The Weather Wire May 2016 Volume 23 Number 5 Contents: Winter Summary Current Colorado and West-wide Snow Pack Drought Monitor April Summary/Statistics May Preview Snowfall Totals Winter Summary The Front Range of Colorado experienced a very snowy winter season, with all areas in the region finishing above average. The winter featured several big storms, with DIA recording greater than 10 of snow in five separate months (November, December, February, March, April). Snowfall Denver often experiences snowier than average winters during strong El Nino phases, and that certainly held true this year. The strong El Nino pattern also resulted in a relatively mild winter temperature-wise, as arctic air was largely suppressed to the north. Although the low at DIA did hit exactly zero twice in late December, the temperature did not fall below zero in most locations at all this winter. Total snowfall for the season at DIA ended up at 72.8, which is well above the long-term average of 57.2. Most of the metro area locations received even higher totals, generally in the 75-100 range across Denver metro, with some totals greater than 100 around Broomfield/Boulder, and snowfall from south Denver metro to Castle Rock ranging from 100-125. Here is a quick month-by-month summary of the winter. November The snow season got off to a late start this year as October featured persistent high pressure and well-above average warmth, but the winter got off to a strong start in November as the pattern turned colder and much more active. The biggest snow event of the month occurred on the 16 th -17 th, favoring Douglas County and southern portions of the Denver metro area, where snowfall ranged from 6-16 with the highest amounts farther south along the Palmer Divide. Several lighter snow events also occurred over the final 10 days of the month, with most areas experiencing above average snowfall for the month. Snowfall amounts for the month ranged from 20-35 across Douglas and Northern El Paso Counties as well as the southern Denver metro area, 10-20 from central Denver metro through Boulder, with lesser amounts of 5-10 from Longmont to Ft. Collins as well as from Colorado Spring to Pueblo. DIA would finish with 11.3 for the month.
December The first 10 days of December were quiet, before the pattern turned more active over the final three weeks of the month, resulting in above average monthly snowfall for most areas. Much of the snowfall for the month occurred in a significant snow event on the 14 th -15 th when a widespread 7-14 fell across the Denver metro area. Snowfall for the month generally ranged from 10-20 region-wide, with lighter amounts in the 4-10 range in the Colorado Springs area. Monthly snowfall at DIA was 11.3, putting them at 22.6 for the season. January January ended up as a fairly quiet month overall, with several small nuisance type snow events, but below average snow over the course of the month. The only snowfall of note occurred on the 7 th -8 th and on the 30 th -31 st. Snowfall for the month generally ranged from 3-8 across the entire region, with some 10 amounts across the Palmer Divide. Monthly snowfall at DIA was 4.4, putting them at 27.0 for the season. February February started strong as a major storm impacted the entire area from Colorado Springs to Ft. Collins on the 1 st and 2 nd, resulting in a widespread 8-15. This one storm would put all areas above average for the month of February, although remarkably, the pattern changed substantially after the first week of February, with well-above average temperatures and dry conditions for the remainder of the month. The vast majority of the month s snowfall came from this one storm, with monthly totals generally in the 10-20 range, with higher amounts in the foothills and along the Palmer Divide. DIA would finish the month with 11.8, putting them at 38.8 for the season. March The first two weeks of March started out the way the final three weeks of February ended, unseasonably warm and dry. However, the pattern turned much more active by midmonth, with multiple snow events occurring through the end of the month, resulting in well above average snowfall. The first meaningful snowfall of the month occurred on the 17 th - 18 th, then the largest snow event of the season occurred on the 23 rd, which featured exceptionally heavy snowfall rates and true blizzard conditions across Northeast Colorado. For the month, snowfall amounts ranged from 20-30 across the Denver metro area and Douglas County, while amounts of 30-40 were common across Boulder County and northern Denver metro. Monthly snowfall in the Colorado Springs area ranged from 10-20. For the month, DIA finished with 18.4. April Similar to March, the first two weeks of April started out quiet, but then a massive, slowmoving low pressure system brought an extended stretch of snowfall to Northeast Colorado from the 15th-17th, favoring the higher elevation areas with multiple feet of snow but also bringing significant snow to the lower elevations Another slow-moving system impacted the region from April 28-May 1, bringing the final snowfall of the season to all but the higher elevation foothills. Snowfall amounts with this storm were spotty and light at the lower elevations as snow had trouble accumulating, but the higher elevations received respectable snowfall. Snowfall amounts for the month ranged from 10-20
across the Denver and Colorado Springs metro areas, 20-35 in Douglas County, 25-45 across Northern El Paso County, and 45-65 in the Jefferson and Boulder foothills. Colorado and West-wide Snowpack Update Colorado s mountain snowpack is now above average in just about all areas after a very snowy April, except for the southwestern corner of the state in the San Juan Mountains where snowpack is near or below average. But even the southwest corner saw gains relative to average during the active April. Heading into the melt season, most of the state is in great shape in terms of water resources thanks to the healthy snowpack. Depending on the rate of snowmelt in the next two months, creeks and streams in the Front Range mountains and foothills will likely begin to run high at times. Elsewhere in the Western U.S., current snowpack is highly variable with northern areas experiencing significant melt over the past month, while southern areas saw gains in snowpack percent of average. Storms during April tended to favor the higher terrain of California, central/southern Utah, southern Wyoming, and Colorado, and these areas are currently experiencing an above average snowpack. However, the Pacific Northwest and Northern Rockies experienced well above average temperatures and missed out on the more significant snowfall events, therefore despite a healthy winter snowpack, snowmelt rates have been much higher than normal over the past month resulting in snowpack values falling well below average.
Precipitation maps can be found at: http://droughtmonitor.unl.edu/supplementalinfo/forecasts.aspx Colorado Snow Water Equivalent maps can be found on the web at: http://www.wcc.nrcs.usda.gov/ftpref/data/water/wcs/gis/maps/co_swepctnormal_update.p df
Drought Update Colorado is now entirely drought-free again, after a wet and snowy April erased the small pocked of moderate drought across extreme southeast portions of the state. A couple of areas of abnormally dry conditions remain across far southern portions of Colorado. Much of California and Nevada remain under severe to exceptional drought, with areas of moderate drought extending into southern Oregon as well as Arizona and New Mexico.
The map below shows forecasted temperature deviances for May 2016. There is a bias toward below normal temperatures for all of Colorado, especially across the southern third of the state. The map below shows forecasted precipitation deviances for May 2016. All of Colorado has a moderate bias toward above normal precipitation.
No drought is forecast for Colorado in the near term. Drought is expected to persist across much of California and southern Arizona, while drought improvement is likely across portions of Nevada and western Utah. April Summary April 2016 featured near average temperatures and well above average precipitation and snowfall. The first two months started out warm and mostly dry, although portions of the Denver metro did receive their first thunderstorms of the season from the 9th-11th. A major pattern change occurred by mid-month as a slow-moving storm system brought an extended stretch of snowy weather from the 15th-17th, with DIA recording 12.1 of snow over this period and much higher amounts falling across the higher elevations south and west of the metro area. A second slow-moving system brought another extended stretch of winter weather to the area at the end of the month, with snow falling steadily from the 28th through May 1st and temperatures running well below average. Snowfall accumulations were limited across the Denver metro area due to warm surfaces and borderline temperatures, but higher elevation areas received respectable snowfall. DIA ended up with 15.6 of snowfall for the month of April, which is well above the long-term average of 8.9. It also marked the fifth separate month this season in which snowfall at DIA exceeded 10. For the season, DIA has now received 72.8 of snow, which is easily above the long-term seasonal average of 57.1. DIA also received 2.56 of precipitation during the month of April, which is above the long-term average of 1.71. For the year,
precipitation is at least 1.31 above average, but likely a good bit higher than that due to a precipitation error that occurred during a late March snow event that resulted in much less precipitation recorded than what actually occurred. Temperatures for the month ended up right about average, with high temperatures slightly below average and low temperatures slightly above average. The high temperature for the month was 77, which occurred on the 23rd, and the low temperature for the month was 25, which occurred on the 1st. April Stats TEMPERATURE (IN DEGREES F) AVERAGE MAX 59.4 NORMAL 61.5 DEPARTURE -2.1 AVERAGE MIN 35.1 NORMAL 33.3 DEPARTURE 1.8 MONTHLY MEAN 47.2 NORMAL 47.4 DEPARTURE -0.2 HIGHEST 77 on 4/23 LOWEST 25 on 4/1 DAYS WITH MAX 90 OR ABOVE 0 NORMAL 0 DAYS WITH MAX 32 OR BELOW 0 NORMAL 0.3 DAYS WITH MIN 32 OR BELOW 11 NORMAL 13.0 DAYS WITH MIN ZERO OR BELOW 0 NORMAL 0.0 TEMPERATURE RECORDS None HEATING DEGREE DAYS MONTHLY TOTAL 526 NORMAL 529 DEPARTURE -3 SEASONAL TOTAL 5230 NORMAL 5731 DEPARTURE -501 COOLING DEGREE DAYS MONTHLY TOTAL 0 NORMAL 0 DEPARTURE 0 YEARLY TOTAL 0 NORMAL 0 DEPARTURE 0 PRECIPITATION (IN INCHES) MONTHLY TOTAL 2.56 NORMAL 1.71 DEPARTURE 0.85 YEARLY TOTAL 4.72* NORMAL 3.41 DEPARTURE 1.31* GREATEST IN 24 HOURS 1.22 on 4/15-16 DAYS WITH MEASURABLE PRECIP. 10 *Error on 3/23 due to undercatch from snow
SNOWFALL (IN INCHES) MONTHLY TOTAL 15.6 NORMAL 8.9 DEPARTURE 7.7 SEASONAL TOTAL 72.8 NORMAL 55.4 DEPARTURE 11.3 GREATEST IN 24 HOURS 12.1 on 4/16-17 GREATEST DEPTH 8 on 4/17 WIND (IN MILES PER HOUR) AVERAGE SPEED 10.9 mph PEAK WIND GUST 53 mph from the NW on 4/5 MISCELLANEOUS WEATHER NUMBER OF DAYS WITH THUNDERSTORM 0 NORMAL 1 NUMBER OF DAYS WITH HEAVY FOG 4 NORMAL 2 NUMBER OF DAYS WITH HAIL 0 NUMBER OF SUNNY DAYS 6 NUMBER OF PARTLY CLOUDY DAYS 15 NUMBER OF CLOUDY DAYS 9 AVERAGE RELATIVE HUMIDITY 55%
May Preview May is historically Denver s wettest month with an average of 2.12 of precipitation and measurable precipitation occurring one out of every three days. Last year, May was exceptionally wet in the Denver metro area with much of the city receiving 5.0-7.5 of rain and at least a trace of precipitation occurring on 26 out of 31 days. The average high temperature during the month of May is 71.5, and the record high for the month is 95, which occurred in 1992. The average low for the month is 42.7, and the record low for the month is 19, which occurred in 1907 and was tied just two years ago in 2013. Denver averages two days of below freezing temperatures during May, with the final frosts and freezes of the season usually occurring during the first two weeks of the month. Snow does occasionally happen in May in Denver, with an average of 1.7 during the month. Measurable snowfall exceeding the historical average actually occurred in each of the past three years prior to this year, including 4 that fell on the 9th-10th of last year at DIA. May is also the first active thunderstorm month and marks the start of severe weather season across Northeast Colorado and the Denver metro area. Typically, severe weather becomes more common during late May, but the first day of severe weather already occurred this year on the 7th across portions of the metro area. This year, May is likely to feature above normal precipitation and below average temperatures as an active storm track looks to continue across the southwestern U.S. The Denver area did receive minor snow accumulations on the morning of the 1st, with only a trace being reported at DIA, but it is unlikely the lower elevations will receive any additional snowfall this year. TEMPERATURE DENVER'S MAY CLIMATOLOGICALLY NORMAL (NORMAL PERIOD 1981-2010 DIA Data) AVERAGE HIGH 71.5 AVERAGE LOW 42.7 MONTHLY MEAN 57.1 DAYS WITH HIGH 90 OR ABOVE 1 DAYS WITH HIGH 32 OR BELOW 0 DAYS WITH LOW 32 OR BELOW 2 DAYS WITH LOWS ZERO OR BELOW 0 PRECIPITATION MONTHLY MEAN 2.12 DAYS WITH MEASURABLE PRECIPITATION 9 AVERAGE SNOWFALL IN INCHES 1.7 DAYS WITH 1.0 INCH OF SNOW OR MORE <1 MISCELLANEOUS AVERAGES HEATING DEGREE DAYS 265 COOLING DEGREE DAYS 21 WIND SPEED (MPH) 9.3mph WIND DIRECTION South
DAYS WITH THUNDERSTORMS 6 DAYS WITH DENSE FOG 1 PERCENT OF SUNSHINE POSSIBLE 64% EXTREMES RECORD HIGH 95 on 5/26/1992 RECORD LOW 19 on 5/3/1907, 5/2/2013 WARMEST 64.6 in 1934 COLDEST 48.7 in 1917 WETTEST 8.57 in 1876 DRIEST 0.06 in 1974 SNOWIEST 15.5 in 1898 LEAST SNOWIEST 0.0 in numerous years Snowfall October 2015 to April 2016 City Oct Nov Dec Jan Feb Mar Apr Total Aurora (Central) 0.0 18.3 14.5 3.4 11.0 26.3 16.3 89.8 Brighton 0.0 13.9 15.9 5.4 8.0 19.1 6.9 69.2 Broomfield 0.0 17.0 17.4 4.2 18.5 39.9 15.3 112.3 Castle Rock 0.0 30.8 16.7 8.1 15.5 22.8 31.3 125.2 Colo Sprgs Airport 0.0 5.6 4.3 5.0 13.2 10.5 13.1 50.7 Denver DIA 0.0 11.3 11.3 4.4 11.8 18.4 15.6 72.8 Denver Downtown 0.0 17.1 13.8 4.6 13.9 24.3 13.9 87.6 Golden 0.0 18.5 17.6 5.1 20.0 29.4 16.0 106.6 Fort Collins 0.0 8.4 16.0 6.2 14.5 20.3 5.8 71.2 Highlands Ranch 0.0 24.1 14.5 4.0 13.8 26.7 25.0 108.1 Lakewood 0.0 13.3 13.2 6.3 14.7 22.6 14.5 84.6 Littleton 0.0 21.9 15.4 5.5 15.0 25.1 14.6 97.5 Parker 0.0 23.4 12.4 5.4 13.4 26.6 22.0 105.5 Sedalia - Hwy 67 0.0 31.1 14.2 7.3 13.6 29.8 34.5 131.1 Thornton 0.0 18.2 18.4 4.8 14.5 32.6 9.6 98.1 Westminster 0.0 18.2 15.0 5.6 15.0 28.1 16.2 98.1 Wheat Ridge 0.0 14.5 15.9 5.7 17.4 32.1 15.6 101.2 Skyview Weather 2350 N Rocky View Rd Castle Rock, CO 80108 Phone: (303) 688-9175 Fax: (303) 380-3338 E-mail: Tim@SkyviewWeather.com On the web at www.skyviewweather.com Copyright 2016 Skyview Weather