PDS Watch Issued...Close call for St. Louis, MO

Well...it's a busy night in America folks...The SPC has recently upgraded the Arkansas Tornado Watch to a PDS Watch. Strong, long tracked tornadoes can be expected well into the overnight hours. There have been reports of damaging tornadoes occurring very close to Little Rock, Arkansas as well as in Missouri and Illinois.

Not to long ago, a tornado touched down just SW of St. Louis, MO. The doppler velocity signature was incredible. Dave has sent me earlier images of today's tornadoes. The reflectivity/velocity imagery was amazing with confirmed tornadoes occurring near or at the time the radar image was captured.

Daylight will show the full extent of the damage tomorrow. Stay tuned...CNN should have a good handle on it...

Oh and one more thing...another big day is expected tomorrow tornado-wise! The craziness continues!

Strongly Worded MD from the SPC

I've read several mesoscale discussions before and this one is quite serious...
DANGEROUS TORNADO SITUATION UNFOLDING ACROSS AR/SRN MO THIS
EVENING...AND THE TORNADO THREAT WILL CONTINUE INTO THE OVERNIGHT
HOURS.

MULTIPLE DISCRETE SUPERCELLS CONTINUE TO INTENSIFY IN A BROKEN BAND
FROM N OF TXK TO NW OF LIT INTO S CENTRAL MO.  THESE STORMS ARE
MOVING INTO AN ENVIRONMENT WITH STRONG LOW-LEVEL AND DEEP-LAYER
SHEAR...AS WELL AS RICH LOW-LEVEL MOISTURE AND MODERATE INSTABILITY
/PER THE 00Z LZK SOUNDING/.  GIVEN THE OBSERVED STORM STRUCTURES AND
ENVIRONMENT...A FEW STRONG/LONG-TRACK TORNADOES NOW APPEAR LIKELY.
THE CONVECTIVE MODE AND STORM ENVIRONMENT ARE NOT EXPECTED TO CHANGE
SUBSTANTIALLY INTO THE EARLY OVERNIGHT HOURS...THUS THE SIGNIFICANT
TORNADO THREAT WILL PERSIST WELL AFTER DARK.


There has already been significant damage reported with these tornadoes...the night is just beginning.
We'll see what happened tomorrow...since the sun is dropping quickly!

Storm caps

Here's a pretty cool look at a storm currently going through Gainesville, MO. There's a tornado warning on it, although no confirmed sightings.

Sorry, Justin, no smoothing. Ha!

The gate-to-gate shear is 110 knots at about 5700 feet above ground.

Reflectivity:


Velocity:

Last day of April

Here we are at the end of April, not even really into the main part of the season. Still, there has been at least one event of note: the Yazoo City tornado.

The last couple of days have been okay for storms, although the moisture has been a little more sparse than preferable for good storms. Today, though, is somewhat different. And that's why I'm writing.

Moisture - dewpoints in the high teens north to low 20s south. (North-south today is a huge area--look at the tornado risk map.)


The lift is good along the advancing cold front, the shear is plentiful with 500 mb winds at or above 50 knots, and instability is strong, too--3000 J/kg.

All this is good stuff, and good for storms.

But.

I don't like it.

Well, maybe I shouldn't be so glib; I don't like this kind of setup, although given the choice between chasing this setup and not chasing at all I'd pick chasing. Of course.

The setup today has the shear oriented almost parallel to the forcing mechanism, so any storm that forms has a higher than usual chance of having its inflow polluted by another storm upstream from it. As well, the isobaric surface flow is southwesterly as opposed to southerly or even southeasterly. (This can be fixed by approaching short-wave troughs dropping surface pressures and the winds backing in response.) And lastly, because of the environmental wind speeds involved, storms in this environment are usually flying along--too quickly to chase.

Justin and I have been having some conversations offline about this chasing thing and our forecasts; we have both entered a virtual chasing contest and submit our forecasts for it. The thing is, though, that the virtual chase is just not real enough that the strategy for winning the contest isn't the same as the strategy for chasing in real life; for the contest you want to catch as many severe reports as possible within a certain radius of your location. In real life (at least for me; Justin can speak for himself) I like to be just south of a storm, watching its inflow and the entire growth of the updrafts and how the whole thing works together. I very rarely (I almost typed "never") want to get into hail from a supercell. Here's why.

The last couple of days have been rather busy at work for me and, I assume, Justin; expect this from time to time so posting may sometimes get inexplicably light.

By the way, my target as described here a couple of days ago hasn't changed much; for picturesque and slower storms today I like tail-end Charlie, near Tyler, TX--close to the 12 bull's eye of the SCP in the following map.

Updated forecast for Thursday, April 29; brief forecast for April 30 and May 1

Not much has changed in the way of thinking. The shear will be there, as will the instability (in the form of lapse rates). But the moisture looks still to be lacking.
This is the SPC's look at it today.

Personally I like the south end of this risk, around Wichita. The surface pressure and wind forecast shows somewhat veered winds at the surface the farther north and east you go. As well, the forcing farther north will be stronger, so storms could blow up all over the place--bad for chasing.

As for twisty things down low, well, the moisture looks to be not that great, not even in Kansas and Oklahoma, so I'd be more thinking about hunting picturesque supercells.

Now how about Friday. Oh boy, Friday. In short, all the ingredients look to be there south of the Dallas Metroplex. And this time, the proximity to the Gulf means that the dewpoints progged (near 70°F) are much more likely to occur in real life.

Saturday looks rather similar to Friday in terms of both region and convective mode. Here's a prog sounding for Palestine, TX for 21Z on Saturday. I would like to be there...

Forecast for Thursday, April 29

So the SPC has issued a slight risk for Thursday, with an enhanced hatched risk area through central Kansas.


I will be the first to admit that, although I do my own forecasts when it comes to chasing and following severe weather, I also check what the SPC is thinking. I mean come on, they're the best in the world at what they do and it would be folly of me to ignore their opinion, usually to check if I've missed anything.

So it made me a little surprised to see the hatched risk across Kansas. The wording, though, does make it clear that they're not that concerned about tornadoes, which is very much in line with my thinking, as the really good moisture isn't likely to be in place.

I looked at the prog sounding for the location, though, and I suppose I see more what they're looking at:

Almost 3000 J/kg of CAPE and over 50 knots of deep shear. That's pretty impressive, and with the 20 knots of 0-1 km shear, if there were moisture in place, tornadoes certainly would be a concern.

The orientation of the shear is such that the storms will likely move rather quickly, though, so I hope any people chasing out there take that into account.

Happy chasing!

Now onto later this week

As the cleanup continues in the southern states, our focus now turns to the future--specifically later this week.

In short, it looks like things are pretty much hooped until at least Wednesday and possibly Thursday or Friday, depending on how much Gulf moisture makes it back north.

The NAM and GFS both depict surface dewpoints in the mid 50s making it up to the central plains by Wednesday and the lower 60s by Thursday. However, the really juicy stuff, mid 60s, doesn't look like it'll make it into the plains until about Friday or Saturday, and even then it looks to be confined to Texas. That's not to say that there aren't going to be good storms, however, and that's also not to say that the models are right; in fact, I can say without equivocation that the models will be wrong (at least to some degree). (Wait, was that equivocation?)

So here's hoping evapotranspiration adds more fuel to the fire, as it were, for the chasers out there to have a good trip.

Why the forecast bust on Friday?

I was pretty hyped up about Friday, as was the CoD team and a lot of other chasers. The setup looked prime for quite a few tornadoes, and given the tornadoes the previous day, I was fully expecting a goodly amount.

So what happened?

In short, I don't know. Sorry, but meteorologists don't have all the answers.
Of course, what we tend to have is a lot of opinions on possibilities. :)

So what might have been wrong?

Moisture - the moisture was there at the surface, and according the the Topeka and Omaha 12Z soundings, it was pretty deep. By mid-afternoon the surface dews were in the low 60s. So I don't know that moisture was an issue.

Instability - by and large this looked okay. Omaha sent out a 20Z sounding.

There was a slight bit of capping at about 700 mb. The amount wasn't huge, and the cap (I don't know why people capitalize the word, Justin--it's a word, not an acronym :P) should have been able to be overcome. But I will discuss this a bit more in depth below.

Lift - there was tons of convergence along the occluded/warm front. It was actually one of the things I had feared the day before, that things would go too early because of all the surface convergence.

Shear - Plenty. But, you say, look at the 20Z Omaha sounding. Not plenty. 23 knots deep shear? True. At 20Z. But with the increasing wind fields, that increased to 46 knots by 00Z.

So that likely wasn't it.

I want to go back to the subtle capping we saw on the 20Z sounding. It wasn't a huge cap, an insurmountable cap, but perhaps a symptom of something that was insurmountable: subsidence.

Whenever you see an inversion with associated drying, it's usually due to subsidence--air sinking. The fact that there was what appeared to be a subsidence inversion at Omaha at 20Z may be enough, in fact, to have prevented convective development until later. Even weak, subtle subsidence can often be enough to prevent storms from going up. It can be annoying.

Later, at 00Z, we saw no evidence of this cap and lo and behold, storms fired around that time. So why didn't they go nuts at that point with tornadoes and big hail all over the place? Looking at the observations from Omaha, the temperature was 22°C at 23Z and 21°C at 00Z. A subtle cooling, but perhaps enough to make it so that the CAPE would decrease by a lot.

So in essence, there was some mid-level subsidence that prevented storms from going for a while--due likely to a short-wave ridge that was nigh on impossible to find on the water vapour imagery. By the time the ridge axis passed and the subsidence turned to subtle lift, peak heating had already passed and the storms that formed weren't able to take full advantage of the energy that had been present throughout the day.

I know there are a lot of disappointed people out there because of this bust, although they have a few things to do until the next chance for chaseable storms comes about, perhaps tomorrow (tornadoes not likely but maybe a picturesque supercell) and more likely Thursday and beyond.

Longest Tornado Track Ever???

The tornadoes today were mainly associated with one long-tracked cyclic supercell that started producing tornadoes in Eastern Louisiana this morning. The supercell then moved completely across Mississippi, lifted for a bit and showed its face again in Alabama late this evening. You can connect the tornado reports to draw a distinct track.

The first tornado occurred around 11:45 am CDT and the same storm is still producing tornadoes as I type around 11:00pm CDT.

So far the storm has been alive for nearly 12 hours. That's one for the books for sure! I bet this tornado will be one of the longest tracked tornadoes ever recorded. It's had multiple touchdowns since its birth, but for a storm to cycle and maintain its strength this long is very, very rare.

The previous record for the longest tracked tornado occurred during the Tri-State Tornado Event on March 18, 1925. The track was around 219 miles and it killed almost 700 people making it the deadliest tornado in history.

So by doing the math for today we're looking at having at least a track of 150-200 miles.

Stay tuned...

The NWS will more then likely send out a damage survey team in the morning to assess the damage. From what I've seen on the news and online I think the 1/2-3/4 mile wide wedge tornado in Yazoo City, Mississippi will be given an EF-4 rating.

Tornado Emergency...It's Happening Right Now!

Supercells have raked their way across the state of Mississippi this morning and early afternoon. I believe there is a tornado still on the ground in NE Mississippi as I type this entry. Towns have been hit, homes flattened, cars blown off the road, and apparently there are fatalities and people trapped in Yazoo City, Mississippi. They have set up a command center and the National Guard has been called in to assist with relief efforts.
The track of this cyclical tornadic supercell is one for the books. It stretches almost entirely the whole way across the state of Mississippi and it's still going...about 150 miles+ so far...
Not many chasers are out there due to the TERRIBLE chase country but keep checking back with the live streams as you might get lucky and catch a glimpse of one of these wedges.
Fortunately, they cancelled the NASCAR event in Talledega, Alabama...at least Emergency Managers are paying attention.

I guess I'm not surprised with these reports (36 so far) given the High Risk and PDS watches that have been issued...the day is NOT over yet...the convective peak is still upon us and these storms WILL go throughout the night with scores of more tornadoes expected. The mesoscale analysis composite indices are off the charts...it's ridiculous...0-1km EHI's around 10...sigTOR's of 10...etc, etc...

Above image is from after the tornado went through Yazoo City...note the red dots...those are the tornado reports associated with the same storm...impressive!



Back to bed I go...night shift part 2...

MS/LA border, watch out

I don't mean there's a watch out. There is, but I mean batten down the hatches. There's a supercell that's discrete and already quite spectacular. What's more, it's moving into an area of higher moisture, instability and shear. This storm could end up going nuts. I therefore hereby eat crow in pooh-poohing Justin's previous forecast.

Here's the significant tornado parameter, the worst of which the storm is moving into.

And the shear. No, this isn't deep shear; this is 0-1 km! Yowza!

News flash: I agree with Justin

Okay, now that I've looked at stuff, I reluctantly agree with you, Justin. Deep shear is almost off the charts (70 to 80 knots), moisture is deep, and the instability and lift are plentiful.

Here's a sounding they did from Jackson, MS at 13Z today. It displays things nicely. Scary nicely. The only mitigating factor is the amount of sunshine, although even in the more or less cloudy air they're getting temperatures in the mid 20s.

On a side note, College of DuPage is doing the cold core play in Iowa today. That could also be interesting.

Tornado Outbreak Tomorrow? Appears Likely

Based on the 00z NAM models, it looks like tomorrow might be the first real tornado outbreak in quite some time...3 years perhaps?

The upper flow is aligning itself in such away that several LEWP (Line Echo Wave Patterns) with embedded supercells will likely develop from Central Kentucky, SW to Louisiana.

Moisture is abundant, so is the forcing, capping will not be an issue since storms are currently ongoing and will likely go through the night, and instability will be quite high with any bit of sunlight to further increase the instability.

Storms will be born rotating. I predict 30+ tornadoes tomorrow. Bold statement yes...but I'd rather be an alarmist. In that area of the USA you have plenty of terrain to focus areas of low level rotation. Now combine these areas with great thermodynamics and dynamics...well then you have outbreak potential. SPC might upgrade to a high risk with PDS watches likely being issued sometime during the day on Saturday.

The size of the potential area affected is what scares me along with the strength and orientation of the Low Level Jet. Storms will be long lived and tornadoes will probably be long-tracked.

I'd be looking for a warm front tomorrow in my morning analysis and I'd likely hover around there. If I had to choose a spot to start off the day, I'd probably start in SW Tennessee...more specifically Memphis.
We also can't forget that the superspeedway in Talladega, Alabama (Northeast) is hosting a major NASCAR race this weekend and that area is under the gun for tornadic weather tomorrow.

Lots of trees and lots of trailer parks are also located in this area. Fatalities will probably occur because people down in that area don't seem so tornado aware as the people are in the Central/Southern Plains. They better keep their eyes on the sky tomorrow.

What do you think about tomorrow Davicus?

After today

Tomorrow it seems there'll still be a pretty good setup, although not in great chase territory. However, for a couple of days after that it looks spectacularly bad. So what would I do?

Well, if I were part of a storm chasing group currently out there I would go chasing tomorrow--Tennessee? Wow. And then take my time getting back to the plains, where it looks like, aside from a crappy northwest flow setup in Texas on day 3, there'll be nothing of note until April 28 or 29.

3 PM CDT

As of 3 PM CDT there's a pretty good cumulus field through most of Nebraska and the northeast corner of Kansas.

I still see our target area as prime. Reasons? NWS put up an 18Z sounding from North Platte, NE (KLBF):
And it shows pretty good instability but the winds are a little goofy--that is, all from the southeast or thereabouts. So this is likely good for those who don't want long-lived tornadoes.

For those of us freaks, we don't mind those winds up to, oh, let's say 850 mb. But above that we want the winds to become more and more westerly.

As we see from the water vapour satellite image:
The midlevel flow will become more westerly the farther east you go. Add in the fact that surface dewpoints are also higher to the east, in the low 60s, then you have the better mix of ingredients.

So right now I would actually hang out in Falls City and watch how things develop. In Falls City you've got the leading edge of the better moisture and the wind profile is more favourable.

11:30am CDT...Getting into Position for the Tornado Eventssss

Well, I've looked at morning analyses and the latest RUC data. I stared at the visible satellite for a bit as well as the water vapor. Based on all of this, I've decided to virtually drive to Tecumseh, Nebraska and wait for initiation. The RUC might be moving the low too fast compared to reality which means everything might trigger a bit further west. I might drift West to Beatrice, Nebraska...but not yet!

From what I've seen it looks like the Low didn't deepen the way I wanted it too. This expands the wind field which in my eyes makes it less favourable for major league tornadoes. I mean there were will be tornadoes...but the backing winds occur over a large area which one would think may be great...but I think that the environment is sharing the winds too much. At upper levels, 700mb, 500mb, and even 250mb, show similar wind directions with height although the speeds increase. Tilting storms yes...strong rotating storms...I don't know. The only saving grace is the SE winds at the surface...will that be enough? Who knows.

Also, Capping appears to not be an issue at all today which is also bad...I'll explain in a bit...similar to what Dave has said.

Moisture...well ha...that's not a problem at all...

So in a nutshell...big nutshell...

I think yesterday had better potential for tornadoes due to the better wind fields in our forecast area. Today I think that storms might all go up at once and precipitate on each other's inflow. This means that the southern most storm will be favoured, but as you head south...the winds become less favourable. Rain needs to evacuate the inflow/updraft region in order for the storm to maximize it's growth potential (severity), and I don't know if that'll happen.

The Pipestone and Aurora set-ups had a deeper low and better direction and speed changes with height...

I'm not writing today off...it just looks like if tornadoes form...they'll quickly become rain wrapped and impossible to see. Wedge tornadoes appear likely today...hopefully chasers can see them for a bit...because this can be dangerous. I've chased in Northern Missouri and the roads curve and dip quite a bit...let's just say the roads aren't exactly aligned on a grid N,E,S and W. This can be dangerous because a chaser might be paralleling a tornado when suddenly the road he/she is on turns into the the area of rotation.

Warm Front = possible gamble...there is still a dryline around so that might be the better play...
I'd look for the triple point and play around there...

Anyways, I've said what I wanted. The MDT risk area for tornadoes is better today in terms of potential, but who wants to chase in the Southern Bayous?

Forecast Convective Initation...2:30pm CDT...tornadoes on ground by 4:15pm CDT...that's my stab!

Today: just had to add

How about this forecast sounding for just north of Falls City for 21Z/4 PM?
Holy low-level shear, holy deep shear, and holy lapse rates. BIG hail possible. Yikes.

Update on today

Today does look pretty good. As I type this the SPC has just issued their first tornado watch of the day, and I expect it's not even close to the last one.

Although there's a higher chance for tornado coverage in the hilly and/or swampy south, my target today would still be along the warm front/dry slot near the Nebraska/Kansas border. The moisture is pretty good and, per RAOBs, pretty deep. In the dry slot the winds have not veered, which is a very good sign.

My concern yesterday about there being morning rumblings turned out to be baseless, and this just adds to my excitement about this afternoon. I actually suspect that, because of this, the SPC might upgrade to a moderate risk for KS/NE for their 11:30 AM update. Time will tell.

Moisture - check. Surface dews are solidly into the upper 50s and low 60s and 850 mb analysis shows a moisture axis poking northwestward from the Gulf to central Nebraska.

Instability - check. Mid-level lapse rates are pretty impressive to the southwest of the target area--just perfectly juxtaposed to advect over the region of interest this afternoon.

Lift - warm front. Convergence all over the place. 'Nuff said.

Shear - pretty impressive. Dodge city, KS shows 60 knots at 500 mb. There's the deep shear. Backing winds along the warm front--there's the low-level shear.

As always now I must play devil's advocate with myself. What limiting or mitigating factors can I think of to downplay this event?

Well, the orientation of the wind fields is such that a storm would have to take a hard right turn for it to stay surface-based.

There seems to be little cap right now; storms could go too early to tap all the available potential instability.

For right now, Justin has virtually gone a bit south. Fair enough. I still like Falls City, NE as a start location. It's pretty easy to get to lots of places for initiation. Besides, I think that storms will get better and better as the day goes on--and picking the first storm that goes up could be a mistake. I'd wait and watch the RADAR until one storm begins to be an obvious beast, as there could be many potential beasts out there.

CoD is right now just west of Des Moines, IA and heading west. The thought process of theirs is pretty much the same as ours. Except they actually get to be out there today.

Great Tornado Day...Main Outbreak Event Still Expected Tomorrow...continuing Saturday too!

Nice day tornado wise across the Southern Plains. Dryline lit up as forecasted but not exactly the way I thought it would. Couple of long tracked tornadoes developed though which was nice to see. Looks like the main action of the day took place in Eastern CO and Western KS. The warm front did wonders today.

Storms have decoupled from the boundary layer ahead of the warm front for the night. Further south, tornado chances still exist ahead of the cold front/mixed out dryline, but I think the main threat tornado-wise is done for the night.

About the warm front tonight into tomorrow...hopefully these elevated storms will leave some nice boundaries for tomorrow's convection. Capping may be an issue for the warm front play so any boundary to focus lift will be critical tomorrow.

Several tornadoes...probably more then today will occur over a widespread area. Again, all modes of severe weather will be possible.

My new target for tomorrow has shifted a little bit West...to lie around NE Kansas...more specifically Marysville.

Stay tuned...Saturday's tornado threat looks to be around Central Tennessee...but that's ways away!

7:11 PM CST

And if you're looking, there's some sick rotation just northwest of Dodge City, Kansas.

6:25 PM CDT

Now it's my turn to add images. However, mine will not be smoothed. :P

First off, the base reflectivity.


And now how about the velocity.
Mousing over the major couplet there was 96 knots of gate-to-gate shear at 3300 feet. Tornado much?

Explosive Development w/ Confirmed Tornadoes

Tornadic supercells are rapidly developing ahead of the dryline East of Amarillo, Texas. I said 5pm would be the time tornadoes would occur. I was off, touchdown around 5:15pm. Not bad...lol

Anyways, monitor the radars down there. The storms are absolutely beautiful. This is a classic dryline set-up!

I am uploading GRLevel3 images to the U of M Wx Club Page every 5 minutes.

The above image is from 5:25 pm CDT East of Amarillo, Texas

The tornado in the image above is occurring right now as I type (5:38pm CDT)...amazing day!!!!!!!!!!!!!!!

Warm front plays: trickiness all around

So Justin asked me to expand a bit on why warm front plays can be tricky. Whew, have you got a day?

Really, there are a few difficult things about chasing this kind of setup. First off, the major problem I have with them is that often the upper winds are aligned such that any storm that forms will not interact with the front for long. There are of course many exceptions to this, and when an exception happens your storm can be a prolific tornado and giant hail producer.

But setups like tomorrow's make me a little leery. See, the 500 mb winds, while good and strong, are forecast to be from the south-southwest--maybe around 220 or so. With a warm front draped more west-east or even northwest-southeast, the storms could end up either forming on the front and then moving into an area with stable surface air (and therefore becoming elevated) or, worse, not even tapping surface air parcels at all.

Second, often with warm front setups you get a lot of low cloud obscuring your ability to see things like towers going up. Sure, you could have all the information in the world with mobile internet and such, but nothing beats seeing a tower going up and being able to tell where that one is the one.

Third, if you do get setups like this, sometimes you will get a zillion storms going up on the front and then you have to choose which one will go nuts. Good luck.

And fourth, the inevitable chaser convergence.

Regardless, if I had a chance I would of course go out chasing tomorrow. The actual evolution of things, including convective debris, can't be known until the morning of.

(PS to Justin: "golden ticket to the main event"? Have you been watching a little TV recently? :P)

Severe weather season really begins

So a couple of days ago there was a somewhat unexpected tornado just outside Amarillo, TX. The thermodynamics were marginal and the shear wasn't really there, either. Well, at least so far as we were able to ascertain, but obviously things came together just right at least on that storm.

Anyhow, this led to this watch being issued yesterday because both thermodynamics and dynamics were better. But it didn't pan out. Hmm.

Anyhow, onto today. Today is looking pretty good. I did an analysis by hand (remember those?) and the 500 mb wind makes me think that today could be a sleeper. Better than tomorrow, which BTW looks really good. At least better in terms of chase-able storms.

My pros today: morning convection has dropped some moisture in the area, a dryline is setting up, and winds and cooling aloft should be in the right place at prime time. Cons: the moisture isn't huge--dewpoints are in the 15 to 17 degree range.

My target is Amarillo, TX right now. I like the moisture to the southeast better but the upper winds to the northwest better. And besides, I'm sure there'd be good BBQ to nosh on while waiting. And then as the day progresses and the dryline mixes eastward, I like drifting toward Childress. I figure tornadoes are a good possibility and if not, just a picturesque dryline storm today would be worth it.

Now onto tomorrow.

I have my suspicions tomorrow could be a good day stormwise with a gigantic asterisk next to it. See, the forcing for this event is so good, so strong, that I suspect there could be a regenerating MCS all day. That would mean outflow boundaries galore, convectively overturned air all over the place and not a single area to focus on. Unlike today, where there will likely be a string of pearls along the dryline and you could essentially choose your storm, tomorrow will likely see a convergence of chasers all around the warm front, and I agree with Justin: Falls City, NE or just north thereof.

(Full disclosure: while I was writing this I got a text from Justin telling me to get on with it; then I necessarily got distracted because something more pressing came up, and Justin told me he had already blogged about it. Keener.)

Low-level shear looks better tomorrow than today, at least on the forecast soundings, but I just can't discount that Texas panhandle dryline magic.

Incidentally, the College of DuPage is embarking on their trip this evening. It therefore looks like they can make it to their destination (wherever that may be) in time.

Tornado Threat Increasing Rapidly Today and Tomorrow...Finally

Spring has finally arrived here in Canada with leaves showing their light green faces all over the Capital region of Alberta. Dave in Winnipeg has also reported some leaves starting to emerge in and around the city. What has been an early Spring for us has been an earlier Spring for people in the Southern Plains...albeit a quiet one.

Things are about to change today as a Low Pressure system moves in from Colorado setting the stage for a two, possibly three day severe thunderstorm outbreak. All facets of severe weather can be expected today and especially tomorrow.

I don't want to really get into the meteorology leading up to my decision about where the greatest tornado threat would be, but I will say that areas 50 miles North, East and South of Childress, Texas look amazing in terms of tornado potential.

A Warm front play is uncertain today because of cloud cover (tomorrow looks amazing). The greatest play would be in the Eastern Panhandle area of Texas where I think the dryline will bulge out allowing discrete storm development ahead of it. Shear profiles are great with capping being removed by 21z. Forcing along the dryline should trigger development by around 3pm CDT. Storms should rapidly begin rotating as they move East into juicier air. As cloud bases drop in the increasingly moist boundary layer, the attendant tornado threat will increase and I think the tornado show should begin around 5pm CDT. We have the 4 ingredients today...moisture, instability, shear, and a trigger. RUC models do show the cold front catching up to the dryline eventually, if the two forcing features stay separated, similar target areas might see a one-two punch, with the tornado threat and all modes of severe weather first, then a large hail and wind threat during the late evening/overnight hours.

Remember, tornadoes will likely occur in other areas today, I'm just addressing where I think the greatest potential will exist. Here is where I think the long lived tornadoes might develop. My name is F5's only for a reason...

Tomorrow is another story...this could actually be the bigger story in terms of the area affected. Moderate to high risks might be tagged on tomorrow's outlook once the Low takes shape and models get a better handle on the situation poised to unfold tomorrow. If cloud cover moves off and if convective boundaries from today's convection exist...then tomorrow could be a tornado outbreak for the books. My best bet for large cyclical supercells capable of producing long-tracked tornadoes will be centered 50-75 miles North, East, South and West of Falls City, Nebraska. Here the warm front may the the culprit for several tornadoes. I will go into more details tomorrow, but for interested readers...look at the Pipestone, Manitoba tornado from June 23rd, 2007 or the Aurora, Nebraska tornado from June 17th of last year. Those were warm front initiated tornadoes...and they were good'ers.

To chasers...remember warm front plays are tricky. DO NOT CHASE a storm that is way ahead of the warm front. It may look good on radar, but it will not produce a tornado...I REPEAT...it will not produce. The supercell is elevated which simply means that it is not tapping into air from the surface...therefore a surface based circulation cannot exist. A storm forming near the warm front that reaches the warm front is the golden ticket to the main event. It will be elevated initially but as the storm moves toward the boundary or if the warm front lifts to where the supercell is...then the storm can tap into surface based instability where a tornado threat can rapidly increase. Again, warm front plays are tricky...they can be unsuccessful most of the time due to storms forming ahead of the front and staying there with only a large hail/strong wind threat existing for hours. If one does root into the boundary layer along the front or south of it...then get ready for a major league tornado. I've been a bit repetitive here...I just want to burn it in the readers minds that warm fronts can fool many chasers. For further details about warm front plays...maybe Dave can shed some light on this matter.

Anyways...that's it for now...good luck out there to anyone chasing...it should be a good one...and if today doesn't work out for you...well then you have tomorrow.

Presenting the blog

So Justin and I have been having extended weather setup debates over text messages. He suggested we start up a joint blog to discuss things instead--that way we could link images and lower our text message fees, as well as share our thoughts with others out there. Or, judging by my readership, other out there. :)

Watch here for some spirited debates, mainly focused on storm chasing, about targets, strategies, meteorological theory and so much more.