Tornado risks increase substantially across Eastern Colorado for thunderstorms expected later Thursday. In addition, very large hail will be possible. The risk of severe weather has increased in parts of the Denver metro area - higher risks than previous days. Today's risks shouldn't be taken lightly. It is rare for parts of Denver to be in a 5% tornado risk, which the east and south sides are today. > Potential significant weather day across the plains today, with severe storms capable of pr

There's a risk of damaging thunderstorms today, July 4th, including the highest risk of tornadoes in the country will be along the Front Range and Plains, including Denver, Fort Collins, and Cheyenne. The threat for storms continues throughout the day in several 'waves' of storms that may try to move through. The above image is the environment where tornadoes are most likely to form, but other areas carry a lower threat, not a zero threat. Look at the overall threat of damaging thunderstorms,

A tornado watch has been issued for parts of Northeastern Colorado including the Denver metro area and Colorado Springs due to the increased threat that afternoon and evening thunderstorms will be strong enough to produce tornadoes in addition to large hail. The official watch area is as follows with the threat lasting through Wednesday evening: The storms began to fire up after the sky cleared a bit and the instability increased with the heating of the day. > T’storms firing up over Douglas

Tornadoes, wind and hail are all possible threats from thunderstorms that develop Wednesday afternoon through the evening. The highest concern is within the yellow shaded counties shown here. > The NWS Storm Prediction Center has issued a * Tornado Watch for portions of  Northeastern and extreme eastern Colorado Western Kansas Southwestern Nebraska * Effective this Wednesday afternoon and Thursday morning from 440 PM until 200 AM CDT. ...THIS IS A PARTICULARLY DANGEROUS SITUATION... * Pri

As we head into the first weekend of June, we should be mindful of the severe weather chances that cover both days. As you've noticed, temperatures have warmed the past few days, and Denver has returned to the 70s which last this weekend. The warmth is despite a cold front, a weak one, to move through Saturday that will act as a focal point for some thunderstorms throughout the weekend. Saturday Cold front grazes the area and will trigger and steer a few thunderstorms from midday through the

A storm system will strengthen while it moves through the region Friday. This system will spark several thunderstorms, and the environment will provide lots of energy for thunderstorms to be potentially damaging. The SPC outlook shows enhanced risk areas in Nebraska and Texas, and slight risk areas from the Dakotas and Iowa south into Texas. Here is a snapshot of the 3km NAM late Friday afternoon showing multiple discrete thunderstorms in an environment where damaging hail, wind, and tornadoe

Memorial Day's severe weather produced very little damage despite numerous reports of hail and 14 different tornadoes. Since 1991, Colorado has averaged 53 tornadoes per year; we took quite a 'chunk' out of that average number in a single afternoon with those 14 across Fort Morgan, Kit Carson, Washington, and Weld Counties. Here's a link to the full NWS report released late Tuesday.

As part of development at the Esri R&D Center in DC , we've been working on new ways to visualize large amounts of data on a map. Large datasets present several challenges. Simply how to render that much data is one issue, but also how do we visualize large datasets when throwing millions of a points on a map no longer makes any sense to the end user. We want to look at a map of data and understand something about that data immediately. Weather offers an incredible variety

Yesterday's severe weather outbreak turned deadly in Nebraska as several strong tornadoes touch down across the state. The two confirmed fatalities are the first since 2004 for the state, as tornadoes ripped through small communities Monday afternoon. Among the tornadoes that touched down yesterday were two rare "twin tornadoes". These two tornadoes were responsible for much of the damage in northeast Nebraska Monday afternoon as they pushed through the small town of Pilger, NE. Take a look at

There was a lot of buzz yesterday about the active tornado season Colorado is experiencing, and while it has been active, tornadoes in June are very common for Colorado. Climatologically June is the peak for tornado season in Colorado, with an average of 11.42 tornadoes statewide during the month from 1950 to 2013. Yesterday there were eight tornado reports across the state (not all confirmed) as another active day of severe weather kicked off across the region. Not coincidentally, northeast Co

The Storm Prediction Center will likely issue a Tornado Watch for Denver and much of eastern Colorado for this afternoon. Storms are already starting to fire west of Denver, with coverage and intensity increasing through the early afternoon hours. The greatest threat with these storms will be heavy rain, hail, and damaging wind, though conditions will favor a few tornadoes with stronger embedded super cells during early initiation. All of the high resolution models are showing strong storms

Storms Friday spun up early in the afternoon pushing well east of the metro area by 3pm. There were six PRELIMINARY tornado reports in Colorado yesterday, with at least 2 confirmed tornadoes. One was in southern Colorado near Trinidad, the other south of Roggen, Colorado along I-76. Some damage reported with both, but minimal overall. > Another picture of the tornado that touched down near Trinidad, Colorado, via @KRDONC13 pic.twitter.com/3DcjCx2ToQ [http://t.c

Storms continue tonight and into tomorrow across southeast Severe weather continues across the southeast tonight after another round of awful severe weather. According to the Storm Prediction Center (SPC) there have been 44 preliminary tornado reports today. This means several of these reports could be duplicates, and or later determined not be be tornadoes by the NWS. That number may grow as there are still many active tornado warnings at this hour. Here's a look at where the line of storms ar

Last week I published a piece about tornadoes on the United States Tornadoes blog , and it was also a featured article in The Atlantic . With severe weather season right around the corner for Colorado, I thought I would share it here as well. Colorado is home to some of the highest tor

Last week United States Tornadoes put together a post on how "tornadoes progress across the United States throughout the year". This inspired me to dig through the data (every confirmed tornado since 1950) and experiment with different ways to visualize that data. While the original intent was to show the progression across the U.S. throughout the year in a different way than US Tors -- that idea morphed a bit as I started playing with client-side aggregation and s

The large tornado outbreak Sunday that ripped through the upper midwest has claimed six lives and injured hundreds across five states. The Storm Prediction Center fielded hundreds of reports of tornadoes Sunday, and through filtering and cross checking have narrowed down to 82 initial tornado reports as of this morning. These numbers are preliminary (duplicates likely), and will be adjusted over the days and weeks to come. Nevertheless, this was certainly a very large tornado outbreak for Novemb

The Worst Tornado Outbreaks in U.S. History The eight worst tornado outbreaks in the United States have accounted for nearly $40 billion dollars in damage, are responsible for 17,525 injuries, and tragically over 1,500 fatalities. I wanted to share today a project I have been working on that tells the story of these incredible severe weather outbreaks. Tornado Days , built with the D3.js Javascript library, is an experimental way of expl