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Major Severe Weather Outbreak November 17


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BULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL  
936 AM CST SUN NOV 17 2013  
 
THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A  
 
* TORNADO WARNING FOR...  
EAST CENTRAL BOONE COUNTY IN NORTH CENTRAL ILLINOIS...  
NORTHWESTERN MCHENRY COUNTY IN NORTHEAST ILLINOIS...  
 
* UNTIL 1015 AM CST  
 
* AT 933 AM CST...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A  
TORNADO WAS LOCATED 5 MILES NORTHEAST OF BELVIDERE...AND MOVING  
NORTHEAST AT 50 MPH.  

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All the best ingredients are coming together over IL and then eventually into IN as well...the amount of instability present right now across IL is quite alarming given shear/helicity values in that area.  0-1km bulk shear values are exceeding 40-45 knots (That's completely insane) where you have SBcapes running >1000 J/KG, LI values as low as -4C to -5C, and 0-3km cape values exceeding 100-125 J/KG...plus this region is right on the nose of a 90kt MLJ streak.  This is pretty to watch unfold.  

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LOT...

 

MESOSCALE DISCUSSION

950 AM CST

RADAR UPDATE...

TOR ISSUED FOR NW MCHENRY COUNTY DUE TO BRIEF RAPID TIGHTENING OF
THE ROTATION ALOFT NE OF BELVIDERE ON THE 1533Z SCAN. ENVIRONMENT
REMAINS EXTREMELY CONDUCIVE FOR TORNADOES AND HAD ALREADY GOTTEN
CONFIRMED ROTATION AND WALL CLOUD WITH SPOTTER SUBMITTED PHOTO WITH
OTHER REPORTS OF FUNNELS AS WELL. ROTATION HAS SINCE WEAKENED BUT
THE THREAT FOR RAPID INTENSIFICATION OF ROTATION IN THESE STORMS
REMAINS HIGH.

905 AM CST

INITIAL STRING OF CONVECTION IS DEVELOPING ACROSS NORTH CENTRAL IL.
A MODIFIED 14Z DVN RAOB INDICATES WE ARE ALREADY UNCAPPED BASED ON
OUR MID 60S DEW POINTS...WITH SURFACE BASED CAPE 1000-1500 J/KG
ALREADY BASED ON THIS. WATER VAPOR AND VISIBLE SATELLITE CHANNELS
BOTH INDICATE MULTIPLE NORTH-TO-SOUTH CORRIDORS OF CONVERGENCE
WITHIN THE SIGNIFICANT HEIGHT FALLS WHERE CONVECTION WILL LIKELY
CONTINUE TO GRADUALLY DEVELOP...WITH AGITATED CUMULUS FROM
NORTHERN IL THROUGH CENTRAL MO.

INITIAL CELLS HAVE ALREADY SHOWN ROTATION WHICH IS NOT SURPRISING
CONSIDERING THE IMPRESSIVE 35-45 KT OF 0-1KM SHEAR AND 60KT+ OF
DEEP LAYER SHEAR. WHILE THE LOW-LEVEL SHEAR WILL EASE SOME AS THE
LOW-LEVEL WIND MAXIMA MOVES NORTHEAST...IT WILL REMAIN PLENTY HIGH
AND WELL ABOVE WHAT RESEARCH HAS SHOWN WHAT IS NEEDED FOR
SIGNIFICANT TORNADOES. CONVECTIVE MODE INITIALLY MAY BE THESE
STRINGS OF QUICK MOVING NORTHEAST CELLS...BUT IT IS STILL
ANTICIPATED THAT INDIVIDUAL DISCRETE CELLS WITHIN THIS...OR JUST
ON THEN OWN...WILL BE THE MAIN MODE FROM LATE MORNING THROUGH
EARLY AFTERNOON ACROSS MUCH OF THE FORECAST AREA. CONVECTIVE
ALLOWING MODELS CONTINUE TO SHOW THIS TREND AND THE LATEST ONES
ARE FOR THE MOST PART IN VERY GOOD AGREEMENT. THE MAIN TIME FOR
CHICAGOLAND CONTINUES TO LOOK TO BE WITHIN 11AM-3PM.

DEVELOPMENT OF STRONG UPDRAFTS WITHIN CONVECTION CAN BE VERY QUICK
IN THIS HIGHLY DYNAMIC ENVIRONMENT...WITH SHEAR ON RADAR
CORRELATING TO TORNADO DEVELOPMENT IN SHORT TIME. THIS IS EVEN
MORE REASON TO MAINTAIN A HIGH AWARENESS.

PDS TORNADO WATCH IS IN EFFECT UNTIL 400 PM FOR THE ENTIRE AREA.  
 
 

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MESOSCALE DISCUSSION 2011

NWS STORM PREDICTION CENTER NORMAN OK

1001 AM CST SUN NOV 17 2013

AREAS AFFECTED...IND...CNTRL/SRN LOWER MI...NWRN OH

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 171601Z - 171800Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...SIGNIFICANT TORNADO/WIND HAZARDS WILL INCREASE RAPIDLY

MIDDAY INTO AFTERNOON WITH A DOWNSTREAM TORNADO WATCH ISSUANCE

EXPECTED E OF WW 561.

DISCUSSION...RECENT STORM DEVELOPMENT HAS OCCURRED ACROSS E-CNTRL IL

JUST NE OF MTO. ALTHOUGH DOWNSTREAM SURFACE HEATING HAS BEEN

HAMPERED BY ABUNDANT STRATUS...LOW-LEVEL MOIST ADVECTION AND

STEEPENING LAPSE RATES ALOFT SHOULD YIELD INCREASING

DESTABILIZATION. VERY STRONG WIND PROFILES MAY RESULT IN A FEW

SUPERCELLS FORMING WELL AHEAD OF THE MAIN SWATH OF LARGE-SCALE

ASCENT AND WIDESPREAD CONVECTION FARTHER WEST IN SERN WI AND NRN/WRN

IL. WITH TIME...THIS ACTIVITY WILL ALSO SPREAD RAPIDLY E/NEWD WITH

CORRESPONDING RISKS FOR SIGNIFICANT TORNADOES/WIND.

..GRAMS/MEAD.. 11/17/2013

ATTN...WFO...ILN...DTX...APX...IWX...GRR...IND...LOT...

LAT...LON 44168638 44218520 43948421 43148375 40788406 39238535

38968669 39108754 40128748 41748704 44168638

post-7696-0-44721100-1384704313_thumb.gi

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Looking at the movement on radar, wouldn't be surprised if the cell makes a run at the Milwaukee Metro.  Looks like it's moving just a tad N of due NE.  The airport and downtown could be under the gun at least.

 

I'm waiting it out here, in case it turns more eastwards. Pretty dark to my northwest. Winds are really howling right now.

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These types of events are always scary for me.  Many people especially in the upper midwest like this don't associate mid november with tornadic supercells.  I hope people are paying attention, this setup is just potent as hell.  

 

I suspect we'll see these other areas get boxed up shortly.  

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