Previously warm temperatures across the region had caused an aging the snowpack to crust over, limiting its “blowability”. However during the day/evening of the 10th, another quick-moving shortwave brought an additional round of fresh snowfall to Red River Valley region in E ND and W MN. As discussed in a great NWS/FGF forecast discussion on the 10th:
“This is a classic arctic front blizzard set up. The main issue is that the warm temperatures ahead of the cold front will make the current snowpack nearly unblowable. With that said, water vapor imagery indicates an upper level wave (currently way upstream) that should lead to an area of very light falling snow behind the cold front, and combined with the strong winds would lead to a 3-5 hour period of blizzard conditions. Most guidance does indicate very light QPF. Typically, in these CAA regimes we tend to develop additional convective snow showers, which would prolong the blizzard type impacts. However, the development and intensity of these convective snow showers is uncertain. If the snow showers persist, blizzard conditions would last into Friday afternoon.”
As discussed in the above forecast, plummeting temperatures and strong winds behind the front indeed resulted in widespread blowing snow by the early morning hours of the 11th, lasting into the afternoon and aided by the development of HCRs, especially across the Red River Valley. GOES-East imagery was utilized by NWS/FGF forecasters during this event to narrow down the spatial extent of the Blizzard Warning, as discussed here and below. Corresponding GOES-East Imagery is shown over the region in Fig 1, along with the warning decision on the NWS WWA map (Fig 2).
“Along the glacial lake valley floor horizontal convective rolls can be seen on satellite and from KMVX radar indicating blizzard conditions with widespread white outs causing many east to west road closures in MN and portions of I29. With the help of the satellite imagery did narrow the blizzard warning and removed the tier of counties from Roseau to Mahnomen along with western Walsh and Cavalier in ND.”
Afternoon VIIRS passes provide an alternative, high resolution view of the blowing snow and related HCRs (Fig 3+4).
A full day (2/11) GOES-East animation captures the longer term evolution of the blowing snow and HCRs across the Red River Valley (Fig 5).
Bill Line, NESDIS and CIRA