Not going to write much because I am exhausted…but here is a gorgeous rainbow I captured from our Neighborhood Weather Network camera in Woodland Park after a storm moved through that area last night (Saturday).

A Macroburst (large scale…long lasting) producing thunderstorm moved in to SW and central Colorado Springs on Friday afternoon. I was tracking the outflow boundary associated with this gust front on LIVE HD DOPPLER through the event. Note that over time the size of the outflow boundary that I’ve highlighted in dashed blue gets larger as the wind field spreads out. If you go into the archives of our blog from May 2009 and scroll to the bottom, you can read about how Microbursts form. The process is the same, but wheras a microburst occurs over a small area for a short period of time, you see this macroburst affected many in the Springs Metro.

I guess there is a benefit to filling in on the morning show. It’s hard to realize there is anything good about waking up at 2:30am, but filling in for Marty these past couple of days, I have seen some amazing sunrises!
I know Marty is always sharing Neighborhood Weather Network sunrise pictures with you, and now it’s my turn!

This is the time of year when my job gets a bit mundane.  I mean every morning it’s clear or partly cloudy and nice with a chance for storms later.  I might not get in on the excitement too often this time of year, but I sure get to watch some really pretty sunrises, today was no exeption.  Enjoy the images!

…turn the sprinkler on!  At least that’s the request I came home to at lunch the other day.  My son and his cousin were finishing up lunch when I got home, and it didn’t take much time for the request to come along!  I don’t usually water the lawn in the middle of the day, but this seemed like a good cause

It’s likely that you’ve seen some of the commercials on another station over the last 5 or 6 months, and if you have, you know that a lot has been made about 5 minutes. A relatively short length of time, but in the case of a severe weather situation, it could seem like an eternity, especially if someone is witholding, or doesn’t have access to what could be some life saving information. I guess in that sense you’ve probably raised your eyebrows once or twice when you’ve seen the commercials as it has been made to appear that there is a big discrepancy in the weather information being delivered to television.

Whether it is a lack of understanding or a concious decision to mis-lead, I’ll leave that up to you. I’m going tell you what is really happening with the National Weather Service Radar (NEXRAD) when severe storms threaten our area. Storms exist in the atmosphere in 3 dimensions. They are so many miles wide, so many miles long and so many miles tall (think of it as the x,y and z axis from your high school geometry class). When thunderstorms are present, NEXRAD scans at many different angles to the horizon, or what we call “tilts”. The image below depicts how increasing angles of the radar beam can give a 3 dimensional picture of the atmosphere.

In severe weather, or scan mode 21 (below), NEXRAD sends out and receives radar signals at 9 different angles to the horizon. The scheme begins by doing a 360 degree scan at half a degree above the horizon, it then performs a 360 degree scan at 1.5 degrees above the horizon and repeats this process by ending with a 360 degree scan at 19.5 degrees above the horizon line. This produces a volumetric or 3D picture of the atmosphere in a process that takes 5 minutes to complete. Each of these tilts arrives independently in our Live HD Doppler as they occur, we just don’t typically show you these individual scans as storms start to not really look like storms at the higher tilts and the reflectivity doesn’t represent precipitation that is falling from the storm.

So why do we need all of these tilts? By scanning in 3 dimensions we are able to ascertain depth of rotation (knowing that a storm has a tight circulation from its base through a 20,000′ layer makes you more concerned about a potential tornado), hail core positions and height within an updraft before they fall out the storm, intense updraft and storm height (typically the higher the storm top the greater chance of severe weather occuring). In contrast, the image below shows how a television station owned radar operates. It only scans one level. Scanning like this gives us very little to no information about the severity and potentially life-threatening imapact a storm may have.

In the image on the right, a bounded weak echo region (BWER- depicted below right in what would be the space between the high heel and the rest of the shoe) will show a tornado’s location when a hook echo is present. Note the difference in seeing the entire storm structure in 3D versus one slice on the left. Just under the 13 in our logo, you can see an overshooting top, also an indication of enhanced storm strength. In the single slice, you have no idea that one is present.

In the image above,  our sister ABC station in Houston, TX uses 3D NEXRAD imagery to show the intensity of rain bands in Hurricane Dolly as it came on shore near Houston. Note under the abc13 logo how a band that looks pretty intense at the surface (typical radar view you see on TV looks intense), but the slice shows that precipitation isn’t as intense higher up, so rainfall rates are weakening within that band. Below, you see a 3D radar image that allows us to see the condensation funnel of an actual tornado that moved through Moore, OK in a significant tornado outbreak that occured on May 3rd, 1999. A 2D radar image at one tilt just doesn’t give us all of the information, storms don’t exist in 2D.

Do you want the whole story or just a slice of it? You decide.

Not as impressive as yesterday’s tornadoes, but nice nonetheless…

I must say, it’s an honor to be a guest blogger on the KRDO WX blog. Matt, Marty, Stacy, and Josh provide some the best weather coverage I’ve seen since my days growing up in Kansas. A bit about myself…I’m a Kansas “kid” who grew up on a farm where weather determined our livelihood, making or breaking a crop in any given year. I maintain this interest, now in CO, as my in-laws farm on the plains of Kit Carson county in eastern Colorado. The interest in weather peaked in college, and I’ve continued my education constantly by studying the weather, particularly thunderstorms, as an on-going hobby. I chase a bit on my own in addition to participating with the El Paso county ARES Skywarn group, providing important “ground truth” and reports to our NWS Pueblo office through amateur radio. I was asked to blog specifically about my chase on 6/11, last week, during the storm which started in Pueblo county, and continued well past the KS border.

My mornings start with a check of the SPC outlooks, model interpretations, surface observations, satellite interpretations, and sounding evaluations. On this day, the front range east through the plains were “painted” in a slight risk for thunderstorms. Following the late morning updates, I decided to take the afternoon off from work to chase storms. A short-wave disturbance was forecast to interact with the moisture and shear already in place across the plains. I was headed to Falcon with road options to go NE to Limon or south to Hwy 50. As I ventured east a decision was made to stay along Hwy 94 to see what the original cells had to show as they “popped” SW of Colorado Springs. These storms eventually went outflow dominant after producing a good quantity of pea-sized hail. The decision was made to head south to intercept a cell Tstorm warned around the Pueblo area.

I chose a paved road which happened to pass by the NWS Pueblo Doppler radar. After snapping numerous pictures of the cell, I ventured south to verify the NWS warning with 1.5” hail which caused me to retreat back north! I relayed the report via ham radio since cell service was non-existent in this area. Once this cell passed I became a bit “snap-happy” with the camera with the storm backlit showing rainbows up against the structure. Soon the cell was tornado warned, and I found myself playing catch up to see the rotation.

I ventured east on Hwy 50 through a number of small towns before catching up with the storm to see a lowering wall cloud and significant rotation. I caught up to it near Swink where the sirens were going off. I followed it through La Junta on to Las Animas, both of which had sirens sounding. This is an eerie sound no matter how many times it occurs while chasing!

Along the way I was passed by vehicles which were part of the Vortex2 project, so I knew I was in the right place to observe severe weather! I observed numerous wall clouds, large hail, and circulation not more than ¼ mile from my position along the way! I eventually called off the chase outside Las Animas as it was apparent I’d have a LONG drive back home.

All in all, it was a “successful” chase, helping the NWS verify their warnings, and having documented an array of severe weather along the way. Storm chasing is not about seeing a tornado every time out, at least not to me. It’s about enjoying one of the most spectacular shows put on by Mother Nature, assisting in keeping public safe, and documenting severe weather events to help educate the public.

I hope you’ve enjoyed my blog entry, and I look forward to adding to the coverage when I am able to do so. Weather is not an exact science, but it IS the most discussed topic amongst everyday people! We are exiting a very active pattern in CO, and as we exit the most active month in CO for sever weather, I hope you take the time to purchase a weather radio, pay attention the forecasts, and prepare your families for the next time severe weather strikes our neck of the woods.

Its been an active week or so in Colorado in terms of severe weather and it continued as many of you saw the storm going up from Colorado Springs on Monday during the noon hour. Several updrafts are visible on this image Marty grabbed from the Falcon NWN. The most mature updraft is on the right and the convective pushes get younger as you head to the west (left) in this picture. Note how crisp the clouds are, an indication of intense convection and updraft strength.

Underneath this updraft the storm was showing many features of being a supercell thunderstorm. A supercell storm consists of a rotating meso-cyclone (small scale area of low pressure) with separated updrafts and downdrafts that allow the storm to exist for usually several hours or more. Most of our severe weather, especially the strongest tornadoes (EF4-EF5), are produced by supercells. Some of the low storm structure taken in this photo by Leroy Mills as the storm was developing the tornado that destroyed several buildings to the west of Elbert include several inflow features (Beaver’s Tail and Feeder Band), the rain free base with a wall cloud hanging from it and a clear slot just to the left of the wall cloud. This feature is associated with the rear flank downdraft.

The rain cooled air in the rear flank downdraft (RFD) rotates around the backside of the storm and undercuts the warm and moist flow of air feeding in to the supercell. When the conditions are right, the RFD air is able to be ingested back up in to the rotating updraft of the storm and is a key component of tornado formation. Its important to note that not all RFDs will produce tornadoes, some will spill out away from the storm and choke off the updraft as it cuts off the inflow. Occasionally new updrafts will form downstream, but many times the RFD will weaken and kill the storm.

Helps on a Monday morning to see views like this…