Friday, April 30, 2010

Can't get enough

I took my eyes off the weather today and BAM! night time tornado's abound.

Quick off the cuff impressions and analysis:
1. I am utterly impressed but not that surprised that the sounding structures observed from FWD, LIT, SHV, LCH, SGF changed so little with respect to the moisture and degree of saturation, and height of the inversion. The soundings appeared to be tropical like... with near saturation to 700 hPa.

2. infrared satellite loop over the last few hours indicate Convective Initiation along multiple parallel boundaries (presumed boundaries). The cloud fields developed on the individual cells perpendicular to the flow (like transverse bands). They slammed into the main cloud mass as they moved northeast. Early cells did not survive individually. All appear to be training with common initiation areas in bursts. This was prevalent 20-23:59 UTC.

Nice case to model I would bet. 5-1-10 0000 UTC.

Less Interesting event

Nice forecast by SPC today. I was concerned that the threat was marginalized by the wording of their outlook this morning. The concerns of the day were going to be the timing of CI and the strength of the cap in the warm sector, and the position of boundaries. There wasnt much mentioned about the tornado threat other than isolated threat. That is true, of course. The reasoning of limited moisture and also that storms would weaken after dark were incorrect.

There was little mention of hodograph shape or the evolution of hodographs. This was surprising to me and seemed to be quite important. The hodograph evolution I saw was that of little curvature near the front but big curvature away from the front. Worse was the evolution from curved to straightline hodographs. The 21 and 00 UTC soundings from OAX and TOP pseudo-confirmed the hi-res model hodographs I saw (NCAR WRF 3km convection from their 18-24 hour forecast from 29 April 00 UTC Run). I am not using a direct comparison mind you ... more like temporal neighborhood similarity.

That is the forecast reasoning depended was sullied by rather typical information and model data were discounted. Bias is models is always problem. When do you trust them and when don't you. In highly dynamic environments it is easy for them to be correct. When they go astray is usually in organizing the convection or missing the initial convective mode. The linear nature to todays convection was fully captured by the model even if the forecasters did not anticipate this initial mixed mode.

I say mixed mode because I am sure there were a few supercells, but they were lined up on the front. The scale of such linear organization along a boundary might be predicted well as opposed to smaller scale isolated cells. This is the big test of these models. What CI events do they capture well AND how well do they predict the evolution? Current techniques exist to test for this and I believe them to be regime dependent. Just dont ask which regimes yet. That awaits further research. I will update when I get the model hodographs downloaded and compare to the soundings.

Saturday, April 24, 2010

High risk for Day 3

The high risk certainly verified today. Looks like either a few tornadic supercells were out prowling around or 1 cyclic tornadic supercell was about laying down multi-state sorts of damage. Cant wait to see the damage survey. I wish you well Yazoo City (and all the other cities/people affected ) in your recovery efforts.

Today was a story all about large hodographs despite what can only be considered to be marginal instability (in general) but still enough to be dangerous.

Situational awareness needed to be much higher for the average citizen out there today. I cant blame the people as much as I might want to. The High and Moderate Risk areas for today was LARGE; 4 and 6 states respectively. The event was ongoing in the morning, with multiple waves of severe weather expected.

The first tornado report was listed 2.5 hours after the convective outlook was issued. We all need to be better equipped to explain and communicate the risk. Its a serious business we are in. We dont just provide information for the average person to consume. We provide meteorological information from which a serious number of people make decisions.

From the local TV and radio coverage disseminating NWS warnings, to emergency managers trained to respond to a crisis, to the fire and police department who are also trained to monitor (in a limited role) and respond. By what do real people need to know?

This phenomena is distinct. It is short lived locally (5 to 90 minutes). Can occur in waves or epsiodes. They can be misleading. One storm can be tornadic and depending on your position can come "out of nowhere", be right in front of you for 10 minutes, or appear to be suddenly upon you though you didnt think it was that close. The local motion of the storm and the tornado may be different. The storm itself may not be that visible.

1. should you travel during the storm? Check the radar. Read about the people who had their kids in the car and were caught in the storm as power lines and trees pummeled them. They claimed taking the kids out of the carseat was a good idea when they hid inside the car. A tree hit them apparently damaging the car where one child would have been. I dont want to know what would have happened if the car became airborne in that situation.

2. should you flee the storm and drive somewhere else? No. Read the article about the people who drove to the family restaurant to hide in the freezer. They ended up in the restaurant ... in their car ...thrown by the tornado they were trying to hide from.

If you are out, stay put. its easier to find shelter where you are than to relocate and find shelter.
If you are home, the basement of a well built house, or a bathroom on the lowest floor s the best option (not necessarily safe though; remember we are talking about tornado's ... they make cars fly far).

Friday, April 23, 2010

The day after tornado season started

An interesting severe weather day. Big threats for supercells in multiple regions.

The models gave us false impressions of the cap. This is a case for extensive numerical modeling of a null event in Nebraska and Kansas. The water vapor imagery combined with multiple soundings available for analysis make this case worthwhile to explore numerically.

The instability and moisture were well predicted. It appears the shear was well predicted. The timing in the NSSL and NCAR WRF models was too early and too widespread. I want to say that the models ejected the long wave trough out too quickly...but is a few meters per second really too quickly in phase speed? Or perhaps the models did not capture the vorticity evolution on the back side of this large rossby wave?
anyway the cap issue is nicely shown by the Topeka sounding (where the action was predicted by 21-00 UTC.
Note the low level cloud layer. There appeared to be shallow cumulus. Does parcel theory collapse when a cloud layer is already present? To speculate is poor science, but ideas emerge from speculation. Perhaps the cloud layer is so dynamic (entrainment at the PBL top, less than well mixed below) that parcels can only emerge or organize with the thermodynamics of the cloud layer. In that case, a parcel lifted from the cloud layer would immediately have convective inhibition.

Dr Adam Houston has published some work indicating that the lapse rate above the LCL and LFC might be very important here as well. The steeper the better which is not really observed on this sounding. Another factor may very well be the path that parcels take. That is the forcing for ascent locally may not have been favorable despite the PBL circulations.

Clearly though, the dry layer alofyt at TOP was associated with a dry intrusion of very limited extent as the inversion is not present just 4 hours later at any station. water vapor loops indicate the invsersion may have been present from 1845 to 2045 and was weakening. It was oriented north to south ... probably why SGF showed only a hint of it and why it wasnt seen elsewhere.

As the event unfolds now, Iowa and Nebraska are just now seeing the late evening initiation I was expecting if the afternoon stuff didnt go. I have some anecdotal evidence that when the warm front in Iowa is involved, chances are the cap holds until night time. I wish I could explore that issue further.

Not too much actual severe weather to report on. 8 tornado reports in 4 states.

Thursday, April 22, 2010

Tornado season is upon us

Some quick facts. Today marked the latest day in the year where a moderate risk of severe weather was forecast by SPC. Interesting enough, the MOD risk was not forecast until the 20 UTC update.

Overall, the NSSL WRF model did pretty well from what I can see. It was spotty and sluggish but the put the idea out there that small scale convection was possible.

The result: 31 local storm report tornadoes.

The hodographs were nicely curved today and the moisture got into eastern Colorado. The low level cloud cover kept dew point depressions low (low lcl heights) near the warm front. There were a number of splitting supercells in very close proximity to other supercells which did not split. At the very least, my perception tells me they were supercells but it is possible that supercells were not the only organizational mode out there today.

I dont know what to make of the deep low level cloud layer at OUN. The OKC ASOS showed the overcast skies but did not that much moisture really pour into Oklahoma today? Preliminary analysis says yes since FWD reported similar low level moisture observations almost of the tropical variety.

In fact, in searching through the soundings, the elevated mixed layer was surprisingly far south in Brownsville and still weak in DRT. Not really sure what to make of that factoid. Then again I wasnt following this event very closely.

anyway, here are the pics. Wish I was out there chasing. The Plains of Colorado is some nice empty country.

Saturday, April 3, 2010

The passion

It is all about the passion. From the blogs I read to the articles I read to the TV I watch. I am drawn to the people who have the BIG passion and it shows remarkably well.

A few people come to mind:
Seth Davis from Sports Illustrated. He has a personable writing style. I can hear that guy talking basketball when I read his articles as if I were watching the run-up to MarchMadness.

Miles O'Brien from and This week in space. And its nice to see that since being let go from CNN he is absoluetly immersed in NASA and space and community and people and wow his passion just shines. I think he got picked up on PBS! Even more passion to come.

How about some people I don't know but feel like I have a clue from the blogroll: Madison Richards posts are filled with that passion (though the blog updates come in spurts ;) ). Chuck Doswell also has a big passion for science and photography and calling it how he sees it. I can identify with their passion. And lately both of these people have shared life experience I wish I had heard years ago.

I just completed the Strengths Finder 2.0. the premise is simple. Have you been improving yourself by working on weaknesses or by working on your strengths? Seems silly to even ask that question. There is an implication that by not working on your weaknesses you are ignoring them. But you cant do both at the same time. You find your passion by working your strengths.

Its interesting to adopt the point of view that smart people succeed because they are smart. I postulate that smart people succeed because they are naturally good at working at their strengths. And when they aren't doing that they are probably exposing their weaknesses.

I also like Jaime Oliver, the naked chef. He said something profound: "When I dont follow my heart I screw up. When I do, its like magic".

So lets get back to what I ignored...the weakness. The weaknesses still need to be addressed and only life experience through your strengths can you learn how to minimize their importance by properly accounting for those weaknesses and developing strategies to counter them. You might not be able to close that hole but you can learn to avoid the traps they cause.