A potentially significant winter storm is expected to impact the area this weekend as a large area of low pressure tracks into the region by Sunday and collides with another system from the north. This complex will flood precipitation into the state, as it currently is already doing across Kansas with rain-snow mix falling this morning. As this moves into the state, we should begin seeing some rain falling across central Iowa as early as 5 PM and continuing into the late evening. As temperatures fall from north to south, we should begin seeing a rain to snow transition, marking the beginning of expected travel difficulties across the state.

We are expecting the northern one-third of the state to be all snow by early to mid evening with central and southern Iowa following later on. Southern Iowa should be able to be warm enough for the majority of the evening and potentially a part of the overnight before quickly transitioning into snow. However, above the surface, it will be below freezing, which will be supportive of snow. This will likely lead to snow falling, but not sticking to the ground (and simply causing wet pavement). Things should begin to get colder overnight and snow will begin accumulating by late evening.

As we mentioned earlier, precipitation will flood into the state allowing for very heavy snow quickly. Precipitable water values (a tool to see how much moisture is in the atmosphere) have been sitting over an inch recently, which are typically seen only during severe weather season (very unseasonable for this time of year). Quick snowfall rates in the late evening should result in snow piling up quickly and continuing through the early morning. Another concern will be the winds – combining the tight pressure gradient as the original low moves off to the southeast and an overhead trough, sustained winds of 15-20 MPH with gusts to 30 MPH will be possible. Therefore, we could possibly see not just issues with rapid snowfall, but with blowing snow to potentially blizzard conditions as well.

Storm total accumulations with this system are expected to be in the nine to eleven inch range for a large portion of the state, including Des Moines, Ames, Cedar Rapids, Iowa City, Davenport, and surrounding areas. Those outside of this area with the exception for the far northern part of our coverage area (five to seven inches) will see seven to nine inches. For this reason, all of the National Weather Service offices across the state have issued either Winter Storm Warnings or Winter Weather Advisories in advance of this event.

Traveling will be very hazardous and dangerous Saturday night and into Sunday. Large amounts of snow plus gusty winds will lead to near-whiteout and unsafe conditions. Only travel in an emergency if possible. If you absolutely MUST travel, make sure to have an emergency survival kit (flashlight, food, blanket, water, etc) with you. Stay tuned to the Iowa Weather Network for the latest information on this impending system.