MODERATE-HIGH RISK OF SEVERE STORMS/TORNADOESNovember 16th, 2013 at 2:15 am by Bill Steffen under Bill's Blog, News, Weather
Click here to see the outlook map enlarged and read the complete discussion from the Storm Prediction Center. SPC has upgraded to a HIGH RISK, the highest level of warning for much of Indiana, eastern Illinois, and a small part of southern Lake Michigan and also the southern part of Berrien and Cass Counties in Michigan. This is only the 2nd high risk area issued by SPC in 2013. Much of Southern Lower Michigan, parts of Indiana, Ohio, Illinois and Kentucky is in a MODERATE RISK (in red on the map – generally south of a line from Whitehall to Saginaw). The moderate risk area has been nudged farther north. The Slight Risk Area (in yellow on the map) has been expanded north past Traverse City and Alpena. SPC says: “SURFACE-BASED CELL INITIATION SHOULD OCCUR AHEAD OF THE FRONT BY MID MORNING ACROSS NRN AND CNTRL IL WITH STORM COVERAGE EXPANDING EWD INTO IND AND LOWER MICHIGAN BY EARLY AFTERNOON. SHEAR PROFILES JUSTIFIES THE ISSUANCE OF A HIGH RISK ACROSS ERN IL…IND AND SW LOWER MICHIGAN. AS DISCRETE CELLS INTENSIFY. 0-3 KM STORM RELATIVE HELICITIES OF 400 TO 450 M2/S2 WILL BE FAVORABLE FOR STRONG TORNADOES WITH SEVERAL LONG-TRACK DAMAGING TORNADOES EXPECTED TO OCCUR FROM ERN IL ENEWD ACROSS MUCH OF WRN AND CNTRL IND FROM LATE MORNING INTO EARLY AFTERNOON. AS CELL COVERAGE INCREASES AHEAD OF THE FAST MOVING FRONT…A SQUALL-LINE SHOULD ORGANIZE LATE THIS AFTERNOON. WIDESPREAD WIND DAMAGE WILL BE ASSOCIATED WITH THE LINE ALONG WITH TORNADOES.” THESE WILL HAVE A WINDOW OF OPPORTUNITY FROM MID-LATE AFTERNOON INTO THE EARLY EVENING TO PRODUCE SWATHS OF DAMAGING WIND GUSTS…SEVERE HAIL AND POSSIBLY SEVERAL TORNADOES /SOME STRONG “. The Grand Rapids NWS Saturday morning discussion says: “EVERY ONCE IN A WHILE EVERYTHING SEEMS TO LINE UP FOR A SIGNIFICANT WEATHER EVENT AND IT’S BEGINNING TO LOOK LIKE SUNDAY IS THAT TIME.”
SINCE 1995, THERE HAVE BEEN TWO HIGH RISK AREAS ISSUED BY SPC IN NOVEMBER. ON NOV. 15, 2005 – 49 TORNADOES WERE CONFIRMED, INCLUDING AN EF4. ON NOV. 10, 2002 – THERE WERE 64 TORNADOES AND 34 FATALITIES.
The overnight runs are slow to come in this Sat. night…might be a server issue at NCEP.
The Probabilistic Map has a 45% chance of a severe report within 25 miles of a given spot in the Moderate Risk Area. There are two NFL games in the Moderate Risk Area (at Chicago and Cincinnati). While tornadoes are possible, there is a much greater threat of damaging wind from low-topped thunderstorms. This late in the seasons, you can get damaging winds out of a line of showers along a fast-moving cold front, so you may not get a lot of lightning, but if you do see lightning to your west or southwest Sunday PM – head for shelter and expect strong wind. To be severe a storm has winds of 58 mph or greater or hail 1″ in diameter or greater. CHECK THIS OUT – A SIMILAR WIND AND TORNADO EVENT on NOV. 10, 2002 – including an EF4 tornado in Van Wert, Ohio. Here’s more on that fateful November tornado outbreak.