A tornado crossed the edge of the Denver International Airport this afternoon.  Here is the observation from the airport:  0222 PM TORNADO DENVER INTL AIRPORT 39.87N 104.67W 06/18/2013 DENVER CO OFFICIAL NWS OBS TORNADO TOUCHDOWN EAST OF DIA CONCOURSES. ASOS REPORTED 97 MPH GUST.   No injuries were reported.   Passengers at the DIA were evacuated to designated tornado shelters. The airport’s normally busy concourse was completely empty during the warning period.  Here’s pictures and video.  The storms also produced hail over an inch in diameter.  Picture from the Denver NWS.

    From Patrick DeHaan at GasBuddy:  “Hey Bill – Tell your readers to continue holding off on filling their tanks. GR prices could drop into the $3.50s in the next week at some stations.  Today’s average of $3.88 will likely be in the 3.60s a week from today.”

   Click the picture (from NBC5) to enlarge.   A mysterious silver slime has closed two Lake Michigan beaches.  The Porter Beach and the Indiana Dunes State Park beaches were closed after children came out of the water with a silvery, almost metallic material sticking to them.  Lifeguards went up and down the beach telling everyone to “get out of the water immediately”.  Several agencies are investigating the substance, including the United States Geological Survey, which took samples of the more than 1/4-mile slick.   Winds are northeast today and winds will remain unfavorable for any of this substance to move toward Michigan beaches over the next 3 days.    There’s also a Beach Hazards Statement in effect through tonight from Berrien Co. Michigan around the lake to Lake County Illinois.

   Another great pic. from Jack Martin showing Thursday’s bright blue sky.  Click on the image or click here to enlarge.    The water level of Lake Michigan(Huron) is up another inch.  We are now back to the same level we were at one year ago.  The lake is up 5″ in the last month (each inch is 390 billion gallons of water) and 11″ above the lowest June level of 1964.   We’re still 19″ below the long-term average level.  Lake Superior continues to add water.  Superior is up 7″ in the last month and is now 4″ higher than one year ago.  Lake Superior had the second biggest monthly increase in water level ever earlier this spring and is now just 7″ from the long-term average level.   Lake Erie is up 5″ in the last month and is now at the same level as one year ago.  Erie is 4″ below the century average.  Lake Ontario is on the plus side on all counts.  Ontario is up a whopping 9″ in just the last month.  It’s 7″ higher than one year ago and 2″ above the long-term average.

Rainfall from the storms Weds. PM/Night:  4.85″ Diamondale,  4.1″ west of Wayland, 3.92″ near Lansing, 3.75″ Middleville (thru 1 AM – it was still raining there), 3.31″ Hopkins, 3.07 E. Lansing, 2.97″ Grand Ledge, 2.87″ Dorr, 2.83″ Hastings, 2.42″ Holland, 2.37″ Freeport.  35,000 customers lost power, mainly due to strong wind and mainly in Van Buren, S. Allegan and Barry Counties.  Winds hit 74 mph on the S. Haven beach.  The water level on the Grand River at Lansing went up 6 feet in less than 12-hours with the rain.  Both the Macatawa River at Zeeland and the Rabbit River at Hopkins rose nearly five feet.  Early Friday AM, the crest on the Grand River was just east of Ionia, where the flow of water was more than 3 1/2 times average flow for June 14.  In downtown Grand Rapids, the river is up about 2 feet (and rising) and is approaching double average flow.   The recent rains will likely bump up the water level of Lake Michigan another inch in the next 10 days.  Michigan river levels here.

Also:  First look at a shipwreck and Happy Flag Day!

    Flash Flood Warning until 5 AM.   Numerous reports of wind damage across Van Buren, S. Allegan, S. Barry, N. Kalamazoo, N. Calhoun, Eaton and Ingham Counties.  Gust to 74 mph at the S. Haven Beach.  There were trees and wires down east of Grand Haven.  Power poles snapped and a tree on a school north of Kalamazoo.  +4″ of rain at Middleville with significant flooding from E. Allegan into Barry, Eaton, Ingham, SE Kent, S. Ionia Counties.  1″ hail at Coldwater.   Measured 80 mph winds and 1″ hail at the south end of Lake Michigan at Griffith IN.  Roof off house there.  Here’s a summary of severe storm reports from W. Michigan, N. Indiana (inc. Michigan Counties that border Indiana and NW Ohio), NE Illinois and SE Wisconsin.

Tornado on the ground at Belmond IA…Tornadoes and golfball-sized hail west of Chicago at Aurora, Rockford, Oswego and Naperville.  Gust to 65 mph at Sandwich, IL, 69 mph at Liston IL and 70 mph at Yorkville IL.  Gusts to 52 at NWS at Romeoville IL.  This line tracks to Berrien around 8:15 PM.  Golfball-sized hail in Pulaski Co., Indiana.   Video of Illinois tornado.   SHABBONA LAKE STATE PARK (Illinois)  BOATS TOSSED ONTO BOATS. LARGE TREES SNAPPED AT TRUNK OR UPROOTED. POWER POLES DOWN NEAR STATE PARK OFFICE.  Tornado pics. and video from Iowa.  Valparaiso IN – 60 mph winds for five minutes.

  Back to a Moderate Risk as of 9:15 PM.   Tornado Watch out for NE Iowa, NW Illinois, SW Wiscconsin.  This is a PDS Tornado Watch – Particularly Dangerous Situation.   Storms have started in NE Iowa.  Next Watch east will be for SE WI, NE IL, SW MI and N. IN.  Warm front and 70-degree dew points up to the Indiana border.  Follow rapid satellite scans here.    South of a line from Holland to Lansing looks to have very significant threat of wind damage.  SPC says: “A SIGNIFICANT SEVERE WEATHER OUTBREAK APPEARS INCREASINGLY LIKELY ACROSS PORTIONS OF THE UPPER MIDWEST/LOWER GREAT LAKES FROM THIS AFTERNOON THROUGH THIS EVENING. INTENSE STORM DEVELOPMENT IN A VERY UNSTABLE AIRMASS…COINCIDENT WITH A COMPACT AND INTENSIFYING SURFACE LOW SHOULD RESULT IN NUMEROUS DAMAGING WIND EVENTS AS WELL AS SCATTERED…POSSIBLY STRONG TORNADOES…Potentially EXPLOSIVE Storm Development to occur….Potentially Strong Tornado Threat may be maximized…possible DERECHO…WRF-ARW SIMULATION TAKES THE APEX OF THE PROGRESSIVE MESOSCALE COMLEX FROM CHICAGO TO DETROIT IN UNDER 6 HOURS WITH A FORWARD SPEED IN EXCESS OF 50 MPH….SHEAR AND INSTABILITY WITHIN AND AHEAD OF THIS CONVECTION WILL REMAIN SUPPORTIVE OF BOTH HIGH WINDS, PROBABLY WELL IN EXCESS OF 70 MPH, AS WELL AS A FEW TORNADOES.”  LINK TO DISCUSSION.   Here’s specific probabilities of tornadoes, damaging winds and severe hail.   This is the probability of a severe report within 25 miles of a point in that area.   A 60% probability on wind damage is an extremely high probability for an SPC forecast.

From GRR NWS:  “FLASH FLOOD WATCH BASED ON THE POTENTIAL FOR HEAVY RAIN WITH THE TROWAL FEATURE NORTH OF THE MAIN UPPER LEVEL WAVE AS IT COMES THROUGH TONIGHT. THE SPC SREF…THE 15Z HRRR AND THE 15Z ESRL RAP MODELS ALL SHOW 2 TO 3 INCHES OF RAIN TONIGHT JUST SOUTH OF INTERSTATE 96. GIVEN THE CONVECTIVE NATURE OF THE EVENT IT WOULD SEEM REASONABLE THAT FLASH FLOODING IS POSSIBLE IN THIS AREA.”

Tornado Watch likely for S. Michigan with the most likely time for storms in the 5 PM to 10 PM range.  Eastern Iowa likely to see explosive thunderstorm development between 2:45 and 4 PM EDT.  People are taking this seriously:  “Magic Waters, the large water park in the Rockford, Illinois Area, will be closing at 1:30 CDT due to the threat of severe weather.

Check out Regional radar to see the rain across the Great Lakes. Here’s GRR radar, local lightning data, meso-discussions and current watches from SPC and a satellite loop. Here’s current Michigan temperatures, National lightning data and the latest discussion from GRR NWS. Here’s National Storm Reports for today and yesterday. Here’s a live pic. of the beach at Grand Haven, Here’s the latest Grand Rapids NWS discussion.  Here’s radar from Chicago, Milwaukee, E IA and NW IL and N. Indiana.

Your friends in the high and moderate risk areas need to be aware of the potential for significant wind damage.  Please forward the link to the blog and watch for updates on WOOD-TV.  We may start streaming coverage later tonight online.   In my view, the greatest threat remains in N. IL, N. IN with a significant threat along and south of I-94.   See links in the threads below this one.

The Storm Prediction Center is upgrading to a very rare HIGH RISK AREA for tornadoes and Severe Thunderstorms!  (It was only a moderate risk for the Oklahoma tornadoes).   SPC says:  “THE 1630Z CONVECTIVE OUTLOOK WILL INCLUDE A CATEGORICAL UPGRADE TO HIGH RISK FOR DAMAGING WIND POTENTIAL FROM EXTREME EASTERN IOWA INTO NORTHERN PORTIONS OF ILLINOIS AND INDIANA…AND NORTHWEST PORTIONS OF OHIO. IN ADDITION…TORNADO PROBABILITIES WILL BE INCREASED TO 15 PERCENT OVER PORTIONS OF EXTREME EASTERN IOWA INTO NORTHWEST ILLINOIS. DISCUSSION…SVR TSTMS ARE EXPECTED TO DEVELOP THIS AFTERNOON IN THE VICINITY OF EASTERN IOWA/NORTHWEST ILLINOIS AND QUICKLY BECOME SEVERE SUPERCELLS WITH A RISK FOR TORNADOES…POSSIBLY SIGNIFICANT…WITH UPSCALE GROWTH INTO A FAST-MOVING AND FORWARD-PROPAGATING MESOSCALE CONVECTIVE SYSTEM. WIDESPREAD DAMAGING WINDS ARE LIKELY ACROSS THE HIGH RISK AREA…WITH SOME SIGNIFICANT SEVERE GUSTS POSSIBLE.”

Click on the map to enlarge.  This is accumulated rainfall over the past week.   Trees are more apt to be uprooted in strong wind when the ground is saturated.  Note where the heavy rain has fallen in SW Michigan and across N. Illinois and N. Indiana.  Those are areas that will be more susceptible to toppling trees.   Right now, if you’re in N. Illinois, N. Indiana, W. Ohio or extreme SW or S. Michigan – think about where to park your vehicles so any tree damage can be minimized.  Take down hanging baskets, make sure the yard is picked up and the garbage bin won’t go flying down the street.  For those of you esp. in N. Illinois and far NE Iowa…remember the tornado safety rules….Lowest Floor, Away from Windows – esp. windows that face south and west, try to avoid getting caught in a vehicle on the open road.

  Here’s NAM model precipitation…heaviest SW corner of Lower Michigan down into Indiana.  At 11 AM, warm front is Moline IL to Fort Wayne IN.  Watch for tornadoes as the storms start late aftn. along and just north of the front in N. Illinois.  Wind damage threat greatest nearer the front (so south of Holland to Ann Arbor).  Low 70s dew points south of the front.  Lots of fuel for the fire.    The 7:20 AM update from the Storm Prediction Center now has the Moderate Risk up to the Michigan-Indiana border.  The Moderate Risk covers much of IL, IN, OH.  The Slight Risk Area comes north to a line from Muskegon to Flint. The likelihood of a severe weather report within 25 miles of a single location in the moderate risk area is 45% for wind, 30% for hail and 10% for tornado.  Here’s SPC TORNADO RISK (highest in N. Illinois), DAMAGING WIND RISK (highest N. IL, N. IN, NW Ohio), and HAIL RISK (size of hail is always a concern, but wind-driven, smaller-size hail is also a concern…force = mass x velocity x velocity…the faster an object is traveling, the more force it has).   The Storm Prediction Center says:

“Widespread Damaging Winds…Large Hail and a Few Tornadoes Expected across a Large Area from Iowa to West Virginia.  Iowa, Illinois and S. Wisconsin Early Afternoon into Indiana, Ohio, N. Kentucky and far Southern Michigan during the Evening.  Increasing wind fields will favor a forward propagating convective system…possibly a DERECHO CAPABLE OF WIDESPREAD DAMAGING WINDS.  Embedded areas of rotation may also exist periodically…indicating either TORNADOES or ENHANCED AREAS OF DAMAGE WIND POTENTIAL.  LARGE HAIL IS ALSO LIKELY, POSSIBLY WIND DRIVEN.”   7:20 AM update:  “…Highest severe probabilities and the most significant severe weather potential still appears focused in a corridor across E. Central IA into N. Illinois late this afternoon, into N. Indiana and W. Ohio later tonight.” 

Accu-Weather talking about a DERECHO from Chicago to Pittsburgh.  #derecho on Twitter.

Here’s the RPM rainfall prediction, showing the t-storms getting north into the G.R. area.

Check out the GRR NWS discussion and the latest surface map.   If I were storm chasing…I’d start along the MIssissippi south of Dubuque, north of Moline…then east along I-80 to NW Indiana…then to Fort Wayne to Findley OH.

Check out Regional radar to see the rain across the Great Lakes. Here’s GRR radar, local lightning data, meso-discussions and current watches from SPC and a satellite loop. Here’s current Michigan temperatures, National lightning data and the latest discussion from GRR NWS. Here’s National Storm Reports for today and yesterday. Here’s a live pic. of the beach at Grand Haven, Here’s the latest Grand Rapids NWS discussion.

    WOW – look at the Heat Burst they had in Kearney, NE last night.  Check out the weather observations.   At 12:55 PM it’s calm, fair, 75 degrees and the humidity is 74%.  Twenty minutes later they report a thunderstorm and the temperature is up 2 degrees to 77, the dew point is 68 and the wind is SW 9.  Twenty minutes after that, the wind is SW at 29 G. 35..the temperature has shot up 7 degrees to 84 and the dew point drops to 54.  The humidity has plunged from 74% to 33%.  We advance another 20 minutes and the wind is now west at 26, gusting to 54 mph.  The temperature continues to rise to 88 and the humidity is now down to 25%.  Twenty minutes later the wind is NW 21 G 47 – add another 20 minutes and the wind is now north at 10 mph  with gusts to 18 mph…and twenty minutes after that, the wind has flipped from north to south at 17 mph gusting to 25 mph and the temperature is up to 90 at 3 AM!    But wait!   At 3:15 AM, the temperature is up to 97 and the south wind is now gusting over 50 mph!  The humidity is down to 16%!   Here’s more on the heat burst from the National Weather Service, which appears to have affected a relatively large area of central Nebraska.

Also, check out the pics. of noctilucent clouds from western Canada.  and recent aurora pics.

  Joplin Tornado Damage from NBC.  Click the pic. to enlarge.  Here’s a very interesting article.  A team of structural engineers toured the 22-mile long path of the Joplin Tornado and found “that more than 83 percent of the damage on May 22, 2011, was caused by winds of 135 mph or less, which is equal to the maximum wind speed of an EF-2 tornado.   Only 4 percent of the damage could be linked to an EF-4 tornado, which can have winds speeds ranging from 168 to 199 mph. The ASCE investigators found no EF-5 level tornado damage to buildings at all.”  The Structural Engineers Association of Kansas and Missouri (SEAKM) report is available for free. It contains much the same observations and recommendations noted in this article. There are other reports which are notable; many more than the links below.
SEAKM report, May 2012:  http://www.seakm.com/uploads/Joplin_Committee_Report_05262012.pdf