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PROGRAM END: TWISTEX Field operations

As of today, TWISTEX operations have concluded operations for the year.

The crew had one last trip last Friday/Saturday (June 25, 26) where they intercepted a rain-wrapped tornado that wasn’t visible near Courtland, Minnesota on 25 June.

TWISTEX had a very successful 2010 with several in-situ deployments and numerous mobile mesonet datasets collected.  Some in-site hail data was also collected.

The new 450 pound in-situ instrument was deployed once in the path of a developing EF4 tornado near Bowdle, South Dakota on June 22.  We’ve collected the first-ever wind speed data at two different heights (.7 and 2 meters).

Several abstracts have been submitted for approval to be presented at the upcoming Severe Local Storm Conference to be held the week of October 11-15 of this year as a result of TWISTEX operations.  Topics include:

‘Recent In Situ and Very Close Proximity Tornado Observations (Karstens, et. al.).’

‘Surface Observations of the Rear-Flank Downdraft Evolution Associated with a Violent Tornado near Bowdle, SD on 22 May 2010(Finley, et. al.).’

‘Surface Observations of the Rear-Flank Downdraft Evolution Associated with the Aurora, NE Tornado of 17 June 2009 (Lee, et. al.).’

‘Wind Measurements Within a Tornado Core (Samaras, et. al).’

We wish to thank all of the TWISTEX participants for their tireless efforts as we logged nearly 28,000 miles traveling from Montana to Arkansas-from southern Texas to Minnesota from the middle of April until the end of June.  Crews had to endure hardships of being away from their families, and having to deal with hotels and food of varying qualities on the road.

With five to six vehicles within the TWISTEX armada, there was not one safety/traffic incident the entire 11 weeks being on the road.

Everybody’s efforts have been rewarded with some of the richest datasets ever collected from Supercells and tornado cores/environments to date.

I also wish to thank all of the supporters of TWISTEX both in funding and vehicle support hardware.  Without all of your support, the TWISTEX research mission would not have been possible.

TWISTEX investigators are currently planning TWISTEX 2011 for next season with hopes to have mobile Doppler RADAR aboard.  RADAR is the research tool that TWISTEX needs to help provide kinematic descriptions of tornadoes and supercells.

Continued improvements to current tornado in-situ technology are also planned for more accurate wind and pressure measurements in the future.

In a few months, my attention will turn towards lightning research, and a similar email dissemination will begin around the first of August.

Please let me know if you wish to be REMOVED from the lightning research list.

Until next year!

Tim Samaras

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TWISTEX Field operations for June 18, 2010

Currently in Minneapolis/St. Paul

Yesterday:

A frustrating day for part of the TWISTEX group. A flat tire in Lemmon, South Dakota yesterday morning delayed our departure to the tri-border area of South Dakota, North Dakota and Minnesota where the triple point of a pre-frontal trough, a cold front, and a warm front come together.

Fortunately, part of the TWISTEX group (M1, M2) were ahead of us and were able to witness numerous tornadoes including the wedge tornado that eventually caused significant damage in Wadena, Minnesota.

We (Probe, M3) were 10 minutes late, but was able to witness the RFD (with rain-wrapped tornado inside) move over the Wadena area from the southwest. On the southwest side of the RFD, a smaller sattelite circulation/tornado was observed going through the south part of Wadena, where stunned residents were outside trying to asses the damage. We (M3, Probe) stopped to let law enforcement know of the pending situation while in town, as nobody was focussed on the sky at that point.

Drove through the western part of the township only minutes after the tornado passed through and met up with the TIV group (Tornado Intercept Vehicle). We assisted to help extract an injury (Marcus mentioned possible broken pelvis, possible back injuries) from a severely damaged house, and loaded into a waiting ambulance. After that-myself, Carl Young, and son Paul went house to house looking for people needing assistance. Extensive damage was found in the main damage path including vehicles lofted and thrown 10s of meters. Observed significant damage to the local high school-which looks like a total loss. A school bus was smashed to half it’s size. Several rail cars were derailed, as well as an unknown steel building or grain bin being tossed several blocks and smashed on several houses. Based on our observations–probably EF3 damage, perhaps more pending a more detailed NWS survey of the vehicles that might have been lofted and thrown.

Once the town had enough emergency workers on site, group left to pursue another tornado warned storm to the distant north east that we failed to keep up with.

Strongly mixed emotions prevail with our group this morning, as TWISTEX could not totally operate on this storm, due to Probe being only 10-15 minutes late. We halted the chase (letting the tornadic storm drift off to the northeast) so that we can assist the hard hit area of Wadena. Spending time searching for victims puts into perspective on why TWISTEX is so driven to understand these powerful storms.

Today:

Looks like a reasonable play in north central/northeast Iowa today along the cold front as extreme CAPE values reach nearly 5000 J/Kg. Wind profiles aren’t perfect, but should be adequate for very large hail and possible tornadoes. If the windfield can remain backed (RUC shows a small meso-low in northeast Kansas), a strong tornado is possible. Big unknown today is how the current convective line will affect mid-late afternoon storm initiation. Model data suggests that renewed convection should initiate by 22z.

Future:

Chances of operations may continue through early next week as the last piece of energy passes through the midwest. Variances in the model data precludes specific targets, but it appears that operations are possible in Nebraska and South Dakota.

After Wednesday, the model data suggests that the summertime ridge will settle in, thus its quite possible that TWISTEX may terminate by the end of next week.

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TWISTEX Field operations for June 15, 2010

Currently in Norman, Oklahoma

June 13:

Team intercepted a long lived tornado at very close range north of Booker, Texas in the Oklahoma panhandle. Tornado was moving too fast towards us for deployment of instruments, and the path was mostly off the east-west road we were on. TWISTEX had two mobile mesonets to the immediate east of the tornado, and two mesonets to the west collecting data from both sides. Observed another tornado 7 miles away near Slapout, Oklahoma

Forecast:

Looks like two more days of operations are likely Wednesday and Thursday. Strong mid level flow emerges into the plains on Wednesday from Montana through western Nebraska.

On Thursday, the mid level wave pushes hard to the east providing a very strong environment for supercells and tornadoes from Manitoba through Minnesota and Iowa. Mid level flow along with a very powerful low level jet across a broad region of the northern plains will create very favorable hodographs that will favor strong supercell development.

It appears that after Thursday, operations will likely go down for an extended period due to zonal flow fo several days through the weekend.

Denver team plans to drive to Denver today, and will depart for the Dakotas/Nebraska early Wednesday morning.

M1/M2–let us know of your participation status for Wednesday–and will discuss tentative targets for tomorrow afternoon.

All participting teams–please do bring your passport, as there is a chance that we might be crossing the border into Canada on Thursday.

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TWISTEX Field operations for June12, 2010

Currently in Goodland, KS

June 10:

Team intercepted tornadic supercell near Last Chance, Colorado (we were too late to see the tornadoes–they touched down in a roadless area anyways). Followed the storm to the Colorado border where the storm struggled to produce any more tornadoes. Stayed overnight in Goodland, Kansas

June 11:

Drove to Limon, Colorado where the team eventually intercepted a large supercell coming out of Simla, Colorado. Storm briefly produced baseball hail where several high-speed images were collected from falling hailstones impacting the plate (need to review yet). Followed the storm eastward down I-70 where team members witnessed several ’spinups’ along the way, but no significant tornadoes reported. Stayed overnight in Goodland, Kansas.

Today:

Cut-off low is centered over New Mexico, and a cold front will push through most of western Kansas into the Texas panhandle where the front (hopefully) stalls. A short span of easterly/southeasterly surface winds, with 30-40 knot mid level winds should provide a reasonable environment for supercells and very large hail. Tornadoes are also possible across the Texas panhandle northwest of Amarillo.

Crew will depart around 8:30 for the northern Texas panhandle for possible early initiation around 20z.

Future:

Chance of severe storms on Sunday, as the cold front stalls across the Texas panhandle. At the moment, it appears that the chances of tornadoes will be less than Saturday, but given the fact that the team will be in place in the panhandle already, we’ll give it a shot.

After Sunday, it appears that the chances drop significantly, and its quite possible that operations will briefly end until late in the week when the next wave emerges on the plains Thursday.

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TWISTEX Field operations for June 10, 2010

Currently in Lakewood, CO

June 9:

Intercepted severe storm as it initiated about 20 miles southwest of Torrington, Wyoming. Several attempts at tornado genesis were witnessed as strong RFD winds continue to wrap into updraft base, but failed. Followed the storm into Scottsbluff, Nebraska, where the storm died. Stayed in Scottsbluff for the evening

Forecast:

Surface low is forecast to deepen in Colorado, and in response-modest upslope flow develops across northeast Colorado, southwest Nebraska, and southeast Wyoming. A disturbance is expected to pass through the area by mid evening, thus thunderstorms are expected to develop across the Colorado/Wyoming front range, and rapidly become severe as they move off into the eastern plains. A low level jet is also expected to develop by mid-late evening, and will aid in the development of tornadic supercells especially after 6 PM. Limiting factor are the warm mid level temperatures-but with the expected short wave, thunderstorm initiation shouldn’t be a problem(?)

Preliminary target is Julesburg, CO–or we may choose to stay near the I-80/I-76 junction to give us mobility to either adjust to Colorado or remain in Nebraska (perhaps McCook?) as the day progresses. Not an easy forecast.

Current parameters could come together for a big day.

Future:

Low continues to dig south, and will likely ‘cut off’ by the weekend. The speed and progression of the cut-off low is difficult to predict, but it appears that we’ll have opportunities for field deployments through the weekend. By Wednesday, the system finally ejects east, thus the severe threat lessens considerably, thus TWISTEX will likely be down for a period of time beginning the middle of next week.

However–current model variation suggests that the above outlook will change.

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TWISTEX Field operations for June 9, 2010

Currently in Lakewood, CO

June 7:

Intercepted two supercells from Torrington, Wyoming to Scottsbluff, Nebraska. The western most cell seemed to be the one most likely to produce a tornado. Intercepted the supercell when it was north of Scottsbluff, and when it was tornado warned (actually produced a brief tornado). We stayed north in hopes of getting into the path of the 70+ dBZ core for in-situ hail measurements. Did encounter some large hail (maximum size was 1.5″). Returned to Denver for the evening

Forecast:

Zonal flow continues over the high plains where some modest upslope remains (although the surface winds are more southeasterly by 0z). Moisture improves significantly by early afternoon with 60+ dewpoints against the Colorado/Wyoming front range with RUC forcast CAPE of 3,000 J/Kg by late afternoon. Thunderstorms should initiate by ~22z in the higher terrain, and (hopefully) move off into western Nebraska panhandle by 0-1z.

Future:

Opportunities for higher end severe should be much better tomorrow as modest southwesterly flow finally returns across the western Dakotas and Nebraska. At this point, it appears that south central South Dakota or western Nebraska could be the play tomorrow with strong instability and reasonable winds, although it seems the low level jet that develops later in the evening is displaced a bit too far to the east.

After Thursday, the NAM suggests that the low digs far south into New Mexico by Saturday morning. Wild variances between model fordcast products brings low confidence in any attempts at a long-range planning except that we’ll have southwest flow, and good instability in the plains–and operations should (hopefully) continue through early next week.

Teams should ‘target’ Valentine, NE for planning purposes, with a more defined target decided tomorrow morning.

Denver teams will be departing ~12 Noon today for the cheyenne ridge area for storm initiation by 22z. Plan on a multi-day mission that could exceed 4+ days.

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TWISTEX Field operations for June 7, 2010

Currently in Lakewood, CO

Forecast:

Zonal-slight southwesterly flow aloft with easterly upslope surface winds across the front range of northern Colorado should provide a reasonable environment for supercells that should generate large hail and possible tornadoes. Excellent cape values are suggested by both the NAM and the RUC to be ~4,000 J/KG along with some capping-that should prevent thunderstorms from initiating until mid-late afternoon.

Biggest issue today is the cap–hopefully, thunderstorms should initiate over the higher terrain and move off into a pretty good environment late this evening.

Denver teams plan to return back to Denver for the evening, but should be prepared to overnight in case we get too far out.

Future:

Appears that the next system should begin to ‘dig’ on Wednesday/Thursday–possibly providing fielding opportunities from Thursday through Sunday. Model data is a bit inconsistent on timing and location, but it appears that the general area will be the northern plains–at least to start.

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TWISTEX Field operations for June 3, 2010

Currently down

May 31:

Drove to Wichita for an engagement on Tuesday from Denver–taking the long route through southeast Colorado on the chance of intercepting some hail–but managed to watch a very photogenic tornado 3 miles south of Campo, Colorado.  The tornado  lasted 15+ minutes, but the circulation persisted for 45+ minutes and produced 2-3 more tornadoes as the supercell and tornado drifted southeast into the Oklahoma panhandle. Certainly a nice surprise for a low expectation day.  We followed the system until dusk, then drove to Wichita for the evening.

Forecast:

Currently under westerly flow aloft that seldom provides significant weather.  This current flow patter will persist through next week, and although there are chances that some disturbances will ‘ride’ along the westerly flow, chances of any operations are slim.  We’ll be looking for these slight possibilities through next week.

A very quiet June so far.

Will provide further updates within the next day or so.

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TWISTEX Field operations for May 31, 2010

Currently in Lakewood, Colorado

Forecast:

Westerly winds aloft are suggested by the 12z model run and with surface winds veering near the surface will provide an environment for some hail across southeast Nebraska and western Iowa. Conditions are not favorable for good tornado development–thus TWISTEX will remain down through tomorrow. One vehicle will be in south central Kansas tomorrow–and may opt to find a good hailstorm in the late afternoon on Tuesday.

Future:

Forecast looking bleak beginning on Wednesday through a better part of a week as a ridge begins to build in the area on Thursday. Clusters of thunderstorms are forecast on Wednesday in eastern Kansas and Missouri that may have a very slight chance of a tornado threat under westerly winds aloft.

There may be a chance for limited operations on Wednesday if conditions warrant. The issue is that the cost of getting vehicles out for a single day event that is not significant may outweigh the need of a full mission.

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TWISTEX Field operations for May 29, 2010

Currently in Spearfish, South Dakota

Yesterday:

Targeted several areas where conditions were supportive of supercells. One area was to the east of Dickinson, North Dakota, and the other area was to the southeast of Buffalo, South Dakota. Unfortunately, the capping layer proved to be too strong, thus no thunderstorms developed in either area before dark.

Forecast:

Less than excited about the forecast area today. A cold front will plunge across the Dakotas and northern Nebraska by mid evening forcing lift along its axis, and will move away from the stronger winds aloft resulting in a squall line. Squall lines are not good tornado producers, thus TWISTEX will target the end of the squall line that pushes up against the cap where the best low level turning is present due to the developing surface low in northeast Colorado.

Confidence isn’t high for tornado production this afternoon, teams are planning to return home after the chase today (Denver, Colorado and Ames, Iowa).

Future:

Slight chance of severe for Tuesday/Wednesday, but after mid week–it appears that the chance of significant severe is low as a ridge builds into the area.

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