LP Supercell NW Texas

Hey chasers!

Here is a link to the first video (albeit hastily made) from our chase near Mabelle, TX on Monday this past week, 720p HD available. Keith and I sat on this bad boy for at least 3 hours. A few times, it had a nasty hook on it, but LCL's were too high (temps in mid 90s). Still all in all a great storm to get the lawn chairs out and just enjoy. As always, thanks to Dan and Croix for helping us out. I think we chose the right storm that day... enjoy!

Also, here are a few pictures from that day that are stills in the video. This thing seriously looked like a volcanic ash cloud a few times once it went beast mode. Awesome.

Brief Recap of May 24 Outbreak.

The top image is from initiation and the bottom is from the morning. 

Couple of keys to the setup. First, the morning convection cluster limited the warm fronts progression north. Second it left a broad area of subsidence as highlighted by the red X. Also, due to this subsidence there was no development of shallow cumulus, which lead to afternoon highs in the region from the upper 80s to low 90s. This left dew point depressions of in excess of 30F where the yellow X is located. Why was it so favorable south? No subsidence, shallow cu field limiting day time heating (circled in yellow) and the further south than expected warm front/triple point which increased helicity in central Ok. The top image shows initiation, which, with a bulging dryline seems to change the low level shear, ie surface winds to have more of an easterly component, which only increases the lowest few km directional shear. 

Really think this is the reason why central Ok was hit hard and north along the KS/OK border was spared for the most part. 

Convergence

chasing update aos 455

Current location: Wichita, KS (12:08 PM)

Current destination: KS/OK border in less than 30 min or so

Reasoning: shortwave off rockies heading for KS/OK border. Things should start getting interesting when this moves east into a region full of CAPE and shear (especially near warm front as expected)

Over/under on tornadoes: my guess is 55 reports, 20 tornadoes

OCD says 62 reports, 8 tors

Helicity

AOS 455 chasing day 1 briefing

What up team,

I am typing this from my phone, so it will be short and sweet. Today the one and only aos 455 storm chasing van (including blog co authors OCD and Helicity) are on our way to Wichita, KS to do some dryline chasing in the south tomorrow. Along the way, and for fun, we will be checking out both the MCS and any cells that develop in front of it in southern IL. Our goal is more aimed at getting cool pics rather than tornadoes, as any cells that do develop may be too far east by the time we get to southern IL. We will keep you posted. The good news is that the shear is visible in the sky, and we like our chances albeit small.

Peace out,

Hel-to the-icity

Today's Chase Update

Hello Chasers,

We have decided to make our play for this afternoon, and opted for the southern most area (highlighted per our prevoius post). Reasons for this:

1) models under-estimated the amount of instability in the area along the dryline - mixed layer capes around 4-5k everywhere up and down the dryline.

2) Convective mode - seems to be less-discrete cell oriented towards the northern Go Zone, probably due to the enhanced stationary-frontal forcing in that vicinity.

3) If it blows up into a squall-line of rotating supercells, we want to be on the southern-most bit of convection.

We plan to cross the Red River ~18z (near Wichita Falls) and hang out around the vicinity of Vernon, Texas. Should be there by 19z... in time for initiation.

Update to follow this evening, post-chase. Happy chasing!

-Triple Point

Tornadoes from this afternoon in West Central Missouri

Hey Chasers,

Today has been a ridiculous severe weather day with tornadoes being reported from The Twin Cities all the way south to the dryline in West Texas. I was able to get out this afternoon and head east 35miles on I-70 and caught three quick tornadoes on a line of cells that just kept reforming to the southwest and tracking over my general location. It was the perfect setup to get some quick touchdowns in a short period of time. which was the Waverly-Concordia-Higginsville, MO area. Here are the three tornado videos:










Fresh off the presses, ENJOY

Dan aka Squall Line

Videos from Chase 5-21-2011 Supercell NE of Topeka

Hey Chasers,

Just wanted to share the video I got from that insane storm yesterday in Northeast Kansas. Croix was my base support (Thanks as always). I got on a Supercell that formed sw of Topeka and then tracked it (Supercell went into Beast Mode) as it moved ene up through the Perry Lake area and eventually in Oskaloosa, KS and the long video finishes with a nighttime time lapse just outside of Levanworth, KS. This cell put down several shorter lived tornadoes, which you can see in the reports.

Video Compilation:


Shorter HD video:


Time to get out there and do it again today!!! :)

Enjoy,

Dan aka Squall Line

Dryline (monster) Chasing - Monday / Tuesday

Hello blog posters and followers!

First off - sorry for the non-professional mspaint-edited photos...

Here's the DL - myself and Keith are flying into Tulsa, OK on Sunday night, and plan on dryline chasing on Monday and Tuesday in the Oklahoma / Texas / Kansas region. After taking a look at 12z and 00z models for today, here's what we have found...

Monday:

Upper level dynamics - not looking like a 'hell yes' situation, but good enough for supporting surface based convection in the western oklahoma region, or northwest texas. Skipping through all the traditional in-depth analysis, which we all know everyone on this blog is capable of... here is the EHI map for Monday evening (00z) in that region:
We highlight two dryline bulges right off the bat - one in northwest Oklahoma, and one in northwest Tay-has. To accompany this - here's a forecast sounding for the southern-most bulge (21z) ...
Aside from the super-adiabatic lapse rates at the surface, this southern most area is what we are leaning towards right now for our day on Monday. Of course, that could all change, but at this time it looks like about equally good upper level support for the entire region on Monday evening, but much better moisture return in the Wichita Falls vicinity, reaching slightly higher instability and just as good lower level directional shear profiles. Either way, we could end up in both of those highlight areas on Monday pending further model analysis. Should support supercell storms easily, with chaseable storm vectors.

Tuesday:

Dryline advances East. The actual dryline becomes 'muddy' overnight and into the early morning on Tuesday due to the forecast surface circulation, which wraps the moisture around the backside of the feature. However, during the afternoon the dryline looks to become more distinct as the developing surface low pulls dry air in behind it and acts to punch the dryline / dryslot in the northeast direction. Here, we focus on one location - near Enid, OK. The low level helicity is enhanced by the surface low, warm front, and advancing dryline. This looks like a non-traditional dryline bulge, but indeed is in the triple point area of the entire system for Tuesday.

Pictured: 18z sfc dewpoints.
Which evolves to this by 00z Wednesday:

Along with this, here's a forecast sounding for 00z just southwest of Enid, OK. Right in the middle of the highlighted circle on the above image...


To summarize: Go-Zones... Monday - either Northwest Oklahoma, or Northwest Texas (definitely leaning towards Texas play as of right now). Tuesday - Central Oklahoma.

Haha... Of course, if we sound like fools... please, somebody, anybody... say something!

But in all seriousness, if anyone has other thoughts on these two days, let me know. Hope to see other people out there as well... 608-448-1766 if you're looking to reach us either day. Hooray for chase-cations! As always, I appreciated both Dan and Croix's opinions on this preliminary forecast yesterday while we were deciding on booking our flights ;)

Big uncertainty and potential

Greetings chasers,

I wanted to quickly bring attention to the forecast for severe weather over the next few days & next week. We are currently beginning to setup a hefty Rex block with a strong cut-off upper-level anticyclone sprawling over Canada and a trough positioned off the Front Range. This kind of pattern is sure to provide fun forecasting as well as the occasional bust. There's a cut-off low that's slowly trekking E / NE giving the potential of severe weather and that will continue in the next few days. My hunch is that all the severe weather target maps for the next few days will be transitioned westward to account for the unanticipated "stronger than anticipated" ridge...

For next week, I wanted to point out why the models have difficulty in high amplitude, stationary regimes (such as the Rex block). The following shows the mean 500mb height contours of today's 12Z GFS ensembles valid next Monday (or maybe Tuesday). The shading represents the spread (or standard deviation) from the mean state, which is just the average of all the ensembles. Note that the spreads among the ensembles are fairly low west of the Miss. River (< 40m, on par or slightly higher than your typical day to day noise).

Now let's fast forward just 24 hours later and look at the same plot of 500mb heights.

Wham! Clearly there's action off the west coast! The spread among the ensembles is now > 100m, just west of the west coast. But, if we look closely, we can see why ... this is the typical diffluence region of a Rex block, and the model must take the strong jet streak (and associated vorticity) either to the north "over top" of the ridge axis or to the south into the developing cut-off. Yesterday, the models were taking most of the dynamics northward. Today, they're split, which explains the bullseyes in spread. Some of the ensembles, like the operational GFS itself is taking quite a bit of action to the south, which in additional to the dryline's 4000 cape may make things fun next week.....

Dima

Severe Weather Southern Plains 5/11/2011:

Hey Chasers,

It's been a slow start to the month of May especially after that kind of April. Historically and statistcally May is the most active tornado month during the year and it looks like tomorrow will be this month's first shot at an outbreak. SPC has already issued a Moderate Risk for tomorrow and rightfully so. I actually agree to a large part with their forecast discussion and think they have done a very nice job highlighting the synoptic setup and mesoscale setup. If you're curious to read more you should head to www.spc.noaa.gov and click two-day outlook. So lets get right down to the point brief overview covering highlights and "The Go Zone"



Strong negatively tilted upper level trough exiting the four corners region. Broad area of strong upper level diffluence (250-500mb) across TX stove pipe, OK panhandle, western KS. Interesting subtropical jet feature ahead of main shortwave trough (upper level pattern looking similar to 4/14/11 though shifted 200 miles farther west, spc touches on this). Mid level flow from SW, advecting strong EML from Mexican Rockies over southern plains. At sfc, developing lee side heat low with attendant warm front/cP cold front. Surface flow is S/SE off the gulf and large area of > 60s Tds across Central/Southern Plains and Midwest. Very well defined dryline extending North from West Texas north/northeast through central KS. Moderate upper level forcing, teamed with developing sfc low, and dry line will set the stage for tomorrows action.

The Go Zone:
SPC has its highest probabilites in a zone from west of Wichita, KS south through West Central OK to around the Red River Valley for severe storms (depicted on map with blue and red zones). While I agree with this large area focused to the East of the dryline, I will elect to put my "Go Zone" for the northern (red portion) for tomorrow. 12 model guidance is suggesting elevated convection will begin early afternoon farther to the north in Central NE and NorthCentral KS closer to the warm front. As afternoon temperatures climb signifcantly farther south in KS/OK/TX. The dryline is expected to begin mixing out with moist BL to the east. SFC convection should occur later in the afternoon along/just ahead of the dryline bulge (sfc forcing). Here backed flow ahead of the sfc low and moderate 0-6km bulk shear will be maximized. Mixed layer cape should be around 2,000 J/kg and even greater as you head south towards central OK and into the Red River Valley. Veering profiles with height and backed sfc flow (above) should yield discrete rotating supercells capable of tornadoes. Main concerns with tomorrow are large dewpoint depressions (Temperatures ahead of dryline in warm sector look to reach 80s and 90s). Very strong downdrafts and wet bulb profiles are indicative of very large hail. Also, the strength of upper level forcing and mid level shear does not look as impressive as earlier systems. Storms will be slow movers (15-30kts) and could seem some classic LP dryline monsters.

Since it looks as though there will be a lull after tomorrow and wednsday, I'm thinking about heading out and trying to verify my forecast above. It's close and should be a good show!

Fearless Fantasy Forecast: o/u 18 tornado reports (probably only 4 actual tors, :]), 50 hail reports, 50 wind reports

Happy Hunting,

Dan aka Squall Line

Chase-cation

Hello Everyone,

I just wanted to post a heads-up for the end of this month... myself and a co-worker have a 5 day span of days dedicated to chasing. These dates are May 26-30th. If anyone is interested in joining us, please let me know. As of right now, we have just two people guaranteed (Croix may or may not join us pending the UW chase class's plans) and are looking for a one or two more to potentially split costs, etc for driving and hotels. We plan to go wherever is necessary, and leaving as early on the first day as we can. Of course, the schedule is tentative on severe weather that week. Let's hope the 'severe wx cock block' breaks down by then (which, if you buy into the long range GFS, it looks to break down around May 23 or 24th... ish).

Omega Block: The Proverbial Severe Weather "Cock Block"

Hey Chasers,

All is quiet severe weather wise for the next day or two. Following that there should be several intersting tough dryline forecast type chase days capped off with a decent upper level system that will affect the Central Plains late Wednsday (isolated tornado potential). Unfortunately after that, it seems all the rumors are true for an Omega block pattern to take shape across the Nations heartland. See the two images below





I did a quick outline to emphasize the "omega" shape that is clearly evident in the upper level pattern. What does this mean for severe weather? Read the title again to get the vulgar interpretation of this pattern. I agree with Dima that all should be pretty quite severe weather wise while this pattern holds (at least as far as large outbreaks are concerned). The two positives chase wise though are: 1.) This omega block pattern looks to break up around the last week in May (just in time for storm chasing class to begin) 2.) Despite the lack of favorable upper level support, there should be some really challenging but fun dryline forecasts with isolated tornado potential.

For those of you who aren't too familiar with dryline chasing stay tuned as I am going to try and do a few "Go Zone" forecasts dedicated only to the dryline. They are traditionally Low Risk/High Reward kind of days. Maybe I or someone else can do a quick dryline chasing tutorial beforehand highlighting the dryline (of course), dryline bulges, upslope flow, thermal heat lows, monster cape, low shear, weak upper level dynamics, meso-scale features that induce low level helicity, storm propagation tendancies, and the sexiest Supercell of them all: the LP Supercell.

These kinds of chase days have large bust potential but if storms do fire and you happen to catch one that produces a "tor" it's a real treat.

Sorry Dima, couldn't stand to look at that shameless promotion of an absolutely crappy excuse for a video game anymore, lol...

Let the Dryline Extravaganza Begin!!!

Dan aka Squall Line

In case the omega block sets up

and there's no severe weather anywhere, fear not ... I just found that Sony made this video game a few years ago: