A storm system produced bands of heavier snow in and near the Front Range Foothills, where storm totals ranged from 8 to nearly 14 inches. 7 inches at Denver International Airport.
Every event with a place to put it; 7 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS BOU wrote it up.
A storm system produced bands of heavier snow in and near the Front Range Foothills, where storm totals ranged from 8 to nearly 14 inches. Further east, storm totals generally ranged from 3 to 7 inches, including 5.7 inches at Denver International Airport.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Denver/Boulder, CO wrote its last area forecast discussion before the first event at Apr 14, 10:13 AM MST, 3 hours 47 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 1113 AM MDT Wed Apr 14 2021 .UPDATE... Issued at 1031 AM MDT Wed Apr 14 2021 The upper trough to our west is still lingering over the Great Basin with a large dry slot pushing into Colorado from the Desert Southwest. The dry, warm air is clearing the sky out as expected and warming seems on track with the midnight forecast update. Showers have also cleared the area and are still expected to redevelop in the high country late this afternoon, spreading to the plains in the evening and overnight. The forecast is on track with only minor adjustments this morning. && .SHORT TERM...(Today and tonight) Issued at 425 AM MDT Wed Apr 14 2021 Water vapor shows a broad trough over the Great Basin this morning with a few small shortwaves rotating around it. One of these shortwaves is moving over northern Colorado currently and the associated warm air advection with it is producing snow showers across the far northern mountains as well as portions of Larimer and Weld Counties. These snow showers may linger until shortly after sunrise but they will move out of Colorado by the mid morning. Another thing water vapor reveals is the substantial dry air that is over much of the Desert Southwest. It is this dry air that will move over our forecast area during the day today that lead to the majority of locations staying dry for the entire day. PoPs were cut drastically because there will not be enough lift to overcome the dry air. From I-25 to the eastern plains on Colorado, I took out the mention of rain/snow showers for today. Considering the lack of precipitation and the likelihood that clouds will dissipate over much of the area, high temperatures were raised about 5 degrees above the previous forecast. A high in the low 50s is well within reason in Denver. The tricky part of the forecast will be the possibility for precipitation to develop later this afternoon and evening across the mountains and foothills. With the elevated mixed layer moving overhead along with relatively strong heating, decent instability will develop. Low to mid level lapse rates will be around 9 C/km with mixed layer CAPEs in the 500 J/kg range. So if convective showers were to develop, they would be intense with brief heavy snowfall/graupel. The issue will be whether convective initiation can even occur due to the weak forcing. Recent high resolution model runs have been backing off on convection in the mountains indicating the forcing will not be strong enough to overcome the dry air. With that being said, I wonder how well the models are picking up on the dry intrusion that is currently moving through southern Utah and northern Arizona. If this feature were able to move across the central mountains of Colorado around peak heating, it could provide that extra lift for convective initiation to occur. Healthy PoPs were kept in the mountains and foothills to indicate the possibility for good coverage of showers late this afternoon and through the overnight hours. Showers will eventually make their way onto the urban corridor and plains this evening and overnight tonight but since there will be less instability farther east, any precipitation that falls should be on the lighter side. 1 to 5 inches of snow are possible in the mountains and foothills with minimal snow accumulation across lower elevations. .LONG TERM...(Thursday through Tuesday) Issued at 425 AM MDT Wed Apr 14 2021 With the trough still upstream of Colorado, Thursday will continue to be cool with increasing chances of precipitation. Models are in good agreement that the trough will slowly move east across the northern half of Colorado Thursday into early Friday. QG lift ahead of the trough is maximized Thursday afternoon first across the east slopes and I-25 corridor then spreading east across the northeast plains. With a very strong downstream trough across New England on Friday and a massive ridge across the PacNW, the movement of the trough over us will be very slow. In fact, a piece of the trough looks to hang back just to our west most of Friday into the first half of Saturday with a positive tilted trough axis going southwest to northeast across Colorado. This means cool and wet conditions are likely to continue until early Sunday. Details are always important, especially in terms of what to expect in terms of impacts. The best QG lift is from Thursday afternoon through Friday midday. At the mesoscale, strong frontogenesis occurs east of the Divide late evening into early Friday. These two factors alone should lead to moderate precipitation rates resulting in QPF of a few tenths to over a half inch of QPF Thursday afternoon through Friday midday for much of the area east of the Divide. Surface-700 mb wind direction is north for the most part, but starts off northeast for several hours on Thursday afternoon and evening. The primary surface low develops across E. NM late Thursday and moves east, weakening along the way as the parent trough ejects much further north. This is the main reason for more northerly winds across the I-25 corridor. The surface to 700 mb low position should drive a cold front across our area thursday afternoon, with temps plummeting to -11 degC at 700mb and the upper 20s at the surface across the plains by Friday morning. PW values should be in the 0.4-0.6" range, not too shabby for mid-April and with a cold storm. All told the best snow rates will begin across the west slope Thursday morning into afternoon, spreading east afternoon and evening, and continuing across the eastern plains into Friday morning. Rates should remain below 1" an hour with lapse rates weakening by Friday morning. In terms of P-type, the west slope valley and east slope foothills and urban areas nearest the foothills should be all snow. Some rain should occur east of I-25 during the afternoon, but even there it should change over to snow by sunset Thursday. From Thursday afternoon through Friday morning advisory level snow amounts are possible especially east of the Divide, but travel impacts should remain minor with modest snow rates expected. With a piece of the trough still upstream on Friday, expect very light precipitation (most likely snow) across the area but very little additional accumulation. Any travel impacts should be just about gone mid-morning with the April sun angle despite temps in the 30s across the plains and mostly cloudy skies. Highs should reach close to 40. In the mountain valleys, expect highs in the low to mid 30s. Despite a lull in the precipitation east of the Divide on Friday and Saturday, the central mountains along and south of I-70 may pick up a few inches of snow via QG lift and some frontogenesis along the remnant trough axis. There is no upslope and lapse rates are weak, but there are enough ingredients in place for continued light snow through Saturday. Additional snow across the northern mountains Friday and Saturday shouldn't be much, and the plains could just see flurries. Temps don't rebound much on Saturday with decent cloud cover and continued cold advection aloft. For now it's looking like low 40s for the plains and 30s in the mountain valleys and eastern foothills. If you couldn't tell by the discussion above, overall confidence in the forecast is pretty low. Confidence in Sunday's weather is much higher, given the remnant piece of the trough looks to slide south (too far) of our area, leaving us in northwest flow aloft and some warm advection. PW drops to 0.2" and with dewpoints in the teens, no precip is expected. Temps should rebound into the 50s across the plains, with 40s in the high country. There is one pretty important potential impact to pass along, and that's the low temperature Sunday morning around sunrise. Only the GFS/GEFS keeps clouds around and some lingering low-level moisture Sunday morning, and thus low temps are not overly cold. The Canadian and EC ensembles really dry it out at the low levels and clear us out. Though not much snow cover is expected across the plains and I-25 corridor, any snow cover combined with ideal radiational cooling would result in very cold lows indicated by a about half of the ensemble member. Lows around 10-15 degF are not out of the question along the I-25 corridor Sunday, and thus we have begun the process to undercut blended guidance to account for this potential trend for Sunday morning. Monday and Tuesday looks cool and unsettled again as ensemble solutions bring a trough in the northwest flow across the northeast quadrant of Colorado. Depending on timing, some rain could occur Monday afternoon below 7,000 ft, but all model guidance for now shows a strong cold front sometime in the latter half of Monday which would result in snow as the p-type into Tuesday morning. It looks to be a quick moving system with moderating temps and drying during the day on Tuesday. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 1031 AM MDT Wed Apr 14 2021 Expect MVFR and ILS conditions for most of the TAF period. The low and mid level clouds should clear up enough for VFR conditions in the afternoon, but return quickly to MVFR in the evening. There is a chance of light showers in the vicinity of the terminals this evening and overnight. Rain in the evening should turn to a rain snow mix overnight. A persistent mix seems most likely due to the warm temperatures, and little to no accumulation is expected. There is currently a weak low pressure circulation in the vicinity of KDEN keeping a westerly to northwesterly component in the wind when they aren't light and variable. Moderate southeasterly winds should push in this afternoon with gusts up to around 25 kt possible through the evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && UPDATE...Direnzo SHORT TERM...Danielson LONG TERM...Schlatter AVIATION...Direnzo
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 1122 AM MDT Wed Apr 14 2021 COZ030>051-151730- Jackson County Below 9000 Feet- West Jackson and West Grand Counties Above 9000 Feet- Grand and Summit Counties Below 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet- Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below 9000 Feet- Central and Southeast Park County- Larimer County Below 6000 Feet/Northwest Weld County- Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County- North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield County- Elbert/Central and East Douglas Counties Above 6000 Feet- Northeast Weld County-Central and South Weld County-Morgan County- Central and East Adams and Arapahoe Counties- North and Northeast Elbert County Below 6000 Feet/North Lincoln County- Southeast Elbert County Below 6000 Feet/South Lincoln County- Logan County-Washington County-Sedgwick County-Phillips County- 1122 AM MDT Wed Apr 14 2021 This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight There is a chance of rain and snow showers over the mountains and foothills this afternoon into the evening. Snow showers are likely in the mountains overnight and a chance of rain-snow mix will spread across the plains. Precipitation should be light, with 1 to 5 inches of snow expected in the mountains and foothills and minimal snow accumulation across lower elevations. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday A cool and unsettled pattern will continue Thursday through Saturday. Snow showers will develop in the mountains Thursday and spread east across the plains by Thursday afternoon. Widespread rain and snow is expected across the plains later Thursday into midday Friday, with all snow expected after sunset on Thursday. Decent snowfall amounts are possible. Snow showers are likely Saturday mainly in the mountains and foothills as another couple inches of snow may accumulate. Warmer and drier conditions are forecast for Sunday. Yet another storm system will increase snow chances across the area late on Monday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight, but any snow accumulation reports would be appreciated.
The national radar mosaic for the moment the first event began.
5 winter weather, 2 winter storm. Local standard time, as filed.
Storm totals included: 8 inches near Sedalia, 7 inches near Kiowa, 6 inches near Elbert, 5.5 inches near Elizabeth, with 5 inches near Castle Rock and The Pinery.
Storm totals included: 12 inches, 5 miles south of Glen haven; 7.5 inches near Estes Park, with 4 inches, 7 miles west of Pingree Park.
Storm totals included: 13.8 inches near St Mary's Glacier; 12.9 inches at Aspen Park; 10 inches in Genesee, 9.5 inches near Ken Caryl; 9 inches in Crescent Village, and 8 inches in Evergreen.
Storm totals included: 8.5 inches in Arvada and Westminster; 7 inches in Littleton and Louisville, with 5.0 inches in Lakewood.
Storm totals included: 6 inches in Englewood; 5.7 inches at Denver International Airport, 5 inches in East Denver and Lowry, 3 inches in Edgewater.
Storm totals included: 5.8 inches in Erie, 4.5 inches near Frederick, with 3.5 inches in Ft Lupton; with 3 inches around Greeley.
Storm totals included 5.5 inches near Wiggins, with 4.5 inches near Brush.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2021Every state in 2021This day in weather historyWarnings in Colorado, April 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 952505, 952506, 952496, 952498, 952499, 952501, 952504.