Absolute Instability weather notes

Historic winter storm progressing

2011-01-31T19:00:00.002-05:00

Above image has been my favorite so far, explaining whats going on. Big problems LOL. Lots of this kinda thing but this was my favorite. Courtesy of Hedi Farrar (spelling) my last name is spelled farrer, wierd!

Strong wording from the Tulsa and Indianapolis weather offices suggests ongoing threat getting worse! The main low hasnt even really formed yet. The models are saying its going to form and move in a certain direction. Which is what we are mainly looking for as the big game changing factor! Ice pounding my windows as I type this. I am really keeping an eye on how much moisture is advecting in, to see just how bad things are going to get? Significant icing is possible for a large area. Not to mention all the possible snow!

Historic winter storm shaping up!

2011-01-31T13:44:00.004-05:00

First Mesoscale discussion up now due to low level jet ramping up causing low level convergence. Forcing up precip in the form of freezing rain. The warmth of the roughly 850 mb layer is above freezing. This means that precip is falling melting and then re freezing on the ground. This is only the beginning of what looks to be a very large system impacting a great deal of the midwest. The 500mb map shows the scale of whats happening.

Hermine induced tornadic supercells

2010-09-09T01:07:00.004-04:00

Hermine has been wreaking havoc on the TX country side. Causing major flooding all over central to northern TX. A recent threat however has come in the form of tornadic supercells. Mini supercells that is. Fast moving storms, that are not very tall or wide. But tight and able to spawn tornadoes due to the presence of instability and wind shear. As this once tropical system interacts with the jet stream or westerlies. It is encountering dynamics that are mostly inherent in extra tropical systems. Meaning it is transforming into a somewhat powerful extratropical cyclone. Stronger upper level winds are now interacting with the low level winds causing some significant wind shear, on the order of 300m/s SRH!

Above images of 500mb wind speeds, and Storm relative helicity. Showing enviroment capable of tornadoes! Below is a video shot from some height. Its great in that it shows the circulation on the ground look closely!

March 8th 2010 "cold core" event.

2010-03-16T16:46:00.021-04:00

Image by cloud9tours. This image is important because it shows important structure. Which helps us evaluate what exactly we are dealing with here. This cell is actually more reminiscent of a classic supercell. And is probably more reflective of a somewhat higher cape higher shear event than a true cold core low type setup. So besides the classic cold core setup we are dealing with something of a hybrid. Temps were in the low 60s with dewpoints in the 50s. But with the extremely cold mid level temps cape values were a little higher than usually. Plus we had some very intense wind profiles! Overall nature always has the ability to surprise us. Even when we think we are starting to figure things out!

Surface analysis at 2107z right around the time the first towers were going up along the boundry. The boundry being what was labeled as a pacific front. But was really a dryline/occlusion due to surface heating. The occlusion was a dryline/warmfront. The surface heating was very important in raising the temp/dewpoint spread which slowly transforms the airmass into something very different than a cold airmass type frontal system. Which for reasons not well understood helps in the types of storms that are produced. Instead of Linear forcing, and subsequent forced convection. We have spotty non-linear convection. Which could be due to a bulge in the dryline/occlusion. But a bulge wasnt evident and convective initiation seemed to be due to surface convergence in key areas where good CAPE was present along with almost no CIN whatsoever. The greater convergence at the surface is also a key function of the compact system allowing the backing of surface winds just ahead of the surface low. Aiding in a triple point type convective situation. Or so it would seem.
Whats also important is the fact this is a vertically stacked system, which is common for cold core type systems. The system is compact and tight. Due to the dynamics, rapid cyclogenesis takes place at the surface which aids in the winds backing and increasing in strength near the low and just ahead of it. This can help speed up the occlusion process. Which in turn is important for convergence. This convergence pushes air in and up helping to fire storms.

The Hammon mini-supercell underway here on radar and satellite. Whats interesting and usually highly important is the dry slot wrapping around the low. Surface heating had a chance to augment the airmass and help with destabilizing the atmosphere ahead of the 500mb low. Whats also important is you can see dust being kicked up by the strong surface winds on the satellite image.

Modified RUC sounding showing some fat CAPE even for a cold core event. Due to the steep lapse rates and very cold upper level temps! The hodograph also shows some pretty decent shear. Interesting moisture profile.

RUC surface analysis. Confirming setup is prime for development and already underway. Alot of convergence along the dryline/pacific front, warm frontal occlusion. It also confirms what we were seeing on satellite with the dust being kicked up. 30 knots down in west central TX behind the dryline kicking up some dust!

RUC 500mb analysis for 23z showing strong negatively tilted closed cold core low. With temps at and around -20 C. Strong Jet max rounding base. This as you can see is a very compact, vertically stacked system which is important in cold core tornadic events. This system is supplying alot of shear and alot of upper level forcing!

Unlike alot of cold core events some parameters started to show up right around the time the Tornado was occurring. Although by this time its far too late and still doesn't really highlight an area of huge concern. Cape values around 1000 j/kg, co located with high SRH values (but still not that high) had painted a nice EHI bulls eye around the Hammon area.

Feel free to comment with questions and critiques afterall this is a learning process for all of us. And I certainly dont know much in the way of meteorology, I am no expert. So feel free to comment!

Big system Christmas Eve!

2009-12-24T23:27:00.013-05:00

Awesome system, with severe weather all over the place. 992mb low with just an insane upper and lower level pattern. Vertically stacked even though it is highly baroclinic. The 500mb vort map below shows another low ejecting down and south towards the main system. With a Vort lobe extending south. Not sure what this is going to mean for the whole evolution. Besides keeping alot of snow falling up in the Dakotas.

Infrared map showing cloud cover and a somewhat atypical baroclinic leaf system. With rain falling throughout, LOL besides on the backside north and northwest. You can even see the cold frontal boundry in the gulf, it appears as a sharp line of clouds extending to the south.

Satellite image earlier today, showing the intense system. It shows up as a comma type cloud pattern in the south east. With strong jet wrapping in.

Surface pattern via RUC surface analysis.

500mb winds showing strong jet wrapping into system. This long wave trough is also negatively tilted. Showing lots of potential for extreme cyclogenesis. And with the secondary upper level low, we have a secondary cold front surging south behind the first system.

What this all means. Well with an occluded front and maturing wave. We have wide spread rain and wind and on the backside a major blizzard. Luckily all severe weather should be confined to the open waters of the gulf. Widespread wind should start to over spread the western parts along with frigid temps. Winds should also start to strengthen overnight on the eastern side as this low actually curves north. Fun fun fun!

Classic Nor'easter

2009-12-02T21:01:00.006-05:00

A Nor'easter is developing and quickly deepening over the southeast! It is being driven by a pronounced shortwave trough at mid levels. At the surface we have a large mature wave moving quickly northeast through new england. A typical path for powerful cold core lows called nor'easters. This wave is mainly comprised of a cP air mass and a mT air mass.

Below is 500mb map showing the negatively tilted shortwave. Very powerful, rotating around a long wave trough bringing in a very cold air mass!

Surface analysis, showing a mature wave moving northeast, with moist warm air out ahead of a prefrontal surface trough/convergence zone thats forcing up a mean squall line. Along with cold front in blue. At this time squall line is ongoing through florida and up the coast!

Below is earlier today. Satellite image of the wave as it slowly gains strength before nightfall! Large system, very pronounced! Very large dense coma shape (common) as you can see.

Snow was falling on the backside of this system, as well as Tornado watchs on the leading edge of the warm front and south into the warm sector. Due to CAPE values in and around 2500 and SRH up around 500 in most places. Typical for these very powerful systems. The satellite image is very impressive just the size is amazing!

Oct 28th 2009

2009-10-28T21:27:00.009-04:00

Severe threat possible ahead of developing severe squall line! This line is just starting to gain momentum. Threat could intiate an on going severe weather threat that may be on going through thursday! The severe potential tonight still remains out ahead of this developing line with any discrete cells that can form. Tornadoes are possible with any of these discrete cells but a qlcs or quasi linear convective system still has the potential at forming a tornado with the large shear in place.

Tomorrow looks even more potent as the system moves east. With an ongoing line expected the same story will apply. Discrete cells ahead of the line rooted in the boundry layer are going to have ample shear to develop low level rotation! This is an on going threat as low deepens and continues to pull in moisture along the gulf! Friday the models begin to diverge a little! But overall picture is pretty clear! Below is an image of the 850 millabar winds. Showing a very fast low level jet up around sixty knots (around 70 mph) thats a WOW! So any updrafts that do get going could just be sheared apart. But if any vigorous convection can get going and sustain itself on the partially moist LLJ! Look out!

Another thing to note is the partially backed but strong low level flow, which is leading to largely curved hodographs! Hodographs that denote definite tornado potential enviroments. Low level advection should not be an issue with a large deepening low, despite models. The main problem the models seem to suggest, is the upper level temps are just to warm. If this changes we could have a large outbreak of severe weather on our hands friday. If not the severe potential is going to be quite limited.

Radar image around 9:27pm is of a squall line forming in western TX. This could be ongoing through tomorrow!

July 8th 2009 Severe weather potential

2009-07-08T14:47:00.006-04:00

Large trough and associated upper level low moves in over the upper northwest. At the surface a 999mb low is moving east through the northern plains. With an occluded front/surface trough extending north to another low center in Canada. Backing winds at surface look to converge with south westerly winds behind front later this afternoon. This should act to initiate storms, with forecasted dew points in the upper 60s and lower 70s ample moisture should be in place over ND and SD!

500mb RUC forecast for 20z showing the trough and associated jet streak. Low level jet should increase late afternoon to around 30 kts increasing low level shear. This coupled with steep mid level lapse rates and surface temps reaching the upper 70s lower 80s CAPE values should reach 2000 j/kg.

Hodograph for 23z southwestern ND. Note the turning and relatively decent speeds at lower levels. Should be an interesting enviroment for any storms in this area. Tornadic supercells are going to be very likely today!

2009 an analysis

2009-06-10T22:55:00.005-04:00

Looking through the past couple events 2009 seems to be lacking something in the tornado market. What it is isnt exactly clear! Most explosive events with what seemed to be adequate shear have failed to produce with one or two exceptions. What it seems to boil down to is a lack of significant surface features. and when there seems to be adequate moisture the winds are lacking. The past two events that should have held high tornado potential specifically June 7th and June 5th which did yield a tornado before the cells were rooted on a cold/stationary front. June 7th seemed to yield the same results. With cells going up then moving into unfavorable air. Which is highly unlikely for a triple point event. Cells normally go up then move into the warm sector. With these events they seemed to take paths that lead them in the other direction. The lack of surface winds on the 7th really made a difference. It seemed the instability was obviously good but the cells on the 7th lacked good low level rotation. And maybe even in the lowest 1km.

It seems that 2009 is going to continue to be a frustrating year. Where most other years seemed to get better later on. Its interesting to study such cases in detail which I have yet to do. But its always a nice contrast from a learning perspective.

Chasing June 5th 2009 Live!!

2009-06-05T16:00:00.005-04:00

Absoluteinstability.net will be teaming up with 4849 productions for the chase today and tomorrow! 4849 productions will have a live feed going for the chase through severe studios. So you'll be able to watch a chase live in the high plains today and tomorrow just follow the link below.

http://www.severestudios.com/cgi-bin/player.pl?username=walt.vanrheen

Possible tornadoes IL, MO, OK 5/13/09

2009-05-13T09:20:00.003-04:00

Intense upper level low now over Ontario, Canada is quickly moving east with associated trough. Jet max with core winds at 90 to 100 knots within this trough now over MN will lift northeast. With intense system aloft surface cyclone will remain very deep at 988mb. Cold front trails southwestard and connects up with another low over KS, OK, TX panhandle area. 850 mb jet will be nosing into MO, and IL around 14z bringing along very moist and warm air mass. 850 jet is forecast to strenghtin to around 50 knots and with 500mb speeds approaching 40 to 45 knots shear will insane. Main forcing will be cold front later, but with likely convergence and complex surface features a few cells will go up ahead and quickly develop rotation.

I will be targeting the IL MO area later today.

Below is an image of the RUC 500mb forecast!

Severe weather outbreak and bow echo.

2009-05-08T17:50:00.011-04:00

May 9th 2009 was forecasted a few days ago to actually be a severe weather day for the red river vallery and central plains. Due to model inconsistencys and mesoscale uncertaintys a moderate risk was issued by the storm prediction center for the red river valley, then taken away the night of May 8th. Then the morning of Fri may 9th a moderate was reissued for portions of the ohio valley!? Partly due to an on going derecho and forecasted severe indices ahead of the on going system lead to a reissue of moderate risk.

Below is an incredible image of the bow echos book end vorticy/comma head. Also rooted in the upper levels it gets called an MCV or mesoscale convective vortex. This thing is extreme though an extreme case. With a gust measured at or around 100 mph its more like a hurricane! It also has an eye type feature if you look closey.

Below is the RUC analysis for 21z and it shows an area of max CAPE and 0-1km helicity values at or around 250-300, which is incredible. It should be noted however that, that area is in the appalachians. Not chase friendly country I might add. But none the less thats concernedly high and would be prime for supercells if not tornadic supercells.

Below are the same areas right around 21z and oh look, several supercells with probable tornadoes on the ground, not good! That area is in the mountains and so visibility can be obstructed, so warnings are all speculative until someone either confirms damage or a sightning takes place. It was a very dangerous situation situation today. The image below shows two main supercells in TN.

Showing the cells to the north of the previous image, several tornado warnings were issued at the time of this image.

Difficult forecasting ahead.

2009-04-29T20:10:00.004-04:00

Models are now having trouble picking out whats going to happen at anytime in the near future. Why this is happening is unknown. One thing you can always rely on is the three ingredients as is needed by severe weather. Instability, shear, and lift. The present system is one that is not giving clear signs of evolution. The only thing that is clear is that its spring and severe weather is likely somewhere in the united states everyday, usually. Most likely spring is still trying to set in in some places leaving everything backed up like last year. Indiana has not really had a normal spring yet. With snowfall in april and temps being wild everywhere, its no surprise to see anomalous things popping out of the models lately.

Below is an GFS (500mb heights and wind) model image grab valid for 21z friday may 1st. It shows a huge hudson bay vortex that is usually associated with blocking patterns. This can be bad for chase prospects but in this case it is hard to determine.

March 23rd 2009 Possible tornadoes!

2009-03-23T11:50:00.003-04:00

Around 988 mb low is emerging from the high plains area and forcast to move across NE during the day. With a decent warm sector south to OK and great shear profiles thoughout, a big day is likely for large hail and possibly a few tornadoes, with a chance for some long tracked violent tornadoes. However this threat is not clear cut, with moisture one of the big concerns. Such a hugh area possible its hard to really narrow down an area. I am thinking the greatest threat for daytime supercells and possible tornadoes will be up in NE around the warm front close to the low.

March 8th 2009 reports

2009-03-09T13:32:00.005-04:00

I ended up chasing a cell at the tail end of a small line in west central IN. The storm motions, speed of the storms were to fast to really keep up with. The main tornado producer on this day was a small bow echo that went pretty much straight thur southern IL and IN. Preliminary reports indicate that this bow echo did EF-3 damage in southern IN. I am a little upset that I missed the storm and a chance to document a tornado with a bow echo type stucture. But given that area being mostly trees and hills and the fast storm speeds it would have been a dangerous pursuit. I will have a chase account up later today on my site. My info on the storms and damage can be obtained here http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=ind&storyid=22735&source=0

Mean while another severe event is expected for tuesday! This event will be for mainly IL but western IN could see some severe weather!

Possible tornadoes in IL, IN

2009-03-08T12:55:00.005-04:00

Both images are courtesy of UCAR. Below is the ruc model forecast surface MLSP and wind field. Much of the area I mentioned is in the warm sector of an approaching extra tropical cyclone. With marginal instability inplace and good upper level support plus wind shear (see 500mb map below) the threat will continue for possible tornadoes this afternoon.

Supercells in se OK

2009-02-27T00:56:00.006-05:00

Well the dryline did light up with storms unlike what a couple models wanted to do with the scenario. I will make this quick. Chased the Boswell, OK storm got cored by it twice. Hail quarter sized to near golfballs! Post video here later. Then I watched that cell and one down by Paris, TX

go crazy with lighning. Here are just a couple pics more later!

Another Blocking pattern

2009-02-22T19:00:00.007-05:00

Well Feb is coming to an end and we are under another blocking pattern! An Omega block is taking shape. A cut-off low is hanging out off the northwestern coast of america while another upper level low is hanging out over the northeastern portion of america. A high pressure region over the rockies is for now leaving things blocked up. Usually the low in the pacific has to work its way to the south before the pattern can let go of it. The models do not want that hudson bay vortex to move though. It'll be interesting to see how this thing gets moving again. Theirs some interesting stuff going on here! As soon as that low over the west can free up we could get things moving again.

Below is from the ruc valid today!

Below is the GFS 180hrs valid for Mon, Mar 2nd.

Photography trip 2009

2009-02-22T18:44:00.004-05:00

I am taking a trip down into southern OK. Its the first photography trip I have ever taken thats not weather related. I was not able to attend the storm chasers convention this year due to my brothers wedding. So instead I am going to Oklahoma to do some shooting and research. Since we are under a blocking pattern again and it could be a while before we see any storms. I have some time to kill. I am hoping to see some pretty interesting places while there. I might go up to OU and peruse around, hangout with some other chasers. I have to do something because I have come down with quite a case of SDS, LOL!

Feb 10th 2009 Central OK tornadoes

2009-02-13T12:37:00.003-05:00

As some of you may already know, during the afternoon and evening hours of Feb 10th 2008 tornadoes occurred in central OK and north TX. Portions of OK city were hit around the Edmond area. A deadly tornado had also occurred and moved right through Lone Grove, OK around 726 pm. The Lone Grove tornado had exhibited EF4 damage on the south side of town according to preliminary damage surveys! Surveys are on going at this time. There were a few other tornado reports as well but they have not yet been confirmed. For more information you can visit the NWS Norman, OK Feb 10 2009 tornado webpage at http://www.srh.noaa.gov/oun/wxevents/20090210/

Below is a video courtesy of KFOR of the Edmond Tornado

The Science behind the artic blast! 01/14/09

2009-01-14T17:12:00.008-05:00

As most of you should know A major cold air outbreak is under way! The models have been quite consistent about this for at least a week now. A great deal of the midwest is in the cross hairs as well as the northeast and especially the great lakes region! NOAA and the NWS are saying this is the biggest outbreak of artic air since 2000 and 1997.

There are two main reasons for this. But the main one is the strength and size of a high pressure system now over Saskatchewan. The high is right now around 1050 millibars!!! WOW! Its forecast to fill in some and move into the states by 0z or 6:00pm CST. In the mean time a Low pressure system is now positioned over IN and is forecasted to move to the northeast. This sets the stage for major cold air advection to flow in behind the Low. The High is pushing in the artic air mass, which in turn is getting pulled downward and eastward by the Low. The Low is being fueled by a somewhat warmer air mass that was pulled in and around it from the southwest.

The blue line is the cold front the red is the warm front. The warm front will be the area of snow fall.

After the cold air sets in and the snow falls the skys will clear mostly due to sinking in the atmosphere. Most of the snow that did fall was in part due to the long wave troughing, and some ascent due to dynamic forcing. If you look at the map above you will see the black lines which are isobars. The pressure is rapidly rising. Which will cause the wind to pick up and since the sir mass is artic it will cause some intense wind chills!

Look at the temps for Thursday above, ouch! Major wind events are also forecast to bring wind chills down to -30 and below to some places. Wind chills and drifting snow should make for some interesting morning commutes on thursday for some. I wouldnt want to be in Chicago right now thats for sure.

So far its been a colder winter than normal and somwhat dry for the most part. It will be interesting to figure out why and what it holds for the future. Major patterns are at work and this is an important time for collecting data! Be safe out there!

North Atlantic Oscillation (NAO)

2008-12-12T20:57:00.008-05:00

The NAO is an index based on the pressure difference between the subtropical Azores high and the subpolar low. The polar pressure is taken near Iceland and the subtropical pressure is taken near the Azores.

Positive NAO: A positive value leads to more intense subpolar lows and a greater frequency of subpolar lows that track from the U.S. toward Europe. The tracks of the storm systems tend to be more northerly. The Eastern U.S. has relatively mild and moist conditions in winter. Europe tends to have more storm systems and warmer weather in winter. The subtropical high tends to be stronger and the hurricane season tends to be more active.

Negative NAO: A negative value leads to less intense subpolar lows and a slackened frequency of subpolar lows that track from the U.S. toward Europe. The Eastern U.S. tends to have colder and snowier winters. Europe tends to be colder in the northern portions and wetter in the southern portions. There tends to be more blocking due to a stronger Atlantic ridge.

The first half of December has been dominated be a negative NAO which helped to generate a blocking pattern for much of the Americas. The Upper air pattern was stuck in a long wave troughing pattern for the eastern half on the United States! This helped to keep the eastern states colder than average. The pattern was also responsible for developing fast moving low pressure systems called Alberta Clippers. Clippers typically move southeastward and because of their position, forming in Alberta, and speed they have little moisture to work with. What snow does fall is usually lake affect snow.

The long wave troughing was also causing the subtropical jet and the polar front jet to merge together for much of the United States. A Rex block type pattern over the eastern pacific was keeping a weak low off the southern coast of cailforna for a couple days before allowing it to move freely. This low then moved eastward as a shortwave trough splitting the two jets. Once this low moved within reach of gulf moisture it caused a few good rounds of severe weather.

NAO in its negative phase!

Taking things seriously! Gustav!

2008-09-01T02:37:00.015-04:00

As a storm chaser I cant stress enough how important it is to take weather seriously! I mean I have seen over and over how violent weather can be! A hurricane is no exception no matter what the intensity is. Talking tornadoes for example?! I have seen Greensburg, KS obliterated and then a year later Parkersburg, IA was wiped out! In 2005 everyone saw what New Orleans had to endure! People thought they would be o.k. and then they were screaming for help. In 1992 Andrew came through and destroyed thousands of homes! Remember the damage that was caused in the 1990s by tornadoes! If anything remember the super outbreak of 1974. April 3rd and 4th rendered 148 tornadoes with 2 F5s, one in Depauw, IN (my home state) and one in Xenia, OH (famous one) with multiple F4s in the same system. Mother nature can unleash fury on almost any location with little notice! If you do not live in tornado alley then you live out west in earthquake prone areas, not to mention forest fires. I am just stunned sometimes, that people don't take heed and flee. I guess people really dont know what they are up against?! I can tell you from experience it is awful. If you can help it, you do not want to go threw something like that!

Hurricane Andrew

This image is a link to hurricane Andrew info!

June 22nd 2007 Elie, MB Tornado

2008-08-22T22:33:00.004-04:00

The day gave way to around 8 tornadoes in Manitoba Canada. I am unsure of the exact setup but it was textbook perfect for supercells. All the tornadic storms fired in the warm sector. I think there was a lake breeze boundary in place and it was the focus. I am not sure what exactly happened but it was a busy day. The big tornado of the day formed outside Elie. And pretty much sat in one place slowly moving back and forth. It managed to make its way to the south side of town where it caused 1 million in damage. A few houses were involved, but the main thing was the mill. Winds were estimated to be around 250 mph! This tornado was also rated F5 later and I believe is the first F5 in Canadian history.

The footage I posted below is some of the best tornado footage I have seen. And it was taken by locals in the area. You will see in the video just how fast the winds in the funnel were moving. It was a violent tornado, which luckily didn't move very much.

TS Fay Deepens/strengthens

2008-08-19T15:28:00.005-04:00

It looks like tropical storm Fay strengthens as it tears through central Florida! Now at 986mb with sustained winds near 55 knots(65 mph) its teetering on Hurricane status.

A tornado watch is ongoing at this time. Moderate Instability together with increasing shear profiles, gives way to imbedded mesocyclones within the outer rain bands. This is a radar grab, you can see as of now there is a tornado warning for Osceola county.

I wouldnt be surprised if Fay made Hurricane status here soon. But its unlikely it will stay that way for any amount of time.

April 14th 2006 Case study.

2008-02-25T18:26:00.009-05:00

I am not going to go into detail but I will make a case to help prove that these cells were in fact tornadic. Damage was documented and there were eye witness reports to validate the possibility of tornaodoes. I am however going to focus on the reports that the Indiana state police gave that night.

Below are the reports for the day and you can see the tornado reports in red. These were at first reported as tornadoes then wind damage, then later turned back into tornadoes. It can get confusing!

Tornado reports below!

Tornado Reports (in CSV format)
Time Location County State Lat Lon Comments
2245 MODESTO STANISLAUS CA 3766 12099 EYEWITNESSES DESCRIBED DEBRIS CLOUD ABOUT 200 FEET WIDE IN LAUDING WAY. BROKEN ROOF TILES...SMALL TREES SNAPPED IN HALF...WATER SUCKED OUT FROM SWIMMING POOL. (STO)
2357 AMBIA BENTON IN 4049 8752 (LOT)
0002 BATTLE GROUND TIPPECANOE IN 4051 8684 TORNADO REPORTED NEAR BATTLE GROUND (IND)
0100 4 W CRAWFORDSVILLE MONTGOMERY IN 4004 8697 STATE POLICE RPT TORNADO (IND)
0120 NEW ROSS MONTGOMERY IN 3996 8671 TORNADO RPTD AT NEW ROSS IN MONTGOMERY COUNTY (IND)

Below is a radar grab of the monsterous HP storm that produced the reports. You can see an eye there of a very high reflectivity. Sometimes these eyes can be debris being picked up by the tornado on radar.

Velocity image, red is wind blowing away from the radar and green is toward the radar. The radar is located in Indianapolis to the southeast of the image. You can see where red and green are right next to each other signifying rotation! Pretty big area there!

I have circled the area of rotation. This is right around the time in question. The first Crawfordsville report (look above). I have put a black dot were the officer might have been, thats right around were 400 west is. He would have been looking east at the tornado probably every time the lightning flashed.

If you look at the reports above the last one that is, I have put the corresponding image below. you can see that the rotating portion of the storm is right where the reports say it should be!

The twins! Both are supercells, and both probably produced at least brief tornadoes. The one on the left however is a HP supercell. And probably made the most trouble.

Not hard to see that the damage was most likely caused by a tornado. Very aggressive storms, persistant rotation at the time of these images.

NSCC (National Storm Chasers Convention)

2008-02-25T17:46:00.006-05:00

The 10th annual Storm Chasers Convention. Its a pretty cool get together of chasers from all over. We had two guys come from England this year, which is really neat. At the conference there is a room dedicated to exhibits, and a room for lectures. I did learn a little which is always important.

This year the keynote speakers were Dr. Josh Wurman and Sean Casey. I didnt take alot of pictures but I did manage a few of the TIV and one of the older DOW trucks.

This is a picture of a couple probes. These probes can be seen on the Discovery channels show Storm Chasers. If you havent seen the show its all about Sean Casey whos goal is to capture footage from inside a funnel using a special Imax camera. He is teamed up with Dr. Josh Wurman whos goal is to place Sean in the right place at the right time, as well as collect data from various instruments scattered throughout his entire team. Of course that is a really watered down explanation but you'll just have to watch the show.
Below is a Dow (doppler on wheels)truck. The sole purpose is to collect doppler based data from out in the field, close to a tornado for example!

TIV stands for Tornado intercept vehicle. It has instrumentation on a mast that barly visible in this picture. It was built as a kinda armored tripod for the IMAX camera.

This is my world I can easily see how alot of people might think that chasers are crazy. But if you have ever had a passion you might be able to relate in some way. There is still alot of stuff to learn out there. We understand so little about the world around us, but little by little we are starting to unravel the mistery!!!

Severe weather in January

2008-01-06T14:07:00.000-05:00

Their is a high probability for severe weather on Monday, January the 7th. The areas involved as of right now look to be Arkansas, Missouri, into Illinois and maybe Indiana. Although the most severe portion will be southern Missouri into Arkansas. UPR level trough with embedded short waves is forcast to approach the eastern plains on Monday.

Below is the temperature forecast valid 12z Monday, 8:00am eastern. Below is the forcasted dewpoint temperature valid 12z. This is amazing for January! MLCAPE values are forcasted to reach around 1000 j/kg.
More organized storms may be able to become more surfaced based late in the event south into Arkansas. The southern portion of the forcasted area will have the strongest area in the LLJ. Therefore they will have better deep layer shear to deal with. All this should develop well east of a trailing cold front associated with surface low.

It should make for an interesting day. And in January this will be, if everything pans out, very rare. This has the potential to be a historic event!

Storm Basics Radar Anatomy

2007-12-04T21:23:00.002-05:00

What I have set up below is a radar grab from the April 11th 2007 Lizton mini-supercell. I have pointed out some important features here. For example, the updraft, which is not always visible via doppler radar. I have also pointed out the hook echo which is essentially the RFD cut. The RFD rotates around and into the updraft base.

Forgive the crudeness, but the white horseshoe looking draw-in is the updraft base/rain free base. I have also pointed out the area most likly to form a tornado. And as you can see, it is pretty much on a coupling between the updraft and RFD. Of course all storms are different but this will give you some idea as to the general structure.
Now here I have marked with common weather symbols (i.e. cold front, warm front) the interactions taking place. Cold dry, or cold wet, air flowing out from the FFD region scouring up juice (warm moist air) into the storm. You can see too the pure warm air here being driven into the heart of the supercell, by the warm front symbol. In most cases supercells make there own mini weather systems. You can see also the RFD gust front here on the back side. The two cold front symbols are where the storm has generated cold pools that run out ahead of the main storm, called gust fronts. These areas are the likely place to find shelf clouds. The main FFD pseudo-front is also the place to find inflow cloud phenomena, e.g. a beaver tail and the like.

Not all supercells are the same! Some work intirely on drier air. Due to adiabatic processes, and complex thermodynamics, I will not get into that right now. But again some also ingest warm very moist air then spit out very cold wet air. Some are exceptionally windy, with gusts near 100 mph, and some have almost no wind at all. It also has to do with what phase the storm is in. Storm phases include, intiation, growing, mature, and dying. Some supercells manage to kind of recycle themselves. They are generally called cyclic supercells. What happens is when a storm cuts itself off of warm moist air, usually the RFD wrapping all the way around part of the updraft base, disrupting good structure. It will redevelop a replacment further east, but still connected to the orignal. And finally taking its place. Thats were those rain wrapped tornadoes come in. Meaning the storm produced a tornado but cut itself off, thereby hiding the tornado in a sheath of rain. Then a new tornado develops out of the new circulation.