MN TRAINED SPOTTER RETIRED NWS EMPLOYEE REPORTS AT LEAST 8 UPROOTED LARGE TREES IN A CONCENTRATED AREA ON HIBISCUS AVENUE BETWEEN A SMALL LAKE AND LAKE EDINA PARK. ESTIMATED SPEEDS OF 75 MPH OCCURRED. TIME ALSO ESTIMATED. 0930 PM TSTM WND DMG EDEN PRAIRIE 44.85N 93.46W 06/14/2008 HENNEPIN MN FIRE DEPT/RESCUE TWO 24-INCH TREES DOWN AT EDEN PRAIRIE ROAD AND JUST NORTH OF HWY 5 0930 PM TSTM WND DMG 5 NNE MINNEAPOLIS 45.03N 93.23W 06/14/2008 HENNEPIN MN TRAINED SPOTTER THIRTY TO 36 INCH DIAMETER TREE DOWN AT 3417 BELDEN DRIVE IN ST. ANTHONY. 0935 PM TSTM WND DMG 5 NNE MINNEAPOLIS 45.03N 93.23W 06/14/2008 HENNEPIN MN TRAINED SPOTTER A 20 AND 30 INCH DIAMETER TREES TOPPLED. DAMAGE OCCURRED IN ST. ANTHONY AT 2415 30TH AVE. 0935 PM TSTM WND DMG 5 NNE MINNEAPOLIS 45.03N 93.23W 06/14/2008 HENNEPIN MN TRAINED SPOTTER A 28 INCH DIAMETER TREE FELLED AT 30TH AND STINSON AVE IN THE CITY OF ST. ANTHONY. 0935 PM TSTM WND DMG 5 NNE MINNEAPOLIS 45.03N 93.23W 06/14/2008 HENNEPIN MN TRAINED SPOTTER AN 18 INCH DIAMETER TREE TOPPLED AT 3205 BELLE LANE IN ST. ANTHONY. 0936 PM TSTM WND GST MINNEAPOLIS 44.88N 93.22W 06/14/2008 M62.00 MPH HENNEPIN MN ASOS 0940 PM TSTM WND DMG MINNEAPOLIS 44.96N 93.27W 06/14/2008 HENNEPIN MN AMATEUR RADIO TWO FOOT DIAMETER TREES DOWN AT 43RD AND XERXES AVENUE SOUTH 0941 PM TSTM WND GST ST PAUL 44.93N 93.06W 06/14/2008 M60.00 MPH DAKOTA MN ASOS 0941 PM TSTM WND DMG MINNEAPOLIS 44.96N 93.27W 06/14/2008 HENNEPIN MN AMATEUR RADIO 6 TO 8 INCH BRANCHES DOWN AT CEDAR AVENUE AND NAKOMIS 0943 PM TSTM WND DMG COTTAGE GROVE 44.82N 92.93W 06/14/2008 WASHINGTON MN TRAINED SPOTTER TENTS AND STAGE ITEMS BLOWN OVER AT CITY FESTIVAL. TWO PEOPLE RECEIVED MINOR INJURIES WHEN TENT STRUCK THEM. 0958 PM TSTM WND DMG BLOOMINGTON 44.83N 93.32W 06/14/2008 HENNEPIN MN TRAINED SPOTTER 6 TO 8 INCH BRANCHES DOWN AT HWY 169 AND OLD SHAKOPEE RD. 1002 PM TSTM WND DMG COTTAGE GROVE 44.82N 92.93W 06/14/2008 WASHINGTON MN TRAINED SPOTTER SMALL TREE FELL OVER ROAD 1003 PM TSTM WND DMG MAPLEWOOD 44.99N 93.02W 06/14/2008 RAMSEY MN TRAINED SPOTTER FOUR INCH TREE DOWN 1028 PM TSTM WND DMG CLAYTON 45.32N 92.17W 06/14/2008 POLK WI TRAINED SPOTTER THREE TO FOUR INCH DIAMETER BRANCHES DOWN. PRELIMINARY LOCAL STORM REPORT...SUMMARY NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS 947 PM CDT SAT JUN 14 2008 ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 0530 PM HAIL 4 W BORUP 47.18N 96.59W 06/14/2008 E0.88 INCH NORMAN MN PUBLIC DIME TO NICKEL SIZED HAIL COVERING THE GROUND IN SPOTS. 0535 PM TSTM WND DMG FARGO 46.88N 96.82W 06/14/2008 CASS ND AMATEUR RADIO BRANCHES 2 INCHES IN DIAMETER DOWN ALONG WITH SOME STREET SIGNS. 4 INCH BRANCHES DOWN AT INTERSECTION OF 26TH ST AND 13TH AVE. MORE AND MORE LARGER BRANCHES DOWN AS YOU MOVE EAST CLOSER TO THE RED RIVER. 0545 PM TSTM WND DMG WEST FARGO 46.87N 96.90W 06/14/2008 CASS ND AMATEUR RADIO TREE DOWN IN THE NORTH END OF WEST FARGO. 0612 PM FUNNEL CLOUD 4 W FERGUS FALLS 46.28N 96.15W 06/14/2008 OTTER TAIL MN TRAINED SPOTTER 0643 PM HAIL ELBOW LAKE 45.99N 95.98W 06/14/2008 E0.75 INCH GRANT MN TRAINED SPOTTER HAIL LASTED FOR FIVE MINUTES. 0816 PM TSTM WND GST 2 NNW FARGO 46.90N 96.83W 06/14/2008 M63.00 MPH CASS ND ASOS MEASURED AT KFAR FARGO HECTOR AIRPORT. 0830 PM TSTM WND GST BELTRAMI 47.54N 96.53W 06/14/2008 E60.00 MPH POLK MN FIRE DEPT/RESCUE 0840 PM TSTM WND DMG HENDRUM 47.26N 96.81W 06/14/2008 NORMAN MN LAW ENFORCEMENT POWER OUT DUE TO TRANSFORMER DAMAGE. 0840 PM TSTM WND DMG ADA 47.30N 96.51W 06/14/2008 NORMAN MN LAW ENFORCEMENT POWER OUT IN ADA AREA...TRANSFORMERS DAMAGED AND TREES DOWN. 0840 PM TSTM WND GST 5 ESE MOORHEAD 46.84N 96.66W 06/14/2008 E60.00 MPH CLAY MN TRAINED SPOTTER JUST NORTH OF I-94 AT MP 5. 0921 PM TSTM WND GST 2 S MAHNOMEN 47.29N 95.97W 06/14/2008 M58.00 MPH MAHNOMEN MN MESONET MEASURED AT THE MNDOT RWIS SITE NEAR HWY 59.