The Weather Wire January 2019 Volume 26 Number 1 Contents: Current Colorado Snowpack Denver Snowfall Since 1999-2000 Denver 2018 Climate Review Drought Monitor December Summary/Statistics January Preview Snowfall Totals Current Colorado Snowpack Although snow has been meager along the I-25 corridor the mountains have seen respectable snow with all of the central and northern river drainages near normal or slightly above normal in snowpack. The San Juan s of SW Colorado continue to be below normal in snowfall up to this point in the snow season.
Denver Snowfall Since 1999-2000 Since the 1999-2000 snow season only 7 years have provided above normal snowfall with 12 seasons providing below normal or well below normal snowfall. The years that have been above normal have not been well above normal with the exception of 2015-2016 and 2006-2007. However, the years that have been below normal, many of them have been well below normal. The result is that our normal snowfall has decreased over the past 19 years with an average of 47.1 compared to the historical average of 57.1. Much of the decrease in snowfall is due to the official climate data site moving from Stapleton to DIA in 1995. Denver 2018 Climate Review 2018 started off on the right foot with 2 of the first 3 months (January and March) coming in with above normal precipitation but that would be the end of above normal precipitation for the remainder of the year. The dry conditions in tandem with above normal temperatures for 2018 has resulted in areas of drought intensifying over portions of the I- 25 corridor. Below are graphics from the NWS showing temperature, precipitation and snowfall compared to average or over the historical climate record. This data can also be found on the web at: https://www.weather.gov/bou/denver_2018_climate_summary
Drought Update Drought conditions continue over most of Colorado with the most severe drought conditions over SW Colorado and the San Juan mountains. The map below shows forecasted temperature deviances for January 2019. There is a slight bias towards above normal temperatures over much of Colorado with a lesser bias towards above normal temperatures over S and SE Colorado.
The map below shows forecasted precipitation deviances for January 2019. There are equal chances for above or below normal precipitation over most of the state with a slight bias towards above normal precipitation over SW Colorado. Drought conditions are expected to persist across much of Colorado.
December Summary December of 2019 was above normal in temperature and well below normal in precipitation. The average monthly high temperature at DIA was 46.1 degrees, which was 3.3 degrees above the normal of 42.8 degrees. Average lows were 18.8 degrees which was 1.7 degrees above the normal of 17.1 degrees. The monthly mean temperature was 32.5 degrees, 2.5 degrees above the normal of 30.0 degrees. The highest temperature during the month occurred on the 21 st at 63 degrees and the coldest temperature for the month was only 0 set on the 31 st. There were not any temperature records for the month. Precipitation was a meager 0.03 which occurred on the 31 st. the 0.03 of moisture resulted in 0.5 of snow, which was the monthly total. There were 7 days during the month with a trace of moisture and a trace of snow. The 0.5 of snow was 8 below the monthly average of 8.5. For the snow season so far only 8.2 of snow has fallen at DIA which is 14.3 below the normal of 22.5. We are starting to create a snow deficit for the season that will be difficult to make up over the coming months which will likely result in another below normal snow season. The last season with above normal snow was 2015-2016. The map below to the right shows how the Denver Metro area was one of the driest areas in the state compared to normal. December Stats TEMPERATURE (IN DEGREES F) AVERAGE MAX 46.1 NORMAL 42.8 DEPARTURE 3.3 AVERAGE MIN 18.8 NORMAL 17.1 DEPARTURE 1.7 MONTHLY MEAN 32.5 NORMAL 30.0 DEPARTURE 2.5 HIGHEST 63 on 12/21 LOWEST 0 on 12/31 DAYS WITH MAX 90 OR ABOVE 0 NORMAL 0.0 DAYS WITH MAX 32 OR BELOW 4 NORMAL 5.8 DAYS WITH MIN 32 OR BELOW 31 NORMAL 29.4 DAYS WITH MIN ZERO OR BELOW 1 NORMAL 2.0 TEMPERATURE RECORDS
NA HEATING DEGREE DAYS MONTHLY TOTAL 999 NORMAL 1086 DEPARTURE -87 SEASONAL TOTAL 2372 NORMAL 2468 DEPARTURE -96 COOLING DEGREE DAYS MONTHLY TOTAL 0 NORMAL 0 DEPARTURE 0 YEARLY TOTAL 1026 NORMAL 769 DEPARTURE 257 PRECIPITATION (IN INCHES) MONTHLY TOTAL 0.03 NORMAL 0.35 DEPARTURE -0.32 YEARLY TOTAL 8.53 NORMAL 14.54 DEPARTURE -6.01 GREATEST IN 24 HOURS 0.03 on 12/31 DAYS WITH MEASURABLE PRECIP. 1 SNOWFALL (IN INCHES) MONTHLY TOTAL 0.5 NORMAL 8.5 DEPARTURE -8.0 SEASONAL TOTAL 8.2 NORMAL 22.5 DEPARTURE -14.3 GREATEST IN 24 HOURS 0.5 GREATEST DEPTH 0.5 WIND (IN MILES PER HOUR) AVERAGE SPEED 9.6 mph PEAK WIND GUST 53 mph from the N on 12/12 MISCELLANEOUS WEATHER NUMBER OF DAYS WITH THUNDERSTORM 0 NORMAL 0 NUMBER OF DAYS WITH HEAVY FOG 1 NORMAL 1 NUMBER OF DAYS WITH HAIL 0 NUMBER OF SUNNY DAYS 6 NUMBER OF PARTLY CLOUDY DAYS 22 NUMBER OF CLOUDY DAYS 3 AVERAGE RELATIVE HUMIDITY 56%
January Preview The month of January is the second coldest month on average in Denver, just slightly warmer than December by 0.7 degrees. However, the all-time record low temperature for Denver of -29 degrees occurred during the month of January, way back on January 9, 1875. January is typically a drier month for Denver and is the 4th snowiest month with an average of 7.0. Major snow events are relatively rare in Denver during January. Instead, lighter but cold and powdery type snowfalls are more common, especially following arctic cold fronts from the north, which are fairly common at this time of year. Average precipitation during January is only 0.41, which also owes to the low-moisture content that is typical of snowfall events at this time of year. Temperatures can be very cold at times in January with an average of two days below zero, but mild spells with high temperatures in the 60s are not uncommon either. The warmest temperature on record in Denver in January was 76 degrees set back in 1888. January 2019 is likely to feature above normal average temperatures overall, but we will be susceptible to a cold outbreak or two by month s end. Long range models indicate that precipitation and snowfall will be near normal but the long range models have not been reliable up to this point during the snow season so there is little confidence. Eastern Colorado will most likely experience 2-3 appreciable snow events over the course of the month, but the chances of seeing any major snow events is low. TEMPERATURE DENVER'S JANUARY CLIMATOLOGICALLY NORMAL (NORMAL PERIOD 1981-2010 DIA Data) AVERAGE HIGH 44.0 AVERAGE LOW 17.4 MONTHLY MEAN 30.7 DAYS WITH HIGH 90 OR ABOVE 0 DAYS WITH HIGH 32 OR BELOW 6 DAYS WITH LOW 32 OR BELOW 29 DAYS WITH LOWS ZERO OR BELOW 2 PRECIPITATION MONTHLY MEAN 0.41 DAYS WITH MEASURABLE PRECIPITATION 4 AVERAGE SNOWFALL IN INCHES 7.0 DAYS WITH TRACE OR MORE OF SNOW 2 MISCELLANEOUS AVERAGES HEATING DEGREE DAYS 1063 COOLING DEGREE DAYS 0 WIND SPEED (MPH) 8.6mph
WIND DIRECTION South DAYS WITH THUNDERSTORMS 0 DAYS WITH DENSE FOG 1 PERCENT OF SUNSHINE POSSIBLE 71% EXTREMES RECORD HIGH 76 on 1/27/1888 RECORD LOW -29 on 1/9/1875 WARMEST 40.3 in 1986 COLDEST 16.9 in 1930 WETTEST 2.35 in 1883 DRIEST 0.01 in 1933 SNOWIEST 24.3 in 1992 LEAST SNOWIEST TR in 2003, 1994 Snowfall October 2018 to May 2019 City Oct Nov Dec Jan Feb Mar Apr May Total Aurora (Central) 2.5 4.6 0.9 8.0 Boulder 10.0 15.9 5.7 31.6 Brighton 3.4 4.6 0.7 8.7 Broomfield 5.1 8.3 2.1 15.5 Castle Rock 5.5 9.2 3.2 17.9 Colo Sprgs Airpor 5.3 2.8 1.5 9.6 Denver DIA 3.2 4.5 0.5 8.2 Denver Downtown 2.5 6.0 1.4 9.9 Golden 7.0 7.0 2.4 16.4 Fort Collins 6.0 5.6 1.1 12.7 Highlands Ranch 6.5 7.0 1.2 14.7 Lakewood 3.4 6.6 1.2 11.2 Littleton 4.5 6.2 2.2 12.9 Parker 3.8 7.4 2.1 13.3 Sedalia - Hwy 67 5.2 6.6 2.4 14.2 Thornton 5.0 5.9 0.7 11.6 Westminster 3.2 6.8 2.5 12.5 Wheat Ridge 4.1 8.5 1.5 14.1 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 2019 Skyview Weather