Archive for May, 2008

May 23rd quick outlook

There is no time to write a lot… but as I noticed from all models and especially latest RUC, today’s its going to be another HIGH risk day with major tornado outbreak likely again! Maps are even more impressive than they were for yesterday when first HIGH risk was in place. Extreme instability with SBCAPE over 5000 with great shear over it.

Our target will likely be a bit ENE of Garden City where we expect storm initiation and then rapid tornadic supercells development in this insane environment. SPC will likely upgrade from MDT into HIGH risk over west central KS in the next update.

Again, there are massive strong long-lived tornadoes expected as cyclic tornadic supercells will have all ingredients to build and maintain themselves…

This is our last chasing day this season and detailed reports, case studies, etc will follow in the next days when we come back home.

Cheers from the Dreamland!

May 22nd chase – tornadofest!!!

This is just quick report from today’s chasing… I am too tired to write a full report. But shortly this was the best chasing day in my life! SPC upgraded MDT to HIGH risk in the afternoon as numerous strong tornadic supercells were ongoing over central KS. We were chasing south and north of I70 around Wakeeney and closer cities.

We managed to see at least 6 tornadoes (or maybe even 7 with a possible brief tornado touchdown on the first supercell, but not sure about it for now) including one rapidly rotating multi-vortex wedge north of Hoxie! What could be better today? Absolutelly nothing! Structures were insane, tenths of rotating wall clouds and few tornadoes. As expected, this day ended up as a major tornado outbreak over KS! I will post just some pictures for now, while detailed chase account and more pictures will follow later…

First supercell north of Garden City…

A bit later and just before it may produced a brief touchdown…

New supercell south of Gove producing wall cloud…

Brief tornado touchdown north of Gove…which roped out soon, but funnel remained there…

Big tornado touched down from the same supercell as above, existing for about 10min…

Another view over this beauty…roped out soon after this shot…

Massive multi-vortex wedge tornado, several hundred meters wide, north of Hoxie… when we passed Hoxie the same supercell went through a cycle and impressive clear slot went over mesocyclone and soon produced massive wall which continued into large wedge coming onto the ground…

About 10-15min later…massive strong tornado still on the ground…

Later on it roped out…

Here we got two tornadoes at the same time, again from the same supercell just south of Dresden, but new cycle and mesocyclone…it was really dark and I got crappy photos, but still… visible cone and debris on the ground…tornado left of the town…

Tornado right of the town…

We then continued NEwards and another strong, wedge alike tornado, appeared in front of us for about 30s, it was very dark and we were in heavy rainfalls and winds in RFD… no photos from there, but we got it on the video.

Tomorrow is a new likely massive tornado day over KS/OK (might be another outbreak as well) and our last chase day this season. I am not sure if I’ll have time to update and write an outlook, but what I recall from models we might be chasing in almost the same spots again tomorrow and then driving all the way down to Dallas airport overnight.

Stay tuned for possible update tomorrow morning!

May 21st chase & tomorrow’s outlook

We had a nice marginal chase day today. We had a room in Colby, KS and first went west on Interstate I70 towards NE CO where our initial target was. We were targeting Fort Morgan towards Yuma. We stopped in Burlington where we checked the latest RUC model run and surface observations and the surface pressure system with three separate surface lows was deepening; one over SW WY, and two over west central CO and over SW CO. They were merging and moving into eastern CO. A dryline was siting from just east of Cheyenne extending southwards over near Fort Morgan towards Limon. A tongue of unstable airmass was slowly moving NNW from western KS into extreme NE CO towards the triple point. Surface dewpoints in SE WY were only in high 40s and in low 50s over western KS and as it was questionable that they will rise up to mid 50s towards SE WY and W NE, we decided to stay closer to the possible storm initiation along the dryline near Limon. Limon’s area is known by getting help for storm initiation a bit earlier than it would be usually expected as there are some orographic effect helping triggering the storms.

We first moved from Burlington towards Wray and when we turned west towards Yuma, we noticed few towers going up towards south. Wish we would have stayed in Burlington, but we still weren’t so far away from there. A look over the radar showed a nice cell poping up along I70 near Stratton and in town Eackley we turned south towards it. It was a dirty road, but we were able to drive easily about 30-40mi south where we came under the storm. It had some nice structure and was becoming supercellular soon, first LP supercell. It got severe warned and radar was showing not more than 1.5in hail markers. At one stage it also had a nice wall cloud and we observed few small funnel clouds. Short shower and some small, up to 1cm, hail hit us. We continued tracking this cell northwards back on the dirty road towards Eckley where supercell first split and then got organized again. A nice rain free base formed just above us and soon wall cloud appeared under the mesocyclone with several inflow bands. On the the western side of this split system, several rotating updrafts formed and at least two of them got LP supercell features. We then headed north of Eckley to track the closest supercell which unfortunatelly died soon.

We dropped south to Eckley again and several cell were on going more SSW of us. As we didn’t want to use dirty road again, we first went west to Yuma and then continued south towards Interstate I70. When we arrived somewhere in the middle, we were quite close to the first cell to our west, it had a massive shelf cloud already, pretty high based. We stopped a bit north of Joes to take some photos. As there was a new cell forming south of this one, we dropped more south of Kirk to have a better view over the whole shelf cloud and to wait for the next storm to come closer. The structure was actually pretty good, we also managed to capture some lightning strikes there, although they were not really frequent. Soon the southern cell arrived, it was more active with strikes, including CGs. An interesting feature formed over the reorganized cell we were observing before, it might have been a wall cloud for few minutes which soon turned into another shelf cloud heading NEwards with strong RFD in the back. There were also active flashes in that time.

A bit later storm hit us with some rainfalls, so we dropped south to Stratton and then went east on I70 to come in front of the rain as we wanted to try with some more lightning photos. Not much of a luck there, so we just continued eastwards into Goodland, KS where we booked a room to have a good sleep for tomorrow. I’ll post photos later, as there is absolutelly no time now.

So as regarding weather setup for tomorrow, it does look incredibly impressive with great potential for tornado outbreak over central KS! SPC has a MDT risk area with 15% area hatched for strong tornadoes and 45% area hatched for very large hail which is pretty impressive an dangerous on the other hand. Models have been showing this possible outbreak for tomorrow in the last few days already with very strong shear and extreme instability in place.

Severe weather convective outlook map from Storm Prediction Center…

A large upper-level low continues to effect Great Plains with a continuing development of an impresively strong surface low of around 985mb pressure centered over eastern CO by tomorrow afternoon and evening. Additional increase of winds and shear are expected. By the Friday 00z timeframe an intersection of dryline and warm front is expected to be near the CO/NE/KS triple border which will make an arc of warm and moist sector extending SEwards between the dryline (extending SSEwards into SW KS through west OK into central TX) and the warm front (extending from extreme SW NE along the NE/KS border into central MO. Dryline is expected to be mixing out eastwards during the afternoon, creating a strong surface winds convergence. Surface winds which are expected to be relatively strong, likely around 30-35kt sustained with gusts 60kt locally which will be much higher with storms inflow later. Some damage might be a result from these winds. There is left-exit of 250mb jet positioned over western KS by Friday 00z with 70-80kt of 500mb SSW winds! With around 45-50kts of SE 850mb winds this makes a very strong deep-layer shear of 60-80kt.

When warm front shifts northwards in the early afternoon, skies will be clearing out and a strong surface heating is expected across the warm/moist sector which will, along with the rapidly returning moisture into the mid 60s towards the NW KS and steepening lapse rates aloft, create a very unstable boundary layer airmass, which will then weaken the cap along the dryline convergence and storm initiation is expected by mid to late afternoon. Given the forecasted 3500+ J/kg SBCAPE and also 3000 J/kg of MLCAPE storm will rapidly become severe and most likely tornadic in this high shear environment. Very high numbers of SR helicity, SRH 0-1km of 300-400 and SRH 0-3km of above 500 m^2/s^2 are extremely favorable for strong (possibly) cyclic supercells capable of producing strong long-lived tornadoes and very large hail! First storms will likely form closer to the triple point and will quickly continue to form SEwards along/ahead of the dryline as cap weakens/erodes later across the warm sector. Given the strong ~50kt southerly mid-level winds storms will be moving pretty fast somehow from SSW to NNE directions. As the warm sector closer to the dryline/warm front intersection is pretty narrow, those supercells will go off the warm frontal boundary earlier and will weaken soon as they will come into non-favorable environment. However given the strong helicity values along the warm frontal boundary strong tornadoes are possible there for a short time before storms enter into the worse conditions. So according to this fact, higher chances for strong and long-lived tornadic supercells are more likely a bit more southwards along the dryline just south of I70, as they will have enough space and favorable environment to maintain themselves. There are still some questions regarding the storms coverage and SPC might even go out with an upgrade to HIGH risk if widespread tornadic supercells with strong tornadoes will become more likely across warm sector and not only along the dryline.

Here are just a few maps by model WRF by which my outlook was based on…

500mb winds…

850mb winds and theta-e…

Surface winds and dewpoints…

MLCAPE…

SRH 0-3km…

We will be targeting an area around Wakeeney as our initial target regarding latest WRF model and will probably shift southwards of I70 towards Ness City. Definately we will be watching the next models update, especially the morning RUC 12z run and will position ourselves into the best conditions.

Hopefully this is gonna be a big and long day for all of us out there! We do expect a massive chasers convergence in north/central KS tomorrow due to likely a major tornado outbreak in place there.

Wish us good luck and stay tuned for future updates!