Northern Colorado Weather

June 13, 2011 Report

Pat Darrow — Tue, 14 Jun 2011 16:25:39 +0000

Today was definitely one of those “I’m bored and need to get out” kind of days. Thunderstorms were forecasted for northeast Colorado, southeast Wyoming and southwest NE. In fact, SPC had been maintaining a consistent slight risk for the area the past couple of days. I began looking at the numerical models and mesoanalysis data and decided that while storm chances were pretty good, they weren’t great for severe stuff. I decided to hold off making any chase plans until early afternoon. In the meantime, chaser convergence was already being realized as the Colorado chasers along with many others began trekking to their target areas by late morning. On release of the 1630Z outlook for SPC, and looking over current surface data and local AFD’s, it became apparent I needed to make a decision.

Now, the interesting thing about the “better area” was the CAP in place and would that break to allow storms to go up. The easterly flow (upslope) started bringing better moisture a little earlier than expected, with a “dry line” of sort setting up in east central Colorado, I was not convinced the “better area” was where SPC outlined it. However, it appeared most chasers settled on initial targets in the northeast corner of the state and as expected, a MD was issued for that area at about 1pm. By 2pm MDT, I took one last look at things. Nothing was really going yet but the potential for some quality garden shower chasing was there. So, I left Loveland with an initial target of Hoyt, CO. My thinking was pretty simple: I didn’t want to spend a whole lot of time and gas on uncertain outcomes and, given this is Colorado and the parameters in place, I figured if nothing else, we always get storms off the foothills near Denver that follow I-76 northeast. Hoyt put me in a great spot if I needed to adjust north or south, east or west. After a few errands, by 3:30pm, I was in place. A quick look at the satellite imagery and more importantly, the sky, made me feel good about my initial target.

By this time, a storm was blowing up near Limon as I was watching a cell trying to get its act together just southwest of my location. Several chasers were on the Limon storm. What was funny was to watch all the chasers that initially picked northeast Colorado and even the panhandle of Nebraska, start racing south toward Limon. By 4:30pm, the Limon cell had been severe warned and the cell I was watching was getting more impressive.
Given the fact that a chaser convergence was going to take place on the Limon cell, I chose to stick with my storm. For the next couple of hours, I followed the storm until it merged with the Limon cell and became more of a MCS event than anything near Ft. Morgan. I never could find any significant hail in my storm and the rain and lightning were not that great. But, it did have some serious winds.
Besides structure, I also got some pics of gustnadoes southwest of Ft. Morgan. No video as there was nothing really to tape.

After watching the cells merge and continue northeast as a line, I called it a day. On my way back to Loveland, I stopped and got a pic of the backside of the line as it hugged the Colorado/Nebraska border. I also got a pic of a new cell forming over Denver that eventually would get severe warned.

June 8, 2011 Report

Pat Darrow — Fri, 10 Jun 2011 13:58:16 +0000

This was one of those typical June days in Colorado where SPC issues the “2% Slight Risk” outlook for Colorado. Essentially, it meant there were upslope conditions (east-southeasterly winds) and while we don’t think anything will happen, it could. However, the more interesting (and rarer) aspect of this day is that the slight and 2% tor prob were situated right over the foothills of northern Colorado. SPC maintained this outlook through their 01Z/09 issuance. The convergence was expected to take place against the foothills where better moisture was located. Instability was weak but it is Colorado so you got to have the tor prob included. If storms became severe, they would be rain and hail makers more than anything else and most likely late evening/night activity.

I had prior commitments and based on my experience with these “setups”, it was not worth it to cancel those. I noted from blogs and tweets that a lot of chasers were going to be out in the area given the way this year has gone and the chronic SDS they all seem to suffer. Anyway, the day proceeded as expected with storms showing up but not overly impressive; especially, to those wanting more extreme weather. By 4:30pm MDT, satellite was showing some Cb building off the mountains. While the cloud layer next to the foothills was pathetic, by 5:30pm, I saw towers going up just south and east of Loveland.

I headed out from Loveland a little after dark with my goal to get into lightning and hail (again, I had no confidence in rotating storms in this environment). At about 10:10pm, NWS Boulder issued a severe t-storm warning for the area. Mostly due to the 1″ hail and some strong winds. I spent the next couple of hours playing in the lightning, wind and hail. I saw hail on the ground in Ft. Collins (with hail fog which is always cool) and some minor street flooding. Never could find the bigger hail core. Lightning was intense with most of it being of the cc (cloud-to-cloud) variety. Every now and then, some would try to make it to the ground. All in all, not a bad little venture away from the house for some garden shower chasing. Had some unexpected camera issues so pics of the hail, hail fog and such did not come out very well. Did grab some dashcam video though. It can be watched here.

June 7, 2011 Flooding

Pat Darrow — Wed, 08 Jun 2011 02:47:47 +0000

It’s been nearly a week since alerts were issued regarding the possible flooding that may occur in our area in the upcoming days. After a few days of below normal temps with extensive cloud cover, Loveland hit 90F on June 2. A slight cool down for a couple of days but then we were back up to high-80′s and low-90′s. I decided to take an impromptu tour around the area and see how the two biggest rivers, the Cache La Poudre and Big Thompson were doing. Flood advisories have been out a couple of days and minor flooding of trails and low-lying parks was underway. Temps were expected to reach the high-80′s today with no chance of clouds. I glanced at the hydrology reports for stations around our area. The Cache La Poudre river flows into Ft. Collins from the mountains. It is by far the most worrisome of the two rivers as it flows through Ft. Collins and through Greeley. With Greeley’s lower elevation and farmland, flooding occurs there every year. The Big Thompson flows out of the mountains and into Loveland. For the most part, it is only a concern for communities and areas upstream of Loveland. Many of the canyon parks, trails and residences get affected each year by this river.
Finally, I looked at the hydrology data for the Cache La Poudre as it moves through Greeley. Although fluctuations are to be expected over the course of a single day (increase in flows lag behind the heating of the day), we can see the general trend is for flows to increase. I left Loveland around 10am and made my first stop at the west end of Greeley. I was notified en route that north 71st Ave. in Greeley had been barricaded due to water over the road.

In speaking with some of the homeowners in the area, I learned the flood waters were within 6″ of the 100-year flood plain. I also watched as trucks with gravel and sand arrived to help build a dam around one of the houses at the northeast corner that is at a high risk of being flooded out. I also learned that last year, flooding in the area occurred when flows were running about 4700 CFM. Residences and others were told this year, they may be looking at flows of 8000+ CFM. needless to say, there are some worried folks in that area right now. I left Greeley and headed for the Poudre river trail head south of Windsor. Got on the trail and was able to get a look at the river at that location.
Left the trailhead and made my way to the Big Thompson river to get a look at those flows.
Left the dam area and got one more pic of the Big Thompson flow as it entered west Loveland. The weather over the next ten days will be critical in determining the extent of the flooding. After some pretty warm days, we are expecting progressively cooler days through the remainder of the week. While this may slow the melt, we are expecting a chance of some pretty good rains in the area. I posted some video b-roll footage here

May 30, 2011 Report

Pat Darrow — Tue, 31 May 2011 20:19:03 +0000

An interesting day! While the mass of chasers converged on Nebraska/Kansas/South Dakota and North Dakota for the SPC moderate risk area, a few of us were treated to some similar storms much closer to home and at a much lower cost. The day started at about 8a MDT while I was having coffee and looking at the soupy mess out my window. As the sat pic shows below, we were socked in with low strata and fog. In fact, with temps in the low 50′s and dews nearly the same, it should have been drizzling at least.Other than SPC’s usual “see text” that is a daily occurrence in northern/eastern Colorado about this time every year, nothing was special (weather-wise) for the day. All the exciting stuff was supposed to be in the central/northern plains as a low tracked across our area. As I went about doing other things, I noticed the low strata thinning a bit and as the sat pic below shows, noticeable breaks were taking place. It also appeared some sort of convergence might be taking place between Loveland and Greeley. Temps were now in the mid-60′s and dews in the mid- to upper-40′s. However, the surface winds in Loveland were out of the ssw while the winds in Greeley (20 miles east of Loveland) were out of the nne. The mountain top winds had picked up and were coming out of the west at a pretty good clip.About 20 minutes later, I saw towers rapidly going up just south of Loveland and could hear thunder. The winds were picking up as well with gusts near 20 mph.Further analysis showed the upper trough to be heading north. As it was passing, the winds out east of Loveland shifted to more easterly. These opposing winds (convergence) were enough to cause the lift needed to fire convection given the dewpoints and temperatures. Storms began quickly along the I-25 corridor. Storm speeds were not all that great 25-28 mph but they were traveling in a nne direction. Not really good tornado producers but more of a hail and straight-line setup. But, it is Colorado and landspouts (nonsupercell tornadoes) and gustnadoes were real possibilities. My “gear” was being used on another project so armed with a little point-and-shoot, I headed out.At about 1:10p MDT or so, the first of many severe warns went out. These warnings were for quarter-size hail and up to 60 mph winds. Not long after, tornado warnings were getting issued as is typical with MCS-type systems. These were all doppler indicated and were no doubt issued due to the gust front turbulence of the line.By the time I was heading for position, the storms were going more east and faster. I was unable to catch them before they got rain-wrapped and not so picturesque any more. I took a couple of pics from the backside and headed home.Local storm reports show hail and wind as the predominant severe weather. A tornado was allegedly observed southwest of Hoyt, CO but it is not listed on the NWS LSR.

May 17, 2011 Report

Pat Darrow — Wed, 18 May 2011 03:30:05 +0000

Well, it has been quite a while since I updated this blog. Over the last month or so, things have been really quiet. Aside from a few fires, weather has been benign – consisting of some snow and some rain. Today was a little different. We finally had a chance for more significant weather in the area. Beginning a couple of days ago, others were talking about the possibility of some upslope storms in eastern Colorado. These typically result in high-based, LP-type cells that yield amazing structure and some landspouts (non-supercell tornadoes). Others talked about this event as being a cold core setup that could result in supercell tornadoes. Regardless, this year has been one where forecasting beyond the day of usually resulted in disappointment (the April 27, 2011 outbreak being an exception). Got up first thing this morning and began looking at the possibilities for the day. On their 13Z day 1 outlook, SPC issued a 2% tornado risk for most of eastern Colorado, and a small area in southwestern Nebraska and western Kansas. However, their wording was so-so and in fact, the slight risk assigned today was for the east coast! Looking at the visible satellite and water vapor images told the story. Lots of low clouds, low temperatures and a brisk wind made today’s possibilities more of a dream than reality. Dewpoints weren’t expected to get out of the 40′s and with the lower temps, even eastern Colorado would have a tough time pulling this one off. However, Hi-Res models consistently indicated some severe storms starting around 5p MDT. I left Loveland at about 1:15p with an initial target of Carr, CO. My thinking was the storms coming off the foothills would yield a landspout or two. Unfortunately, once the clouds started burning off, a wind shift to the northwest caused everything to congeal. Colder air and lower dp’s soon followed. I headed east toward the “better” environment but was soon overrun with rain and wind. No lightning – no hail. Called it a chase after that. As I approached home base, a supercell went up south of Ft. Morgan and would soon be inundated with lots of chasers, followed by numerous tornado warnings.

Better luck next time!

ChaserCon 2011

Pat Darrow — Sat, 26 Feb 2011 15:58:15 +0000

Well, another year and another National Storm Chaser Convention (aka ChaserCon) has come and gone. This year was the 13th annual event and it topped all others. Unlike last year, I was not constrained by prior commitments and was able to stay for most of it. Also Like last year, I decided to commute each day. Living only 40 miles away has its advantages. Day 1 started out with picking up friend and fellow chaser, Johnathan “JB” Brouwer, from the Amtrak station in Denver. JB traveled from Indiana for the convention and after some delays, finally arrived around 10:45a MST. Due to construction around Union Station, Amtrak set up a temporary station near the west side of Coors Field. While not the most convenient place, it serves its purpose. The construction is supposed to be done in 2014 – we shall see.

After loading JB’s gear, we headed off to the Red Lion hotel where the convention was held. Some others arrived earlier and were milling around the hotel lobby. JB couldn’t check in yet, so after visiting with other chasers, we headed to Texas de Brazil for some lunch. A comment about lunch – awesome! A huge salad and soup bar, along with 9 different meats. We were stuffed. Back to the hotel we went. Spent the rest of the afternoon getting ready for the mixer. This required setting up the booths and cameras for the live feed. By 6p, all was ready to go. The mixer was well attended.

This year, we kept the interviews more informal with Kory, Will and JB doing the interviewing. Many of the attendees bugged out for the forecast class taught by Jon Davies. By 9p, we wrapped it up and day 1 came to a close.

Day 2 started out early as I had to get to the hotel in time to set up for the live stream of the day’s activities. With setup completed, the rest of the day was spent listening to the talks and networking with other chasers. Highlights included great technical talks from the V2 folks. Reed Timmer graced us with a presentation as well. Got to see the dominator and Twistex vehicles. That night we had the banquet followed by an always entertaining presentation by Tim Marshall and of course, video night.

Day 3 started out not so early as the equipment was already set up. More talks in the morning including a great one by Steve Hamilton on orographics and the DCVZ. The convention concluded with an informative panel discussion and finally, wrap up by Roger and Tim. We broke down and packed the equipment and booths and headed off to Famous Dave’s for some bbq.

The weather was good during the convention. Some TCU went up near Colorado Springs late Saturday afternoon and the threat of some “weather” had us all wondering if any chasers would be around on Sunday. California even had a tornado warning Saturday night. Anyway, it was great to see old friends and make new ones. I posted more pics on my facebook if interested.

Time to go chasing!

February flooding – White River

Pat Darrow — Wed, 16 Feb 2011 16:20:02 +0000

A quick little post about my old home town. The White River winds through the mountains and valleys of northwest Colorado. My old town of Meeker, CO lies on its west banks. When the temps get down to the -20F/-30F range for extended periods of time, ice jams form. The river flows out of its banks and into the low-lying areas. My former residence, which I sold last June, sits about 250′ from the west bank of the river. I built the house up a ways to prevent it from being flooded. For 13 years, while the other residences around me got flooded, I managed to stay dry. However, this year, the water was relentless. A good friend of mine sent the pic below. It is shot looking east toward the river. My former residence is on the left. Not a pretty site. The river’s flood stage is 7′ and as of this writing, it was running a little over 4′ (not adjusted for ice).

February 7-8, 2011 Winter Storm

Pat Darrow — Wed, 09 Feb 2011 19:06:08 +0000

Haven’t done a blog for awhile – mostly due to the unexciting weather in our area. However, this past weekend showed some promise for a significant winter storm for northern Colorado. The biggest discussion centered around the cold air heading toward us. Wind and snow were also mentioned. In fact, the February 5, 2011 HPC forecasts were painting quite the snowfall picture with a moderate chance of having more than 4″ and a slight chance of having more than 12″ of snow from 5pm (00Z) Monday night through 5pm Tuesday afternoon.

On monday evening at about 8:15pm (0315Z), the winds arrived in force (22mph sustained with gusts to 35mph), signaling the arrival of the storm. Temps were in the mid-20′s. The RADAR image below was taken at 9:11pm (0411Z) showing the snow to be all around us. By 10:48pm (0548Z), the hole closed and light snow began. Winds were still sustained at about 24mph but now gusting to 45mph. Temps fell to 10F.
Over the next few hours, howling winds along with the light snow created poor visibility in the area. Winds stayed gusty and temps settled down to around 8F. By about 3:00am (10Z), the front had passed and things were quieting down.

The next morning (February 8, 2011), light snow was falling but the winds had lessened. Total accumulation was around 1-2″ with drifts about 8″. Roads were icy and snowpacked but no major travel issues were noted. Further south, more snow and wind led to numerous reported crashes.

As it turns out, not a big winter event for us. Dirier air in the lower levels led to the pathetic snowfall (actual) amount. HPC did back off their estimates prior to the event so it was not unexpected. However, given the season so far, the wind with this event made it better than nothing.

January 9, 2011 – Northern Colorado snow

Pat Darrow — Tue, 11 Jan 2011 15:33:55 +0000

Well, it’s a new year and we finally had a shot as some real snow this time. A week prior, models were hinting at a possible big snow and cold event for northern/northeast Colorado. As with most forecasts (winter especially), it is a tough call until about 2 days before the event – so, I remained cautiously optimistic. A trough was approaching our area as was the cold air. Timing put snowfall to begin early Sunday (January 9) morning. A winter weather advisory was issued starting at 6am MST with 6-10″ of snow predicted. Cold air would slowly filter in throughout the day but the winds were expected to be light (probably why only an advisory was issued). Models showed the better forcing (upslope and moisture) to arrive late Sunday evening = more snow.

Shortly after 1:00am, a band of rain/sleet/ice pellets made its presence known around Denver. Snow started for us a little later and by 7:30am MST, we had about 1.5″ on the ground. The heaviest band arrived at about 9:00am MST adding another 3+ inches to the total. A few accidents were being reported on the interstate but by far the most numerous were on the side roads. Most were slide-offs and no injuries.

By late afternoon, models, radar, sat images were all in disagreement with each other. It appeared that any setup for heavy snow was going to be south of Denver and maybe east toward Kansas. Water vapor imagery showed drier air coming at us from the northwest. Main arteries were mostly wet with the interstate and other major arteries dry. All things considered, I believed we had received all the snow we were going to receive.

On Monday (January10), I took a a little tour around northern Colorado. The morning was clear and the temps were crisp. I noted the farther east I got, the less snow was on the ground. The major cities closer to the foothills (Loveland, Ft. Collins, Windsor). Not a big event by any stretch but at least it was something in this otherwise, lacking winter season.

Some video from my tour can be found here

Last winter storm of 2010

Pat Darrow — Fri, 31 Dec 2010 16:07:16 +0000

The last week of the year held promise for big snow, at least according to local WFO’s. Alas, that did not happen. However, some snow was expected and that was a good thing – we were woefully lacking precipitation and farmers were beginning to get nervous. Climatologists placed a large portion of eastern Colorado in a moderate drought.

On December 30, 2010 at about 6:30am MST, the snow began falling in northern Colorado. Although light at first, a strong cold front rapidly arrived, bringing winds and heavier snow bands into the area. Roads got trashed early and shortly after it started, I-25 north of Loveland began seeing its first accidents of the day. It wasn’t long after that folks were sliding off on nearly every road in the area. When it was all said and done, we received about 3.5″ of snow. Not a lot – but, better than nothing. Below is some b-roll footage I took from my dashcam while out covering the storm.