Why were those storms so windy?
Storms that are in a bowing line, as shown above, are called bow echoes. However, in more intense wind events, such as today's storms, the name becomes a derecho (der-AY-cho), also known as a long-lived wind event. While these storms may not have been sustained as powerfully as they were at the beginning, it is still considered a derecho, and can be called either a derecho or bow echo.
With all the wind, is it possible that there was a tornado?
During the entire storm, The Weather Centre team was watching velocities - or a special radar type that determines tornadoes by wind direction- , and we never saw a defined rotation in these storms. Another telltale sign of a tornado would be the broken branches spread in almost a circular direction. However during our damage survey, we did not find that at all. Our damage survey was conducted in one of the harder hit areas.
How strong did the winds get?
At Midway International Airport, winds officially reached 75 miles an hour- equivalent to the bare minimum strength of a Category 1 hurricane. So you can say that you were in a hurricane if you lived near Midway!
Monday, July 11, 2011
The Weather Centre's Headquarters has issued a Special Weather Warning
for areas immediately north of Dayton, OH
At 7:18 PM... The Weather Centre's Mobile Storm Track Team indicated that VIL's were reading at an extremely high level, indicative of very large hail.
Additionally, velocities indicated rotation was likely occurring in that area.
People in the yellow boxes should immediately prepare for life threatening hail and potentially a brief tornado.
This warning will expire at 9:00 PM, and may have to be extended.
It will remain in the 50's and 60's in the North Plains and into the West Coast tonight. Montana will have a chance for precipitation, more around the mark of 30-50%.
Arizona, New Mexico and into Utah and Colorado will rise above 50% in the way of chance of rain tonight.
From top to bottom:
-Whole tree fell and destroyed
-Large branch fell down
-Large branch fell on house (same branch as 2nd picture)
-A garbage can ended up in the street
If you have pictures, we would appreciate if you would send them to us.
From The Weather Centre's Headquarters,
The Weather Centre Storm Team has issued a Special Weather Watch
for the following areas:
At 10:00 AM...Strong and dangerous storms were moving east into the mentioned areas in the form of a derecho.
These storms have produced damage in North IL and Iowa.
People affected should immediately secure outdoor objects and make preparations for extremely strong winds and potential brief rain wrapped tornadoes.
This watch will expire at 11:30 AM
THE NATIONAL WEATHER SERVICE IN NORTHERN INDIANA HAS ISSUED A * TORNADO WARNING FOR... WESTERN BRANCH COUNTY IN SOUTHWEST MICHIGAN... ST. JOSEPH COUNTY IN SOUTHWEST MICHIGAN... * UNTIL 1130 AM EDT * AT 1043 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE SQUALL LINE CAPABLE OF PRODUCING BRIEF RAIN-WRAPPED TORNADOES IN ADDITION TO WIDESPREAD STRAIGHT LINE WIND DAMAGE. ALONG A LINE EXTENDING FROM 6 MILES SOUTHWEST OF SCHOOLCRAFT TO 6 MILES NORTHWEST OF CONSTANTINE TO 4 MILES NORTHEAST OF BRISTOL... AND MOVING EAST AT 50 MPH. * LOCATIONS IN THE PATH OF THESE SEVERE STORMS INCLUDE... CENTREVILLE... STURGIS... COLON... UNION CITY AND BRONSON... OTHER LOCATIONS IMPACTED BY THESE SEVERE THUNDERSTORMS INCLUDE KLINGER LAKE...FISHERS LAKE...WASEPI...NOTTAWA...MENDON...LEONIDAS... FINDLEY...FAIRFAX...FAWN RIVER...BURR OAK...SHERWOOD AND MATTESON LAKE. PRECAUTIONARY/PREPAREDNESS ACTIONS... THIS LINE OF SEVERE HAS A HISTORY OF PRODUCING WIDESPREAD WIND DAMAGE ACROSS NORTHWEST INDIANA AND SOUTHWEST MICHIGAN. THIS IS AN EXTREMELY DANGEROUS SITUATION. GO TO A BASEMENT OR SMALL INTERIOR ROOM. EVACUATE MOBILE HOMES...AND SEEK SHELTER INSIDE A STURDY STRUCTURE.
...SEICHE WARNING FOR THE ILLINOIS SHORE OF LAKE MICHIGAN UNTIL 100 PM CDT... .A STRONG LINE OF STORMS MOVING ACROSS THE LAKE THIS MORNING LIKELY WILL CAUSE WATER TO PILE UP ALONG THE MICHIGAN AND INDIANA SHORES AND BE REFLECTED BACK TOWARD THE ILLINOIS SHORELINE. THIS PHENOMENA IS KNOWN AS A SEICHE. ILZ006-014-111800- /O.NEW.KLOT.LS.W.0002.110711T1431Z-110711T1800Z/ LAKE IL-COOK- 931 AM CDT MON JUL 11 2011 ...LAKESHORE FLOOD WARNING IN EFFECT UNTIL 1 PM CDT THIS AFTERNOON... THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A LAKESHORE FLOOD WARNING...WHICH IS IN EFFECT UNTIL 1 PM CDT THIS AFTERNOON...IN ANTICIPATION OF A POSSIBLE SEICHE. * LAKE SHORE FLOODING...ALONG THE ILLINOIS SHORELINE OF LAKE MICHIGAN. * TIMING...THROUGH THE MORNING INTO THE EARLY AFTERNOON. * IMPACTS...WATER LEVELS ARE EXPECTED TO RISE AND FALL...PERHAPS BY 2 OR MORE FEET...DURING THE PERIOD OF THE WARNING.
A MCS is currently moving across the Lower Great Lakes at this hour and producing very strong winds and torrential rain.
Damage has been observed in these storms, to the extent of trees falling on houses.
MCS means Mesoscale Convective System, or a cluster of thunderstorms in a fairly big area.
This moderate risk was ignited by the risk of damaging winds.
|Today's Hail Threat|
|Today's Tornado Threat|
|today's wind risk|
There are severe thunderstorm Warnings in effect for areas near Chicago as this bow echo moves east.
Because it is a bow echo, we can expect the main severe weather threat will be damaging winds.
From The Weather Centre's Mobile Storm Centre,
The Weather Centre has issued a Special Weather Warning
for the following areas:
At 7:20... The Weather Centre's Mobile Storm Centre detected thunderstorms with cloud tops reaching past 50,000 feet and a high indicator of hail occurring. Maximum hail size was determined to be upwards of 1 inch.
People in these areas are advised to do the following:
-Secure outdoor objects if it is safe.
-Prepare for damaging winds and potentially quarter size hail.
This warning will expire at 8:30 am CDT.