Wednesday, June 23, 2010

HP intercept

Turned a bummer day into a pretty interesting one by getting out ahead of the line in north-central Illinois this evening. Things looked pretty bleak, but I noticed some isolated cells erupting ahead of the line west of La Salle, IL. I quickly made my way towards Interstate 39 and dropped south. I recalled that the outflow boundary from morning storms was draped along Interstate 80 and made my way that way in hopes something could root to this and remain discrete. The line more or less congealed, but I noticed one storm that was an obvious embedded HP supercell. I made this my play, getting ahead of it and stopped on the west side of Oglesby to watch it come in.

Witnessed a good circulation in the "notch" region of the HP which passed almost directly over head. Noted very strong *inflow* blowing into the mesocyclone as the circulation passed -just- to my south right over town before everything got blown over by the main core and straight line winds. Thought maybe I'd get a brief touch down right near me, but it wasn't to be. Pretty darn fun core, no less.

Made my way back up towards DeKalb detouring around a blown over semi thanks to a heads up from Scott Weberpal. Tia and I then enjoyed some Italian Beef sandwiches and a big chocolate shake at Portillo's up here under a big yellow mammatus filled sky.

Not a bad chase at all, albeit tornado-less.

Wall cloud passing just south:

Updated forecast for today (6/23)

Not quite as gungho as I was yesterday about the tornado potential in Illinois this afternoon, but that could be my morning MCS goggles. What gives me trouble is the convection training along the target area across northern Illinois into central Iowa. Rather than one single bow echo moving thru the area laying down an OFB and leaving clearing skies in it's wake, we've had a very disorganized training east-west line along Interstate 80. Thus, confidence in the location of the OFB and the extent of destabilization are somewhat in question at this point in the morning.

That said, the risk still exists and I will be paying close attention to any areas of significant destabilization ahead of the low today near the OFB. Extensive WAA should help lift the OFB north slowly thru the afternoon, but ultimately it should end up very near Interstate 80, not overly far from where it sits now. After a couple waves of convection, destabilization should begin to occur in southeast Iowa, and eventually extend into northern Illinois. Initially, convection should begin to develop in southeast Iowa but rapidly explode into northwest Illinois during the early-mid afternoon hours. My current target time for initiation is 2-3 PM CDT from near Quincy, IL to the Quad Cities. While low level shear will again remain fairly unidirectional, early in the afternoon hodographs will have some slight turning, which coupled with potentially significant destabilization and the aid of one or more boundaries could favor early storm mode in the form of supercells. This remains conditional, as line segments or multicell clusters are easily a plausible scenario as well which would favor a damaging wind threat. Should initial storm mode take the form of quasi-discrete supercells, a few tornado reports would be possible, likely very near Interstate 80 in northern Illinois. My target for tornado development is between Interstate 88 and 80 in northwest Illinois from the Quad Cities toward Mendota, IL... or a triangle from Moline, IL to LaSalle, IL to Rochelle, IL. Should the currently forecast extreme instability be realized along with the unseasonably strong wind fields associated with the wave, perhaps we can begin talking about a strong tornado or two with any storm initially interacting with the boundary in this area. Storm speeds will also be faster than you'd normally expect in mid-late June, so this is something to consider.

Eventually, congealment into a linear storm mode seems more than likely across central into northeast Illinois as storms move into northern Indiana. Given unseasonably strong wind fields, isolated embedded tornadoes would remain a legitimate threat through the evening.

I'll be hanging here in DeKalb for the afternoon, waiting to see how things unfold but may eventually drop slightly SW to intercept initial convection.

Tuesday, June 22, 2010

Time Lapse, and Tornadoes Tomorrow?

Well here we go, Andrew is gungho again. It's been one of those years. I poo-poo events and they go berserk, and then I finally get gungho about an event and am quickly nailed with a forecast bust. This forecast should be taken for what it's worth considering the above disclaimer!

Tomorrow is really peaking my interest now. I should be sitting pretty here in DeKalb for at least one round of significant severe weather, if not two. The obvious threat, is the potential for significant wind damage across Iowa early, moving into southern Wisconsin and here in northern Illinois thru the early morning hours. It appears this may take some time to organize out west early tonight, but may move into the Mississippi River valley by 4 AM. Associated with the 50 knot H5 trough ejecting out of the northern plains, a long-lived forward propagating MCS appears the likely end scenario with scattered reports of potentially significant wind damage possible likely along and north of Interstate 80. The most likely area to see significant damage from this complex may be along and near Interstate 88 from the Quad Cities towards the Chicago area in the early morning hours.

While some questions still exist, it is appearing increasingly likely that the air mass in the wake of the morning MCS will recover over northern Illinois and southern Wisconsin ahead of the final approaching wave and cold front moving in from Iowa. Shear profiles should be largely unidirectional across most of the warm sector, however given the presence of one or more outflow boundaries and enhanced low level shear along the warm front near the Wisconsin and Illinois borders, a tornado threat should exist early in storm evolution. The most likely area for tornadoes at this time appears to be from the Quad Cities towards Rockford, IL north to Madison, WI. Should the air mass recover enough and significant instability can be realized, given the much stronger speed shear compared to previous days any storm that is able to root to one of the aforementioned boundaries early in evolution may hold a strong tornado risk. That detail remains to be seen and will not be evident until tomorrow afternoon. This risk again would be along the Interstate 88 corridor into southern Wisconsin. It should be noted, that given a sufficient cold pool with early convection, the outflow boundary and warm front may both be shoved further to the south, and the target area for tornado development could shift further towards the Interstate 80 corridor. That will also be determined tomorrow.

As for yesterday's supercell, I did go ahead and upload a brief time lapse showing the at time significant rotation, but then later the storm struggling with it's outflow thus undercutting the updraft and effectively choking off any potential tornadogenesis.

Western Illinois HP supercell

I had been eyeing western Illinois and far eastern Iowa for a potential chase most of the day with the shortwave that was forecast to eject into the area. Inititally early convection dampened my hopes a bit, but upon checking the situation out around 2 PM it became evident that the conditions were becoming ripe for a surprise event around the Iowa/Illinois border. I had commitments in DeKalb until 3 PM, but after a quick check to confirm my earlier forecast target of Burlington to Davenport the show still looked like a go. I was convinced the wave in Iowa was stronger than most were giving it credit for, and that the supercell threat was being under forecast. I shot Colin Davis a quick phone call who agreed, and Tia and I hit the road targeting a cu field in se Iowa.

Intercepted the tornado warned storm shortly after producing the last of it's visible tornadoes around the Colchester area. Several tornadoes allegedly touched down while I was on the storm, including one "lofting trees into the air" while I was literally under the mesocyclone but never saw anything. At times the storm exhibited very significant rotation and looked to produce a potential damaging tornado, but surface flow was too weak for the better part of the evening and the storm had trouble containing it's gust front.

I may put up a time lapse tomorrow, as the entire storm was spinning like a top. Probably about the best display I've seen a supercell put on without even squirting out a little tornado for me to play with.

Wall cloud was exhibiting very strong rotation at this point, shortly before the "tree lofting" tornado was reported.

Another tornado was reported near Industry at the time of this photo. May I be proven wrong... but I don't see anything at all tornadic in this image. The storms outflow was constantly undercutting any attempt at surface based rotation, and I was simply staying ahead for structure at this point.

Saturday, June 19, 2010

Double Bow Echo fun!

Stayed home today and had two significant bow echos come to my front porch. I intercepted the first west of DeKalb just south of Malta, IL. Pretty disorganized structure, but some fierce winds gusting to around 70 mph. Took down a chunk of the tree in my front yard which last evening, not 24 hours before I had said "this tree needs pruned, it's hanging down way too low". Well, thanks mother nature.

More on my flickr set here:

Tuesday, June 15, 2010

Isolated Tornadoes possible in central Illinois today...

This is a somewhat late notice, but I like the odds at a couple tornadoes in central parts of Illinois today, likely around the Interstate 72 corridor. My target triangle at the moment for a few reports would be from Bloomington to Springfield to Mattoon this afternoon.

A decaying MCS and associated shortwave is approaching from Missouri this afternoon. Associated with this wave will be deep layer shear on the order of 40 knots with the H5 jet streak. Thunderstorms currently over the target area are hindering destabilization at the moment, but in their wake clearing skies should allow for a quick recovery and moderate destabilization. Ahead of the wave, surface winds should increase slightly and turn out of the south and even southeast further north at about 10 knots. This, along with a strengthening LLJ should supply the low level shear needed for rotating thunderstorms, and the 40-50 knot streak at H5 should be more than enough for sustained updrafts and supercell storms.

Storms should begin to develop early in the afternoon in southwest Illinois from around Quincy to St. Louis. Organization may take some time, but storms should reach severe levels by the time they reach the Interstate 55 corridor from Springfield south, as they move northeast. An upscale growth into an MCS is eventually likely, thus this early period from Springfield to Interstate 57 approximately is where tornadoes would be most likely with any storm. Low level shear should be greatest along Interstate 72, so I'd likely try and hug this area.

I'm still on the fence as to whether I will chase this event or not, but at this point am leaning more towards a yes. I'll likely make a decision by noon, and head south towards Bloomington to adjust from there, likely south a little more.

Tuesday, June 8, 2010

Redemption. Part two.

Really liking a corridor from Jacksonville to Peoria in western Illinois today for a few tornadic supercells. Early morning MCS clearing out very early with clearing skies almost to the Mississippi River. A couple hours is all it usually takes along these Illinois warm front / ofbs and it appears we will get at least that. By 0z the instability tongue should reach in along and south of the warm front from Missouri into central Illinois reaching approximately the Bloomington area. Along the warm front, long looping hodographs will definitely favor supercell development and assuming ample instability return, which appears to be the case, tornado development. Again, given sufficient destabilization 0-1 km helicity values on the order of 200 m2/s2 along the warm front a significant tornado is possible in western Illinois in that triangle.

Visible satellite trends will need monitored closely over the afternoon, but I think a regional tornado event could be unfolding this evening where the instability tongue intersects the heightened low level shear over western Illinois.


Looking like another potentially major day in Illinois tomorrow evening. While this looks like a much more conditional day than Saturday, it holds a more violent potential in my opinion. Looks like the same exact areas under the gun as well. Looking like the Iowa border from near Burlington east towards Peoria tomorrow evening could be a very interesting place to be. Looking like plenty of early day convection along and north of the warm front. Getting into specifics is not worthwhile at this time as a complex convective scenario will prevent many details from being apparent until morning or even well into the afternoon. However, the GFS and RUC (and the NAM, to a lesser extent however) hint at a potentially volatile situation over NW Illinois in that Burlington to Peoria corridor tomorrow evening with extreme June instability and unseasonably strong shear profiles along and near the warm front which should be south of Interstate 80 a tad.

Should this situation unfold, and NW Illinois sees some clearing from early convective debris, prolific tornadic supercells are certainly possible. GFS soundings for Galesburg, Illinois tomorrow evening show surface cape values surging to approximately 3000 j/kg under 0-1 km shear of 30 knots, and 0-1 km helicity values near or surpassing 300 m2/s2 along the warm front.

Again, this is a conditional scenario and could fail to be realized, but is certainly a day that needs very close attention. June 7th 2008 and April 20th 2004 are both days that come to mind when looking at this setup. While they are not carbon copies, they are perfect examples of these late evening warm front situations that may not be realized until very late in the period. Convection thrives for most of the day, but then the area along the warm front sees simply 2-3 hours of heating and a potential tornado outbreak ensues. Of course, there are countless examples when this backfired and a rainy day ruined storm chaser's dreams.

I'll have an update tomorrow morning, hopefully including a continued positive outlook on things. I need a little redemption after Saturday's debacle.

For what it's worth on the topic of Saturday, the NWS ILX confirmed a 300 yard wide tornado from the wall cloud that I photographed near Lincoln, Illinois after dark. I could tell something large was about to develop, but well, night chasing sucks.

Saturday, June 5, 2010

Yesterday's Supercells and Today's HP Forecast

Excellent chase yesterday minus a tornado. I expected maybe a couple marginal tornadoes yesterday, but instead was treated to a couple gorgeous supercells in western Illinois near Macomb. The following photos are from near Astoria, Illinois at 6:30 PM. The hail shot is near Havana near sunset.

Today... looking like HP supercells in eastern Iowa and northern Illinois this evening. Perhaps a late show in Illinois, but that remains to be seen. I do see a few tornadoes being likely, possible a strong tornado, but don't expect a major outbreak at this point. I'd like to stay in Illinois, but right now I'm concerned that thing may not erupt until almost sunset. At this point in the morning my target is Iowa City. Most of Iowa should be convection free by noon, and rapidly become unstable. Sbcape values near 5000 j/kg are not unreasonable. Hmmm. I don't know. I think stuff will go in Iowa first, but I think northern Illinois has the best shot at significant tornadoes this evening. Perhaps I'll sit around the Quad Cities and wait? Or just be a man and stay in Illinois and wait it out. I really like a beast or two from Iowa City to Ottumwa by 5 PM, but think supercells will rapidly develop near Interstate 80 in northern Illinois near sunset.

Most likely scenario, I get on the road and make an impulse decision and rue the day. Either way, I like Ottumwa, IA to LaSalle, IL for a big tornado this evening.

Friday, June 4, 2010

IA/IL Morning update

Still targeting far SE Iowa early on, and then possibly into western and NW Illinois in the evening. Target for now is the Burlington area so I can wait to commit to either SE Iowa or NW Illinois. Currently leaning the way of the se Iowa into western IL target, but I would not rule out a surprise isolated supercell in northern Illinois today, probably right around DeKalb where I'll be wishing I had stayed.

Live tracker should be up, and I'm debating running live streaming again so just check in periodically.

SE Iowa or NW Illinois tomorrow...

The NAM looks less than ideal, with the GFS slightly more kind. I'm not inclined to believe one over the other. I'm not expecting a big day, but a surprise tornado is certainly possible in an area from Ottumwa, Iowa to Galesburg, Illinois. Current thinking is that the outflow boundary from the dying mcs currently located over western Iowa should lay across the Highway 34 corridor in southern Iowa. Seasonable moisture with td's approaching 70 or even slightly above in some areas along the boundary coupled with ample surface heating and the approaching shortwave arriving in eastern Iowa in the early evening should aid in the development of isolated severe thunderstorms by early evening in southeast Iowa. Surface convergence should also increase considerably in the region as the boundary sags southward. Low level shear won't be overly strong, but with the aid of the potential interaction along the outflow boundary I think storm rotation should be manageable. HP storm mode is a concern.

Current thinking is that a tornado or two is possible in southeast Iowa tomorrow evening in an area around Ottumwa to Mount Pleasant, Iowa. This area could shift tomorrow with the movement of surface features, but se Iowa into far nw Illinois has seemed pretty consistent over the last day or so.

Saturday looks potentially big in central Illinois.

Wednesday, June 2, 2010

Another Illinois Shelf Cloud...


That's from my SW Iowa target yesterday that I talked myself out of last minute. Instead of showing you images of this, I'll share another classic Illinois shelf cloud, illuminated by the city lights of Champaign, IL.

Tuesday, June 1, 2010

Stormy Wednesday

Holding off on chasing today, though I do think there is some potential in southwest Iowa this evening. I was targeting the Red Oak, IA area, but am going to hold off on chasing. The replacement grille for the mazda should be arriving in a matter of hours, so I'll just spend the day getting that replaced (though it should take maybe 20 minutes) and relaxing as I just returned home from the Wisconsin trip yesterday evening. Tia and I "roughed it" with a tent placed out in a field surrounded by trees, and ticks. I had heard rumblings that the ticks were bad this year, and boy are they ever. Tia managed to acquire three ticks in the span of one 8 hour night. She was less than thrilled.

Wow. Okay. Southwest Iowa looking better and better. I'd be there at 7 or 8 PM though if I left right now. Argh. There should be a beast of a supercell around Red Oak, Iowa this evening. Looks like I'll be stuck waiting for the local mess we'll have in Illinois tomorrow. The lack of a focused area of convergence or stronger shortwave is the only thing keeping me at home today, hopefully not for loss. The RUC does develop a warm front of sorts right in my target and erupts an area of deep convection however, but we'll see how that plays out. Wondering if the weaker upper level flow won't result in HP storm mode as well. Nothing to be done now, as I'm well beyond my time of departure.

Tomorrow there will be severe weather in the central Illinois region, but I'm having a hard time twisting my head looking at the monitor sideways while hopping on one foot to find any tornado potential. The only saving grace is the fact that it is June in Illinois, and there should be an outflow boundary involved. More than likely we'll see a large area of strong to severe convection erupt along Interstate 72 by early afternoon. The only hope for anything supercellular at this time, would be very very early in the system's evolution, as an upscale growth into training storms seems likely. I guess it will just be nice to not have to drive far and just watch some storms. There will be a nice 50-60 knot jet with the shortwave as it ejects into central Illinois during the afternoon. However below it, no real turning to speak of. Surface winds should veer to southwesterly by afternoon south of the boundary as it sags to the south, lending towards linear training storm modes in the area. Target for tomorrow will be the livingroom down here in Urbana until initiation occurs it would appear. My region for anything interesting tomorrow is around Decatur to Champaign to Mattoon in central to eastern Illinois. GFS slightly better directional shear, but no speed shear. Bah. At least I don't have to drive anywhere, right?

One advantage we have for tomorrow, is the hope for change. When dealing with the likely scenario of a complex convective situation for today (day 1) it can have adverse affects on the day 2 situation. Whatever happens today could drastically affect tomorrow's forecast, for the worse, or better! For that reason, I'll hold off on whining or griping on the forecast for tomorrow.

Here's a shot of Tia and my resting spot over the holiday weekend. Ticks aside, it was an awesome little spot.