Tornados in CO? How common are they? (Denver, Boulder: transplants, tornadoes)

[BillRadio]

Originally Posted by Pettrix

1 - Is the above accurate?

Yes, but only slightly more prone.

2 - Are they usually F2 and lower?

Yes

3 - How common are they?

There's probably a funnel cloud sighting every year near the airport, but that's a number possible in most parts of the metro area

4 - Does this deter people or lower property values in those areas?

Not at all, mostly because of 2 & 3 , above. There was a small tornado that touched down in the area several years ago, and people realized nobody knew where to go when they sounded the alarm. As a result, the city added "Tornado Shelter" signs to all the bathrooms, safe because they have no glass in them. There hasn't been a real tornado near the terminal since.

[jobrosluver]

I'm pretty sure that colorado is in tornado alley...right?? WHat's the average of tornadoes in colorado?? So if you could please reply...Thank you and GOD BLESS!!! :-D

[Charles]

Originally Posted by jobrosluver

I'm pretty sure that colorado is in tornado alley...right?? WHat's the average of tornadoes in colorado?? So if you could please reply...Thank you and GOD BLESS!!! :-D

There hasn't been a tornado fatality in Colorado in like 48 years. I'm more worried about my neighbors' dogs.

NWS Denver-Boulder, CO - Local Climate Page

[jazzlover]

Originally Posted by Charles

There hasn't been a tornado fatality in Colorado in like 48 years. I'm more worried about my neighbors' dogs.

NWS Denver-Boulder, CO - Local Climate Page

Actually, the 48 year record was broken by fatalities in the tornadoes at Holly last year. That said, Colorado is not especially tornado-prone, and many areas of the state are virtually tornado-free. Tornadoes in Colorado tend to be less severe than in states to the east--the tornado that hit Holly last year was a notable exception. As I have posted before, though, the Front Range and eastern plains of Colorado are in "Hail Alley," and those areas are some of the most hail-prone areas in the US.

[Mike from back east]

Let's dissect the numbers in the great graphic that Charles posted.

Shows 1563 tornadoes in 54 years (inclusively). That's roughly 30 per year. If we assume the peak storm season lasts 15 weeks, then that's two per week. Most are small and very short lived. Bigger, longer lasting ones are out on the flat prairie, the eastern third of the state, as demonstrated by the numbers in the graphic. That area is farm country, sparsely populated, with small towns and none of the density we see in metro areas, thus little damage.

There was one fatality, March 28, 2007 in Holly, CO. This was the first tornado-related death in Colorado since June 27, 1960, or 47 years ago.

Meanwhile, for the period 1950-1994 (45 years inclusively) here are the top 15 states and number of fatalities:
TX-475 MS-386 AR-279 AL-275 MI-237 IN-218 OK-217 KS-199 IL-182 TN-181 OH-173 MO-155 LA-134 GA-111 KY-105

Colorado came is at spot 38, with 2 fatalites during this 45 year stretch.

IMO, no one should worry about tornadoes in CO. Use the link below for all the stats and see that CO is among the SAFEST places. Meanwhile, in 2005, an average of 11.5 people PER WEEK were killed in CO traffic wrecks. Keep your eye on the road, not the sky.

For all stats, see: Tornado Ranks by State, 1950-1994

[LBear]

Colorado has had:
1,113 tornadoes
2 fatalities and 157 injuries since 1950.
Actually, those 2 fatalities took place 30 miles west of the Kansas border in Colorado. The first one was in SEDGWICK COUNTY and the most recent one in Holly was in PROWERS COUNTY. These counties sit right on the border of Kansas.

Myself personally, I would rather have MORE tornadoes but weaker in strength, than fewer tornadoes with greater strength.

Remember Chicago got hit with two F4s and one F3 since 1950! back in April 21, 1967 and F4 tornado tore a 16.2-mile (65 mph ground speed) swath of destruction through Oak Lawn, Hometown, Evergreen Park, and devastated the south side of Chicago before moving offshore to Lake Michigan as people were stuck in traffic during Friday rush hour. Thirty-three people were killed and 1000 were injured, including 16 deaths alone at the intersection of Southwest Highway and W. 95th St. in Oak Lawn. It destroyed 152 homes and damaged 900, causing $50 million in damage.

Illinois = 129 reported F3 tornadoes
43 reported F4 tornadoes
03 reported F5 tornadoes (1990 Will county - 29 dead, 350 injured

Illinois is 7x more likely to get an F3 tornado & 43x more likely to get an F4+ tornado than Colorado. (hope my stats are right

Colorado =18 reported F3 tornadoes
01 reported F4 tornado (Baca County - Kansas Border
ZERO F5 tornadoes

Arizona = (who would have thought AZ gets tornadoes!)
211 TOTAL since 1950
105 reported F0 tornadoes
62 reported F1 tornadoes
10 reported F2 tornadoes
02 reported F3 tornadoes
ZERO F4 & F5

Once again, it should be noted that most of the tornadoes are weak in Colorado and that is why the low injury and fatality rates.


For instance, Adams County:

88 tornadoes in the F0 range (40 - 72MPH)
47 tornadoes in the F1 range (72MPH -112MPH)
09 tornadoes in the F2 range (113MPH -157MPH)
02 tornadoes in the F3 range (158MPH - 206MPH)
ZERO in the F4 or F5 range

A home should be able to withstand a direct hit from an F2. Once it gets to an F3, there will be damage, but as shown only TWO F3's recorded in Adams County since 1950. F4 or greater are complete devastation.

Also, it should be noted that the HOLLY tornado was a very strong F3 and it hit a trailer park. Trailer homes can be knocked over with winds around 70 MPH. They are VERY unsafe when compared to a home built with a foundation that is anchored in. According to the IBC codes, a new home should be wind sheer resistant to 100MPH.

[gypsy_night]

Thanks for the stats; I always believed that the midwest, even Chicago has the worst weather,even for those powerful tornadoes. Colorado is a place we're looking into. Should we be worried about tornadoes in the upper areas of Colorado? Fort Collins or Golden?

[denverian]

Originally Posted by gypsy_night

Thanks for the stats; I always believed that the midwest, even Chicago has the worst weather,even for those powerful tornadoes. Colorado is a place we're looking into. Should we be worried about tornadoes in the upper areas of Colorado? Fort Collins or Golden?

The closer you are to the mountains, the less the threat.

[jazzlover]

Originally Posted by denverian

The closer you are to the mountains, the less the threat.

But, the foothill areas are much more prone to high winds in the winter and spring--100 mph+ on occasion. There are always tradeoffs . . .

[NickMan7]

Originally Posted by jazzlover

But, the foothill areas are much more prone to high winds in the winter and spring--100 mph+ on occasion. There are always tradeoffs . . .

I was just about to note this. While any tornadic activity should be taken seriously, I would not base whether or not you choose to move to Denver on the possiblity of encountering a tornado or any other weather event. Like any place in the nation, you are susceptible to the elements that are common in that particular location. There are some excellent posts here detailing the history of tornadic activity in Colorado, so there is no need to go into great detail.

Wind storms during the winter months can rake Metro Denver with very strong and damaging winds. As several people on this board know first hand, living anywhere near Boulder (especially just south and southwest) for a year will give you a very clear picture of what chinook winds are like. NCAR, Table Mesa, Rocky Flats and Highway 93 connecting Boulder with Golden are notorious for having some of the strongest wind speeds during these events. Wondervu and Nederland are also noteworthy. The difference in chinook events vs. tornadoes and other weather phenomena is the duration. I have seen wind events last 3 or 4 days (the closer to the foothills you are). Living in Superior (just east of Rocky Flats), we routinely had wind gusts exceeding 70mph on our apartment balcony (I had an anemometer mounted on the support post). Most suburbs south (Aurora, Centennial, Littleton), west (Lakewood, Golden) and north (Arvada, Westminster, Louisville, Lafayette, Longmont) of Denver are hardest hit. Downtown Denver and points eastward record significantly lower wind speeds during most events, although winds occasionally creep east of I-25. During most strong chinooks, you will hear reports from local media outlets of wind gusts exceeding 100mph not too far from where you live.

Previous posts have stated this and I will reiterate. Hail is most certainly one of the costliest and most dangerous severe weather systems the Front Range experiences. It is unlikely that you will encounter an entire spring and summer season without experiencing hail at least one time. Hail often accompanies thunderstorms in the Denver area and many areas see thunderstorms daily for several weeks. This is especially true during May and June. Although rare, hail storms can occur through October. We had an isolated, nasty hail storm roll through Erie in September 2006 that completely shredded our trees, shrubs and yard. Last spring we had to replace 13 trees, 8 bushes and some patches of grass. I talked with some friends who live less than a mile away (and in the direction the storm was moving) and they had no idea what storm I was talking about, because they never received a drop. A very real example of how fickle and unpredictable weather in the region can be.

Honestly, the variety in weather is what makes living here so wonderful! You see dark clouds and the anxiety and anticipation of what might happen makes you nervous and excited. It's like a good movie! I wouldn't trade it for anything!

I might add that a good homeowner's insurance policy is necessary.