Mike's Weather Blog Archive: May 2009

The presence of a strong ridge of high pressure will allow the atmosphere to continue to warm up slightly above what we are used to seeing this time of year. Our average high temperatures for this time of year are in the mid 70s and through the weekend we are expecting highs in the low to mid 80s. With the intense daytime heating and limited moisture in the area we'll see mostly high based thunderstorms, with little rain. Any significant precipitation will be isolated and mainly over the foothills. Lows this weekend will be moderate in the mid 50s, making it a nice time to be out and about.

On Monday, temperatures drop as a cold front passes over the area, bringing with it an increase in moisture which will promote the growth of thunderstorms in the afternoon. Depending on the upper level conditions, a few of these storms may become severe.

As we transition from this more moist spring air to warmer more dry summer weather we have our greatest chance for severe weather. Late May into early June is the peak of severe weather season so be prepared! An easy first step in your weather safety plan is to pick up one of our 24/7 Weather Alert Radios! For more information, check out the 24/7 Weather Alert Radio Webpage! You can get free weather text alerts directly to your phone, just click on weather text alerts on the top of the weather page.

Memorial Day weekend brought lots of showers and unfortunately some severe weather as well. Many people witnessed funnel clouds across the metro area on Sunday afternoon and other areas experienced hail. Because of the slow moving storms, several places reported localized flooding. Precipitation totals reached as much as 3.01" in Lakewood, 2.22" in Wray and 2.02" in Denver. Although we have been experiencing some moist weather lately, conditions are expected to dry out and warm up as we head toward this upcoming weekend.

More sun will cause temperatures to rise Wednesday and Thursday. The expected high for Wednesday is 74 degrees with a low of 49 degrees. For Thursday, look for a high of 79 degrees and a low of 53 degrees. These pleasant conditions will stick around for a few days, however there is a possibility of showers during the weekend. Despite the chance of storms, temperatures will still remain warm in the mid to upper 70s.

Although it seems like we have been getting drenched, the amount of precipitation for May is still below average. The official rainfall measurements for the Denver area are taken from DIA, and it has been drier out there. For the year to date, we are still 0.94" below the normal. For the month of May, thus far, we have received 1.05," which is still 0.95" below normal for the month. So, enjoy the drier days ahead but watch out for those afternoon thunderstorms!

Tornadoes are no strangers to Colorado, in fact we average about 50-60 twisters per year across the eastern plains. Ninety percent of the tornadoes in our state occur east of I-25 and most hit in the late afternoon, especially in June. Fortunately, there have been very few fatalities in our state.

Nearly a half century passed between the tornado fatalities in Sedgwick County in 1960 and the next killer storm in Holly in late March of 2007. It took less then 15 months before another deadly twister struck in Colorado. The morning of May 22, 2008 dawned cool and cloudy across northern Colorado, with light east winds and high humidity. A powerful upper level storm system was swirling over the Desert Southwest, with a band of jet stream winds roaring toward Colorado at over 120 mph. Temperatures were already warming into the 70s over the southern plains of our state, setting the stage for an outbreak of severe thunderstorms and tornadoes.

The storms developed rapidly after 11 A.M., blossoming into a large supercell thunderstorm just north of Denver. Feeding off the contrast in temperature, humidity and the powerful winds aloft, the thunderstorm quickly intensified and dropped a tornado near Milton Reservoir around 11:30 A.M. Warnings were issued for western Weld County as radar and spotters tracked the storm.

The tornado knocked two semi trucks off Highway 85 and caused some damage in Platteville and Gilcrest as it raced to the north-northwest at nearly 50 mph. Just before Noon, the twister moved through extreme western Greeley and slammed into Windsor.

As the tornado ripped through this fast growing community, it tore through century old trees and buildings, as well as new residential neighborhoods.

The terror lasted only minutes before the tornado spun away and dissipated just east of Fort Collins, but the storm left brutal memories that will last forever. One fatality – 52 year old Oscar Manchester, dozens of injuries, hundreds of homes and businesses damaged or destroyed and a sense of vulnerability that did not exist before in the rapidly growing I-25 Corridor.

The Windsor Tornado was unusual in three ways – timing, movement and intensity. The storm struck early in the day, most Colorado twisters occur after 3 P.M. The majority of tornadoes will move in some form of a west to east direction, this one moved toward the north-northwest. Large supercell tornadoes are much more common on the far eastern plains of Colorado, having one occur so close to the mountains is very unusual – a testament to the powerful dynamics in the atmosphere that day, and a sobering reminder that our Colorado climate can create truly destructive and surprising weather.

Keep in mind, we are in "prime time" for severe weather! It is a good time of year to review your tornado and flood safety plans for work and home. If you would like some free tips and severe weather advice, please contact 24/7 WeatherCenter Forecaster/Producer Steve Hamilton . Steve will be happy to review the dangers of severe weather with you and your coworkers.

An easy first step in your weather safety plan is to pick up one of our 24/7 Weather Alert Radios! For more information, check out the 24/7 Weather Alert Radio Webpage!

However, it is not all bad news for the the weekend across the Denver area. The cold front will arrive Friday evening into the night dropping our temperatures on Satuday a bit into the mid 60s. The cold front will bring isolated May showers at times to Denver. No real heavy rain is to be expected from this cold front.

As the cold front pushes out of our state it will leave in its wake beautiful sunshine and above average temperatures. Saturday might keep you indoors a bit for a little rest and relaxation time, but don't worry Sunday will be perfect to finish planting the tomatoes and flowers in the garden.

Look for temperatures on Sunday to warm up nicely with highs in the low 80s and just wait it gets better just in time for the work week. Monday we will be pushing close to 90 and much for the same on Tuesday.

Just because we are having nice weather now doe not mean bad weather couldn't strike right around the corner. After all this is the time for server weather across Colorado. It is important to be prepared. So far, we have not had the elements necessary for our typical May thunderstorms. It does seem that things are about a month off. Think back on it. We didn't get heavy snows in March, we got them in April. Now that we're into May, we're getting capricious April-style weather; cold and drizzly, or warm and sunny. Well, Colorado's month for severe thunderstorms is yet to come...June. Be sure to check our storm chaser blogs for updates from all over the Great Plains, including eastern Colorado as the severe thunderstorm and tornado season kicks into high gear. Also, be prepared for severe weather by picking up one of our 24/7 Weather Alert Radios! It's like a smoke alarm for weather, and they do save lives!

For more information, check out the 24/7 Weather Alert Radio Webpage!

Tuesday was a hot one over Colorado as highs reached the low 90s in the southeast and mid 80s in Denver. Even the mountains were in the 70s, under a sunny sky in the morning, but a cloudy one late in the day.

The clouds rolled in along with a cold front that pushed across the state Tuesday night. In the wake of the front, temperatures will be about 15-20 degrees cooler today, with highs in the 60s.

The cold front came through with very little precipitation, just some scattered thunderstorms over the northeast corner of Colorado last night. The airmass was just too dry across our state to develop much in the way of rain - just a few hit or miss showers.

Most of May to date has been dominated by a fast moving west to east flow that has kept the air pretty dry over our state. We would need a big, slow moving low pressure system to develop over the eastern plains. Such a low would serve to pull moisture into Colorado from the southern plains and even the Gulf of Mexico. We just have not had one of these storm system develop for a while, so the pattern has stayed pretty dry over Colorado.

The reason so many destructive storms happen in the spring is essentially the clash of differing air masses. Cold, dry air bumping into warm, moist air usually results in turbulent weather. Except, this, all we will have here is dry air. When the air lacks sufficient moisture, even strong daytime heating will not generate thunderstorms. The ingredients necessary for a healthy thunderstorm are lift, moisture, shear and instability.

All of these ingredients need to be in place, in the right amount, at the right time. So far, we have not had the elements necessary for our typical May thunderstorms. It does seem that things are about a month off. Think back on it. We didn't get heavy snows in March, we got them in April. Now that we're into May, we're getting capricious April-style weather; cold and drizzly, or warm and sunny. Well, Colorado's month for severe thunderstorms is yet to come...June. Be sure to check our storm chaser blogs for updates from all over the Great Plains, including eastern Colorado as the severe thunderstorm and tornado season kicks into high gear. Also, be prepared for severe weather by picking up one of our 24/7 Weather Alert Radios! It's like a smoke alarm for weather, and they do save lives!

For more information, check out the 24/7 Weather Alert Radio Webpage!

In Colorado, we expect May to bring soggy thunderstorms, strikes of lightening and even some snow flakes! Yes snow, remember last year when Colorado saw 3.1 inches of snow accumulation on May first and a few more flakes on the 14th? With the spring snowstorm we saw at the end of April this year, I would imagine nobody is disappointed that May 1st 2008 did not repeat itself...

This year we have seen a fairly mild start, relatively speaking. The storm system that moved through on the 2nd and 3rd of may brought only 0.09 inches of precipitation to Denver. With an average of about 2.32 inches of precipitation for the month of May, we are anticipating a few more storms before June comes along. We might actually start seeing this month's rainfall totals increase by the middle of next week. This week we saw a high pressure ridge sitting over the Western US. As a result, Colorado saw westerly flow bringing dry, hot air down the eastern side of the Rockies.

A low pressure system off the northwest coast of the US will start moving inland, bringing a troughing pattern with it. This western trough begins to intensify on Tuesday and moves closer to Colorado on Wednesday. What does that mean? It means cloudy conditions, slightly cooler temperatures and stormy weather! The models are showing this atmospheric trend remaining in place for the remainder of next week which means that these stormy conditions will most likely bring us through the weekend.

May is considered to be the wettest month of the year, so these stormy conditions were bound to arrive sooner or later! Want a little good news? The average temperature for the month of May is around 70 degrees, so at least the temperatures are typically pleasant!

May in Colorado can mean turbulent weather as we see a return to our old friend, the thunderstorm. As the sun climbs higher in the sky, and the days lengthen, we see an increase in surface temperatures. However, the air higher up is still cool. Warm air near the surface wants to rise, and the cooler the air above it, the faster it moves. This is one of the basic rules for thunderstorms and severe weather. Conditions can quickly change, and what starts off as a sunny morning can often turn to a dark and stormy afternoon. We all remember the big Windsor tornado that devastated that community on May 22 just last year.

Tornadoes, lightning, damaging downburst winds, hail and forest fires are among the many severe events that can occur during the spring and summer. When severe weather strikes, being prepared is very important and being aware is crucial to saving lives.

What happens when you are camping and the clouds start taking on an ominous look? Television is not accessible, so what do you do? What happens at the office, when a television may not be readily available? You could call a friend or family member and ask for an update on weather conditions where you are, but this could be a waste of valuable time...and by the time the "phone a friend" concludes with "tornado warning" it may be too late...

For this reason, the 24/7 Weather Team recommends adding a 24/7 Weather Alert Radio to each household, school and place of business. About the size of a transitor radio, this discrete device has the power to protect yourself and loved ones from potentially dangerous weather. One feature that makes these radios so convenient is the fact that they can be programmed to only relay information based on the county specified by you! After specifying the counties that you want to information about, these radios will provide information regarding any advisory, watch or warning issued by the National Weather Service. During this time of increased homeland security risks, these radios will also provide any civil defense, national emergency, chemical spill, or other non-weather related warnings as they pertain to your specified region. '

It is recommended to keep these radios plugged into a wall, but during a power outage or should you want to bring these small information centers on your fishing adventure or to the little league baseball game, three AA batteries are all you need. Different than other radios, this one will remain silent except for during the event of severe weather. These make great gifts for the graduate, the tailgater, the camper, the fisher, the hiker, the boater, fathers, mothers, daughters, sons, grandparents, the list goes on and on!

Due to the importance of these devices, they are currently being sold for the low price of $29.99. These radios usually retail for $49.99! So when you are unable to catch the alerts presented by the 24/7 Weather team, make sure that your 24/7 Weather Alert Radio is near because you never know when Mother Nature will take a turn for the worst...

For more information, check out the 24/7 Weather Alert Radio Webpage!

Now you are prepared for the hazardous weather conditions...but want to know what causes them? Then check out a copy of my book, THE COLORADO WEATHER ALMANAC. The book is available at all local bookstores, or you can order it on-line from this website MIKE'S COLORADO WEATHER ALMANAC!

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