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May 20th Severe Weather


Chicago Storm

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Might as well have a seperate thread...

Slight risk expanded a bit on the latest SWOD1.

..UPPER MI..WI..NRN/CNTRL IL INTO NWRN IND

WATER VAPOR IMAGERY INDICATES A STRONG UPPER TROUGH MOVING TOWARD

THE UPPER MS VALLEY...WITH LARGE SCALE ASCENT SPREADING INTO WI AND

WRN UPPER MI ATTM. SURFACE LOW OVER WEST CENTRAL WI IS EXPECTED TO

MOVE INTO NERN WI/CENTRAL UPPER MI BY THIS EVENING BEFORE LIFTING

INTO ONTARIO TONIGHT. A COLD FRONT EXTENDING SWD FROM THE LOW WILL

MOVE EWD ACROSS MUCH OF WI AND NWRN/WEST CENTRAL IL THIS AFTERNOON

REACHING A LINE FROM SERN LOWER MI INTO THE LOWER OH VALLEY BY LATE

TONIGHT. AHEAD OF THE COLD FRONT...VISIBLE IMAGERY SHOWS LARGELY

CLEAR SKIES PROMOTING STRONG DIURNAL HEATING...WITH SURFACE

TEMPERATURES EXPECTED TO REACH THE MID/UPPER 80S THIS AFTERNOON.

SUFFICIENT MOISTURE IS IN PLACE WITH SURFACE DEW POINTS NEAR 60F AND

PW AROUND 1 INCH...AND WHEN COUPLED WITH STEEPER MID LEVEL LAPSE

RATES THE ENVIRONMENT WILL BECOME MODERATELY UNSTABLE WITH MLCAPE OF

1500-2000 J/KG THIS AFTERNOON.

AN EARLIER BAND OF ELEVATED PRE-FRONTAL STORMS OVER NORTH CENTRAL WI

INTO WRN UPPER MI HAS SHOWN SIGNS OF WEAKENING SLIGHTLY...WHILE NEW

STORMS HAVE BEEN DEVELOPING OVER THE LAST 1-2 HRS JUST AHEAD OF THE

COLD FRONT FROM NEAR EAU NWD TOWARD ASX. AS THE COLD FRONT MOVES

EWD...THIS CONVECTION IS EXPECTED TO INCREASE IN INTENSITY AS IT

MOVES INTO AN INCREASINGLY UNSTABLE ENVIRONMENT. SWLY MID LEVEL

WINDS OF 40-50 KT ARE RESULTING IN SUFFICIENT DEEP LAYER SHEAR

/40-45 KT IN THE LOWEST 6 KM/ TO ENHANCE STORM ORGANIZATION AND

INTENSITY INCLUDING POTENTIAL FOR A FEW SUPERCELLS TO FORM...WITH

SOME STORMS POSSIBLY BECOMING SEVERE AS EARLY AS 17-18Z. ACTIVITY

IS EXPECTED TO SPREAD EWD ACROSS PARTS OF WI AND UPPER MI THROUGH

THE LATE AFTERNOON AND EVENING BEFORE GRADUALLY WEAKENING TONIGHT.

DAMAGING WIND GUSTS AND LARGE HAIL WILL BE THE PRIMARY

THREATS...ALTHOUGH A TORNADO OR TWO MAY ALSO BE POSSIBLE.

STORMS ARE EXPECTED TO DEVELOP SWD ALONG/AHEAD OF THE FRONT THIS

AFTERNOON INTO PARTS OF NWRN AND WEST CENTRAL IL AS STRONG HEATING

WEAKENS THE CAP. ALTHOUGH WINDS ALOFT AND ASSOCIATED VERTICAL SHEAR

WILL GRADUALLY DIMINISH WITH SWD EXTENT...ORGANIZED MULTICELL STORMS

ARE LIKELY TO DEVELOP AND SPREAD EWD AHEAD OF THE FRONT THROUGH THE

EVENING WITH A THREAT FOR LARGE HAIL AND DAMAGING WINDS.

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LOT

1134 AM CDT

TEMPERATURES ARE QUICKLY JUMPING INTO THE UPPER 80S TO LOW 90S

ACROSS THE REGION THIS MORNING AHEAD OF AN APPROACHING COLD FRONT

ACROSS EASTERN IOWA. THERE ARE TWO AREAS OF CONVECTIVE DEVELOPMENT

THAT WE ARE WATCHING THIS AFTERNOON. THE FIRST WILL BE ASSOCIATED

WITH THE COLD FRONTAL ZONE. CONVECTIVE DEVELOPMENT ALONG THIS

FRONTAL ZONE SHOULD COMMENCE ACROSS NORTH CENTRAL AND NORTHWESTERN

ILLINOIS BY EARLY TO MID AFTERNOON (AFTER 19 UTC). THIS ACTIVITY IS

THEN EXPECTED TO SPREAD EASTWARD ACROSS NORTHEASTERN ILLINOIS BY

LATE AFTERNOON AND EARLY THIS EVENING (5 TO 8 PM FOR CHICAGO).

HOWEVER...ADDITIONAL CONVECTIVE DEVELOPMENT IS POSSIBLE ACROSS

NORTHEASTERN ILLINOIS AND NORTHWESTERN INDIANA BY EARLY TO MID

AFTERNOON AHEAD OF THE MAIN ACTIVITY. THIS ADDITIONAL AREA OF

POSSIBLE CONVECTIVE DEVELOPMENT APPEARS TO BE ASSOCIATED WITH LOW

LEVEL CONVERGENCE ALONG A PRE FRONTAL TROUGH ACROSS EASTERN

ILLINOIS AND NORTHWESTERN INDIANA.

MODEL GUIDANCE CONTINUES TO INDICATE DECENT MID LEVEL LAPSE RATES IN

EXCESS OF 7 DEGREES C/KM WITHIN THE WARM SECTOR ACROSS NORTHERN

ILLINOIS AND NORTHWESTERN INDIANA. SURFACE DEWPOINTS WILL LIKELY

REMAIN ONLY IN THE UPPER 50S TO LOW 60S THIS AFTERNOON (SOME MID 60S

POSSIBLY POOLING ALONG THE FRONTAL ZONE) AS SURFACE HIGH PRESSURE

ACROSS THE GULF COAST WILL IMPEDE BETTER MOISTURE TRANSPORT INTO THE

REGION THIS AFTERNOON. HOWEVER...IN SPITE OF THESE MODEST DEW

POINTS...AFTERNOON HEATING WILL ALLOW TEMPERATURES TO EASILY TOP OUT

IN THE LOW 90S. THIS WILL BE ENOUGH TO PRODUCE ML CAPES IN EXCESS OF

1500 J/KG. THE ONLY LACKING INGREDIENT WILL BE DEEP LAYER

SHEAR...WHICH IS PROGGED TO ONLY BE AROUND 25 KT. IN SPITE OF THIS...

THETA E DIFFERENCES BETWEEN THE SURFACE AND THE MID LEVELS ARE

FORECAST TO BE IN EXCESS OF 20 DEGREES C AHEAD OF THE COLD FRONTAL

ZONE AND DOWNDRAFT CAPE IN EXCESS OF 1500 J/KG. THESE PARAMETERS

SUGGEST AN INCREASED THREAT OF STRONG DAMAGING WIND GUSTS ASSOCIATED

WITH MICROBURSTS. THIS APPEARS TO BE THE PRIMARY THREAT...ALTHOUGH

SOME MARGINALLY SEVERE HAIL CANNOT BE RULED OUT WITH AN MULTI-CELLS

DUE TO THE STEEP MID LEVEL LAPSE RATES.

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Storms are now firing in McHenry and Boone County! Cumulus are really on the increase here.

Edit: Pretty good small cell south of where Cyclone lives. Looks like cell popping near Rensselaer, IN too.

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Things starting to cook off to the west with some audible thunder amid the gusty winds. Little prefrontal convergence goin' eh?

250+ craft exhibitors with tents set up on the Square for the annual Fair Diddley. We'll see if we can keep it dry through the afternoon.

post-855-13375407658.jpg

post-855-133754130105.jpg

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Nice pictures Kevlon. I recognize the location of the 2nd picture!

Severe T-storm warning near Cyclone's place:

SEVERE THUNDERSTORM WARNING

ILC011-195-201930-

/O.NEW.KDVN.SV.W.0038.120520T1906Z-120520T1930Z/

BULLETIN - EAS ACTIVATION REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE QUAD CITIES IA IL

206 PM CDT SUN MAY 20 2012

THE NATIONAL WEATHER SERVICE IN THE QUAD CITIES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

NORTHWESTERN BUREAU COUNTY IN NORTH CENTRAL ILLINOIS...

SOUTHEASTERN WHITESIDE COUNTY IN NORTHWEST ILLINOIS...

* UNTIL 230 PM CDT.

* AT 204 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS AROUND 60

MPH...AND QUARTER SIZE HAIL. THIS STORM WAS LOCATED APPROXIMATELY

15 MILES SOUTHWEST OF DEER GROVE...OR 14 MILES NORTHEAST OF

KEWANEE...AND MOVING NORTHEAST AT 40 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO

WALNUT.

THIS INCLUDES INTERSTATE 80 IN ILLINOIS BETWEEN MILE MARKERS 36 AND

42.

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GOES19252012141ey2o1N.jpg

The lake breeze convergence cumulus line is getting some taller towers forming on it. Can see them out my window.

Some good SBCAPE pooling as well. If that 2000 j/kg is accurate. Mid levels are kind of dry though so it may be tough to get anything going without a deeper lifting mechanism.

sbcp.gif

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Things are definitely more humid here with 60 dew point. At 1:15 EDT in Goshen had a clap of thunder from a microcell overhead near the library with sunshine all around it. Only a few sprinkles but the atmosphere is getting primed. Could be an interesting afternoon and evening at least compared to what we've had to watch lately even if multi cells do predominate.

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I'm a little worried CB tops from the WI convection may be out over the lake during the solar eclipse, blocking my view. I'm heading out anyways but it would be nice if there was a sun break between cells. Don't know if I'll have better luck heading towards Muskegon, Holland, or Suagatuck.

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I really think we will be severely limited per the eclipse here in the eastern part of the U.S. even with absolutely clear skies. With respect to svr wx it does seem like there is a pre frontal trough or convergence zone of some sort along the IL/IN line extending downstate. If only we had upper air support today.

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I really think we will be severely limited per the eclipse here in the eastern part of the U.S. even with absolutely clear skies. With respect to svr wx it does seem like there is a pre frontal trough or convergence zone of some sort along the IL/IN line extending downstate. If only we had upper air support today.

There is a 45 minute window of partial eclipse prior to 9:00 PM near the lakeshore. It's just that that is exactly when that line of storms in WI will be moving in over the lake.

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Those thunderstorms by Rockford are growing in number. The party in the center of Woodstock might have to end early!

Edit:

SPECIAL WEATHER STATEMENT...CORRECTED

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

324 PM CDT SUN MAY 20 2012

ILZ008-010-011-202045-

DE KALB IL-LEE IL-OGLE IL-

324 PM CDT SUN MAY 20 2012

...SPECIAL WEATHER STATEMENT...

AT 316 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED STRONG

THUNDERSTORMS ALONG A LINE EXTENDING FROM STILLMAN VALLEY TO

AMBOY...MOVING NORTHEAST AT 30 MPH.

ONE HALF INCH DIAMETER HAIL...WINDS TO 55 MPH...FREQUENT CLOUD TO

GROUND LIGHTNING...BRIEF HEAVY DOWNPOURS...ARE POSSIBLE WITH THESE

STORMS.

LOCATIONS IMPACTED INCLUDE...

ASHTON... STILLMAN VALLEY... AMBOY...

FRANKLIN GROVE... HILLCREST... ROCHELLE...

KIRKLAND... MALTA... PAW PAW...

THE FOLLOWING LOCATIONS MAY ALSO BE IMPACTED...

LEE COUNTY FAIRGROUNDS.

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LOT

302 PM CDT...

AREA OF CONCERN OVER NORTHEASTERN ILLINOIS AND NORTHWEST INDIANA

LOOKS DIFFUSE ON VISIBLE SATELLITE IMAGERY BUT WEAK RETURNS CONTINUE

TO PULSE UP AND DOWN ON RADAR AND WILL HAVE TO CONTINUE TO MONITOR

THIS AREA. FOR NOW THOUGH...THE MAIN FOCUS HAS SHIFTED WEST TOWARDS

THE COLD FRONT WHICH IS MAKING A PUSH ACROSS THE MISSISSIPPI RIVER.

A FEW THUNDERSTORMS HAVE ALREADY DEVELOPED OVER PORTIONS OF

NORTHWEST AND NORTH CENTRAL ILLINOIS ALONG THE INSTABILITY AXIS.

DESPITE THE MODERATE INSTABILITY IN EXCESS OF 1000 J/KG PER LATEST

SPC MESO-ANALYSIS...DEEP LAYER SHEAR OF LESS THAN 30 KT CONTINUES TO

LIMIT THE SEVERE POTENTIAL. BEST DCAPE VALUES ARE CLOSER TO THE

IL/IN STATELINE WHERE HIGHER DEW POINT DEPRESSIONS PERSIST...SO

UNLESS WE SEE DEVELOPMENT MOVE FARTHER AHEAD OF THE FRONT...THINK

THE WIND THREAT //AND OVERALL SEVERE THREAT IN GENERAL// WILL BE

MARGINAL.

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Severe Thunderstorm warning:

SEVERE THUNDERSTORM WARNING

ILC007-037-111-141-202145-

/O.NEW.KLOT.SV.W.0029.120520T2041Z-120520T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

341 PM CDT SUN MAY 20 2012

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

SOUTHERN BOONE COUNTY IN NORTH CENTRAL ILLINOIS...

NORTHERN DE KALB COUNTY IN NORTH CENTRAL ILLINOIS...

SOUTHWESTERN MCHENRY COUNTY IN NORTHEAST ILLINOIS...

EAST CENTRAL OGLE COUNTY IN NORTH CENTRAL ILLINOIS...

* UNTIL 445 PM CDT

* AT 338 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE

HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH. THESE STORMS WERE

LOCATED ALONG A LINE EXTENDING FROM 5 MILES SOUTHEAST OF CHERRY

VALLEY TO 6 MILES NORTHWEST OF MALTA...AND MOVING NORTHEAST AT 30

MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...

BELVIDERE AND KIRKLAND AROUND 350 PM CDT.

KINGSTON AROUND 400 PM CDT.

GENOA AROUND 405 PM CDT.

MARENGO AROUND 425 PM CDT.

THE FOLLOWING LOCATIONS MAY ALSO BE IMPACTED...

BOONE COUNTY FAIRGROUNDS.

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mcd0853.gif

MESOSCALE DISCUSSION 0853

NWS STORM PREDICTION CENTER NORMAN OK

0350 PM CDT SUN MAY 20 2012

AREAS AFFECTED...NERN IL THROUGH SERN WI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 202050Z - 202215Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...STORMS HAVE BECOME A LITTLE BETTER ORGANIZED AS A LINE

SEGMENT OVER NCNTRL IL. THIS ACTIVITY WILL POSE A RISK FOR DAMAGING

WIND AS IT MOVES INTO NERN IL AND SERN WI. TRENDS ARE BEING

MONITORED FOR A POSSIBLE WW.

DISCUSSION...STORMS DEVELOPING ALONG A PRE-FRONTAL CONVERGENCE AXIS

HAVE BECOME BETTER ORGANIZED AS A LINE SEGMENT. ACTIVITY IS FORMING

WITHIN AN ENVIRONMENT CHARACTERIZED BY 30-35F BOUNDARY LAYER

TEMPERATURE-DEWPOINT SPREADS...STEEP LOW-MID LEVEL LAPSE RATES AND

MODERATE /1000-1500 J/KG/ INSTABILITY. THIS ENVIRONMENT IS FAVORABLE

FOR ISOLATED STRONG TO DAMAGING WIND GUSTS...ESPECIALLY WITH STORMS

THAT HAVE HIGHER REFLECTIVITY CORES ABOVE 5 KM. CONCERN IS THAT AS

STORMS BECOME MORE LINEAR...THE THREAT MAY BECOME A LITTLE MORE

WIDESPREAD.

..DIAL/WEISS.. 05/20/2012

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Those thunderstorms by Rockford are growing in number. The party in the center of Woodstock might have to end early!

Edit:

Going to see what's doing down there now. NNE movement seems to have yielded to a more NE to E direction for that SVR warned cell. Could have us written all over it.

They are scheduled for exhibitor break down at 5 p.m. Might have to call it a bit early...

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Going to see what's doing down there now. NNE movement seems to have yielded to a more NE to E direction for that SVR warned cell. Could have us written all over it.

They are scheduled for exhibitor break down at 5 p.m. Might have to call it a bit early...

Severe Weather Statement for the entire county. Cell just popped over Woodstock!

SEVERE WEATHER STATEMENT

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

358 PM CDT SUN MAY 20 2012

ILC007-037-111-202145-

/O.CON.KLOT.SV.W.0029.000000T0000Z-120520T2145Z/

MCHENRY IL-BOONE IL-DE KALB IL-

358 PM CDT SUN MAY 20 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHERN DE

KALB...SOUTHEASTERN BOONE AND SOUTHWESTERN MCHENRY COUNTIES UNTIL 445

PM CDT...

AT 355 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE

HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH. THESE STORMS WERE

LOCATED ALONG A LINE EXTENDING FROM BELVIDERE TO 6 MILES WEST OF

MARENGO TO KINGSTON...MOVING NORTHEAST AT 35 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...

MARENGO AROUND 410 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER

HOUR...LARGE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR YOUR

PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME

OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO

AREAS WHERE WATER COVERS THE ROAD.

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Thunderstorms turning more NE now. Warning for northern Lake County now.

SEVERE THUNDERSTORM WARNING

ILC097-111-202200-

/O.NEW.KLOT.SV.W.0030.120520T2106Z-120520T2200Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

406 PM CDT SUN MAY 20 2012

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

NORTHWESTERN LAKE COUNTY IN NORTHEAST ILLINOIS...

MCHENRY COUNTY IN NORTHEAST ILLINOIS...

* UNTIL 500 PM CDT

* AT 404 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE

HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH. THESE STORMS WERE

LOCATED ALONG A LINE EXTENDING FROM HARVARD TO MARENGO...AND MOVING

NORTHEAST AT 40 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...

WOODSTOCK AROUND 415 PM CDT.

BULL VALLEY AROUND 420 PM CDT.

HEBRON...WONDER LAKE AND MCHENRY AROUND 425 PM CDT.

MCCULLOM LAKE AROUND 430 PM CDT.

SUNNYSIDE...SPRING GROVE...RICHMOND AND PISTAKEE HIGHLANDS AROUND

435 PM CDT.

FOX LAKE AROUND 440 PM CDT.

LAKE CATHERINE...CHANNEL LAKE AND ANTIOCH AROUND 445 PM CDT.

THE FOLLOWING LOCATIONS MAY ALSO BE IMPACTED...

CHAIN O LAKES STATE PARK AND MCHENRY COUNTY FAIRGROUNDS.

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