Thanksgiving Week Severe Weather

[cyclone77]

I ended up having a good chase for late November standards...

I ended up catching what ended up being the lead cells in Southern De Kalb County. Radar showed the cell had a defined hook and rotation and was eventually tornado warned. The cell featured a lower/wall cloud the whole time I was on the cell across De Kalb and as it entered Kane County. I was position on Route 30 between Waterman and Hinckley most of the time as that is where the best view was. The lowering ended up crossing the road a bit to my east, though portion of the board area of rotation did pass overhead. As it passed I tried to keep up, but storm motions were to fast and I lost it in Kane County.

Here are a few pictures of the lowering/wall cloud as it as it passed Route 30 between Waterman and Hinckley..

Sorry for the low quality, I have a horrible camera...I can't wait to get a DSLR camera.

Nice pics. Can definitely see the supercell structure. Looks like it had a fairly large rain free base. In the second pic it looks like it really wants to produce, but can't see much of an RFD punching in there. Kind of hard to tell in the pic though.

[Hoosier]

Just scanning some records, it looks like this will be the first November tornado in the WFO LOT area since 1984.

[Chicago Storm]

Nice pics. Can definitely see the supercell structure. Looks like it had a fairly large rain free base. In the second pic it looks like it really wants to produce, but can't see much of an RFD punching in there. Kind of hard to tell in the pic though.

Thanks.

As you mentioned, it was a fairly large rain free base.

Also, at the point when the picture was taken that was probably the best it looked while I was on it. At that time I thought it may get it's act together, but it wasn't able to. A stronger RFD surely would have helped.

[oldlogin]

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE WILMINGTON OH

205 AM EST TUE NOV 23 2010

THE NATIONAL WEATHER SERVICE IN WILMINGTON HAS ISSUED A

* TORNADO WARNING FOR...

SOUTHERN CHAMPAIGN COUNTY IN WEST CENTRAL OHIO...

NORTHERN CLARK COUNTY IN WEST CENTRAL OHIO...

EASTERN MIAMI COUNTY IN WEST CENTRAL OHIO...

* UNTIL 230 AM EST.

* AT 202 AM EST...RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF

PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED NEAR HAVEN

VIEW...MOVING EAST AT 45 MPH.

* LOCATIONS IMPACTED INCLUDE...

ST. PARIS...

URBANA...

MECHANICSBURG...

IN ADDITION...NORTH HAMPTON...DIALTON...THACKERY...LAWRENCEVILLE...

TERRE HAUTE...TREMONT CITY...WESTVILLE AND NEW MOOREFIELD ARE NEAR

THE PATH OF THIS DANGEROUS THUNDERSTORM.

[janetjanet998]

pockets of CAPE1000-1500ish showing up on ther 12z NAM for tomorrow

old day 2

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1257 AM CST TUE NOV 23 2010

VALID 241200Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS EASTERN OK/SOUTHEAST KS

AND MUCH OF SOUTHERN MO/NORTHERN AR...

...EASTERN OK/SOUTHEAST KS/ARKLATEX TO THE MIDDLE MS/LOWER OH

VALLEYS...

A BROAD/STRONG UPPER TROUGH IS EXPECTED TO ADVANCE EASTWARD OVER THE

NORTHERN/CENTRAL PORTIONS OF THE ROCKIES AND PLAINS ON WEDNESDAY. IN

THE LOW LEVELS...WITH A RESERVOIR OF RELATIVELY RICH MOISTURE ACROSS

THE ARKLATEX/LOWER MS VALLEY...A WARM/MOIST AIRMASS WILL QUICKLY

RETREAT NORTHWARD AHEAD OF A CENTRAL PLAINS/LOWER MO VALLEY SURFACE

LOW AND COLD FRONT/PRE-FRONTAL TROUGH.

IT IS LIKELY THAT SHOWERS/TSTMS WILL BE ONGOING EARLY IN THE DAY

ACROSS MUCH OF THE REGION. THIS PROVIDES SOME UNCERTAINTY REGARDING

THE DEGREE OF SUBSEQUENT SURFACE BASED DESTABILIZATION ESPECIALLY

WITH NORTHEASTWARD EXTENT INTO THE MIDDLE MS/LOWER OH VALLEYS.

NONETHELESS...AS THE BOUNDARY LAYER GRADUALLY DESTABILIZES AND

HEIGHT FALLS BEGIN TO OVERSPREAD THE NEAR-COLD FRONTAL WARM

SECTOR...CURRENT THINKING IS THAT SURFACE BASED/POTENTIALLY SEVERE

TSTMS WILL PROBABLY DEVELOP/INCREASE DURING THE AFTERNOON/EARLY

EVENING HOURS...PRIMARILY AHEAD OF THE AFOREMENTIONED SURFACE LOW

AND SOUTHWESTWARD EXTENDING COLD FRONT/PRE-FRONTAL TROUGH. THIS

INITIAL DEVELOPMENT APPEARS MOST LIKELY ACROSS PORTIONS OF SOUTHEAST

KS/EASTERN OK/SOUTHWEST MO/NORTHWEST AR.

WITH SURFACE DEWPOINTS IN THE LOWER TO MIDDLE 60S F ACROSS THE WARM

SECTOR...SUFFICIENT /ALBEIT MODEST/ INSTABILITY COUPLED WITH

INCREASINGLY STRONG DEEP LAYER/LOW LEVEL FLOW...ACCENTUATED BY 65-95

KT AT 500 MB AND 1 KM FLOW STRENGTHENING TO IN EXCESS OF 50

KT...WILL SUPPORT THE POSSIBILITY OF AN ORGANIZED/SUSTAINED SEVERE

RISK. SUCH A THREAT MAY PERSIST WELL THROUGH THE

EVENING/OVERNIGHT...AND DEVELOP AS FAR EAST AS THE MIDDLE MS/LOWER

OH VALLEYS. EARLY MODAL SUPERCELLS ARE A DISTINCT

POSSIBILITY...BEFORE A FAST MOVING/QUASI-LINEAR MODE DOMINATES. SOME

SEVERE HAIL MAY BE POSSIBLE WITH INITIAL DEEP CONVECTIVE

DEVELOPMENT...BUT OTHERWISE...THE PRIMARY SEVERE POTENTIAL SHOULD BE

FOR DAMAGING WINDS/ISOLATED TORNADOES.

..GUYER.. 11/23/2010

ACUS03 KWNS 230829

SWODY3

SPC AC 230829

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0229 AM CST TUE NOV 23 2010

VALID 251200Z - 261200Z

..SYNOPSIS

THE PREVALENT CONUS LONGWAVE TROUGH WILL SHIFT EASTWARD OVER THE

CENTRAL STATES ON THANKSGIVING DAY. THE BRUNT OF THIS TROUGH WILL

TRANSITION EASTWARD OVER THE UPPER MIDWEST/UPPER GREAT LAKES...AS

THE BASAL/SOUTHERN PORTION OF THE TROUGH CROSSES THE

CENTRAL/SOUTHERN PLAINS. THE ASSOCIATED COLD FRONT /AUGMENTED BY

EXTENSIVE EARLY DAY CONVECTION/ WILL CONTINUE TO STEADILY ADVANCE

SOUTHEASTWARD OVER THE OH/TN VALLEYS AND ARKLATEX/LOWER MS RIVER

VALLEY. WHILE THE WARM SECTOR ACROSS THE OH/TN VALLEYS SHOULD BE

CONVECTIVELY OVERTURNED BY EARLY THURSDAY MORNING...SOME SEVERE RISK

MAY EXIST ACROSS THE ARKLATEX/LOWER MS VALLEY THROUGH THE DAY.

..ARKLATEX/LOWER MS VALLEY

AS THE COLD FRONT CONTINUES TO STEADILY ADVANCE SOUTHEASTWARD ACROSS

THE REGION...TSTMS WILL BE POSSIBLE ALONG/JUST AHEAD OF THE FRONT

THROUGHOUT THE DAY. THE PRIMARY UNCERTAINTY/LIMITATION IS THE

OPPORTUNITY /LACK THEREOF/ FOR CONSEQUENTIAL

DESTABILIZATION...ESPECIALLY GIVEN UNKNOWNS REGARDING THE

EXTENSIVENESS OF EARLY DAY CONVECTION AND THE EFFECTIVE LOCATION OF

THE FRONT. NONETHELESS...WITH LARGE SCALE HEIGHT FALLS/STRENGTHENING

DEEP LAYER NEARLY UNIDIRECTIONAL FLOW...VIA THE EASTWARD RACING

BASAL PORTION OF THE CENTRAL CONUS LONGWAVE TROUGH...SOME SEVERE

RISK MAY CONTINUE INTO THANKSGIVING DAY PROVIDED SUFFICIENT

DESTABILIZATION ALONG/JUST AHEAD OF THE SOUTHEAST ADVANCING FRONT.

WILL INTRODUCE 5 PERCENT SEVERE PROBABILITIES FOR WHAT IS CURRENTLY

EXPECTED TO A BE MARGINAL SEVERE RISK...WITH DAMAGING WINDS/PERHAPS

A BRIEF TORNADO BEING THE POSSIBLE IMPACTS IF A SEVERE RISK

MATERIALIZES WITHIN THIS STRONGLY SHEARED ENVIRONMENT.

[tornadotony]

I am a little surprised by the strength too, I may dig a little deeper into it tomorrow and see if it's just something I missed.

High low-level CAPE and shear. I'm going to surmise (because I'm actually in NW OH visiting my girlfriend and her family) based off of what I've read in this thread that the NAM was probably not too far off on low-level (0-3km) CAPE values in yesterday's environment. Mid-level lapse rates became strong enough to support sustained convection (and then some with 2" diameter hail) and so, with that being the only real question mark in play, it's no wonder what happened actually did happen. You had 0-1km SRH higher than progged by the NAM (not a shock, it seems to always be underdone and especially in cases where there is convection prior to the event). That high low-level CAPE allowed for rapid near-sfc parcel acceleration and extreme updraft vorticity stretching in the lowest-levels. It is no shock (and should absolutely be no shock at all) that there was a (very likely) strong tornado yesterday. With low-level CAPE that high, any tornado was going to have the potential to be strong, and in fact once we get this late in the year, most tornadoes in this region are strong (and that's speaking statistically).

[tornadotony]

High low-level CAPE and shear. I'm going to surmise (because I'm actually in NW OH visiting my girlfriend and her family) based off of what I've read in this thread that the NAM was probably not too far off on low-level (0-3km) CAPE values in yesterday's environment. Mid-level lapse rates became strong enough to support sustained convection (and then some with 2" diameter hail) and so, with that being the only real question mark in play, it's no wonder what happened actually did happen. You had 0-1km SRH higher than progged by the NAM (not a shock, it seems to always be underdone and especially in cases where there is convection prior to the event). That high low-level CAPE allowed for rapid near-sfc parcel acceleration and extreme updraft vorticity stretching in the lowest-levels. It is no shock (and should absolutely be no shock at all) that there was a (very likely) strong tornado yesterday. With low-level CAPE that high, any tornado was going to have the potential to be strong, and in fact once we get this late in the year, most tornadoes in this region are strong (and that's speaking statistically).

Bingo-bango. This the 00h image of 0-3km CAPE from the 21z RUC.

Extreme 0-3km CAPE values.

[csnavywx]

Bingo-bango. This the 00h image of 0-3km CAPE from the 21z RUC.

Extreme 0-3km CAPE values.

Yes, and that was a great call. I was a bit skeptical at first, especially since late season events seem to be plagued by low-level cloudiness. The subsidence behind the early day shortwave and convective complex earlier in the day really did the trick though, and served to cap the atmosphere until the parent s/w was there later (18z DVN sounding showed that weak cap perfectly).

[David Reimer]

The 12Z NAM has increased forecasted instability amounts for tomorrow afternoon and evening. Based on the amounts now being shown, combined with the shear present, I believe we're now treading on a potentially dangerous situation as we head into tomorrow evening. I'm definitely watching tomorrow for a possible chase.

[Thundersnow12]

Paul Sirvatka and I sitting here at CoD trying to figure out why that one storm produced and the more robust supercells to the southwest near GBG to princeton didn't produce. The low-level lapse rates were a tad better in the area of the sw storms along with slightly better instability but the southwest winds at the sfc were not helping the cause. He thought maybe there was small ridge axis up to near the low with the Caledonia storm in that axis. Were the sfc winds alittle more southerly at the time near that storm? I will have to go back and look at a sfc map.

[Moneyman]

EF1 Tornado - Walworth County

Start: 3.2miles SE of the Village of Walworth at 3:33PM

End: 2 miles NNE of Zenda at 3:38PM

Length: 4 miles

Width: Approximately 100 yards

Details: 2 homes recieved significant roof damage. Approximately 80% of each roof destroyed. One of these homes shifted on its foundation. Additionally, 2 other homes recieved minor damage. 4 barns were damaged, and several power poles downed. From the Wisconsin Emergency Operations Center: Eight structures were damaged. Four were homes and the rest were farm buildings

EF1 Tornado - "Union Grove"

Wind speed: About 90 mph.

Start: 4:01 PM. On Racine/Kenosha County line at intersection of county road KR & 224 Ave

End: 4:12 PM. In Racine County at Intersection of Highway 20 and Interstate 94

Width: 100 Yards

Length: About 8.2 Miles, intermittent path, some straight line wind damage as well

Details: Worst hit was the southwest side of Union Grove. Old Settler's Park had major tree damage. Across from the park, there was roof damage to an industrial building. There was minor residential damage at the intersection of Pleasant Run & Mill Avenue in Union Grove. At the intersection of Hwy 20 and I-94, an RV trailer was ripped in half and a Citgo gas station sustained roof damage. From the Wisconsin Emergency Operations Center: Local officials conducted an aerial damage assessment to determine the extent of damage to the Union Grove area. Racine County officials report that there is widespread damage including the dome over the Union Grove sewer plant and the fairgrounds. Some parts of I-94 were closed during the storm, due to debris and a blown over semi-truck

Source: http://www.crh.noaa.gov/mkx/

[Chicago Storm]

http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=lot&storyid=60148&source=0

EF2 Tornado confirmed at Caledonia

The tornado touched down at approximately 3:04 pm ¼ mile southwest of the intersection of Argyle and Harlem Roads. A school bus was rolled by the tornado winds where 6 people were injuried, fortunately those injuries were minor. The tornado crossed the path of high tension lines that run just west of Argyle and 11 towers were downed. The tornado moved northeast into Caledonia – damage there included significant damage to around 6 buildings, with approximately 20 additional buildings sustaining minor damage. Several large trees were snapped or uprooted. A grain bin was partially collapsed. The tornado continued northeast out of Caledonia with several power poles down across roads. As the tornado crossed various lines of trees in the fields sections of trees were snapped or uprooted. Around 3 farm outbuildings sustained damage ranging from roofs blown off to complete collapsed of structures. One of the 3 outbuildings, located 2 miles northwest of Capron, was also damaged during the January 2008 tornado. Sporadic tree damage continued to the end point where the tornado lifted... 1 mile west of Lawrence at approximately 3:23 pm.

Path width: 200 yards (varied between 50 and 200 yards)

Path length: 16.4 miles

Estimated winds: 135 mph

In addition to the above tornado, thunderstorm wind damage occurred near McFarland and Thomas Drive in Loves Park where shingles were blown off roofs and fascia was damaged on several houses.

[Hoosier]

high end EF2...

[Stebo]

high end EF2...

1 mph from a EF-3. I'm kind of surprised there wasn't a range of winds like 130-140 so to speak

Edit: 135 is in the lower half of the boundary conditions for metal power poles being collapsed

http://upload.wikimedia.org/wikipedia/commons/8/80/EF_DI_24_%28ETL%29.jpg

[Hoosier]

Based on the map that LOT drew for the 1/7/08 tornado, I put that track on the map of yesterday's tornado. The red line represents the 1/7/08 tornado (to the best of my ability). As you can see, they were amazingly similar and even crossed paths.

[OceanStWx]

Interesting pics. The supercell that produced tornadoes in the Rockford area points northeast actually passed just to the north of DVN. A few smaller supercells developed right over DVN and seemed to get absorbed into the larger, more dominant supercell just north as it progressed northeast. I had a pretty nice glimpse of the towers to the north of here before the weaker supercell to the southwest moved in and impacted our area with rain. Even with our much weaker supercell there was some interesting cloud formations on the back side. It was very disorganized though. Couldn't really pick out a single strong updraft base.

I am almost positive that the first cell (and the one that we have pictures for) is the cell that went on to produce the tornadoes near the IL/WI border. After all these storms were moving at a high rate of speed.

[tornadotony]

Based on the map that LOT drew for the 1/7/08 tornado, I put that track on the map of yesterday's tornado. The red line represents the 1/7/08 tornado (to the best of my ability). As you can see, they were amazingly similar and even crossed paths.

You know, when I was comparing yesterday to 1/7/08, I didn't think we'd have a nearly identical result like this...this borders on the absurd...

[JoMo]

You know, when I was comparing yesterday to 1/7/08, I didn't think we'd have a nearly identical result like this...this borders on the absurd...

what do you think about tomorrow? Think anything will fire in Oklahoma?

[tornadotony]

what do you think about tomorrow? Think anything will fire in Oklahoma?

I'm taking a look now...haven't really been on too much...just got back from Findlay, OH...

[OceanStWx]

High low-level CAPE and shear. I'm going to surmise (because I'm actually in NW OH visiting my girlfriend and her family) based off of what I've read in this thread that the NAM was probably not too far off on low-level (0-3km) CAPE values in yesterday's environment. Mid-level lapse rates became strong enough to support sustained convection (and then some with 2" diameter hail) and so, with that being the only real question mark in play, it's no wonder what happened actually did happen. You had 0-1km SRH higher than progged by the NAM (not a shock, it seems to always be underdone and especially in cases where there is convection prior to the event). That high low-level CAPE allowed for rapid near-sfc parcel acceleration and extreme updraft vorticity stretching in the lowest-levels. It is no shock (and should absolutely be no shock at all) that there was a (very likely) strong tornado yesterday. With low-level CAPE that high, any tornado was going to have the potential to be strong, and in fact once we get this late in the year, most tornadoes in this region are strong (and that's speaking statistically).

Couldn't have said it better myself. Many of the storms featured a majority of the CAPE at the lower levels, especially as you headed north where the mid level lapse rates weren't as good. The storms that really tapped the mid level lapse rates and showed off the models under-forecasting them were the western Illinois cells. 2" hail at this time of year is pretty impressive.

[OceanStWx]

Paul Sirvatka and I sitting here at CoD trying to figure out why that one storm produced and the more robust supercells to the southwest near GBG to princeton didn't produce. The low-level lapse rates were a tad better in the area of the sw storms along with slightly better instability but the southwest winds at the sfc were not helping the cause. He thought maybe there was small ridge axis up to near the low with the Caledonia storm in that axis. Were the sfc winds alittle more southerly at the time near that storm? I will have to go back and look at a sfc map.

We went out to make sure it didn't today. Had some reports of pretty significant damage, and it's a fairly short ride from the WFO. There will be more later tomorrow afternoon, but here is our survey info.

DVN Storm Survey

[OceanStWx]

1 mph from a EF-3. I'm kind of surprised there wasn't a range of winds like 130-140 so to speak

Edit: 135 is in the lower half of the boundary conditions for metal power poles being collapsed

http://upload.wikime...4_%28ETL%29.jpg

We were faced with the same decision as LOT on 6/5/10. The Magnolia tornado took down a cell tower and we rated it 135 mph too. Sometimes it's the context of the damage. If the tower is taken down but a structure around it is undamaged, it is unlikely that an EF3 tornado came through. This happens quite a bit with the poorly built houses. They may be wiped clean off the foundation, yet a car is still in the driveway, or a flagpole is still erect, or the tree in the front yard doesn't have a leaf out of place.

[Hoosier]

You know, when I was comparing yesterday to 1/7/08, I didn't think we'd have a nearly identical result like this...this borders on the absurd...

Yeah, I knew it was close, but it's really shocking to see that it's this close. This tornado started a bit farther west though.

[Thundersnow12]

Based on the map that LOT drew for the 1/7/08 tornado, I put that track on the map of yesterday's tornado. The red line represents the 1/7/08 tornado (to the best of my ability). As you can see, they were amazingly similar and even crossed paths.

gonna save that map to my computer would be curious to see how that path length ranks for tornadoes in the LOT CWA in november.

[tornadotony]

Just as an FYI, the last time there were two months in a row that had significant tornadoes in the LOT CWA was April and May 2004. The last time two significant tornado events occurred within a month of each other in the CWA was 8/5 and 8/18/79.

[Stebo]

You know, when I was comparing yesterday to 1/7/08, I didn't think we'd have a nearly identical result like this...this borders on the absurd...

Yeah its pretty crazy, hell this tornado crossed the 08 one's path twice, and I wouldn't doubt again up in WI too...

[tornadotony]

gonna save that map to my computer would be curious to see how that path length ranks for tornadoes in the LOT CWA in november.

The longest of the 11/12/65 tornadoes had a path length of 35.9 miles, so though yesterday's was respectable, it falls quite a bit short.

[Stebo]

We were faced with the same decision as LOT on 6/5/10. The Magnolia tornado took down a cell tower and we rated it 135 mph too. Sometimes it's the context of the damage. If the tower is taken down but a structure around it is undamaged, it is unlikely that an EF3 tornado came through. This happens quite a bit with the poorly built houses. They may be wiped clean off the foundation, yet a car is still in the driveway, or a flagpole is still erect, or the tree in the front yard doesn't have a leaf out of place.

Yeah I can see where that would be a problem.

[northpittweather]

2 EF1 Tornadoes Confirmed in Southern Mississippi from a brief supercell

[roardog]

I don't like severe weather this time of year. There isn't enough daylight and no leaves on the trees to make high winds interesting. I guess a tornado would still be good if it occurs during the few hours of daylight this time of year.