Bill Kappel’s Snow Season Summary  

Snow Season Summary 2007 to 2008
July 1, 2006 to June 30, 2007
Lat 39.0994 N Lon 104.7636W El. 7371’

Summary Tables for the Season

Summary of the Snow Season’s Weather  

July 2007:
July turned out to be right about average for most of us, although we started out warm and dry, cool, wet weather at the end of the month brought us back to normal in the temperatures department and produced enough rainfall to get us up to average.  However, as is typical this time of the year when the majority of our precipitation falls from thunderstorms, the rainfall amounts across the Tri-lakes varied quite a bit. 

The first full week of July was quiet and warm, with only a couple of scattered, weak thunderstorms that didn’t produce much more than some brief showers. This made for nice weather on the 4^th of July for all the festivities, but it would be nice to get some soaking showers.  Highs from the 1^st through the 9^th stayed in the 80’s to low 90’s through the entire period, with overnight lows in the upper 40’s to mid 50’s, not making for the best of sleeping weather for those of us without air conditioning. 

The second week of July started off with some active weather as several rounds of thunderstorms developed during the afternoons of the 11^th and 12^th.  Temperatures were held down as well, with highs holding in the mid 70’s to low 80’s.  The storms produced a half inch to a couple of inches of rainfall, along with some hail, over the two day period.  This was a bit a nice relief after things had gotten pretty dry over the last few weeks.  Weather conditions were quiet over the next several days, with dry and warm weather returning.  Highs returned to the 80’s and low 90’s through the weekend of the 14^th and 15^th.  Skies remained mostly sunny to partly cloudy as well, making for some nice weather to enjoy the beautiful outdoors. 

Hot and dry weather returned during the third week of the month, with highs holding in the upper 80’s to low 90’s.  Only a few, weak thunderstorms developed to help cool things down a little.  A couple locations around the region picked up some decent rainfall, but most of us missed out.  Be sure to check out www.cocorahs.org to see who got rain and who didn’t.  It’s a great resource this time of the year because afternoon and evening thunderstorms can be so hit or miss.  Temperatures did cool down to below average levels briefly on the afternoons of the 19^th and 20^th, dipping into the lower 80’s and upper 70’s, but bounced right back to the low 90’s on the 21^st. 

The final week of the month saw a return to much higher levels of moisture.  This produced plenty of clouds and thunderstorms.  Because these storms were able to tap into the abundant moisture available, heavy rains, more typical of a tropical type downpour, were seen across the region, especially from the 26^th through the 30^th.  The heaviest of the rains occurred during the early evening of the 30^th, when two separate storms developed over the area and produced 1-2 inches of rain in a short time.  This led to some minor field flooding and lots of lightning.  These are the best types of storms for us however, because they rarely produce any damaging hail or severe weather.  The storms also held temperatures down during the end of the month, with highs in the 70’s to low 80’s from the 26^th through the 31^st. 

August 2007:
After a dry start to the summer where June and the first half of July received well below normal precipitation, August saw a return to heavy rain and strong thunderstorms.  These rounds of heavy rain this month have now erased our moisture deficit and we are now again well above normal for rainfall so far this summer.  In fact, we are right as last year’s snow season precipitation pace, in which we received over 30 inches of precipitation for the 12 month period.  Overall the month was above normal for temperatures and well above normal for precipitation.

Many areas received well over 3 inches of rainfall during the first week of the month, making up for the deficit a little too quickly.  Rain as heavy as we’ve seen it at times has caused some problems with flash flooding across the area.  During the beginning of the month, the strongest storms developed during the late afternoons and early evenings of the 5^th and 6^th, when thunderstorms strengthened quickly to our west/southwest and raced over the region.  The storms on the 5^th dropped heavy rain, especially from Black Forest Road eastward, with 2-3 inches being reported by several of your neighbors.  The next afternoon, severe storms moved through between 5pm and 6pm.  These again produced heavy rains, but this time they were also accompanied by wind driven hail.  The created quite a pounding for many of our homes and plants, but fortunately these moved through quickly, limiting any major problems. 

Thunderstorms continued dropping localized areas of heavy rain across portions of the region during the second week of the month.   The good news with the storms up to this point was that the environment has been very “sub-tropical” in that the freezing levels have been high and the winds aloft have been weak.  This is important because it prevents the storms from becoming severe, so we didn’t have to deal with any damaging hail or tornadoes-this of course changed by the end of the month.  Unfortunately, this also means the rain come fast and hard, often leading to flash flooding.  And of course, the storms have been accompanied by plenty of lightning, which is always dangerous.  The atmosphere dried out briefly from the 8^th through the 10^th, before moisture returned for the 11^th and 12^th, dropping another .25 to 2 inches of rainfall.  Temperatures warmed throughout the week as well, with highs a little below normal on the 6^th and 7^th, only reaching the mid to upper 70’s.  Then jumping to the low to mid 80’s from the 8^th through the 12^th, which is slightly above normal.   

Rainfall amounts continued to be above normal for the week of August 13^th, with many locations picking up another 1-3 inches of rainfall.  Unfortunately, conditions associated with these storm events allowed some severe thunderstorms to develop, especially on the 14^th and 18^th.  These storms produced, hail, strong winds, and flash flooding for several areas around the Palmer Divide.  The heaviest pockets of rain were very localized as is typical with these summer thunderstorm patterns.  Be sure to check out the CoCo RaHS web site at www.cocorahs.org and click on the Map tab to see how the rainfall varied across the area.  Temperatures were normal to slightly above normal for the week, with highs mainly holding in the upper 70’s to mid 80’s, however, with all the moisture around in the atmosphere, overnight lows were well above normal, dropping back only to the 50’s for most of us.  But don’t worry too much; it won’t be long before we start experiencing our first below freezing overnight lows, usually around mid September. 

The week of the 20^th started off on the dry side, with clear skies bringing a nice relief from the heavy rains earlier in the month.  High temperatures jumped up above normal during this timeframe as well, reaching into the mid and upper 80’s.  Of course, this weather pattern didn’t last long, as more moisture moved into the area with a round of severe thunderstorms just to our east on the 22^nd.  However, on the 23^rd we weren’t quite as fortunate, as the storms that formed that afternoon pounded us with wind, rain, and large-damaging hail in some spots.  This time the storms were anchored to a passing cold front and piece of energy, which both added extra lift and moisture, while lowering the freezing level.  These ingredients led to the formation of the large hail.  The only good thing with the storms on the 23^rd was the fact that the winds which steer the storms were moving fast, and therefore moved the storms through quickly, so no one area got hit too long.  The largest of the hail was reported from the Air Force Academy east/northeast through the Gleneagle-Flying Horse are and point east from there.  After some rumbles of thunder and brief rain showers early in the morning of the 24^th, conditions again warmed up and dried out through the weekend, as high again rebounded in the mid 80’s by the 26^th.   

Cooler and wetter weather again returned to end the month, but things dried out just in time for Labor Day weekend.
   
September 2007: 
Temperatures were right on average for the month, but for the first time since June precipitation was well below normal, with less than an inch falling in most locations.  As usual, we experienced our first below freezing temperatures as we headed into the first days of fall. 

 September started off on the mild side, with highs reaching into the low 80’s from the 1^st through the 4^th.  Scattered afternoon and evening thunderstorms did continue to develop each day, with the heaviest rainfall occurring during the late afternoon and early evening of the 3^rd.  Temperatures cooled down over the next few days, reaching the 70’s from the 5th through the 8^th.  Overnight lows began to show what time of year it is as well, dipping into the upper 30’s and low 40’s on the mornings of the 7^th and 8^th.  Low clouds and fog developed on the morning of the 9^th behind a cold front, giving a nice feel of fall to the region.

 Quiet conditions were prevalent for most of the second week of September, which is typical as we transition from a summer type pattern to a fall type pattern.  Many morning were chilly, with pleasant afternoons.  However, the week started off on the cool and cloudy side, as a cold front brought upslope conditions behind it.  This led to the usual low clouds, fog, and light rain/drizzle scenario from the 9^th through the 10^th.  The moist air mass soon left the region and the 11^th through the 13^th was dry and clear.  Of course, with the longer nights and the already chilly start to the evening before, the morning lows on the 11^th were downright cold.  Many areas experienced their first freeze of the season, but the temperatures never got much below 32°F and were not cold for too long of a period, therefore most plants survived just fine.  Temperatures warmed over the next few days, reaching back into the mid to upper 70’s by the 13^th.  A weak cold front then pushed in some cooler air for the 14^th knocking highs back down to the low 60’s.  Once again however, this didn’t last very long, as westerly winds kicked in across the region on the 15^th and 16^th bringing above normal temperatures back, with high reaching the low 80’s both afternoons and making for a warm last weekend of summer. 

The last week of summer ended with quiet and dry weather, with the exception of some rain showers on the 17^th.  Highs rebounded from the 60’s on the 17^th to the low 80’s by the 21^st with plenty of sunshine for the majority of the week.  Winds also kicked up through the week, signaling a change in the seasons, where the jet stream begins to get stronger and closer to Colorado.  This often allows stronger winds to be felt at the surface, especially during the afternoon when the sun mixes up the air.  The first weekend of fall turned out to be more like summer, with highs well into the 70’s and mostly sunny to partly cloudy skies. 

The month ended much the same as it began, with lots of sunshine and seasonal temperatures.  Morning lows did dip below freezing on several nights from the 25^th through the 30^th.  The most “exciting” weather period occurred from the afternoon of the 29^th through the morning of the 30^th, when a storm system raced through central and northern Colorado.  Ahead of this storm, the jet stream moved right over us and brought with it very strong winds.  As the storm approached, wind gusts reached as high as 71mph around the Air Force Academy.  This storm quickly moved through, bringing a dusting of snow to the mountains and left behind clear, cool weather for us on the last day of the month.
   
October 2007:
As usual for the Tri-Lakes region during October we experienced tastes of summer and winter, with a little bit of fall thrown in.  Overall, the month was warmer and drier than normal, quite a change from a year ago. 

Sunny and mild conditions greeted the region to start off the month of October with highs ranging from the high 60’s to the low 80’s during the first week of the month.  This mild and dry start was briefly interrupted late on the 6^th as a cold front moved through and dropped temperatures by about 20°F on the next day.  Temperatures again warmed right back up the next day however, with highs in 60’s and 70’s under sunny skies from the 8^th through the 12^th. 

However, this was abruptly ended as storm system moved through on the 13^th and 14^th, dropping temperatures and bringing plenty of clouds.  Sunday the 14^th was our first real taste of winter, as highs held in the 30’s and snow showers were present most of the day.  However, the warm ground and generally above freezing temperatures kept the snow from accumulating to any great amount. 

 This storm served to open the door to the Pacific, as a series of quick moving storms raced through the region over the next week.  Each storm brought it own round of winds, some clouds and some precipitation.  However, two of these systems had a little more to work with than the others.   

The first one brought a little bit of everything to the area during the early afternoon of the 17^th, as rain showers, accompanied by graupel, a few snow flakes, and some rumbles of thunder pelted the region.  This system quickly cleared however, and plenty of sunshine returned for the next few days.  Temperatures again warmed quickly as southwesterly winds kicked in ahead of the next storm, which would prove to be pretty powerful. 

 The cold front associated with this storm blasted over the region around 9:30pm on the 20^th and was soon following by light snow around 10:30pm.  Snow increased in intensity during the overnight hours and by sunrise was really coming down.  As this storm continued to develop over the eastern plains of Colorado, the pressure gradient tightened, allowing for the winds to kick up.  Snow and blowing snow was common for the next few hours, as 6-12 inches accumulated and blew around.  Colder air also continued to filter in during the day, with high temperatures only reaching the upper 20’s and low 30’s.  Skies quickly cleared during the evening as the storm moved out of the region, and this allowed temperatures to plummet into the single digits and low teens by the morning of the 22^nd.  Temperatures again warmed over the next few day, going through the 50’s, 60’s, and into the low 70’s under clear skies.  This helped to melt most of the snow and bring quiet conditions to end the month with one brief exception as we did have one more weak cold front move through on the 26^th, and this brought low clouds and cooler temperatures for the 27^th.  Sunshine and above normal temperatures again returned through the 30^th, before a final push of cooler air moved in on Halloween.
 
November 2007:
As expected, we experienced a little bit of everything this November, with 70 degree highs and sunny skies to sub zero lows and a little bit of snow.  Overall, the month was warmer than normal and drier normal.   

November started off much like October ended with sunny skies and mild temperatures.  Highs took a little bit of a roller coaster ride and a couple of dry cold front pushed through the area.  We hit the 60’s and low 70’s on the 1^st, 3^rd, and 4^th, with 40’s on the 2^nd and 5^th.  No precipitation fell during the period; in fact barely a cloud was send during these first five days.  But don’t get too discouraged, as November is usually our driest month of the year. 

 Mild and dry has been the story so far this month.  In fact, we haven’t seen any measurable precipitation since October 21^st!  Although it would be nice to get some moisture, November has been the driest month of the year over the last 6 years.  Therefore, to get no moisture when the average is less than an inch for the month anyway is not as significant as say a very dry August where only an inch accumulates when the average is 4 inches.  Hopefully, you’ve had a chance to enjoy some of the sunshine and mild temperatures because of course this won’t last forever.  One of the reasons we’ve seen such a dry, mild pattern is the fact that a La Nina pattern has set up.  When this occurs, the storm track doesn’t favor Colorado, and this has been the case so far this season.  For more information on La Nina check out the following Web site http://www.elnino.noaa.gov/lanina.html. 

More of the same for the second week of November, with mild temperatures and dry conditions.  There was one brief exception as a cold front moved through late on the 13^th.  This brought much colder temperatures, but once again, this front was moisture starved.  We did get a dusting of snow during the morning of the 14^th and highs stayed right around freezing that afternoon.  Then mild and dry conditions moved right back in to finish out the week with highs reaching back into the 50’s and 60’s form the 15^th through the 19^th.   

Finally, after a month of dry and mild weather, winter made a return appearance to the region, with snow, wind, and cold arriving on the on the 21^st.  The first in a series of cold front moved through during the late morning of the 20^th and the atmosphere soon became saturated.  By evening, clouds had filled in and as another surge of cold air infiltrated the area, snow began to fall just before midnight on the 20^th.  Unfortunately, this system was moisture starved, but most of us picked up 2-3 inches of snow by the afternoon of the 21^st.  The biggest shock was the cold, highs struggled to reach the mid 20’s on the afternoon of the 21^st.  Another reinforcing shot of cold moved in late on Thanksgiving, make for a cold, blustery Black Friday.  Highs on the busiest shopping day of the year stayed in the upper teens and low 20’s.  The next morning was the coldest of the season so far, as lows dipped below zero at many locations.  However, plenty of sunshine returned that day as highs finally broke back above the freezing mark.   

The rest of the month saw an active weather pattern, with a cold front followed by a warm up about every other day.  Each of these quick moving systems brought gusty winds and colder temperatures, but little in the way of snowfall.  We did pick up another half to one inch of snow early on the 28^th, but that didn’t help put much of a dent in the overall dry conditions for the month.
 
December 2007:
Much like the past few months, December started off mild and dry with temperatures above average each of the first few days, but winter soon made and appearance that brought several bouts of cold and snow to the region from the second week of the month through New Year’s Eve.  During that period, temperatures were below normal on 22 out of 24 days and over two feet of snow fell.  The month overall received above normal snow fall, although not nearly as much as last year, and was below normal for temperatures.  This was definitely a nice combination after a couple of warm and dry months.   

Highs hit the 50’s on the 1^st, dropped to the 40’s on the 2^nd and jumped way up into the 60’s on the 3^rd and 4^th and amazingly low temperautres didn’t even fall below freezing on the morning of the 4^th.  Hopefully you had a chance to enjoy it, as big changes soon swept in as the weather pattern finally took a turn towards winter.  The first in a series of cold fronts moved through on the 5^th, keeping highs in the mid 40’s.  However, this first surge of cold air had no moisture to work with, so we remained mostly sunny.  A second surge soon followed late on the 6^th, and this time some light snow fell as fog and low clouds settled in.  Temperatures continued to cool as well, with highs only reaching the upper 20’s and low 30’s on the 7^th as around an inch of snow accumulated.  Another surge of cold air moved in during the early morning hours of the 8^th, again bringing another round of light snow.  Highs on the 8^th were reached at midnight with daytime temperatures holding in the teens as 2-4 inches of snow accumulated. 

 Winter held its grip on the region for the second week of December.  Monday the 10^th saw a strong cold front move through late in the afternoon.  Soon after the front passed, snow began to fall during the early evening hours and continued into the morning of the 11^th.  Most of us received 3-6 inches of fresh snowfall and temperatures remained cold.  Highs on the 11^th struggled to reach the low 20’s and with some gusty winds it felt even colder.  Sunshine returned for the next two days, and we actually managed to break above the freezing mark just barely on the afternoon of the 12^th as highs reached into the low 30’s.  However, this was short lived, as more cold air pushed into the region in two separate surges, the first on the 13^th and the next on the 14^th.  Neither brought much moisture, as we were only able to squeeze out 1-2 inches of snow on the 14^th, but temperatures sure did plummet.  Highs on the 13^th only reached the mid 20’s, and then we struggled to reach the upper teens on the 14^th.  Finally, as skies cleared overnight on the 14^th into the morning of the 15^th, temperatures tumbled, reaching well below zero.  Temperatures did rebound nicely over the next couple of days under sunny skies, going through the 30’s on the 16^th to the 40’s on the 17^th. 

Wintry weather stuck around fro much of the Christmas week as well with three separate storm systems racing through the region from the 21^st through the 27^th.  The first storm brought snow and wind from the afternoon of the 21^st to the early morning of the 22^nd.  Most of us received 4-6 inches of snow which caused some travel headaches around the region.  A brief respite between storm allowed temperatures to jump into the 30’s and 40’s over the next couple of days, but just in time for Christmas the next storm moved in.  Snow and wind again blanketed the region all day on Christmas, providing for a very nice holiday feel. This storm again deposited 4-6 inches across the area.  The final of the three systems was the coldest, but also the driest.  This storm dropped 2-4 inches across the area on the 27^th, and by the morning of the 28^th as skies cleared, temperatures again dropped well below zero.  A final cold front moved through on just before the New Year, but only a few light snow showers developed, but this front did bring a reinforcing shot of cold air for New Year’s Eve.
  
January 2008:
For the second month in a row, temperatures were below normal and we had a nice amount of fresh snowfall.  Our typical January thaw didn’t materialize until the end of the month, when warm southwesterly winds blew in ahead of a strong west coast storm system on the 26^th and 27^th.  Overall, temperatures were below normal and precipitation was right around normal.  Ten mornings during the month saw low temperatures dip to zero or below, bottoming out in the teens below zero on the 16^th and 17^th.   

The first day of the year was very cold, starting off well below zero and only reaching to around 20°F during the afternoon.  Temperatures moderated over the next few days reaching all the way to the upper 40’s and low 50’s from the 3^rd to the 5^th.  However, this warm-up was short lived as more cold air and unsettled conditions moved in on the 6^th.  Varying amounts of snow fell from the 6^th through the 9^th with 5-8 inches accumulating around the region.  Conditions dried out over the next week, but temperatures never warmed much.  Under mostly clear skies, morning lows often dipped to below zero, with afternoon highs remaining in the 30’s from the 10^th through the 14^th.  This allowed plenty of snow to remain on the ground through the period as well. 

Cold and wintry weather stuck around from the 14^th through the 21^st.  We did manage to reach into the low 40’s for high temperatures on the afternoon of the 15^th, but again another surge of arctic air moved in quickly on the evening of the 15^th.  Temperatures tumbled behind this cold front, with highs during the day on the 16^th only reaching into the single digits.  Making things feel even more wintry was the fact that 2-4 inches of fresh snow fell throughout the morning and afternoon.  Skies quickly cleared out that evening and with the fresh snow and cold air mass, it got downright cold.  Low temperatures on the morning of the 17^th were in the teens below zero for most of us.  Temperatures did manage to rebound to the 20’s during the afternoon, but another cold front was headed our way.  This one brought another round of light snow, dropping around 3 inches of very fluffy snow on the 18^th.  Conditions quieted down over the next couple of days, with temperatures again rebounding above freezing on the 20^th.  Once again however, more cold air was just waiting to rush in as another surge of Arctic air moved into the region during the late afternoon of the 20^th.  This one was again accompanied by some very light snow, freezing fog, and plenty of beautiful rime ice.

Cold temperatures and areas of very light snow stuck around through the 25^th as highs moved from the teens on the 21^st to the 30’s by the 24^th.  Mild and windy conditions then moved in ahead of a strong storm system moving out of the southwestern United States.  This type of storm pattern keeps us dry, mild, and windy, but brings lots of snow to the mountains.  This storm moved over the area during the night of the 28^th into the morning of the 29^th.  This brought much colder air back to the region, but the northwesterly winds kept any accumulating snow from falling around the area.  Another quick moving cold front brought our last accumulating snowfall of the month, with 2-4 inches blowing around late on the 30^th.  This also helped to reinforce the cold air and temperatures remained well below normal on the 30^th and 31^st.   
  
February 2008:
For the third month in a row, temperatures were below normal across the region.  We received close to normal moisture and snowfall, helping to add much needed moisture to the soil as we head into Spring.

 The month started of with a quick moving cold front which raced through the region during the evening hours of the 1^st, bringing a shot of light snow and cooler temperatures.  Highs on the 2^nd struggled to reach the mid 20’s under partly cloudy skies.  Temperatures did rebound into the 30’s on the 3^rd and 4^th, but more cold air and snow was headed our way on late on the 4^th through the 5^th as colder air filtered into the area and snow began to fall.  Between the mid afternoon of the 4^th through the morning of the 5^th 4-6 inches of fresh snow accumulated throughout the area.  Temperatures were cold, with highs holding in the teens on the 5^th and morning low temperatures dipping just below zero.  Over the next few days, several fast moving weather systems brought intervening blows of cold air with light snow and brief warm-ups with gusty winds.  The most interesting of these events occurred late on the 7^th when a band of heavy snow set up over the area.  This was a very localized event with 3 inches falling in one hour between 11pm and midnight over just the Palmer Divide from about Furrow Rd through Black Forest Rd.  Temperatures reached into the low 30’s the next afternoon, then warmed to the mid and upper 40’s through the weekend. 

Unsettled and generally cold weather conditions prevailed from the 11^th through the 17^th as a series of fast moves storms races across the region.  None brought heavy snow to the Tri-Lakes, but some light snow did accumulate at times.  On the 11^th, 1-2 inches accumulated around the area, with warmer air briefly making an appearance behind this system, as highs reaching into the low 50’s on the afternoon of the 13^th.  This was only the second time so far this year that we’ve topped 50° for high temperatures (January 27^th was the other).  However, this warm-up didn’t last long, as another cold front moved in on Valentine’s Day, with highs staying below freezing.  Just a dusting of snow fell, but it certainly felt wintry throughout the day.  Another break between systems moved in from the 15^th to the 16^th as highs again rebounded into the upper 40’s.  However, and even stronger surge of cold air moved in quickly late on the 16^th.  This again brought some light snow, generally 1-3 inches, and much colder temperatures as highs on the 17^th only reached into the teens during the day. 

Conditions dried out as we ended the month, but temperatures continued their wild swings.  Highs jumped between the 30’s, 40’s, and 50 during the last week of the month a several storms of Pacific origins moved through the area.  These storm brought more heavy snows to our mountains (good news for reservoir storage and summer runoff, check the current mountain snowpack levels at http://www.co.nrcs.usda.gov/snow/snow/state/current/daily/maps_graphs/index.html), but only brief light snow to the tri-Lakes on the 22^nd, 23^rd, and 25^th.  This pattern represents a subtle change for the area as we head into Spring.  The last accumulating snow fall of the month occurred on the 26^th, when 1-3 inches of snow fell.  Skies cleared quickly behind this last system, and temperature rebounded to above normal levels as we ended the month.
   
March 2008: 
An active weather pattern continued to affect the region during most of March, with rapid swings between cold and mild temperatures, plenty of gusty winds, and our share of snow.  For the month, temperatures were below average and precipitation was near normal.

March has started off just about how you would expect it with record highs on the 1^st and blizzard conditions on the 2^nd.  Strong winds out of the southwest raced over the region on the 1^st bringing in mild air which warmed even more as it descended down the slopes of the Front Range.  This allowed temperatures to jump into the 60’s across the area.  But these winds were ahead of a powerful Pacific storm system that was moving through the Intermountain West.  The cold front associated with this storm moved over the region around 4:30am on the 2^nd and snow quickly followed.  Snow became heavy at times during the morning as temperatures dropped into the teens.  The snowfall combined with strong winds, gusting to 50mph at times, to produce blizzard conditions during the day as the pressure gradient strengthened between the high pressure moving in behind the cold front and the area of low pressure strengthening over southwestern Colorado.  This storm moved out of the region just as quickly as it moved in with sunshine returning on the 3^rd.

Temperature warmed the next afternoon into the 40’s under a stronger March sunshine and breezy southwest winds.  However, this didn’t last long as the next storm moved into the region by evening.  Another 4-6 inches of snow accumulated across the area by the morning of the 5^th and temperatures remained cold.  High temperatures on the 5^th and the 6^th topped out in the 20’s and with morning lows dropping below zero on both the 4^th and the 6^th.  Mostly clear skies returned for the next few days until the evening of the 8^th when the next system brought more light snow through the early morning of the 9^th.  However, as usual this snow melted quickly as the sun angel continued to get stronger as we transition from winter into spring.

The week of the 10^th started off with quiet weather with mostly sunny skies and mild temperatures.  Highs were in the upper 40’s to upper 50’s through the afternoon of the 12^th.  Subtle changes began to take place on the 13^th as the jet stream began to take aim at Colorado.  This put us in for a roller coaster ride of sorts as several fast moving weather systems affected the Tri-Lakes region.  From the morning of the 13^th through the morning of the 17^th, each day saw at least a trace of snow and during the entire period most of us picked up 5-7 inches. However, much the snow melted under the stronger March sunshine so overall accumulations were never that great, but it was a cold and white period.  The jet stream then took a detour to the north from the 18^th through the 21^st which allowed us to clear out and warm up.  Temperatures jumped from the mid 40’s to the low 60’s from the 18^th through the 20^th, allowing spring to start off on a quiet and mild note.  More unsettled and cold weather moved in during the morning of the 22^nd, with light snow falling through the morning of the 23^rd.  Most areas received 2-4 inches of snowfall with this latest storm.

The last week of the month started off quiet and mild as temperatures soared into the 60’s from the 24^th through the 26^th.  However, a weak surge of cold air managed to push into the area during the morning of the 27^th with a reinforcing shot on the 28^th.  These cold fronts brought low clouds, fog, flurries, and freezing drizzle to the area and cooled temperatures off by 20-30°.  Westerly winds quickly kicked this cold air out of the region on the 29^th and high temperatures rebounded into the 60’s, but another surge of cool air moved back into the region to end the month, again bringing low clouds, fog, flurries, and freezing drizzle.

 April 2008:
As is typical around the Tri-Lakes region the transition from winter to spring is never smooth.  This was the case during the first week of April as we were greeted by everything from sun to snow.  The month started off on the cold side with light snow on the 1^st and high temperatures only in the 30’s.  Temperatures warmed the next day under mostly sunny to partly cloudy skies as highs hit the 50’s.  But more cold air moved in overnight and low clouds, fog, freezing drizzle, and flurries started us off on the 3^rd.  This cold air quickly retreated as we warmed into the 50’s and 60’s from the 4^th through the 6^th.  More cool, unsettled weather returned for the 7^th with snow showers across the area during the afternoon.

 Winter tried to hold for most of the week of the 7^th with measurable snowfall occurring on the 7^th and the 9^th through the 12^th.  Most of us received 4-8 inches during this timeframe, however, as is usual this time of the year, anytime the sun appeared the snow quickly disappeared.  The strongest storm occurred on the 10^th as an area of low pressure deepened over eastern Colorado and western Kansas.  This developed a very strong pressure gradient across the area, producing very strong northerly winds.  Snow began to fall steadily that morning and continued through the early evening.  This combined with the strong winds produced blizzard conditions at times.  Just the day before, as the first affects of this system began to move into the region on the 9^th, we saw a little bit of everything around the area.  Snow showers, plain old rain, thunderstorms, and fog all occurred at some point on the 9^th, just about what you would expect for the middle of April.  During the week high temperatures ranged from the low 30’s to the high 50’s, a little below normal for this time of the year. 

Quiet, “spring-like” weather greeted us for most of the 3^rd week of the month.  The week started off on the warm side with highs jumping into the 70’s on the 14^th and 15^th along with sunny skies.  Only some gusty winds took away from the warmth.  These were the warmest temperatures we’d send since late October.  Oh, but just when you thought it was safe to put the snow shovel away, a storm system moved through the region by early the next morning.  A cold front pushed over the area around 2:30am on the 16^th and we said goodbye to the 70’s and hello to snow.  This storm brought 4-8 inches of snow to most of us from the morning of the 16^th to the morning of the 17^th.  With temperatures holding in the 30’s both afternoons.  Temperatures did quickly rebound behind the system under sunny skies, as highs reached back into the 60’s for the rest of the week and through the weekend.  Again, only gusty winds each afternoon put a damper on the otherwise quiet weather. 

 The first week of May started off with winter but ended with spring.  Snow fell on the 1^st with 2-5 inches accumulating around the region.  This made for a beautiful site, with the wet snow clinging to the trees much more proficiently than the dry snow that falls from November through March.  High temperatures held in the low 40’s on both the 1^st and 2^nd and overnight lows were in the teens and 20’s, well below average for this time of the year.  However, the first weekend of the month turned out ok overall, as drier and more seasonal conditions moved in from the 3^rd through the 5^th.  In fact, high temperatures warmed each day, going from the 50’s on the 3^rd to the 60’s on the 4^th, and into the 70’s on the 5^th.  Overnight lows were still chilly, as clear skies and dry air allowed temperatures to touch the teens and 20’s each morning.

 The week of the 5^th started out on the warm and dry side, with highs in the 70’s on the 5^th and 6^th before some changing rolled in.  Higher levels of moisture moved into the area late on the 6^th and stuck around through the beginning of the weekend.  Each day from the 7^th through the 10^th received measurable precipitation.  Regular old thunderstorms developed on the 8^th with several rounds of showers and storm moving through the area during the afternoon.  Some of the thunderstorms contained pea sized hail at times.  Cooler air began to work into the region as this pattern of unsettled weather continued to develop.  As the cold air associated with the system moved over area during the early morning hours of the 10^th, a band of heavy snow deposited around an inch of snow above 7000 feet.  Most of it melted by 10am on the 11^th, so if you slept in you probably missed it.  But scatted snow showers continued through the morning of the 11^th before cool sunshine returned for the remainder of the day. 

The week of the 12^th started of on the mild side, with highs in the 70’s on Monday afternoon, as gusty southwest winds blew in warm air ahead of a storm system moving through the Great Basin.  Things changed quickly late in the afternoon as the storm moved through with light rain developing during the evening.  Temperatures were over 30° colder the next day, with light snow and flurries off and on during the morning.  There was a brief break in between the next system, with seasonal conditions during the day on the 14^th, but by evening the effects of the next storm were being felt.  Light rain showers developing that evening and by early the net morning a band of heavy snow developed.  This dropped a quick 2-4” of snow that fell from 2am to 4am.  The 15^th continued to be active, with several round of snow showers, graupel, ice pellets, and rain showers.  Once this storm began to move out of the region the next morning, high pressure began to move into the region.  This led to clearing skies and warmer temperatures.  Highs through the weekend jumped back into the 70’s to near 80 by Sunday under mostly sunny to partly cloudy skies.

 June has started off warm and dry, with highs reaching well into the 80’s on the afternoon of the 2^nd.  Changes moved into the region on the 3^rd, as higher levels of moisture allowed areas of strong to severe thunderstorms to develop.  Large hail was the main issue with these storms, as .50” to 1.50” hail was reported around parts of the Palmer Divide.  More moisture allowed another round of storms to develop during the afternoon of the 4^th, and then the main storm system moved over the region on the 5^th.  This brought cooler air and upslope flow, which kept us cool and cloudy all day.  Highs on the 5^th only reached the upper 40’s to low 50’s.  Clear skies returned for the next few days and temperatures rebounded into the 70’s.  However, with the clear skies and dry air, overnight lows were chilly; reaching into the 30’s each morning from the 6^th through the 9^th.

 The main weather story for the second week of June was dry conditions.  However, with the dry air in place, each evening was able to cool down considerably, with overnight dropping into the 30’s every morning from the 10^th through the 15^th, with one exception, many of us woke up to lows in the 20’s on the morning of the 13^th.  This late freeze was a little unusual with the average last freeze of spring occurring around the end of May.  High temperatures reached the low to mid 80’s on the 10^th, but a cool front pushed through during the afternoon of the 11^th.  This brought high temperatures back below average as they held in the upper 60’s to mid 70’s from the 11^th through the 13^th.  Temperatures warmed again on Saturday and Sunday, rising well into the 80’s and making for a great Father’s Day weekend.

 An active weather week around the Palmer Divide starting on the 16^th, as several rounds of strong to severe thunderstorms affected the region.  Temperatures started off well below normal, with highs holding in the 60’s on Monday the 16^th, with lots of low clouds and fog, but warmer air quickly moved back in.  High temperatures rebounded to the upper 70’s and 80’s through the rest of the week and into the weekend.   Thunderstorms formed each day, with the strongest storms hitting the eastern areas of the Palmer Divide, from Black Forest through Peyton and Calhan.  Areas further to the west had drier air to work with, which kept the heaviest rains and large hail out of the area-for the most part.  As usual, most of the storms were hit and miss, with some of us picking up brief heavy rain while others picked up very little.  Be sure to check out www.cocorahs.org to see the wide variety of rainfall amounts that occur with these late spring/early summer scattered thunderstorm scenarios.  Also, they are also looking for new volunteers, as we can never have too many rain gauges reporting out there. 

The last week of the month was warm and dry, with one interruption.  Temperatures hit the 80’s and even low 90’s every afternoon from the 21^st (first day of summer) through the 30^th, except for the 28^th when a surge of cool air and clouds held highs in the 60’s.  The 90° highs on the afternoon of the 25^th marked the first 90° or above temperature for us since July 25, 2007 and was about a week ahead of when we see our first 90° high in a typical year.  Are last freeze of the season occurred just twelve days earlier when we hit the upper 20’s throughout the region.  This was a little later than normal, as our average last freeze occurs right about the last day in May.

Station Location, Topography, and Climate

The weather station location is approximately 3 miles north of the crest of the Palmer Divide, just ½ mile east of the intersection of Highways 83 and Highway 105.  I utilize a wireless Davis Vantage Pro weather station which includes a fan aspirated radiational shield and a heated rain gauge.  Several other meteorological instruments are used for backup and verification purposes and include two 4” rain gauges, and a Taylor Min/Max thermometer.  For snow measurement, I use a 36” snow stick and a snowboard for snow depth measurement and new snow fall totals, as well as standard measuring through the station location with a ruler.  Readings are taken at midnight local time each day and represent 24 hour conditions from midnight to midnight local time (Mountain Time Zone) with the exception of heavy snowfall events were readings are taken every six hours, with a 24 hour summary.  Geographically, the Palmer Divide separates Colorado Springs (~15 miles south) from Denver (~30 miles north) as a low, broad ridge generally rising 1000’ to 2000’ above these surrounding cities.  Directly to the west, the Rampart Range rises over 9500’, with the high Rockies rising to over 14000’ a little further to the west.  Many of the mountain ranges that run through central Colorado are oriented in a north south direction, perpendicular to the prevailing wind patters.  This greatly affects the weather and climate in the region, by sapping approaching systems from the west of their moisture and facilitating downslope wind events, which cause drying and warming.  To the east, the topography gradually slopes down to just under 4000’ along the Kansas border over a distance of 100 miles.  This rise in elevations from east to west along the Front Range aids in lifting air masses and helps to produce clouds and precipitation.  This condition is referred to as upslope, and generally leads to the coldest and snowiest conditions during the fall, winter, and spring months. The Palmer Divide is generally covered with Ponderosa pine above the 7000’ elevation.  Top elevations on the divide are around 7600’, with scattered buttes that rise to between 7700’ and 7800’along the Douglas and El Paso county lines.  The highest point is Bald Mountain, with a top elevation of 7881’.  The Palmer Divide has a dramatic effect on the local weather and climate of the region and extraordinary temperature and precipitation gradients are often observed within single storms and throughout the year when compared to Colorado Springs and Denver. Because of the high elevation of the divide and its location continental location, snow is often observed as early as September and as late as May.  In extreme cases, snow may fall in late August or early June.  The dry and generally sunny climate aids, along with rapidly transitioning air masses, aid in melting snowpack rapidly.  Therefore, transportation is rarely affected for more than a few days at a time because of snowfall.  Weather across the area is characterized by rapid changes, with periods of the same air mass types (cold/warm and/or wet/dry), lasting generally less than 2-5 days at a time.  Springtime is usually the wettest and snowiest time of the season, with fall a close second.  The mid winter period, December through February, is generally the driest and coldest time of the year, but because of the high snow to water ratio, snowfall amounts are similar or exceed the fall months (September through November Cold air surges from the northern high plains of North America and Canada often blast throw the region and bank up against the Palmer Divide and the Front Range bringing dramatic drops in temperatures, gusty winds, and stratiform precipitation (generally snow or freezing drizzle depending on the depth of the cold airmass) during the fall, winter, and spring.  Storms accompanied by southerly winds also bring moisture to the area, but have less affect on the north side of the divide because of weak downsloping (drying) effects.  Storms moving in from the west or southwest are mainly wind producers as they down slope off the Front Range to the west, causing the airmass to dry and warm adiabatically.  Because of the topography of the surrounding region, wide variations over short time frames are common during the snow season.  Generally, a cold surge will push through the area with a brief shot of upslope flow, which enhances precipitation, gusty north/northeast winds, and cooler temperatures.  Often west/northwest winds will follow the surges, bringing drier and warmer weather quickly to the region.  Therefore, snowfall, although a common occurrence, usually does not stay on the ground for long periods of time, except in the shaded areas.  Major storms, which can lead to blizzards in the area, most often develop when an area of low pressure develops on the lee side of the Rocky Mountains over the east central plains of Colorado or northern New Mexico.  The biggest snowstorms occur when these storms tap in moisture from the Gulf of Mexico and become cut off from the main westerly flow, sitting in the same region for several days.  This was the case during the March 17-20th, 2003 Blizzard.   These storms may or may not be accompanied with cold, arctic air masses, but often produce tight pressure gradients between areas of high and low pressure, with strong sustained winds the result.  When the winds are in a favorable “upslope” direction, when combined with other atmospheric processes, precipitation is enhanced and cools the air through the process of orographic lift and evaporative cooling processes. The coldest air of the winter season moves through the region when strong areas of Arctic high pressure move out of Canada, down through the central plains, producing north to northeast surface winds (“upslope winds) through the area.  However, these air masses are usually low in moisture content, and snowfall is usually no more than a few inches with high snow to water ratios (often 20:1 or higher).  Generally the cold air masses modify and /or move out of the area within a few days, but sometimes the can last up to a week producing low clouds, fog and snow showers.  This results in the coldest high temperatures of the winter season, where highs may remain in the teens and twenties for several days in a row.

In contrast to the cold and snow scenarios, warm and windy weather is not uncommon during the snow season.  The classic “Chinook” winds are common along the Front Range, including the Palmer Divide, and especially prevalent along and west of Interstate 25.  This occurs when Colorado is under a strong west/southwest flow aloft, with an inversion above the high mountains to the west, creating an ideal condition for the winds to mix down to the surface through turbulent mixing and mountain wave activity.  Wind speeds can often reach over 100mph across portions of the foothills of the Front Range, with the area around the Air Force Academy being a favored spot locally.  The Palmer Divide generally does not receive the strongest of the winds gusts, but temperatures still warm dramatically and relative humidities drop.  This occurs through compressional heating of the air mass as it descends and warm dry adiabatically at approximately 5.4F per 1000’ descended off the mountains to the west.  These “Chinook” winds (Native American for snow eater), are extremely affective at melting and evaporating moisture, whether it be rain or snow.  Looking at the daily temperature graphs for the winter season reveals these patterns of cold air intrusions quickly followed by “Chinook type winds and above normal temperatures.  

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07/01/2008 09:34 AM