Southern Great Lakes derecho - August 4-5

[CrazyC83]

Still capable of 80+ mph as it comes back ashore.

[CrazyC83]

SEVERE THUNDERSTORM WARNING
INC091-099-131-141-149-181-MIC021-027-050245-
/O.NEW.KIWX.SV.W.0152.080805T0137Z-080805T0245Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE NORTHERN INDIANA
937 PM EDT MON AUG 4 2008

THE NATIONAL WEATHER SERVICE IN NORTHERN INDIANA HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
WESTERN MARSHALL COUNTY IN NORTH CENTRAL INDIANA
ST. JOSEPH COUNTY IN NORTH CENTRAL INDIANA
LA PORTE COUNTY IN NORTHWEST INDIANA
PULASKI COUNTY IN NORTHWEST INDIANA
STARKE COUNTY IN NORTHWEST INDIANA
WHITE COUNTY IN NORTHWEST INDIANA
BERRIEN COUNTY IN SOUTHWEST MICHIGAN
WESTERN CASS COUNTY IN SOUTHWEST MICHIGAN

* UNTIL 1045 PM EDT/945 PM CDT/

* AT 932 PM EDT/832 PM CDT/...TRAINED WEATHER SPOTTERS REPORTED A
LINE OF SEVERE THUNDERSTORMS PRODUCING PENNY SIZE HAIL...AND
DESTRUCTIVE WINDS IN EXCESS OF 80 MPH. THESE SEVERE STORMS WERE
LOCATED ALONG A LINE EXTENDING FROM 29 MILES NORTH OF BURNS HARBOR
TO 8 MILES NORTHWEST OF LAKES OF THE FOUR TO 30 MILES WEST OF DE
MOTTE...AND MOVING SOUTHEAST AT 52 MPH. THIS LINE HAS A HISTORY OF
PRODUCING DAMAGE IN AND AROUND THE CITY OF CHICAGO INCLUDING
STRUCTURE DAMAGE.
* LOCATIONS IN THE PATH OF SEVERE THUNDERSTORMS INCLUDE BUT NOT
LIMITED TO...
WESTVILLE AND MICHIGAN CITY...
TRAIL CREEK...
ST. JOSEPH...
FAIR PLAIN...BENTON HARBOR AND BENTON HEIGHTS...
KNOX...
BUCHANAN AND WINAMAC...

THIS LINE OF SEVERE THUNDERSTORMS COULD PRODUCE TORNADOES WITH
LITTLE OR NO WARNING. IF A TORNADO IS SPOTTED...ACT QUICKLY AND MOVE
TO A PLACE OF SAFETY IN A STURDY STRUCTURE...SUCH AS A BASEMENT OR
SMALL INTERIOR ROOM.

THIS IS AN EXTREMELY DANGEROUS SITUATION. GO TO A BASEMENT OR SMALL
INTERIOR ROOM. EVACUATE MOBILE HOMES...AND SEEK SHELTER INSIDE A
STURDY STRUCTURE.

LAT...LON 4219 8622 4208 8622 4208 8595 4176 8602
4176 8607 4149 8609 4117 8643 4117 8647
4112 8647 4075 8664 4072 8677 4057 8679
4057 8709 4084 8711 4085 8700 4092 8699
4093 8693 4172 8694 4190 8663 4225 8637
TIME...MOT...LOC 0135Z 299DEG 45KT 4199 8729 4149 8726
4113 8774

$$

FISHER

[CrazyC83]

The eastern shore of Lake Michigan needs to watch out for a seiche (same as a storm surge), that could be several feet high easily and do damage to lakefront property.

[CrazyC83]

Another watch, also possibly PDS, coming:

MESOSCALE DISCUSSION 2029
NWS STORM PREDICTION CENTER NORMAN OK
0850 PM CDT MON AUG 04 2008

AREAS AFFECTED...PORTIONS NRN IL...SRN LM...EXTREME SRN LOWER
MI...NRN INDIANA...NWRN-CENTRAL OH...ERN IA.

CONCERNING...SEVERE THUNDERSTORM WATCH 806...807...

VALID 050150Z - 050315Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
806...807...CONTINUES.

DAMAGING MCS AND POTENTIAL DERECHO EVENT SO FAR IS RESPONSIBLE FOR
SWATH OF DAMAGING WIND FROM RFD-CHI AREAS -- INCLUDING MEASURED 51
KT GUST AT MDW AT 106Z...AND 82 KT GUST AT 125Z AT C-MAN BUOY ON LM.
ACTIVITY SHOULD PROCEED ESEWD ACROSS REMAINDER WW THEN INTO
PORTIONS EXTREME SRN LOWER MI AND OH. ANOTHER WW MAY BE REQUIRED
BEFORE 03Z.

WELL-DEVELOPED BOW ECHO SYSTEM IS INTERACTING WITH VORTICITY-RICH
LOW LEVEL BOUNDARY REMAINING FROM EARLY-DAY OUTFLOW. THIS BOUNDARY
STILL IS ANALYZED IN WNW-ESE ORIENTATION AND MOVING SLOWLY NWD
ACROSS NWRN/E-CENTRAL INDIANA. ASSOCIATED INSTABILITY/MOISTURE
GRADIENTS SHOULD CONTINUE TO FORM PREFERRED CORRIDOR FOR
FORWARD-PROPAGATION OF MCS...AND GREATEST ACCOMPANYING DAMAGING WIND
POTENTIAL. MODIFIED RAOBS AND RUC SOUNDINGS INDICATE THAT SBCINH
WILL INCREASE WITH EWD EXTENT AND WITH TIME IN PROSPECTIVE INFLOW
LAYER. HOWEVER...EFFECTIVE INFLOW PARCELS WILL REMAIN ROOTED AT OR
NEAR SFC FOR SEVERAL MORE HOURS...AND STRONG FORCED ASCENT IS
EXPECTED TO PERSIST ALONG LEADING EDGE OF SYSTEM. DAMAGING GUSTS
SHOULD CONTINUE...ALONG WITH THREAT OF OCCASIONAL/BRIEF TORNADOES
FROM QLCS SPINUPS AND BOOKEND VORTICES. STG-SVR WIND ALSO MAY
CONTINUE FOR UP TO HALF AN HOUR BEHIND LEADING SURGE OF
MCS...ASSOCIATED WITH REAR-INFLOW JET.

INITIATION ALONG TRAILING OUTFLOW BOUNDARY WILL BECOME LESS PROBABLE
WITH TIME AS BOUNDARY LAYER TO ITS S UNDERGOES GRADUAL DIABATIC
COOLING...AND SLOPE OF COLD POOL NEAR BOUNDARY BECOMES MORE SHALLOW.
HOWEVER...LOW LEVEL WAA ZONE -- WITH ISENTROPIC ASCENT TO LFC --
MAY DEVELOP FARTHER NE ATOP COLD POOL...WITH ELEVATED MUCAPES
2000-3000 J/KG REMAINING IN ENVIRONMENT OF AT LEAST MRGLLY FAVORABLE
DEEP-LAYER SHEAR. MAIN CONCERN WITH ANY SUCH POST-MCS ACTIVITY
WOULD BE ISOLATED LARGE HAIL.

..EDWARDS.. 08/05/2008


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

41338900 41438806 41658768 42108713 42088611 41638347
41028315 39998304 39718421

[Shockwave]

That comma shaped bend in the line right around Valparaiso and Westville, IN has me concerned. That bend is the same sign as a hook echo, am I right?

[CrazyC83]

That comma shaped bend in the line right around Valparaiso and Westville, IN has me concerned. That bend is the same sign as a hook echo, am I right?

Yes, that is where a tornado is most likely (although the northern bend can also have them, as well as any embedded breaks in the derecho).

[Chacor]

-70°C cloud tops is colder than what Edouard is generating right now!

[CrazyC83]

Look out along the US 31 corridor - quite heavily populated there too...

[Shockwave]

I got school tomorrow...but I'm not leaving this action! That is COLD, especially over land. I think this derecho system will only get stronger as the night goes on.

[CrazyC83]

From wunderground:

0825 PM MARINE TSTM WIND 4 NNE CHICAGO 41.93N 87.60W
08/04/2008 M94.00 MPH LMZ741 IL C-MAN STATION
AT HARRISON CRIB.

0825 PM TSTM WND DMG BOLINGBROOK 41.70N 88.08W
08/04/2008 WILL IL TRAINED SPOTTER
ROOF BLOWN OFF OF HOUSE AT BOUGHTON ROAD AND KING RD.

0630 PM TSTM WND DMG N MOUNT MORRIS 42.05N 89.43W
08/04/2008 OGLE IL TRAINED SPOTTER
BUILDING LEVELED ON THE NORTHSIDE.

0801 PM TORNADO ELMHURST 41.90N 87.94W
08/04/2008 DUPAGE IL EMERGENCY MNGR
TORNADO ON GROUND.

0717 PM TSTM WND GST COMPTON 41.69N 89.09W
08/04/2008 E80 MPH LEE IL TRAINED SPOTTER
MULTIPLE ONE FOOT IN DIAMETER TREES DOWN. SHINGLES BLOWN
OFF HOUSES.

0825 PM TSTM WND DMG BOLINGBROOK 41.70N 88.08W
08/04/2008 WILL IL EMERGENCY MNGR
HALF DOZEN HOMES RECEIVED SIGNIFICANT DAMAGE NEAR
BOUGHTON ROAD AND KING

[Shockwave]

Buildings leveled, homes roofs blown off, tower lines collapseing. Sounds a lot like tornado damage, but that's what 90 mph winds can do to structures.

[JonathanBelles]

Quite an amazing storm. Now headed for South bend where there is a TOR.

[CrazyC83]

I just got this:

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1009 PM EDT MON AUG 04 2008

.TIME.. ...EVENT... ...CITY LOCATION... ...LAT.LON

.DATE.. ....MAG.... ..COUNTY LOCATION.. ST.. ...SOURCE.

..REMARKS..

1007 PM TSTM WND DMG MICHIGAN CITY 41.71N 86.88W
08/04/2008 LA PORTE IN BROADCAST MEDIA

WIDESPREAD DAMAGE BEING REPORTED IN MICHIGAN CITY. NO
FURTHER DETAILS AT THIS TIME.

[CrazyC83]

SEVERE THUNDERSTORM WARNING
INC017-039-049-085-087-099-103-113-131-141-169-181-183-MIC027-149-
050315-
/O.NEW.KIWX.SV.W.0153.080805T0214Z-080805T0315Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1014 PM EDT MON AUG 4 2008

THE NATIONAL WEATHER SERVICE IN NORTHERN INDIANA HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
CASS COUNTY IN NORTH CENTRAL INDIANA
ELKHART COUNTY IN NORTH CENTRAL INDIANA
FULTON COUNTY IN NORTH CENTRAL INDIANA
KOSCIUSKO COUNTY IN NORTH CENTRAL INDIANA
MARSHALL COUNTY IN NORTH CENTRAL INDIANA
MIAMI COUNTY IN NORTH CENTRAL INDIANA
EASTERN ST. JOSEPH COUNTY IN NORTH CENTRAL INDIANA
NORTHERN WABASH COUNTY IN NORTH CENTRAL INDIANA
WESTERN LAGRANGE COUNTY IN NORTHEAST INDIANA
WESTERN NOBLE COUNTY IN NORTHEAST INDIANA
WESTERN WHITLEY COUNTY IN NORTHEAST INDIANA
EASTERN PULASKI COUNTY IN NORTHWEST INDIANA
EASTERN WHITE COUNTY IN NORTHWEST INDIANA
EASTERN CASS COUNTY IN SOUTHWEST MICHIGAN
SOUTHWESTERN ST. JOSEPH COUNTY IN SOUTHWEST MICHIGAN

* UNTIL 1115 PM EDT

* AT 1010 PM EDT/910 PM CDT/...TRAINED WEATHER SPOTTERS REPORTED A
LINE OF SEVERE THUNDERSTORMS PRODUCING DESTRUCTIVE WINDS IN EXCESS
OF 80 MPH. THESE SEVERE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM 13 MILES SOUTHWEST OF ST. JOSEPH TO 11 MILES
NORTH OF KNOX TO 7 MILES NORTHWEST OF RENSSELAER...AND MOVING
SOUTHEAST AT 57 MPH. DAMAGE HAS BEEN REPORTED IN MICHIGAN CITY AND
OTHER AREAS ALONG THIS LINE.

* LOCATIONS IN THE PATH OF SEVERE THUNDERSTORMS INCLUDE...
PLYMOUTH...
MONTICELLO AND BREMEN...
SIMONTON LAKE...
ROCHESTER...NAPPANEE AND ELKHART...
WARSAW AND GOSHEN...
WINONA LAKE...SYRACUSE AND LOGANSPORT...

THIS IS AN EXTREMELY DANGEROUS SITUATION. SEEK SHELTER IMMEDIATELY.

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS LINE OF
SEVERE THUNDERSTORMS. SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH
LITTLE OR NO WARNING. IF A TORNADO IS SPOTTED...ACT QUICKLY AND MOVE
TO A PLACE OF SAFETY IN A STURDY STRUCTURE...SUCH AS A BASEMENT OR
SMALL INTERIOR ROOM.

LAT...LON 4140 8627 4207 8598 4178 8541 4106 8553
4101 8559 4101 8564 4097 8564 4057 8609
4057 8637 4070 8639 4070 8652 4074 8653
4074 8668 4074 8674 4072 8677 4058 8677
4059 8701
TIME...MOT...LOC 0213Z 294DEG 49KT 4191 8655 4143 8658
4098 8719

$$

FISHER

[Bunkertor]

When did they upgrade to MDT ?

[CrazyC83]

When did they upgrade to MDT ?

0100Z update (actually about 0000Z), which is rare to upgrade late but they had to in this case as a derecho developed pretty much out of nowhere. They should expand the MDT eastward IMO, but that requires an amended forecast.

[CrazyC83]

TORNADO WARNING
INC049-091-099-149-050315-
/O.NEW.KIWX.TO.W.0026.080805T0217Z-080805T0315Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1017 PM EDT MON AUG 4 2008

THE NATIONAL WEATHER SERVICE IN NORTHERN INDIANA HAS ISSUED A

* TORNADO WARNING FOR...
NORTHEASTERN FULTON COUNTY IN NORTH CENTRAL INDIANA
MARSHALL COUNTY IN NORTH CENTRAL INDIANA
SOUTHERN LA PORTE COUNTY IN NORTHWEST INDIANA
NORTHEASTERN STARKE COUNTY IN NORTHWEST INDIANA

* UNTIL 1115 PM EDT/1015 PM CDT/

* AT 914 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM WITH STRONG ROTATION. THIS SEVERE STORM WAS
LOCATED NEAR BREMS...OR 5 MILES NORTHWEST OF KNOX...AND MOVING
SOUTHEAST AT 57 MPH.

* LOCATIONS IN THE PATH OF THE SEVERE STORM INCLUDE...
PLYMOUTH...
CULVER...
ARGOS...
BOURBON...
OAK GROVE...OBER AND DONALDSON...
HIBBARD...BURR OAK AND TWIN LAKES...

THIS IS A PARTICULARLY DANGEROUS SITUATION!!!

IN ADDITION TO THE TORNADO...THIS STORM IS CAPABLE OF PRODUCING
DESTRUCTIVE WINDS IN EXCESS OF 80 TO 100 MPH..

IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A
STURDY SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE NEAREST
DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

THIS SEVERE HAS A HISTORY OF PRODUCING WIDESPREAD WIND DAMAGE ACROSS
NORTHWEST INDIANA. THIS IS AN EXTREMELY DANGEROUS SITUATION. GO TO A
BASEMENT OR SMALL INTERIOR ROOM. EVACUATE MOBILE HOMES...AND SEEK
SHELTER INSIDE A STURDY STRUCTURE.

THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. GET UNDER A
WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. IF NO BASEMENT IS
AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE BUILDING IN AN
INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE BLANKETS OR PILLOWS TO
COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS.

IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A
SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE
NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

LAT...LON 4148 8677 4146 8653 4144 8653 4144 8648
4145 8647 4141 8607 4117 8607 4117 8608
4110 8608 4110 8607 4104 8607 4131 8688
TIME...MOT...LOC 0216Z 293DEG 50KT 4135 8664

$$

[CrazyC83]

Now that is extremely dangerous. That tornado warning was probably a fake for the extreme winds as I don't see much rotation there.

[Bunkertor]

When did they upgrade to MDT ?

0100Z update (actually about 0000Z), which is rare to upgrade late but they had to in this case as a derecho developed pretty much out of nowhere. They should expand the MDT eastward IMO, but that requires an amended forecast.

Thanks for reply. I was just in deleting my message, because i thought it was a mistake or so...

[CrazyC83]

No new watch? It appears they extended the PDS watch to cover NE Indiana...