Today's "Ask Mike" question is "Do tornadoes spin clockwise in the southern hemisphere? and does the southern hemisphere have tornadoes in the first place?"
and the answer is.......
In general, tornadoes, being low-pressure systems or "cyclones" generally spin counterclockwise in the northern hemisphere (not all, but most) because of coriolis effect, which causes moving objects to deviate to the right in the northern hemisphere and to the left in the southern hemisphere.
It's just the opposite in the southern hemisphere. Low pressure systems (cyclones) spin clockwise south of the equator, and so do most of the tornadoes....and yes, countries in the southern hemisphere DO experience tornadoes.
A few on the list include Australia, New Zealand, South Africa, Paraguay, Uruguay, Argentina, Colombia and Chile.
Wednesday, April 29, 2009
Tuesday, April 28, 2009
When can I plant my garden?
That's a question we're getting more and more frequently in the weather center, and the best way to answer it is to give you the "official" statistics for Colorado Springs and Pueblo.
Let's start with Colorado Springs:
Average Date of Last Freeze...............May 8th
Latest Freeze of the Season...............June 3rd, 1951
and now the data for Pueblo:
Average Date of Last Freeze.......................April 30th
Latest Freeze of the Season.......................June 2nd, 1919
Please note that the dates for the last freeze are AVERAGES over the past 30 years, year by year, sometimes it's a little earlier, sometimes a little later (look at the "Latest Freeze of the Season" numbers too).
Notice that the further we get into May, the less of a chance for that "surprise" freeze.
If you're relatively new to the area, be sure to check in with your local garden shop for some flowers and plants that do best in our "filled with surprises" climate.
Let's start with Colorado Springs:
Average Date of Last Freeze...............May 8th
Latest Freeze of the Season...............June 3rd, 1951
and now the data for Pueblo:
Average Date of Last Freeze.......................April 30th
Latest Freeze of the Season.......................June 2nd, 1919
Please note that the dates for the last freeze are AVERAGES over the past 30 years, year by year, sometimes it's a little earlier, sometimes a little later (look at the "Latest Freeze of the Season" numbers too).
Notice that the further we get into May, the less of a chance for that "surprise" freeze.
If you're relatively new to the area, be sure to check in with your local garden shop for some flowers and plants that do best in our "filled with surprises" climate.
Wednesday, April 22, 2009
Colorado Tornadoes
In honor of Severe Weather Awareness Week, you might look back at yesterday's post about lightning, and today we move on to tornadoes in our state.
Since we're on the western edge of "Tornado Alley", It's no surprise that we get our share in Colorado.
Over the long term, we average 25 per year, with Weld county holding the "distinction" of being blasted by more tornadoes (between 1950 and 2006) than any other county in the nation (which, of course, makes it #1 in Colorado). Adams county is number 2 in the state.
Tornado intensity is rated on the Enhanced Fujita scale, named after Dr. Ted Fujita of the University of Chicago. The ratings are based on the damage created by the storm.
As you can see, the scale runs from F0 to F5, and in the Pikes Peak Region, many of the storms we experience are in the F0 category (fortunately).
The greatest threat for tornadoes occurs during the late Spring and early Summer, when there's lots of water in the air, and temperatures are warm enough to boil up severe thunderstorms. (Tornadoes develop from these storms with damaging wind and hail). Statistically, June is the most active month, but whenever conditions are right, they can spin up.
When a TORNADO WATCH is issued, it means that a tornado is possible...keep your eyes and ears open.
A WARNING means it is imminent or occurring. You'll find a great set of safety tips at
http://www.tornadoproject.com/safety/safety.htm.
Even this early in the season, we've already had 2 tornado warnings (one for eastern El Paso county and another for Prowers and Kiowa counties), so it's time to make some plans.
Since we're on the western edge of "Tornado Alley", It's no surprise that we get our share in Colorado.
Over the long term, we average 25 per year, with Weld county holding the "distinction" of being blasted by more tornadoes (between 1950 and 2006) than any other county in the nation (which, of course, makes it #1 in Colorado). Adams county is number 2 in the state.
Tornado intensity is rated on the Enhanced Fujita scale, named after Dr. Ted Fujita of the University of Chicago. The ratings are based on the damage created by the storm.
| FUJITA SCALE | DERIVED EF SCALE | OPERATIONAL EF SCALE | ||||
| F Number | Fastest 1/4-mile (mph) | 3 Second Gust (mph) | EF Number | 3 Second Gust (mph) | EF Number | 3 Second Gust (mph) |
| 0 | 40-72 | 45-78 | 0 | 65-85 | 0 | 65-85 |
| 1 | 73-112 | 79-117 | 1 | 86-109 | 1 | 86-110 |
| 2 | 113-157 | 118-161 | 2 | 110-137 | 2 | 111-135 |
| 3 | 158-207 | 162-209 | 3 | 138-167 | 3 | 136-165 |
| 4 | 208-260 | 210-261 | 4 | 168-199 | 4 | 166-200 |
| 5 | 261-318 | 262-317 | 5 | 200-234 | 5 | Over 200 |
As you can see, the scale runs from F0 to F5, and in the Pikes Peak Region, many of the storms we experience are in the F0 category (fortunately).
The greatest threat for tornadoes occurs during the late Spring and early Summer, when there's lots of water in the air, and temperatures are warm enough to boil up severe thunderstorms. (Tornadoes develop from these storms with damaging wind and hail). Statistically, June is the most active month, but whenever conditions are right, they can spin up.
When a TORNADO WATCH is issued, it means that a tornado is possible...keep your eyes and ears open.
A WARNING means it is imminent or occurring. You'll find a great set of safety tips at
http://www.tornadoproject.com/safety/safety.htm.
Even this early in the season, we've already had 2 tornado warnings (one for eastern El Paso county and another for Prowers and Kiowa counties), so it's time to make some plans.
Tuesday, April 21, 2009
'Tis the season (for thunderstorms)
Springtime is when we really start thinking (or should) about thunderstorms, as from this point into at least June, we'll see our share.
Our typical weather pattern will be morning sunshine, with clouds building by noon, some afternoon thunderstorms, then clearing for overnight.
Colorado Averages 517,000 flashes per year. (This number was measured over a 9 year time period, 1996 through 2004). During that time, our state was 18th in the nation with respect to lightning strikes, and 3rd when it comes to lightning fatalities. (Thanks to NWSFO Pueblo, for the lightning information).
To determine how far away from you a lightning strike is, start counting the seconds between when you see the flash, and when you hear the rumble of thunder. For every 5 seconds you can count, the lightning is 1 mile away.
The National Weather Service encourages the 30/30 rule, which is..
"If you can count to less than 30 between the lightning flash and the thunder, go indoors, and stay there until 30 minutes after you hear the last rumble".
El Paso, Teller, Douglas and Jefferson counties, together with western Las Animas county, are the "lightning capitals" of Colorado.
Have a great spring, and "let's be careful out there".
Our typical weather pattern will be morning sunshine, with clouds building by noon, some afternoon thunderstorms, then clearing for overnight.
Colorado Averages 517,000 flashes per year. (This number was measured over a 9 year time period, 1996 through 2004). During that time, our state was 18th in the nation with respect to lightning strikes, and 3rd when it comes to lightning fatalities. (Thanks to NWSFO Pueblo, for the lightning information).
To determine how far away from you a lightning strike is, start counting the seconds between when you see the flash, and when you hear the rumble of thunder. For every 5 seconds you can count, the lightning is 1 mile away.
The National Weather Service encourages the 30/30 rule, which is..
"If you can count to less than 30 between the lightning flash and the thunder, go indoors, and stay there until 30 minutes after you hear the last rumble".
El Paso, Teller, Douglas and Jefferson counties, together with western Las Animas county, are the "lightning capitals" of Colorado.
Have a great spring, and "let's be careful out there".
Saturday, April 18, 2009
Storm statistics from our April 17th+ storm
We just went through a set of weather conditions that is very typical for Colorado in the Springtime; sunshine, snow, wind, fog, showers, thunder, thundersnow, severe thunderstorms and at least 2 tornadoes.
A couple of notes..
Initially, lots of us saw graupel. See the last post for an explanation
Many reported thunder and lightning along with the snow, and were surprised that they were getting both. In fact, thunder and lightning often accompany heavy snow, but you don't see or hear them through the power of the storm. (One study suggests that 80% of storms with heavy snow also have thunder and lightning).
Then there are the snowfall totals. I'll list a few below.
52" - Pinecliffe, a location at 9,000 feet in northern Jefferson County
22"+ - Chipita Park and Woodland Park
20"+ - High Forest Ranch (near Hodgen road and Highway 83), and Woodmoor
16"+ - Black Forest (with deep drifts)
14" - Rosita in Custer County
1" - 6" - Across the Colorado Springs Metro Area
7" - Briargate
3" - West side of Colorado Springs.
Now get ready for some sunshine!!
A couple of notes..
Initially, lots of us saw graupel. See the last post for an explanation
Many reported thunder and lightning along with the snow, and were surprised that they were getting both. In fact, thunder and lightning often accompany heavy snow, but you don't see or hear them through the power of the storm. (One study suggests that 80% of storms with heavy snow also have thunder and lightning).
Then there are the snowfall totals. I'll list a few below.
52" - Pinecliffe, a location at 9,000 feet in northern Jefferson County
22"+ - Chipita Park and Woodland Park
20"+ - High Forest Ranch (near Hodgen road and Highway 83), and Woodmoor
16"+ - Black Forest (with deep drifts)
14" - Rosita in Custer County
1" - 6" - Across the Colorado Springs Metro Area
7" - Briargate
3" - West side of Colorado Springs.
Now get ready for some sunshine!!
Thursday, April 16, 2009
Hang onto your hat! It's springtime in the Rockies!
Thursday the 16th, has proven to be an interesting day in southern Colorado. It started breezy and warm, transitioned to windy, with showers and thunderstorms, and will continue to evolve into 2 days of wind, rain and snow.
The culprit is a low pressure system about 20,000 feet in the air (for you up-and-coming meteorologists, that's the 500 millibar level), that will take its time moving across northern New Mexico. That means this isn't a "hit and git" storm, it's a "here's the way it would be all winter if you lived further north" storm.
Snowfall totals will vary WIDELY, but the most impressive will be in northern and western El Paso County, Teller County, the Wet Mountains and Wet Mountain Valley, the southern Foothills and the Sangre de Cristo's. (Initially, lots of the snow that falls will melt, then will become that wet, heavy spring snow that snaps trees and power lines.
Now then, during the couse of the day, a few terms that we haven't used for awhile came up, so here's a quick refresher on some definitions.
Severe Storm - one with any or all of the following:
a) Hail greater than or equal to 1" in diameter
b) Winds 58 mph or stronger
c) A Tornado
Graupel - We saw some of this from thunderstorms in the Colorado Springs area this afternoon. It's defined as either hard snow or soft hail. It looks like hailstones, but it's soft enough that you can crush it in your fingers. (You can't do that with a hailstone).
A Watch - means that whatever kind of weather it refers to is POSSIBLE. The elements are there, but there's still a question about whether or not it will come together.
A WARNING - means that the conditions are imminent or occurring.
As this storm develops, I'd appreciate it if you'd keep me updated with e-mails/photos of what it's doing in your neighborhood.
The culprit is a low pressure system about 20,000 feet in the air (for you up-and-coming meteorologists, that's the 500 millibar level), that will take its time moving across northern New Mexico. That means this isn't a "hit and git" storm, it's a "here's the way it would be all winter if you lived further north" storm.
Snowfall totals will vary WIDELY, but the most impressive will be in northern and western El Paso County, Teller County, the Wet Mountains and Wet Mountain Valley, the southern Foothills and the Sangre de Cristo's. (Initially, lots of the snow that falls will melt, then will become that wet, heavy spring snow that snaps trees and power lines.
Now then, during the couse of the day, a few terms that we haven't used for awhile came up, so here's a quick refresher on some definitions.
Severe Storm - one with any or all of the following:
a) Hail greater than or equal to 1" in diameter
b) Winds 58 mph or stronger
c) A Tornado
Graupel - We saw some of this from thunderstorms in the Colorado Springs area this afternoon. It's defined as either hard snow or soft hail. It looks like hailstones, but it's soft enough that you can crush it in your fingers. (You can't do that with a hailstone).
A Watch - means that whatever kind of weather it refers to is POSSIBLE. The elements are there, but there's still a question about whether or not it will come together.
A WARNING - means that the conditions are imminent or occurring.
As this storm develops, I'd appreciate it if you'd keep me updated with e-mails/photos of what it's doing in your neighborhood.
Saturday, April 11, 2009
It's all about the wind direction
As of Saturday night, April 11, 2009, a big low-pressure system is in the 4-corners area and headed for the Texas Panhandle. The trip will take it across northern New Mexico during the day on Sunday, and that's when we'll see our best chance for rain and snow (and fog).
As I've mentioned in previous posts, when moist air is forced uphill, precipitation increases; moving downhill causes it to warm and dry, and the storm is less powerful, so it's all about the wind direction.
With the storm over the 4-Corners area, the bands of rain and snow have been flowing in from the south and southwest, that's downhill for Colorado Springs and Pueblo (but uphill for some of the mountain locations.
As the center of the storm finds its way to northern New Mexico, the counter-clockwise winds swirling around it will switch to the southeast, then to the northeast as it heads for Texas. That's when we have our best chance for that moisture you lawn needs.
Southeasterly winds enhance the storm for most of us, while northeasterly winds favor the Palmer Divide, Wet Mountains (and Wet Mountain Valley). Teller County and the Sangre de Cristo's could also pick up a good "shot" of snow.
The key for how strong the storm is where you are is..."is the wind moving uphill or downhill to get to my house?".
By the way, northerly winds (not northeasterly...that's a whole different situation) are moving downhill from Colorado Springs to Pueblo, which means minimal rain/snow for both cities.
Happy Easter! and good luck finding those eggs (I hope many of them are Chocolate)
As I've mentioned in previous posts, when moist air is forced uphill, precipitation increases; moving downhill causes it to warm and dry, and the storm is less powerful, so it's all about the wind direction.
With the storm over the 4-Corners area, the bands of rain and snow have been flowing in from the south and southwest, that's downhill for Colorado Springs and Pueblo (but uphill for some of the mountain locations.
As the center of the storm finds its way to northern New Mexico, the counter-clockwise winds swirling around it will switch to the southeast, then to the northeast as it heads for Texas. That's when we have our best chance for that moisture you lawn needs.
Southeasterly winds enhance the storm for most of us, while northeasterly winds favor the Palmer Divide, Wet Mountains (and Wet Mountain Valley). Teller County and the Sangre de Cristo's could also pick up a good "shot" of snow.
The key for how strong the storm is where you are is..."is the wind moving uphill or downhill to get to my house?".
By the way, northerly winds (not northeasterly...that's a whole different situation) are moving downhill from Colorado Springs to Pueblo, which means minimal rain/snow for both cities.
Happy Easter! and good luck finding those eggs (I hope many of them are Chocolate
Monday, April 6, 2009
A day between storms
Well, the weekend was interesting, don't you think? For the storm outlook, see my 4/3 post, "the wind and warm before the storm", and for storm totals, the one from 4/4, "storm totals" (obviously, I'm not great at clever headlines).
The power of the storm hit where we were expecting it...northern El Paso county, Teller county and the southern foothills, while the rest of us got mostly a blast of wind and cold.
Sunday's weaker disturbance still produced an inch or 2 in the Broadmoor area, 3.3" in Beulah and 2.8" in Rye.
Now, let's look to the future;
For the moment, high pressure is building overhead in Colorado, that will give us chinook winds (the ones that move down the east slopes of the mountains, warming and drying as they go) for Tuesday, even stronger winds (and higher fire danger) on Wednesday, then another chance for rain and snow as cold air races in from the north and moist air arrives from the Pacific.
After that, you'll want a brief break, and you'll get it on Friday, before the next round begins to move in on Saturday, with the effects lingering through Sunday.
By the way, after that blast of wind on Saturday, to find the windiest cities in the United States. #1 on the list is Dodge City, Kansas, followed by Amarillo, Texas...care to guess where some of the rest are? (here's a hint, Chicago isn't one of them)...I'll include them in my next few posts.
The power of the storm hit where we were expecting it...northern El Paso county, Teller county and the southern foothills, while the rest of us got mostly a blast of wind and cold.
Sunday's weaker disturbance still produced an inch or 2 in the Broadmoor area, 3.3" in Beulah and 2.8" in Rye.
Now, let's look to the future;
For the moment, high pressure is building overhead in Colorado, that will give us chinook winds (the ones that move down the east slopes of the mountains, warming and drying as they go) for Tuesday, even stronger winds (and higher fire danger) on Wednesday, then another chance for rain and snow as cold air races in from the north and moist air arrives from the Pacific.
After that, you'll want a brief break, and you'll get it on Friday, before the next round begins to move in on Saturday, with the effects lingering through Sunday.
By the way, after that blast of wind on Saturday, to find the windiest cities in the United States. #1 on the list is Dodge City, Kansas, followed by Amarillo, Texas...care to guess where some of the rest are? (here's a hint, Chicago isn't one of them)...I'll include them in my next few posts.
Saturday, April 4, 2009
Storm Stats
A powerful storm moved into Colorado right on schedule, bringing a blast of cold, areas of snow and blowing snow and tropical storm force winds.
On the air, I only have time to show you a few statistics...here's a more complete list.
Wind gusts
55 mph Colorado Springs Airport
67 mph Pueblo
60 mph Fort Carson
58 mph Fountain
57 mph Briargate
55 mph La Junta
51 mph Trinidad
49 mph Lamar/Springfield
and here are a few initial snowfall totals...
11" Cuchara
8" Monument to Woodmoor
6" Divide
4" Woodland Park
4" North of Black Forest
2.9" East of Monument
2" Peyton (the observer says it's tough to measure when it's coming down at a 90 degree angle.
1" Briargate
You might want to compare these initial totals with my post from yesterday, and see how well I did on the forecast.
Oh, by the way, there areas of VERY low visibility in blowing snow across northern El Paso county, including Monument, Black Forest and Peyton.
Now, slowly but surely, a ridge of high pressure will build toward, then over Colorado, and conditions should improve through Tuesday.
On the air, I only have time to show you a few statistics...here's a more complete list.
Wind gusts
55 mph Colorado Springs Airport
67 mph Pueblo
60 mph Fort Carson
58 mph Fountain
57 mph Briargate
55 mph La Junta
51 mph Trinidad
49 mph Lamar/Springfield
and here are a few initial snowfall totals...
11" Cuchara
8" Monument to Woodmoor
6" Divide
4" Woodland Park
4" North of Black Forest
2.9" East of Monument
2" Peyton (the observer says it's tough to measure when it's coming down at a 90 degree angle.
1" Briargate
You might want to compare these initial totals with my post from yesterday, and see how well I did on the forecast.
Oh, by the way, there areas of VERY low visibility in blowing snow across northern El Paso county, including Monument, Black Forest and Peyton.
Now, slowly but surely, a ridge of high pressure will build toward, then over Colorado, and conditions should improve through Tuesday.
Friday, April 3, 2009
The wind and warm before the storm
As another wintry storm moves into Colorado, chinook winds blew on Friday, boosting highs into the 60s and 70s for most lower elevations. Wind speeds have been on the increase, though, and below, you'll find a list of some of the peak gusts so far.
56 mph Monarch Pass
48 mph Colorado Springs, Pueblo, Pueblo West
37 mph Briargate
36 mph Garden of the Gods
Over the next 24 hours, we'll combine even stronger gusts with periods of snow. Practically it means that you're likely to encounter periods of low (or 0) visibility, especially north and west of Colorado Springs.
Storm reports will follow in the next posting.
56 mph Monarch Pass
48 mph Colorado Springs, Pueblo, Pueblo West
37 mph Briargate
36 mph Garden of the Gods
Over the next 24 hours, we'll combine even stronger gusts with periods of snow. Practically it means that you're likely to encounter periods of low (or 0) visibility, especially north and west of Colorado Springs.
Storm reports will follow in the next posting.
Thursday, April 2, 2009
To snow or not to snow?
I write this account on April 2, 2009, and as I do, a low-pressure system is racing from the Pacific Northwest towards Colorado. Winter Storm Warnings are in effect for the mountains, with a Winter Storm Watch for most of the lower elevations from El Paso and Teller counties northward.
How much snow you get depends on the track of that low. If it chooses to spend some time across northern New Mexico, your neighborhood becomes a winter wonderland.
If it takes a more northerly track, the real action will be over the mountains and from northern El Paso county northward, and this far in advance, it could still take either track......but.....
The computer models we use to help forecast the tracks of incoming storms are coming into agreement (for what it's worth), on a more northerly track for the storm, which would put us in the "heaviest snowfall further north" category.
Still, regardless of the storm track, starting late Friday night, you'll feel strong, gusty winds (some stronger than 50 mph), experience a gust of MUCH colder air (highs only in the 30s on Saturday, and even colder wind-chills), and see periods of snow and blowing snow, with poor visibility (near 0 in some spots) at times.
The further north you travel, (say, for example, towards Denver), the more like "The Great White North" conditions will be.
Check the weather page at KOAA.com for the latest information.
How much snow you get depends on the track of that low. If it chooses to spend some time across northern New Mexico, your neighborhood becomes a winter wonderland.
If it takes a more northerly track, the real action will be over the mountains and from northern El Paso county northward, and this far in advance, it could still take either track......but.....
The computer models we use to help forecast the tracks of incoming storms are coming into agreement (for what it's worth), on a more northerly track for the storm, which would put us in the "heaviest snowfall further north" category.
Still, regardless of the storm track, starting late Friday night, you'll feel strong, gusty winds (some stronger than 50 mph), experience a gust of MUCH colder air (highs only in the 30s on Saturday, and even colder wind-chills), and see periods of snow and blowing snow, with poor visibility (near 0 in some spots) at times.
The further north you travel, (say, for example, towards Denver), the more like "The Great White North" conditions will be.
Check the weather page at KOAA.com for the latest information.
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