TornadoVideos.net

Posted At: June 29, 2007 @ 12:26 AM

Posted By: Reed Timmer

A jet streak from a large upper trough approaching from the North Pacific will provide sufficient deep-layer wind shear for tornadic supercells over southern Alberta tomorrow (Friday, June 29).  Given southwesterly 700 mb flow at 30-40 knots, low-level shear will be sufficient for tornadoes, and with un-capped CAPE values of 2000+ J/kg, the possibility will exist for a few large tornadoes.  The WRF forecast 500 mb chart for tomorrow evening is shown above, with the area of highest tornado chances shaded in red.  The CAPE/CIN forecast for the same time is shown below.  Stay tuned for updates!

Posted At: June 28, 2007 @ 3:00 PM

Posted By: Reed Timmer

A cut-off low pressure system has been pummeling the Southern Plains through Missouri with extremely heavy rains and flash flooding.  10+ inches of rainfall in a 24 hour period has been reported over parts of Texas as the low center has been meandering aimlessly around western OK and northwest TX.  Interestingly, this system has been exhibiting tropical characteristics over the last few days, with relatively warm mid- and upper-levels, low-level feeder bands from the SSE, and striated upper-level, anticyclonic outflow.   Essentially, the only ingredient missing for explosive intensification of this tropical cyclone is the warm ocean surface.    The heavy rain appears to be consolidating into a SSW to NNE band from central OK to Wichita Falls, TX and south-southwestward, which is the same area that has been experiencing the heaviest rain from this system.  Shown below is the Frederick, OK radar from just before 3:00 pm CDT.

Accordingly, flash flood watches are in effect for most of central TX into MO, with several flash flood warnings in effect for the hardest hit areas.  These watches will likely continue for the next several days, until the tropical low can dissipate or get picked up by the westerlies.

Posted At: June 28, 2007 @ 11:33 AM

Posted By: Reed Timmer

Here are some reflectivity and storm-relative velocity images from Minot, ND from around the time of the tornadoes in Manitoba on June 23.  Note the textbook structure and huge hook echo on reflectivity: 

The higher reflectivities just on the north and northeast side of the inflow notch are where the huge hail was associated with this storm.  At around the time of this image, we were getting blasted by baseball to softball size hail with the core.

The velocity image below (green towards the radar to the south-southeast, red away) shows a long RFD structure and very strong couplet.  I was told by Matt Chatelain, who was saving these images for us, that the couplet exceeded 100 knots gate-to-gate. 


The rear-flank downdraft (RFD) associated with this tornadic supercell is shown in the velocity image below with the yellow arrows.  The RFD is a downdraft that wraps around the back side of the updraft and impinges on the mesocyclone at low-levels due to strong negative pressure perturbations at the interior of the circulation.  The RFD can be seen visually as the "clear-slot" which yields a tighter sub-mesocyclone-scale area of rotation above (relative to the storm motion) that can strengthen into a tornado. 

Posted At: June 26, 2007 @ 3:51 AM

Posted By: Reed Timmer

Posted At: June 25, 2007 @ 4:36 PM

Posted By: Reed Timmer

Initiation of supercells is possible over central ND over the next few hours as a mid-level jet streak moves over a very unstable airmass east of a well-defined cold front.  We will be monitoring satellite closely and will intercept any supercells that initiate.  Unfortunately, the GPS tracker will not be working because I am using a backup laptop!
The recent RUC model output is forecasting initiation of intense convection in extreme northeast North Dakota at the nose of the low-level jet.  We believe that instability and low-level shear will be maximized here.  The only problem will be chasing the storm into the densely forested northern MN area.  Here is the RUC accumulated precip forecast for 6 pm CDT:

Posted At: June 25, 2007 @ 2:12 AM

Posted By: Reed Timmer

Posted At: June 24, 2007 @ 12:17 AM

Posted By: Reed Timmer

Here is the video from extreme Southwest Manitoba...We were within 200 yards of the rapidly strengthening tornado as it was crossing the road!  We were getting blasted by mud and cornstalks...more to come very soon...we're currently in Brandon, Manitoba..This was one of the most incredible supercells I have ever seen.  Thankfully it remained over very rural areas.

Posted At: June 21, 2007 @ 7:06 PM

Posted By: Reed Timmer

TornadoVideos.net storm chasers will be heading to southern Saskatchewan to chase a tornado setup on Saturday.  We will be leaving in a few hours for a target of Regina-Saskatoon, where CAPE and shear will be maximized, and CIN minimized.  Here are some selected forecasts from the 12z WRF for 00z Sunday, with our target area highlighted in red:

 


 

Posted At: June 20, 2007 @ 4:32 PM

Posted By: Reed Timmer

Today is the 50 year anniversary of a deadly F-5 tornado that tore through parts of North Fargo, ND on June 20, 1957.  Surprisingly, this storm was very well documented via still photography.  The tornado touched down at around 7:30 pm CDT, and sadly killed 12 and destroyed 1300 homes.  Here is a picture of the tornado I found on one of the websites below.


Here is the website dedicated to this anniversary (this is where I found the photo).

http://www.in-forum.com/specials/1957tornado/

Here is a link to the NWS story of this tornado:

http://www.crh.noaa.gov/fgf/?n=fargojune1957f5

Posted At: June 20, 2007 @ 1:38 AM

Posted By: Reed Timmer

An intense mesoscale convective system (MCS) blew through Norman a few hours ago, producing 50+ mph wind gusts, downed trees, and power outages.  Just to the west of Norman in southwest OK, 60-70 mph wind gusts were reported with more widespread wind damage and flooding.  Here is a picture of a downed tree about 1/4 mile from my house!

Here is the central OK radar image from around 1:30 am CDT, about an hour after the line passed through Norman.  I was driving back from Dallas, and intercepted the shelf cloud about 20 miles south of Norman.  Unfortunately I did not have a camera with me, because the laminar striations above the gust front were some of the most prominent I have ever seen.

Posted At: June 19, 2007 @ 3:08 PM

Posted By: Reed Timmer

An environment of extreme instability and relatively weak wind shear will be in place over western KS this afternoon/evening, providing the likelihood for supercells.  A surface trough/boundary also streatches meridionally across western KS, providing the necessary surface convergence for supercell intiation.  Given EXTREME cape and a boundary, the potential exists for a weak tornado or two.  Here is the RUC analysis from 19z for 0-1 km EHI (energy-helicity index).

Based on pattern recognition, EHI values of ~2 are marginal for tornadoes...and today, most of this is contibuted by CAPE, since EHI is a composite index of CAPE and helicity.  The 0-1 km EHI here is based on 0-1 km CAPE and 0-1 km helicity.  We are huge fans of low-level parameters for tornado production, thus the EHI is one of the indices we are most interested in...in addition to 500m - 1 km winds and hodographs.



This southern supercell pictured here produced a supposed tornado about 10 miles W of Hoxie, KS...Based on the radar presentation at the time, this tornado is very believable.  Stay tuned for more updates throughout the afternoon.  I am still in Alabama, or I'd definitely be chasing this event. 

Posted At: June 19, 2007 @ 1:40 AM

Posted By: Reed Timmer

Here are some pictures of the flooding from Gainsville, TX yesterday from the slow-moving convection that moved over the area the night before.  Sadly, 5 fatalities have now been reported from this flash flooding, and hundreds of homes have been destroyed.  Trey said the water had gone down 4 feet when he took the pictures from its maximum depth. 

Posted At: June 18, 2007 @ 7:20 PM

Posted By: Reed Timmer

While visiting Mobile, AL, I decided to explore Dauphin Island, AL for sturdy structures that could serve as a shelter for us while chasing a potential future hurricane there.   The western part of the island was totally under-water during Katrina, and many of the homes there were totally destroyed.  Here are some pictures from this trip:

Heron/Crane on the Dauphin Island pier:


Sand Island, AL, just off the end of the Dauphin Island pier:

Sand Island, AL (above), is a large sand bar that is slowy drifting towards Dauphin Island.  A few years ago, this island could only be reached by boat or raft, but now the Dauphin Island pier stretches to the island!  A single powerful hurricane could eliminate this island entirely, however.  With a life jacket and bike helmet, this would be the perfect place to document a cat 5 hurricane!  If you wanted to be carried 30 miles inland by the storm surge.

A West Dauphin Island house that survied Hurricane Katrina:



West Dauphin Island neighborhood (under 10-15 feet of water during Katrina):


Some of these houses on the west side of Dauphin Island (above) are new since Katrina, and others actually survived the 15 foot storm surge and 100 mph wind gusts (second picture above is one such house that survived, hence the "Lucky Enough" sign).  A local chief meteorologist from Mobile actually rebuilt here 3 separate times after his house was completely destroyed by 3 different hurricanes.  Local officials recently constructed a massive sand berm on the Gulf of Mexico side of this neighborhood, in attempt to block future storm surges.  Many residents complain that this berm blocks their view of the water, and is useless against a devastating storm surge anyway...they are probably right, but the berm will at least protect their homes from minor to moderate surges from coastal lows and weak hurricanes.

New sand berm on Gulf of Mexico side of Dauphin Island:







Looking west along the Dauphin Island sand berm:


The sand berm above was constructed this year, but is not the first berm constructed here.  Previous similar sand berms on Dauphin Island were completely eroded during several tropical storm Iandfalls. 

There are several large hotels/resorts with massive concrete parking garages on the central part of Dauphin Island that would serve as "perfect" shelters for a potential hurricane chase here by TornadoVideos.net.  Still though, given the proximity to the shore, and the low elevation, intercepted a major hurricane on this barrier island would be extremely dangerous.   Hopefully though for the residents, this senario will not become a reality this season or during any future season for that matter.   Despite the relatively high probability for a landfall here, people still seem to rebuild in the same location where previous tropical storms and hurricanes caused total devastation.  I guess the desire to live near the shore far outweighs the potential loss that would be sustained during a tropical cyclone landfall. 

Posted At: June 18, 2007 @ 11:12 AM

Posted By: Reed Timmer

Twin Lakes, OK radar image from 11:08 am CDT

Major flooding has occurred with intense, slow-moving thunderstorms over portions of North Texas and southern Oklahoma last night.  Rainfall rates of over 3 inches per hour have been reported with these storms!  Sadly, two fatalities were reported with flash flooding in a mobile home park in Haltom City, TX last night, which is a suburb of Fort Worth.  Here is a zoomed-in map showing the flood watches and warnings over N TX and southeast OK, as well as the expiring tornado watch for the region (no tornadic activity was reported, however).  The large green dots show the counties with the tornado warnings.  This rain was initiated by the departing upper-low.

 

Posted At: June 17, 2007 @ 9:16 PM

Posted By: Reed Timmer

As the low-level jet intensifies and storms cross the slow-moving cold front into the warm sector, the threat for tornadoes will increase for the next few hours over eastern ND and northwest MN until storms become elevated above the nocturnal inversion.  However, there is a good chance that storms will congeal into an MCS before even having a chance to produce tornadoes.  
UPDATE:  The Fargo, ND radar image from around 9:20 pm CDT shows supercells developing along the cold front, with post-frontal supercells just northeast of Bismark as well.  The supercell that recently developed in northeast ND (see radar image below), will likely become tornadic very soon as it tracks rapidly northeastward within a very unstable airmass and intensifying LLJ.

Posted At: June 17, 2007 @ 5:33 PM

Posted By: Reed Timmer

Two tornado watches have been issued over central/eastern ND and northern MN for this afternoon/evening.  The capping inversion has been holding strong so far, but cold air aloft associated with a strong shortwave is now moving into the Northern Plains.  The low-level jet will begin to intensify soon, so any supercells will have increasing potential for tornadoes.

Posted At: June 17, 2007 @ 3:38 PM

Posted By: Reed Timmer

The Storm Prediction Center has issued a slight risk for severe weather over the extreme north-central U.S. near the Canadian Border today.  The tornado threat appears minimal since the best low-level wind shear is well east of the instability axis and the eventual storms.  However, I have not had a chance to look at things in detail since I am out of town...So I'll just post the SPC Day 1 tornado probabilities for now:

If anyone has had a chance to look at the models for today in detail, please post your thoughts!!

Posted At: June 16, 2007 @ 3:37 PM

Posted By: Reed Timmer

Persistent ESE flow over the high plains of SD and MT has resulted in substantial moisture advection and destabilization over central MT just east of the Rocky Mountains.  Consequently, 0-1 km EHI values have increased to 3+ over this area (see 19 UTC RUC analysis below), and storms have begun to initiate over the higher terrian of western MT. 


Consequently, the SPC has issued a tornado watch over this area, since the storms over the higher terrain will likely become supercellular as the move east into the more unstable and sheared environment of central MT.  A large, persistent supercell has been occurring over the last few hours in extreme northern MT near the Canadian Border.  A few severe straight-line wind reports have occurred along the path of this storm!

Posted At: June 16, 2007 @ 11:21 AM

Posted By: Reed Timmer

Strong upslope flow at low-levels will prevail today over northwest SD and central/eastern MT, providing lift for the initiation of supercells this afternoon/evening.  A strong shortwave moving through the northern Rockies will also provide the wind shear necessary for rotating storms.  The instability will be extreme, especially over western SD along the northward-advancing warm front (see RUC forecast for 00z below).
 
The purple shading in the CAPE map above right represents 5000+ CAPE!  The low-level jet is also forecast to be out of the ESE at around 30 kts at 00z, with the strongest 850 mb flow south of the warm front in a capped, stable environment.  The best area for supercells today is from the warm frontal zone in western SD northwestward into central MT, with 0-1 km EHIs (energy-helicity index - combined measure of 0-1 km CAPE and helicity) maximized in southeast MT to northwest SD, where the cap is forecast to be non-existent by 6 pm MDT.  The directional shear will be huge over this area, with low-level winds out of the ESE and substantially veering with height.  I am currently out of town in Mobile, AL, so unfortunately I will not be able to chase this setup.  Stay tuned for updates!!

Posted At: June 15, 2007 @ 1:36 AM

Posted By: Reed Timmer

Over 5 inches of rain has been reported over parts of Oklahoma during the last 24 hours, as slow-moving thunderstorms continue to drop heavy rainfall as of late Thursday night.  Given that the ground is already saturated, and river levels are very high, numerous flood warnings have been issued for several Oklahoma Counties.

The upper low that has been responsible for these slow-moving thunderstorms has been stagnant over western OK for the past 24-48 hours, and is expected to SLOWLY drift southward into North Texas over the next several days.  The models are forecasting more heavy rain over Oklahoma and N Texas for at least the next 2-3 days over this same region, so the flooding will only become worse.  Here is a 24-hr accumulated precipitation map from TLX, OK:
 

Posted At: June 14, 2007 @ 3:45 AM

Posted By: Reed Timmer

Here are some pictures and video from the Geary, OK supercell yesterday (June 13, 2007) evening.  The storm had incredible structure, with a well-developed clear slot and rapid cascading motion on the west side of the wall cloud.  A very low-hanging cone-shaped funnel developed at around 8:45-9:00 pm just south of Greenfield, OK

Posted At: June 13, 2007 @ 6:48 PM

Posted By: Reed Timmer

A supercell has anchored on an outflow boundary in north-central OK, and has produced a few "elephant-trunk" tornadoes!  People in Major Co, OK should be taking cover.  The tornado is now likely rain-wrapped, but was highly visible from the news helicopters in the region:

Posted At: June 13, 2007 @ 2:32 PM

Posted By: Reed Timmer

Despite major flow weaknesses between 700 and 500 mb, strong instability and sufficient low-level shear (after 7 pm CDT) will yield the possibility for supercells late this afternoon and evening over western OK.  The tornado threat is minimal, however, because storms will likely congeal into an MCS before the low-level jet develops this evening.  Here are the RUC forecast CAPE (for 7 pm CDT) and 850 mb flow (for 10 pm CDT) -- the orange color in the CAPE map represents 3500-4000 J/kg.

 
Accordingly, the SPC has issued a severe thunderstorm watch for southwest KS and western OK, in effect until 10 pm CDT.  If the cells can remain discrete and supercellular after 7:00 pm CDT, the tornado threat will increase dramatically, and the severe thunderstorm watch will likely be upgraded to a tornado watch.  We'll be monitoring this situation closely, and will likely fly west if the low-level jet develops earlier than forecast, or if cells can remain discrete into the evening.  Stay tuned for updates!

Posted At: June 13, 2007 @ 3:15 AM

Posted By: Reed Timmer

Here is the completed chase log video from the May 22, 2007 tornadic supercells in northwest KS.  This supercell exhibited some of the best structure we have ever seen in 9 years of storm chasing!  Several still photos and frame captures are shown in the chase logs section (which is a huge work in progress!)

Posted At: June 12, 2007 @ 6:14 PM

Posted By: Reed Timmer

Watches

Killarney - Pilot Mound - Manitou
5:54 PM CDT Tuesday 12 June 2007
Tornado watch for
Killarney - Pilot Mound - Manitou continued

Conditions are favourable for the development of severe thunderstorms with the potential to produce tornadoes.

These severe thunderstorms will also have the potential to produce very large hail..Flooding rain..Deadly lightning and powerful winds. Use this time to secure outdoor property and to ensure family members and co-workers are prepared to take action should the severe weather approach.

Environment Canada continues to monitor the situation closely for severe thunderstorm development and possible tornado warnings. Please continue to monitor your local media or weatheradio for further updates.

Should severe weather approach or if you feel threatened do not wait for warnings to take action..Take shelter immediately.

Should you spot a funnel cloud or tornado...And only if it is safe to do so...You can call 1-800-239-0484 to report your sighting. Please note this phone number is for reporting severe weather only.
At 5:45 PM CDT weather radar indicates a line of rapidly building thunderstorms from Killarney through Carberry and st laurent. Quarter sized hail has been reported just north of MacGregor. These thunderstorms are expected to track slowly to the northeast. As the storms track slowly heavy rainfall with amounts of 50 to 80 mm and can produce local flooding.



A hot and humid airmass has provided the necessary ingredients for development of severe thunderstorms late this afternoon and tonight over much of southern Manitoba. Some thunderstorms have developed along the trans-Canada highway between Brandon and Portage la Prairie. Some of these storms have the potential to produce tornadoes. Thunderstorms will move east of the Red River late this evening.

Posted At: June 12, 2007 @ 2:55 AM

Posted By: Reed Timmer

 

 
A strong shortwave and associated jet streak will pass over southern Manitoba later this afternoon/evening, providing sufficient deep-layer shear for supercells.  Strong instability and a 30-40 kt low-level jet will also be in place over this region east of a cold front forecast to stretch along the western Manitoba border by late afternoon.  With 30+ knot flow at all levels above 850 mb, and good directional shear, the possibility exists for a few long-track tornadoes over southern Manitoba.  Unfortunately, I will not be able to chase this setup, but will be monitoring the situation continuously throughout this afternoon.  Stay tuned for updates!

Posted At: June 11, 2007 @ 9:39 PM

Posted By: Reed Timmer

I found this picture of the Divide Co., ND tornado from the KFYR-Bismark website.  This picture was taken by Jerry Walter of Noonan, ND,  and shows the tornado as it was 10-12 miles south of Crosby, ND.  You can see that the cloud bases were EXTREMELY high today (6-11-07) in northwest ND!

Posted At: June 11, 2007 @ 6:41 PM

Posted By: Reed Timmer

Supercells have initiated along a cold front in southern Saskatchewan and northwest North Dakota, producing 1 brief tornado in Divide County, ND at 5:25 pm CDT.  The tornado reports in Saskatchewan are unknown at this time, but several storms have exhibited strong rotation on radar there.  Here is the Minot radar reflectivity image as of 6:40 pm CDT.

While brief, weak tornadoes are likely from these storms, the low-level wind fields are not quite conducive for long-track tornadoes today, because of a general weakness in flow magnitude from 700 mb and below.  However, good turning in the flow with height from the surface to 850 mb will provide the necessary low-level shear for brief tornadoes.  If the low-level jet can get going before these storms congeal into an MCS, the possibility for long-track tornadoes will increase dramatically with these cells.  Here is the VAD wind profile from Minot from just before 7 pm CDT. 

Posted At: June 10, 2007 @ 5:35 PM

Posted By: Reed Timmer

Several tornado warnings have been issued this afternoon for supercells in southwest Missouri.  An outflow boundary has been initiating convection over this area today, with deep-layer shear locally enhanced by a jet streak associated with a mesoscale convective system to the northeast.  Here is a radar image as of 5:20 pm CDT from Springfield, MO.

Posted At: June 10, 2007 @ 1:47 PM

Posted By: Reed Timmer

A severe thunderstorm watch was just issued for central/eastern OK and western AR this afternoon and evening until 9:00 pm CDT, with very large hail and strong straight-line winds the main threats.  Hail up to 2.5 inches in diameter is possible with the strongest storms.  There may be enough shear for some brief supercells...I'll definitely be chasing any storms close to Norman that could produce some good lightning shots.

Posted At: June 9, 2007 @ 2:49 AM

Posted By: Reed Timmer

257 severe straight-line wind reports occurred today with a huge squall line that stretched from Ontario to Florida, with no tornado reports!  This was a classic case with unidirectional flow with height and strong linear forcing along an intense cold front. 

Here are some of the more significant reports from yesterday:

• 4.25" hail 3 miles south of Akron, OH at 3:15 pm EDT
• 36" diameter tree blown down in Alliance, OH at 4:35 pm EDT
• 85 mph winds reported in Erie, PA at 4:46 pm EDT
• Person injured in Holmes Beach, FL by wind-drive golf ball size hail to the face!  The report stated they received below their right eye.

Posted At: June 8, 2007 @ 5:46 PM

Posted By: Reed Timmer

Severe thunderstorm watches are currently in effect from New York to eastern TN, with a strong squall line moving through this area.  The main threat will be very strong straight line winds and large hail, but an isolated brief tornado is still not out of the question.  There have already been nearly 70 severe wind reports as of 7:00 pm EDT, and this number will likely double before the night is over.

Posted At: June 7, 2007 @ 3:22 AM

Posted By: Reed Timmer

Unfortunately, we are going to have to play KS/OK on this one due to time constraints! 

Posted At: June 7, 2007 @ 3:09 AM

Posted By: Reed Timmer

Here are some pictures of the tornado we saw about 20 miles WNW of Martin, SD from one of the most photogenic supercells we have ever seen!  This supercell developed just east of the surface low in a highly-sheared environment with ~25 degree dewpoint spreads.  We should have been closer! 

**UPDATED:  CONTRAST ENHANCED!!**

Posted At: June 6, 2007 @ 9:56 AM

Posted By: Reed Timmer

The tornado threat today is highly conditional today in northern NE and SD, with the strong cap likely preventing initiation across the rest of the Plains.  The RUC model mixes the dryline further east than any of the other models, but also produces mid 60+ dewpoints in the warm sector by 7 pm, which is consistent with the WRF and GFS.  These dewpoints appear to be produced from downward mixing, evapotranspiration, and pooling at the nose of the LLJ.  We are skeptical of the models producing these large dewpoints, but if this verifies, a few significant tornadic supercells will likely occur over northern NE and southern SD.  The WRF also forecasts convective initiation over this area shortly after 7 pm.  Here is the RUC forecast CAPE for 7 pm...note the strong cap in place despite the high dewpoints.  If the dryline does not mix as far east as the RUC model predicts, the cap should be weaker, as shown in the WRF.

Another feature favoring initiation over northern NE and southern NE is the approach of the left-exit region of the upper jet streak, which should provide the lift necessary for initiation, if the mid 60 dewpoints verify.  Despite the potential limitation to this severe weather setup, the SPC has maintained a moderate risk over the aforementioned region, with the threat of strong tornadoes.  Here is the 8:00 am SPC outlook map:

Our current plan is to head north to Valentine, NE or Pierre, SD and monitor the eastward mixing of the dryline.  The tracker should be working great.  Stay tuned for updates.

Posted At: June 4, 2007 @ 1:47 PM

Posted By: Reed Timmer

Extreme instability and very strong wind shear will be in place across the Central and Northern Plains on Wednesday ahead of a massive trough forecast to push across the northern U.S. mid-week.  The cap will likely be too strong for initiation from southern NE southward, but explosive development of long-track tornadic supercells is expected from central NE northward through all of eastern SD by late Wednesday afternoon.  Selected WRF forecast plots are displayed below for 7 pm CDT Wednesday:

WIND FIELDS:

 

 

THERMODYNAMICS and WIND SHEAR:

 
As seen above, a DEEP 977 mb surface low is forecast to develop over central South Dakota by 7 pm CDT Wednesday, with a 40-50 knot diurnal low-level jet (850 mb analysis upper right) over the warm sector by Wednesday afternoon.  This LLJ will only intensify as the afternoon/evening progresses, resulting in huge low-level shear values.  The left-exit region of the upper jet (300 mb panel) will be moving over southern SD Wednesday afternoon/evening, providing supplemental upper support for initiation.  However, we still expect supercells to develop further south along the intense dryline into northern NE as well.  CAPE values of 4000-6000 J/kg will also develop across the entire Plains, with a weak to non-existent cap over central NE and SD by Wed afternoon/evening.

Given the extreme low-level and deep-layer shear values, and massive instability forecast to be in place ahead of this strong upper trough, a major tornado outbreak is possible over central and eastern Nebraska and South Dakota on Wednesday.  Accordingly, the Storm Prediction Center has issued a MODERATE risk in their Day 3 outlook over the same region discussed above.  We would not be surprised if the SPC upgrades their outlook to a High Risk by the Day 1 time frame late tomorrow night.  We will be departing for this region tomorrow night, and will stay the night somewhere in northern NE or southern SD, so that we will have time to analyze new model output and observations so that we make the correct forecast.  Stay tuned for more updates....Hopefully, I will be buying a new internet system for our vehicle in time for Wednesday so that the tracker will be fully operational.  

Posted At: June 2, 2007 @ 10:08 PM

Posted By: Reed Timmer

I've been looking for a picture of the damaging Grandview-Muscatine, IA tornado from last Friday, 6/01, and finally found one on a blog.  This stovepipe tornado produced EF-3 damage in Grandview, and was on the ground for nearly 20 minutes.  The NWS damage assessment can be found at the following URL:  http://www.crh.noaa.gov/crnews/display_story.php?wfo=dvn&storyid=8403&source=0

Posted At: June 1, 2007 @ 5:19 AM

Posted By: Reed Timmer

DETAILED CHASE LOG REPORT COMING SOON!