Severe T-Storm WatchMay 20th, 2014 at 4:58 pm by Bill Steffen under Bill's Blog, News, Weather
The latest: “WE CONTINUE TO MONITOR SEVERE THUNDERSTORMS OVER NORTHERN IL INTO SOUTHERN LAKE MICHIGAN AS OF 8:30 pm. THESE STORMS HAVE PRODUCED UP TO BASEBALL-SIZED HAIL AND ISOLATED WIND DAMAGE. INSTABILITY IS LARGELY SURFACE BASED…BUT GIVEN THE STORM OVER LAKE MICHIGAN WAS MAINTAINING ITSELF…THERE APPEARS TO BE ENOUGH ELEVATED INSTABILITY TO NOT IMPACT STORMS COMING ACROSS THE LAKE.
MLCAPE WAS OVER 1500 J/KG SOUTH OF I-96 AND INLAND FROM THE LAKE.
0-6KM BULK SHEAR VALUES WERE AROUND 50 KTS. ALL THIS POINTS TOWARD THESE STORMS MAINTAINING THEMSELVES AND COULD EVEN INTENSIFY ONCE THEY COME ONSHORE….PARTICULARLY SOUTH OF A Holland – Lansing LINE. EVEN THOUGH HAIL HAS BEEN THE PRIMARY THREAT SO FAR…WE MAY SEE THE STORMS BECOME LINEAR AND DAMAGING WINDS COULD BECOME A HIGHER THREAT LATER TONIGHT. HIGHEST SEVERE THREAT REMAINS FROM 11 pm TO 8 am FOR THE GRR CWA. WE WILL ALSO BE WATCHING THE THREAT OF VERY HEAVY RAIN AS SOME OF THE CELL MAY TRAIN OVER THE SAME AREA.
PRECIPITABLE WATER VALUES WERE AROUND 1.3 INCHES. LOCALIZED 2 INCH RAINFALL TOTALS WILL BE POSSIBLE TOWARD I-94.Special Marine Warning from Holland south. Baseball-Sized hail near Rochelle IL, west of Chicago, golfball-sized hail at DeKalb IL. Meso-discussion for SW Michigan – strongest storms to hit Van Buren, Berrien, Cass and St. Joseph Counties. The Discussion says: “ANY ORGANIZED DAMAGING WIND POTENTIAL WILL LARGELY HINGE ON UPSCALE CONVECTIVE GROWTH AND CONSOLIDATING/MERGING COLD POOLS. POTENTIAL FOR THIS REMAINS A BIT UNCLEAR…BUT SEEMS LOW AT THE PRESENT TIME.” Storm now over Lake Michigan NNE of Chicago.
A Severe T-Storm Watch has been issued for N. Illinois and S. Wisconsin for this evening (until Midnight). The Watch includes S. Lake Michigan all the way to the Michigan shoreline. Those storms are aiming straight for West Michigan after 11 pm. The Storm Prediction Center says: ” STORMS WILL SPREAD EAST-SOUTHEASTWARD ACROSS THE WATCH AREA THIS EVENING. MODERATE INSTABILITY COUPLED WITH STEEP LAPSE RATES AND STRONG WINDS ALOFT WILL PROMOTE ORGANIZED MULTICELL OR ISOLATED SUPERCELL STORMS CAPABLE OF LARGE HAIL. DAMAGING WINDS MAY BECOME AN INCREASING THREAT LATER THIS EVENING.” Watch the storms approach on Milwaukee radar. My own personal view is that much of Southern Lower Michigan will come under a Severe T-Storm Watch later this evening, ;with the most likely area for severe weather south of a line from S. Haven to Jackson. Our microcast has the strongest storms producing strong winds in Van Buren, Berrien, Kalamazoo, Cass, St. Joseph and Branch Counties. Keep checking the blog for the latest.
Storm reports: 1.5″ diameter hail at the Dubuque Airport. How appropriate is this: Golfball-sized hail reported at the Fillmore Fairways Golf Course near Dubuque. Egg-sized hail reported at St. Donatus Ia (I’ve been there before – it’s a pretty town on the Mississippi River south of Dubuque – some Luxembourgers settled there – it’s of interest because my dad was 100% Luxembourger).
I’ll update more on the blog in a little bit. Watch me and Kyle on the news now for the latest.
Also: Check out the hail near Denver.