June 2021 Volume 28 Number 6

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The Weather Wire

June 2021 Volume 28 Number 6

Updated Colorado Snowpack Map

Late season snowfall and below normal temperatures has helped to keep the S. Platte river basin well above 100% snowpack while the remainder of the state suffers with well below normal snowpack for early June standards. The lack of snow over large portions of western CO will result in a potentially active fire season and minimal runoff in the major river drainages.

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Selected Season Snow Totals (Sept 2020-May 2021)

One of the longest snow seasons in many years occurred this season with the first snow occurring on September 8-9th, 2020 and the last for most areas on the 10-11th of May, 2021. DIA only reported a trace on the 10-11th with the last official snow on the 21st of April, but DIA does not represent the majority of the Denver Metro area very well… 244 days passed from the first to the last snow which means the snow season was 67% of an entire year! There are very few places with a longer snow season than the Front Range of Colorado. With such a long snow season snow totals ended up well above normal for many areas along the I-25 corridor from Fort Collins to Castle Rock. Below are some selected snow totals for the 2020-21 season: Allenspark – 173.7” Arvada – 79.4” Boulder – 103.5” Castle Rock – 95.6” Conifer – 159.5” Evergreen – 134.0” Fort Collins – 76.3” Glendale – 82.4” Golden – 98.6” Littleton – 85.2” Nederland – 174.6” Sedalia – 98.7” Wheat Ridge – 90.6”

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May Rainfall Map (Denver Metro Area)

Below is a 30 day rainfall map of the Denver Metro area. Some rain gauges may be contaminated with sprinkler system activity or may not have been operational the whole month but overall this map will give you a good idea of the precipitation that fell during the month. In and around the City of Boulder tallied the most rain with many locations reporting well over 5” for the month!

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Drought Update

Drought conditions in Colorado have improved dramatically E of the Continental Divide with the abundant moisture as of late. Currently we are drought free over NE CO! Western portions of the state continue to experience areas of extreme to exceptional drought.

The map below shows forecasted temperature deviances for June 2021. There is a bias over all of CO for above normal temperatures during June. However, this same product said the same for May and we ended up being below normal over NE CO.

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The map below shows forecasted precipitation deviances for June 2021. There is a bias towards below normal precipitation over the entire state. However, this same product said near normal to below normal precipitation for May and we ended up being well above normal from Cheyenne to Trinidad, so take these products with a grain of salt…

Western CO along with nearly all areas W of the Continental Divide to the Pacific Ocean will continue to see drought conditions persist during the month of June with an active fire season expected over the western US.

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May Summary

The active weather in April continued into May of 2021 with slightly below average temperatures and well above normal precipitation. The snow season came to an end for many areas on the 10-11th of May with the last snow observed along the I-25 corridor. Average highs for May were 68.1 degrees, 3.1 degrees cooler than the normal of 71.2 degrees. Average lows were 44.1 degrees, 0.5 degrees above normal. Combining the average high and low for the month resulted in a monthly mean temperature of 56.1 degrees, 1.3 degrees below the normal of 57.4. The last freezing temperature at DIA was on the 12th at 32 degrees. Precipitation for the month was 3.65” at DIA, 1.49” above the normal of 2.16”. Most areas in and around the Denver Metro area reported between 3.5-5” of moisture with isolated higher and lower amounts. There were 13 days during the month with measureable precipitation or 42% of the total days in May. Normally, about 33% of the days in May produce measureable precipitation and it is one of our wettest months of the year. DIA only reported a trace of snow which was slightly below normal. The season snow total at DIA stands at 80.2” which is 26.4” above normal (53.8”) and the most snow reported in a season since 1983-84 when 80.9” of snow was tallied. May lived up to its reputation of being a wet month along the Front Range overall with a high frequency of storms and above normal precipitation for all areas along the I-25 corridor from Fort Collins to Castle Rock.

Over SE CO the trend of well above normal precipitation and slightly below normal temperatures continued. The average temperature in Colorado Springs was 55.9 degrees for the month which was 1.2 degrees below the normal of 57.1 degrees. The airport in Colorado Springs reported 3.98” of moisture for the month which was 1.99” above normal and makes May of 2021 the 16th

wettest on record. Snowfall at the airport was 1.7”, 1.1” above normal and makes May of 2021 the 19th

snowiest on record for Colorado Springs. The season snowfall for Colorado Springs is 54.3” which is 21.8” above normal and makes the 2020-21 snow season the 17th

snowiest on record! The all time record snowfall in Colorado Springs is 89.4” set back in 1956-57. There was a total of 16 days during the month with measureable precipitation of 0.01” or more which was 52% of the total days in May. In Pueblo temperatures were also slightly below normal for the month of May with an average temperature of 60.2 degrees, 1.2 degrees below normal. Pueblo reported even more rain than Colorado Springs with a whopping 4.95” reported, 3.38” above normal and makes May of 2021 the 3rd wettest on record! Season snowfall for Pueblo was 37.4” which is 9.1” above normal for the season and is the 30th

snowiest on record. Below is a map showing precipitation and temperature trends for the month of May.

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May Stats

TEMPERATURE (IN DEGREES F)

AVERAGE MAX 68.1 NORMAL 71.2 DEPARTURE -3.1

AVERAGE MIN 44.1 NORMAL 43.6 DEPARTURE 0.5 MONTHLY MEAN 56.1 NORMAL 57.4 DEPARTURE -1.3

HIGHEST 86 on 5/1, 5/7 LOWEST 32 on 5/12

DAYS WITH MAX 90 OR ABOVE 0 NORMAL 0.8 DAYS WITH MAX 32 OR BELOW 0 NORMAL 0.0 DAYS WITH MIN 32 OR BELOW 1 NORMAL 1.9 DAYS WITH MIN ZERO OR BELOW 0 NORMAL 0.0

TEMPERATURE RECORDS

NA

HEATING DEGREE DAYS

MONTHLY TOTAL 279 NORMAL 261 DEPARTURE 18 SEASONAL TOTAL 5901 NORMAL 5812 DEPARTURE 89

COOLING DEGREE DAYS

MONTHLY TOTAL 9 NORMAL 26 DEPARTURE -17

YEARLY TOTAL 9 NORMAL 27 DEPARTURE -18

PRECIPITATION (IN INCHES)

MONTHLY TOTAL 3.65 NORMAL 2.16 DEPARTURE 1.49 YEARLY TOTAL 10.49 NORMAL 5.57 DEPARTURE 4.92 GREATEST IN 24 HOURS 1.28” 5/22-5/23

DAYS WITH MEASURABLE PRECIP. 13

SNOWFALL (IN INCHES)

MONTHLY TOTAL TR NORMAL 1.1 DEPARTURE -1.1

SEASONAL TOTAL 80.2 NORMAL 53.8 DEPARTURE 26.4 GREATEST IN 24 HOURS TR on 5/1 5/10, 5/11

GREATEST DEPTH 0.0”

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WIND (IN MILES PER HOUR)

AVERAGE SPEED 9.4 mph PEAK WIND GUST 46 mph from the WNW on 5/2

MISCELLANEOUS WEATHER

NUMBER OF DAYS WITH

THUNDERSTORM 9 NORMAL 6 NUMBER OF DAYS WITH HEAVY FOG 5 NORMAL 1 NUMBER OF DAYS WITH HAIL 0

NUMBER OF SUNNY DAYS 4 NUMBER OF PARTLY CLOUDY DAYS 21

NUMBER OF CLOUDY DAYS 6 AVERAGE RELATIVE HUMIDITY NA

June Preview

June is typically the peak of severe weather season for the Denver Metro area and eastern Colorado, with an overall average of 10 thunderstorm days during the course of the month. More tornadoes occur in June in Colorado than any other month of the year, with the greatest threat occurring for areas east of I-25, but occasionally tornadoes can occur across central and western portions of the Metro area. The threat for large hail is also higher during June compared to other months. The Pikes Peak region and portions of the Palmer Divide experience more hail than many areas of the Country. Average temperatures continue their upward trend during June, which is the first month of meteorological summer. The average high temperature during June is 82.4 degrees, with an average of 9 days exceeding 90 degrees during the month. The average low temperature for the month is 52.3. Freezing temperatures are very rare in Denver during June, but it has occurred in the past with an all-time monthly record low of 30 occurring in 1951. Snow is also extremely rare in June in Denver, but it has occurred before with a record amount of 0.5” occurring in 1953. Average precipitation in June is 1.98”, making it the third wettest month on average behind May and July using the 1981 to 2010 climate data set. Often, the bulk of the month’s precipitation can occur from just one or two heavy thunderstorms, and precipitation amounts tend to be more variable in June than during other months due to the convective nature of precipitation. Will the active weather this spring continue into the month of June 2021? If you believe the drought monitor and its projections for the month of June it will feature slightly above normal temperatures and below normal precipitation. Skyview Weather believes that many areas will experience slightly above or below normal precipitation and near normal temperatures.

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DENVER'S MAY CLIMATOLOGICALLY NORMAL (NORMAL PERIOD 1981-2010 DIA Data)

TEMPERATURE AVERAGE HIGH 82.4 AVERAGE LOW 52.3 MONTHLY MEAN 67.4 DAYS WITH HIGH 90 OR ABOVE 8 ‘DAYS WITH HIGH 32 OR BELOW 0 DAYS WITH LOW 32 OR BELOW 0 DAYS WITH LOWS ZERO OR BELOW 0

PRECIPITATION

MONTHLY MEAN 1.98” DAYS WITH MEASURABLE PRECIPITATION 8 AVERAGE SNOWFALL IN INCHES 0.0” DAYS WITH 1.0 INCH OF SNOW OR MORE 0

MISCELLANEOUS AVERAGES

HEATING DEGREE DAYS 133 COOLING DEGREE DAYS 62 WIND SPEED (MPH) 8.9mph WIND DIRECTION South DAYS WITH THUNDERSTORMS 10 DAYS WITH DENSE FOG <1 PERCENT OF SUNSHINE POSSIBLE 70%

EXTREMES RECORD HIGH 105 on 6/25/2012, 6/26/2012 RECORD LOW 30 on 6/2/1951 WARMEST 75.0 in 2012 COLDEST 60.6 in 1967 WETTEST 4.96” in 1882 DRIEST TR in 1890 SNOWIEST 0.5” in 1953

LEAST SNOWIEST 0.0” in numerous years

Snowfall

October 2020 to May 2021

City Sept Oct Nov Dec Jan Feb Mar Apr/May* Total

Aurora (Central) 1.0 3.3 5.2 6.5 3.7 17.1 25.8 8.2/0.5 71.3 Boulder 5.7 12.5 7.5 6.2 6.0 19.6 27.8 18.0/0.2 103.5 Brighton 0.6 5.6 6.7 6.2 4.0 11.4 26.1 9.6/0.0 70.2 Broomfield 1.5 8.0 5.1 5.7 4.9 14.9 25.7 11.4/2.0 79.2 Castle Rock 2.8 7.0 3.8 9.2 5.9 16.2 33.4 14.3/3.0 95.6 Colorado Springs 2.6 3.2 0.2 5.1 7.9 13.6 14.6 5.4/1.7 54.3

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Denver DIA 1.0 4.0 5.0 7.0 3.1 13.5 34.0 12.6/TR 80.2 Denver Downtown 1.5 4.7 6.0 7.1 3.0 16.8 25.6 12.0/0.8 77.5 Golden 2.8 6.7 7.2 8.1 2.8 17.0 39.9 14.1/TR 98.6 Fort Collins 2.3 14.5 3.7 7.0 5.2 9.5 19.8 11.6/2.7 76.3 Highlands Ranch 2.6 6.3 5.3 6.3 2.9 17.3 32.0 12.2/2.3 87.2 Lakewood 2.4 5.0 7.4 6.5 3.0 13.1 30.2 14.8/TR 82.4 Littleton 3.0 6.8 7.1 7.4 2.6 19.0 27.3 12.0/TR 85.2 Monument 7.7 6.0 4.7 15.4 9.4 24.2 44.4 16.1/9.0 136.9 Parker 2.0 6.8 6.8 6.1 2.8 13.5 31.8 10.3/2.0 82.1 Sedalia - Hwy 67 4.0 6.2 6.7 10.1 4.5 16.8 33.9 13.5/3.0 98.7 Thornton 1.7 5.5 7.4 5.2 5.7 15.4 24.4 11.0/3.2 79.5 Westminster 2.0 6.6 9.6 6.9 5.2 18.2 25.6 12.5/1.0 87.6 Wheat Ridge 2.8 5.1 7.8 7.0 3.9 15.2 33.2 15.2/0.4 90.6

* = May snow is included up to 5/4

Rainfall

May 2021 to October 2021

City May Jun Jul Aug Sep Oct Total

Aurora (Central) 4.13” 4.13” Brighton 3.82” 3.82” Broomfield 4.69” 4.69” Castle Rock 4.06” 4.06” Colo Sprgs Airport 3.98” 3.98” Denver DIA 3.65” 3.65” Denver Downtown 3.74” 3.74” Golden 4.13” 4.13” Fort Collins 5.77” 5.77” Highlands Ranch 3.98” 3.98” Lakewood 3.50” 3.50” Littleton 3.54” 3.54” Parker 2.99” 2.99” Sedalia - Hwy 67 3.65” 3.65” Thornton 4.76” 4.76” Westminster 4.49” 4.49” Wheat Ridge 3.78” 3.78” Skyview Weather ® 2350 N Rocky View Rd Castle Rock, CO 80108 Phone: (303) 688-9175 Fax: (303) 380-3338 E-mail: [email protected] On the web at www.SkyviewWeather.com