A brief period of strong bora winds occurred in and near the foothills during the late evening and early morning hours. Scattered but brief electrical outages were reported.
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The episode as NWS BOU wrote it up.
A brief period of strong bora winds occurred in and near the foothills during the late evening and early morning hours. Scattered but brief electrical outages were reported. |On a localized scale, high wind criteria was reached for a brief time. Peak wind gust reports included: 84 mph atop Berthoud Pass, 83 mph at NCAR Mesa Laboratory; 79 mph at Longmont Municipal Airport; 78 mph, 3.5 miles southwest of Superior; 76 mph at Rocky Mountain Municipal Airport and 75 mph east-northeast of Pleasant View.
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 Jan 4, 8:05 PM MST, 2 hours 5 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 805 PM MST Sat Jan 4 2020 .UPDATE... Issued at 759 PM MST Sat Jan 4 2020 Main concern through the night is the high wind potential over the mountains and foothills. Currently, observations showing gusts mainly in the 30-50 mph range. Water vapor imagery showing the drying airmass over far northern Colorado and associated with subsidence with the passing trof. Surface pressures are now on the rise so peak gradient expected around 13mb from GJT-DEN in the next hour or so. High resolution models showing peak wind gusts between 04z- 08z and in the 50-60kt range. This will result in a few peak gusts close to 75 mph but will be of short duration and very localized. Will not issue any high wind warning for this event. Winds will decrease later tonight as high pressure builds over the eastern plains of Colorado which will help to relax the surface pressure gradient and the strongest subsidence shifts away from Colorado. The strong jet aloft will also increase the vertical shear profile which is not good for an amplified mountain wave. Ongoing forecast in good shape. && .SHORT TERM...(This evening through Sunday) Issued at 110 PM MST Sat Jan 4 2020 Tonight, strong post frontal winds still expected to occur in and near northern Front Range Foothills and Cheyenne Ridge late this afternoon and evening. NAM12 spatial cross-sections show a brief wave amplification in the 00-03z window, with a 50 kts cross- mountain wind component along the eastern slopes down to around 750 mb. Sangster Model output from HRRR/RAP and NAM12 show either nothing or watch category but no warning. Weak mid to moderate qg ascent over eastern WY until 00z then weak qg descent through 06z. For this reason, some of the parameters for a strong bora event not really phased together very well. Still expecting a marginal high wind event (just under highlight criteria) with gusts 55-65 mph with maybe one or two stronger gusts around 00z. Some stronger gusts 35-45 mph possible this evening over the adjacent plains along the WY/NE borders. Weakening gradient with the wind expected to decrease overnight. Drying late tonight into Sunday morning with short wave ridge in place. By Sunday afternoon, increasing mid level qg ascent developing with the next trough. A 130+ kt upper level jet will accompany this system. Light snow showers will develop in the mountains primarily along the west facing slopes Sunday afternoon. Cooler and continued dry across the northeast plains. .LONG TERM...(Sunday night through Saturday) Issued at 245 PM MST Sat Jan 4 2020 Models have weak upper troughing over the CWA Sunday night into Monday morning, then strong northwesterly flow aloft later Monday afternoon an night. The flow aloft stays northwesterly in direction on Tuesday but decreases in speed. Upper ridging moves across on Tuesday night. The QG Omega fields show pretty strong downward vertical motion on Monday into Monday night. Weaker downward motion is in place on Tuesday. Weak upward motion moves in Tuesday night. A cold front moves across Sunday night with downsloping west and northwesterly low level winds progged after midnight continuing into Monday evening. More normal diurnal wind patterns are expected Monday overnight through Tuesday night. There is some moisture in the high mountains Sunday night, but not much elsewhere. Moisture is pretty sparse on Monday through Tuesday night, with some in the upper levels only The QPF fields. The QPF fields show some measurable snow in the alpine areas Sunday night then tapering off through the day Monday. Amounts do not warrant highlights. Will keep the pops pretty high in the mountains SUnday night and Monday. No pops over the plains. For temperatures, Monday's highs are 2-4 C cooler than Sunday's highs. Tuesday's readings warm up 2-6 C from Monday's. For the later days, Wednesday through Saturday, models have southwesterly flow aloft on Wednesday. The next upper trough moves in later Wednesday night, then deepens in place over Colorado into Friday. The GFS moves it east by later Friday and the ECMWF keeps around into Friday night. Southwesterly flow aloft is over the CWA Saturday and Saturday night. It should be colder than normal and unsettled && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 759 PM MST Sat Jan 4 2020 Expect gusty west to northwest winds at local terminals through about midnight with strong surface pressure gradient and enhanced subsidence. Strongest winds will be at BJC with lesser winds at DEN/APA. The winds will decrease after midnight as winds then shift back easterly as high pressure builds over the eastern plains of Colorado. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && UPDATE...Entrekin SHORT TERM...Cooper LONG TERM...RJK AVIATION...Entrekin
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 1106 AM MST Sat Jan 4 2020 COZ030>051-051815- 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- 1106 AM MST Sat Jan 4 2020 This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...This Afternoon and Tonight Drier and warmer weather will spread across north central and northeast Colorado. A strong westerly flow aloft will be developing over Colorado this afternoon. Wind gusts over the mountain ridges and higher eastern slopes will be 55 to 65 mph, which will cause areas of blowing and drifting snow. Lighter wind speeds will be felt in the valleys. The gusty winds will continue into this evening, and then decrease overnight. On the plains, wind gusts of 25 to 35 mph with gusts to 45 mph will develop later this afternoon near the foothills and along the northern border of the state. These winds will continue well into the evening before decreasing by midnight. .DAYS TWO THROUGH SEVEN...Sunday through Friday There will be a good chance of snow in the mountains Sunday night into Monday morning. Gusty winds will produce areas of blowing snow. Elsewhere it will be dry with gusty winds spreading from the foothills across the plains Monday afternoon and night. Tuesday will be dry with gusty winds continuing over the higher terrain. Another system will affect the mountains late Wednesday with another chance of snow. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight.
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2020Every state in 2020This day in weather historyWarnings in Colorado, January 2020
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: 863643, 863642.