Cyclone Road


Tuesday, February 28, 2006

I have a few minutes to update this morning and can only wait for the NAM to come in. Overall, I don't think the status of the weekend has changed much. From what I've seen so far on the NAM, which is updated through 78 hours and will finish shortly, Friday simply looks too benign at the surface to warrant serious consideration of supercells. In addition, the signals for early and long-lasting precip along the warm front remain strong. This will likely shunt the warm front even farther south than progged so it remains in relatively deep south Texas or central Texas during the day and evening. Deep layer shear is impressive as is backing shown along the front and the resulting SRH values (more on while I'll probably stop using this parameter in discussions of model data coming later), but deep moisture is absent.

The final NAM panels are in as I'm writing and show meager CAPE values creeping up the plains of eastern New Mexico.

I have focused on Friday over Saturday because I think Saturday is a slam-dunk severe squall line, typical of early March. Saturday is all about forcing and strong jets aloft with some unidirectional shear thrown in for good measure. Friday on the other hand, with more relaxed shear over elevated terrain, had the potential for isolated, if high-based, storms. Even the low 50-ish Tds currently progged out there could create sculpted updrafts if they're not competing in a large-scale rain shield, a distinct possibility.

That's all my time this morning. I'm keeping an open mind.

Monday, February 27, 2006

Things are sketchy for chasing this weekend. The EC leaves the main trough off the pacific and only sends a small wave through the CONUS. This would be great in May when moisture is waiting. But this March and we need something dramatic to advect fuel from the Gulf of Mexico; a ripple in the prevailing flow won't do. The EC is an accurate model and this kind of divergence between it and the GFS is cause for concern. Additionally, the ensembles from last night show a larger spread than before and suggest a cutoff situation. Only the GFS 0z "hot" runs continue to paint a hopeful portrait for chasers. All of this caused the SPC to drop their slight risk on the 4-8 day outlook, a product I'm sure they hate being forced to issue anyway. The weekend could go either way.

Sunday, February 26, 2006

Busy day today. Worked on the novel this morning which makes it okay to goof off later, but I don't have time. I'm finishing all the Sunday chores plus preparations for a possible chase on either Friday or Saturday or both. I give this setup low marks for being early March and having to deal with a cold front sagging south during the midweek. A significant precip event is likely and will spoil severe chances as is often the case this time of year. On Saturday, with so much forcing and marginal instability, a severe squall line seems likely, again, not something we're looking for.

Last night's GFS was exciting but today we're back to reality. This is a Texas/Oklahoma system, and I believe now that the warm front might not make it as far north as I-40 on Friday, possibly the KS/OK border on Saturday. This far out in time, once again, the only information I take from the guidance is that moisture will advect into the southern plains, modest southwesterly midlevel flow will overspread the region beginning late Thursday and increase until the main energy arrives on Saturday, and a warm front will camp somewhere in the neighborhood. There's nothing more definitive to be gleaned from distant progs, even though it's fun to try.

I give the setup extra points for timing since Friday and Saturday are the best days for my schedule. It's possible this could be my only chase in March, as well, since other obligations will impinge over Spring Break and on the last weekend of the month. I'll look for any excuse to head out if I can find one.

Saturday, February 25, 2006

I took a break from the writing long enough to glance at models for the upcoming week. Three things stand out from a scan of GFS operational, ensembles, and ECMWF. First, moisture begins advecting into central, west, and northwest Texas during the middle of the week and into the weekend. Second, brisk mid-level southwesterlies overspread west Texas and the Texas Panhandle beginning late Thursday and continue through the extended. Third and most intriguing, a cold front drops into Texas during midweek and could stall before creeping back north as a warm front from Thursday through Sunday. This last feature draws my interest.

The likely outcome is a big rain event as elevated moisture returns above the warm front. A long-term precip event would create a cold pool and a tight thermal gradient far less supportive of severe storms than a modified boundary. All sort of havoc comes from cold air at low levels and tornadoes don't like any of it. This is what would normally happen in the first week of March and therefore that's what I expect.

However, if we don't have so much rainfall, and if our moisture return can slightly outpace the current progs, then Friday's projected shear isn't so powerful that lower-instability storms would necessarily suffer violent and premature deaths. Saturday the Big Jet arrives and storms will fly at 60 knots like we're accustomed to in March. Those are no fun.

I have so much work today that after this post I'm turning the computer off. But I want to mention that on, the chaser safety/ethics debate has flared again as it does every year about this time. This is a good thing because there are new chasers every year, too, and it can only help them to see the range of ideas and opinion.

If the only product of the annual safety debate is a reminder that we're thinking about it, that's better than nothing and possibly enough to exert as much pressure as CAN be exerted on those who create the most problems.

A moment ago I posted some links I've had on my front page for years. These two essays, by Chuck Doswell and Alan Moller, satisfy the topic for me. Despite the occasional perception that these documents have become too institutionalized to remain effective, I think the writing itself is vigorous and it's the perception of the essays that has grown stale rather than the words, sentences, and paragraphs themselves. They stand the test of time.

Storm Chasing with Safety, Courtesy, and Responsibility
by Dr. Charles A. Doswell III

Storm Chase Ethics by Alan Moller

Thursday, February 23, 2006

The medium range models signal a pattern shift between seven and ten days, perhaps bringing some moisture into the plains and lift over the mountains. To paraphrase General Ripper, I do not avoid early March chases, Mandrake, but I do deny them my essence.

Monday, February 20, 2006

My flight was delayed by winter weather in various parts of the country, although Dallas stayed dry most of the weekend. This will be a short and unpolished post.

I skip the Denver convention every other year, and then when I go again, I wonder why I ever skip. There's something extremely cool about spending time with chaser friends without the stress of a current or upcoming chase, with a bar nearby, and a weekend to kill in a cool hotel. I enjoyed the talks, particularly those by Dr. Markowski, Dr. Gold, and Tim Marshall, but the best part of Denver is always the stuff outside the official itinerary.

My good friend Scott Blair attended the conference unwittingly when his flight FROM Denver to Little Rock, Arkansas was cancelled. Scott intended to visit his fiance' but the ice storm interefered and he wound up at the Radisson with the rest of us. Scott, Tony Laubach and I closed the bar with Dr. Doswell Friday night, which continues my streak of enjoying the icebreaker as much as anything (although we weren't actually IN the "icebreaker room" but at the bar in the lobby). I value the stories people like Dr. Doswell have to tell; he's achieved success in chasing, research meteorology, and as a professional educator, and he was generous enough to talk with us about nearly everything, even the Bears and Cowboys--haha.

One thing I did differently this year was avoid the marathon video session. I'm not a fan of the endless chaser video torture-fest. Several of us stayed for a preview of the new Tim Samaras disc and Jeff Wear's video (it was great that the organizers brought Jeff's parents to the event) then moved to Bill Coyle's room and, yes, we played chase videos, but the room wasn't dark and silence wasn't expected. We talked, drank beer, ate Doritos, admired Samaras's and Doug Keisling's latest discs, and had a good time.

There were a few wrinkles too. The power went out Friday, a problem rapidly dispatched by a room full of scientists, amateur radio operators, and a few engineers. Also a few oddballs tried to make mischief, but what would the chasing world be without them, right? Our room's heater didn't work Friday night, which we discovered around 2:45 AM *after* the long gabfest with Dr. Doswell. We moved to a room where the heater worked like a nuclear power plant.

While I was sitting in the Denver airport this evening waiting for the next delay announcement, I regretted the convention was over. I really did. Thanks for Roger Hill and Tim Samaras for helping make the winter pass a little faster.

Friday, February 17, 2006

Last night's and this morning's NAM runs backed off the lift regime and 850 RH values and decreased the precip forecasted for North Texas over the weekend. There is no point in my attempting a legitimate diagnosis (the only way to get a true *prognosis*) of the atmosphere using real data since when it comes to winter precip, I'm only skilled in looking at the pretty colors on the post-processed graphics.

Plus I think the model is probably underforecasting precip and I don't want to bolster that suspicion. Ignorance is bliss. Sign me up for that FOXNEWS brain implant.

Anyway, I'm off to Denver later this afternoon. Looking forward to the convention!

Thursday, February 16, 2006

The National Weather Service in Fort Worth issued a Winter Storm Watch for most of North Texas effective from tomorrow evening through Sunday night. The NAM and GFS both showed colder air spilling into the region and a greater depth to the airmass, raising the possibility of freezing rain and winter precipitation beginning Friday night and continuing intermittently through late Sunday.

This isn't the news I wanted. I don't like flying in bad weather--not even a little. I don't like driving on ice in North Texas, particularly at night (my flight lands at 9:00 PM Sunday). And the possibility of being stuck in Denver until Monday due to a flight cancellation isn't practical. I have to be back in Denton by Monday morning to teach.

Right now I'm still planning to attend the convention. I'm hoping the models will stop their continued cold-trending, however. If tonight and tomorrow morning's solutions look worse that the runs this morning that prompted the Winter Storm Watch, I'll have to reconsider.

Tuesday, February 14, 2006

Last chase season, the occasional crowds on 146.550 led to some undiplomatic exchanges between chasers. One afternoon, a station asked a question and was told, "Well, if you'll be quiet for a minute, I'm trying to tell you." This wasn't the only bumpy qso on the bustling band; several chasers were "stepped on" or talked over on multiple events.

The idea of using 146.550 as a default "chaser simplex" is useful when the density of antennas is reasonably low. In a massive chaser convergence, however, when chasers line the side of the road and vehicles are stacked three deep in the smallest turnouts and driveways, the ".55" becomes a weird cacophony of half-heard questions and interrupted answers. It's an interesting switch-board effect if you're not trying to communicate with anybody. But most operators are more than passive listeners and sooner or later somebody gets annoyed.

Last year, the friends I chase with and I agreed to a few alternative frequencies when .55 is busy. I learned yesterday that one of the frequencies we chose was not in compliance with the 'band plan' for simplex channels. I knew there were designated intervals for simplex, but out on the road last year none of us remembered what they were. Below I have reprinted a list of accepted simplex channels, divided by the .15 khz increment. There are plenty to choose from.

It's also a good idea for chasers in close quarters to use low power if the receiving stations are nearby. The best solution, of course, is to dial up an open channel when the number of stations and transmissions is impractical. Here's the list of available simplex per the band plan:

"Using these standardized 15-Khz splinter channels minimizes interference to other amateur radio operators. In the interest of promoting good Amateur Practice, Here is a list of those Frequencies.

146.52 National Simplex Calling Frequency

*** The frequency 146.400 MHz is used in some areas as a repeater input."

Wednesday, February 08, 2006

The atmosphere is co-operating with my commitment to avoid chasing in February. Recent medium range progs show no sign of spring or any spring-like intentions, with cold front after cold front driving into the Caribbean to hold moisture at sea. One thing veteran chasers note about particularly good chase days is that deep moisture is in place 24 hours in advance. This isn't a rule and there are many exceptions, but this seems to be a trend for outbreak-style, major events. On the other end of the spectrum is what our first reasonable chase day will probably look like in 2006: moisture barely returning to the target area in time for initiation, resulting in the sort of over-sheared, moisture-starved towers so common in February or early March. But the longer it takes for this to happen, the more tempting it is for long-hibernating chasers.

I also noticed from a glance of the SPC Events Index that the majority of my tornado days since 2000 have featured southwest flow aloft. All but two events I checked (and I didn't check them all) happened with upper-tropo flow from between 225° and 247.5°. This is a frequent pattern for tornadoes in the southern plains where I've logged the majority of my miles in that period. However it may also indicate that I either do not attempt other kinds of events of don't forecast (or chase) them very well if I do. Of course location is the dominant term here, I believe. My friend Mike Hollingshead, who often chases late spring or early summer in the northern plains, mentioned that about half his tornadoes may have occured in west or northwest flow regimes, based on his cursory exam of the same event list.

Another feature I noticed on the tornado days I checked was that 850mb flow backed between 50 and 70 degrees from the 12z maps to 0z. Of course the LLJ strengthens and responds to pressure falls like other wind fields, but the consistency of this pattern stood out. Winds at this level almost always increased during that time, but the increase in flow wasn't always as reliable or pronounced as the backing. 850mb lows by 0z were commonly located in eastern New Mexico, eastern Colorado, extreme western Kansas, or western Nebraska. No surprise there. None of this is really shocking, for that matter. It was just interesting to note the many similarities between setups, that yielded (usually) multiple, high-contrast tornadoes for me. A sort of informal, personal climatology.

Monday, February 06, 2006

Scott Currens conducted a damage survey from the tornado he witnessed on January 28th, located near the town of Fact, Kansas, ironically. Scott's images include the remarkable picture of a vortex mark on the ground indicating the start of the damage path, which he traced then through vegetation and trees that suffered what he estimated as approximately F1 damage.

Saturday, February 04, 2006

Here's another boring techno-entry as much for my own archiving as anything. Last night I configured Franson GPSGate on my new laptop. GPSGate is a small and inexpensive application that allows you to take a single GPS receiver signal and "split" it into multiple channels via the creation of virtual com ports. A user can funnel GPS data to several applications simultaneously with only one receiver. For example, you could send GPS info to Street Atlas, Threatnet (XM/Wx-Worx), and GRLevel3 all at the same time. Creating virtual com ports sounds complex, but GPSGate has about the simplest interface you'll ever see. I enthusiastically recommend the software. For use with a DeLorme EarthMate GPS receiver, however, there are a few tricks.

The problem is that GPSGate doesn't recognize the straight USB-style EarthMate signal. So you have to download a small executable from DeLorme which installs USB to serial drivers. The instructions for this are on a Franson support page here.

The executable is found on the DeLorme page here. Sometimes XP won't recognize the USB to serial drivers and you have to intervene manually with instructions from DeLorme here. I didn't have any problem with XP. Once I installed the drivers, XP recognized the EarthMate as "broadcasting" on Com 7, which was the info I needed to tell GPSGate where to look. (Be sure and set all baud rates to 4800). Once GPSGate finds the signal, the small icon turns green in the system tray and you're ready to split the signal via the virtual com ports. I don't remember how many virtual com ports one can create, but it's more than the stormchasing applications available that use GPS. I created two virtual com ports, 10 & 11, figuring those values would be out of the way of other devices. If I buy GRLevel3 this year, I'll add a third virtual com port.

Then, Street Atlas 2005 has some unique config requirements as well. Remember, SA2005 isn't taking data straight from the receiver now; you want it to look for one of these virtual com ports that GPSGate is creating. I set Street Atlas to look for Com Port 10, set the baud rate to 4800, and set the device type to"Garmin NMEA (w/WPT)" I have no idea why that's required, but if you set the device to DeLorme Earthmate, then Street Atlas somehow becomes very greedy and tries to eat GPSGate, freezing all signals and knocking GPSGate offline. The "Garmin NMEA (w/WPT)" device setting keeps it calm. This was the case on my last laptop and this new one also.

I haven't tested Threatnet or GRLevel3 (don't have the "owners version" of the latter yet) and I can't speak to those configs. I remember that Threatnet, at least, was easier to configure than Street Atlas since it doesn't have a wide range of device input possibilities. I remember adjusting the com port input value only. In my new setup, for example, I'll direct Threatnet to take input from com port 11 (the other virtual port). I'll post more when I test those settings.

Friday, February 03, 2006

I added a Google Adsense spot down at the bottom of the sidebar. If you don't scroll to the end of the "chaser blogs" link list, you won't see it. They only pay for click-throughs so by shoving it out of sight I probably defeat the purpose. I don't like websites crowded with ads, but it would be nice to recoup some of my web hosting expense. There were a lot of people reading this space last spring. I'm a little nervous about what advertisers will appear in that box, however, like the infamous chase tour group, TRADD. We'll see.

I intend to test my notebook computer this weekend and begin to debug the various GPS splitters and radar software and the like. I don't look forward to this on a new machine.

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