The Weather Wire
May 2009 Volume 17 Number 05
Avg High - 58.9
Avg Low - 32.9
Snow - 7.4"
Season Snow - 38.1"
Precipitation - 3.22"
Avg High - 70.5
Avg Low - 43.8
Avg Snow - 1.3"
Avg Precip - 2.32"
2008-2009 Winter in Review
The start of the snow season can begin as early as mid to late September as the Denver Metro area averages 2.1 of snow for the month. September of 2008 was not one of those years as there was no measurable snowfall anywhere along the Front Range. Temperatures never even dropped below freezing in Denver for the entire month. Many years the Denver area can experience its first frost/freeze sometime in late September, but not in 2008.
October of 2008 continued to lack snowfall at lower elevations, but areas above 6000-6500 did receive their first snow of the season on the 11th into the 12th including Colorado Springs with up to 3 reported in northern areas of the city. Even though there was a lack of snowfall, October was above normal in precipitation in the Denver area, but at months end the precipitation deficit for the year stood at -3.89. Without snow during the month we quickly began to fall into a snowfall deficit that would not be easily be made up through the remainder of the winter season.
Some measurable snow occurred in the Denver area by the second week of November, but the month only ended up with 1.7 at DIA. Many areas of the city fared much better with 2-8 in many locations and up to a foot of snow or more in Castle Rock and higher amounts in the foothills. By months end our snow deficit stood at -15.2 at DIA. Precipitation for the month was very low with only 0.18 measured which took the yearly precipitation deficit to -4.69.
More meaningful snowfall amounts occurred in December with 10.3 reported at DIA, but overall precipitation once again was below normal which resulted in a yearly precipitation of 10.21 versus a normal is 15.29, resulting in a yearly deficit of -5.08, right around 33% below normal. With the above normal snowfall in December things were looking better, but the following months would prove to provide little in the way of snow.
January was unseasonably warm with average high temperatures running 5 degrees above normal. Some snow occurred with 4.9 at DIA, but only 0.13 of liquid water equivalent was tallied. Once again, below normal precipitation was recorded in snowfall and precipitation.
February certainly did not help snowfall amounts, as it was the least snowiest in Denver history! Only a trace of snowfall was reported at DIA and 0.04 of precipitation. Temperatures were well above normal with average highs 5.8 degrees above the norm. With the seasonal snowfall and precipitation well below normal, it appear unlikely that snowfall amounts could recover from below normal. The snowfall deficit for the 2008-2009 winter season now stood at -22.7 and we were -0.83 behind in precipitation.
March began warm and dry, but relief finally came the very last week of the month which would continue all the way through April. For March of 2009 there was 13.8 of snow compared to 11.7 on average. Almost all of the snow fell between the 25th and the 27th as one of our famous Front Range blizzards brought over a foot of snow to many locations. Precipitation fell short with 0.83 of snow water equivalent at DIA. This brought our yearly precipitation to -1.28 below normal.
A very active weather pattern persisted through the month of April with measurable snow and rain occurring 1 out of every 3 days! The largest snowfall of the year for many Front Range locations occurred from the 16th into the 18th with 1 to 2 feet of snow above 6000, but DIA only came in with 2.6 for that storm due to rain mixing with snow below 5500. This storm was loaded with moisture as we set a daily precipitation record for the day on the 16th with 1.16 in a 24 hour period. For the month DIA measured 7.4 of snow which was below the normal of 9.1 but much needed precipitation occurred with 3.22 for the month. This was 1.93 above normal and brought us right back to average in the precipitation department for the year. This was much needed moisture as we were below average last year and it was looking like we may be entering a severe drought! Many areas in and around Denver received more than 5.0 of liquid for the month! Our snowfall for 2008-2009 winter season at the end of April stood at 38.1 and normal is 60.4 resulting in 22.3 below normal snowfall.
Once example of how much snow fell in a short time is to look at Skyview Weather's office in Castle Rock. On March 26, 2009, the total snowfall for the 2008/2009 snow season was at 33.9", well below normal (seasonal snowfall for Castle Rock averages approximately 65"). Just over 1 month later on April 29, 2009 total snowfall for the season was at 76.8", an amazing increase of 42.9"! This resulted in total snowfall for the season above normal. This was not unique, many areas above approximately 5500 feet saw similar heavy snow amounts for the period (though areas below 5500 feet received less snow and more rain).
Now that we are in May our chances for snowfall are diminishing quickly, but we still average 1.3. It is unlikely that we will add any more snow this month bringing our season total to 23.6 below the normal of 61.7. Despite the large snow deficit at DIA many Front Range locations from the Palmer Divide northward are near or slightly above normal snowfall for the year with Castle Rock seeing 67.8 in town and 76.8 3 miles northeast at the Skyview Weather headquarters, Golden at 90.1, Arvada 69.7, Cherry Hills North 50.8, Boulder 75.0, Greenwood Village 62.0, Morrison 94.9, Thornton 53.1, Littleton 72.8, Westminster 66.1, Wheatridge 78.8, Lakewood Central 59.3, Lone Tree 69.7 and some higher amounts in the foothills of 87.5 in Evergreen, 121.2 at Monument Hill, 84.5 in Estes Park and 116.6 in Conifer.
One main reason for the well below normal snowfall officially in Denver is due to the fact that old Stapleton is no longer the official site for snow measurements. This is due to lower elevation and its distance away from the foothills. It cannot be stressed enough how much this may change our official snow amounts! Snow amounts will likely come in lower than what the rest of Denver is experiencing for years to come and with time our average snowfall will drop below 60 on average. Take this into account as the media will play games with these official numbers and we are now comparing apples to oranges when it comes to Denver snowfall climatology.
South of the Palmer Divide in Colorado Springs the airport only reported 17.9 of snow for the entire 2008-2009 season! Meaningful snow simply did not fall at the airport for the entire winter season. Just north of the city form the Air Force Academy northward into Monument conditions improved dramatically with near normal snowfall amounts.
Disclaimer: Skyview weather receives snowfall amounts from reliable human spotters and we use them to make generalities for certain areas and where you are located amounts may differ from the information our spotters have provided. Human errors also need to be taken into account for blowing and drifting snow and measurements reflect what falls on grass, not pavement.
Areas of drought have spread across much of eastern Colorado as well as northwest Colorado as a result of our precipitation deficit year to date.
The map below shows forecasted temperature deviances for May2009. As can be seen, it is expected that much of Colorado to have normal temperatures for the month of May 2009, with far southwestern Colorado expected to have above normal temperatures.
The map below shows forecasted precipitation deviances for May 2009. Normal precipitation is anticipated for most of Colorado May 2009, except for far southeast Colorado where above normal precipitation is forecast.
Some improvement in drought conditions is expected along the Front Range of Colorado during the May to July time period.
What a difference a month makes! By the end of March we were 1.28" below normal for precipitation for the year. At the end of April Denver was right at normal, erasing the precipitation deficit. Rainfall and snow water equivalent tallied up to 3.22" which was 1.29" above normal. Many areas of Denver and surrounding areas received much higher precipitation amounts than the 3.22" that what was reported at DIA. Snowfall on the on the other hand fell short with only 7.4" of snow compared with 9.1" being normal, this is due to the fact that old Stapleton is no longer the official measurement site for snow, DIA currently is. If the Stapleton snow numbers were used then we would have been well above normal snowfall for the month like everywhere else in town and most likely around normal for the year instead of 22.3" short. The local media is was using this change in locations to play up the drought earlier in the month and make it appear worse than it really was! The active weather resulted in temperatures being below normal for the first time this year and there was only 62% of possible sunshine. There were 10 days in the month with measurable precipitation which works out to be 1 out of 3 days for the month provided moisture.
Many people may not think of May as a very wet month because most of the precipitation does not fall as snow, but May is usually the wettest month of the year with 2.32" on average. Snowfall is possible with 1.3" of snow on average, but there are many years with no measurable snowfall at all. Temperatures really warm up this month with a 10 degree temperature gain for average highs compared to April. May is also when we typically get our last freeze or frost for the season and people can begin to plant tender vegetation at the lower elevations. The foothills are a different story with wet spring snow common and a threat for freezing up to the end of the month. May is tied with November as the least sunny month on the calendar year with 64% of possible sunshine on average. Thunderstorms become more common with 6 thunderstorm days on average throughout the month. With the active weather from the end of March through the month of April it is unlikely that this weather pattern can continue which makes me think that this month will be slightly drier than average, but we should still get some good rainfall with some wet snow still likely in the mountains and foothills.
Sunrise/Sunset (Jul - December Denver area)
October 2008 to April 2009