By my count, this will be the seventh time this season of having significant impacts from blowing snow. Just four days since our last, and worst, blizzard of the season, we're gearing up for another one. We hinted on Friday night that the wind may be a concern around this timeframe. Today the wind, just strong enough to stir up some minor blowing snow, as shown in the picture below from Andrew H. in Joice, IA.
But for tomorrow, it's looking like the wind will be stronger. Wednesday afternoon into Wednesday night will be the timeframe to watch. The worst conditions are anticipated around 3pm to midnight.
Here's the headlines in place at the time of writing this (7:30PM Tuesday). A Blizzard Warning is in place for areas along and west of I35. To the east, it's a Winter Weather Advisory. Both are in place until 3 AM Thursday. *THE FOLLOWING MAP MAY CHANGE OVER THE NEXT 24 HOURS*
Note, no headlines are currently in place for northern Iowa. That doesn't mean those of you in northern Iowa will miss out on this one all together. In fact, I'm expecting the entire area to deal with the effects of blowing snow. Northern Iowa may very well be upgraded to one of the two alerts listed above.
So why is there so much difference in the map above? There is a set of criteria that needs to be met before a blizzard can be classified as such. We may not achieve this criteria in all locations. The criteria for a Blizzard Warning to be issued by the National Weather Service consists of: 1) Blowing snow reducing visibility to 1/4 mile or less. 2) Wind gusts must 35mph or greater for three or more consecutive hours.
One would note, there's nothing that says new snow needs to be falling. That, in fact, is what we have (or don't have) in Wednesday's scenario. No new snow is expected to fall. That's confined more to our northeast. The snow currently on the ground is our problem, it's still pretty loose and powdery. A powerful cold front will slide through the area Wednesday evening. While no snow is expected, the wind is anticipated to kick up as the front moves through and lingering behind it.
The wind speeds will be sustained around 20-35 mph sustained with gusts frequently hitting 40 mph Wednesday evening. Here's the wind trend below from 8 AM Wednesday to 8AM Thursday. In the local area, I'm expecting the strongest winds to impact areas along and north of US 14. Likely the worst impacts would be felt in those areas.
With current snow depths hanging out around 16-24" across southeast Minnesota and northern Iowa, there isn't too many places left to put snow, or snow to blow into. Ditches are full, driving down many highways is like driving down a hallway, with so much snow piled on the shoulder.
And you don't need me to tell you, roads are still recovering from our blizzard last week, with still some spots, especially lesser traveled roads, with compacted ice clinging to the pavement. Still some stretches of road in southeast Minnesota remain listed as 'fair' to 'difficult' driving.
Sub-zero temperatures are noted for the next couple nights and daytime highs just above zero. Chemicals used to treat roadways are less effective in extreme cold. So, as we start to see the wind die down Thursday morning, it doesn't mean things are instantly better on the roads. It will likely be another slow recovery, especially considering the setbacks currently still in place from the last round.
In summary... Worse impacts are from 3pm to Midnight Wednesday. Strongest gusts will likely be seen in the open areas of SE Minnesota, especially along the US 14 corridor.
Here's the main impacts I'm expecting:
-Widespread Blowing Snow
-Reduced visibility in the open, away from cities/protected areas, White outs in spots
-Very difficult travel Wednesday evening into Wednesday night
Again, don't get hung up on the whether your in a Blizzard Warning, Winter Weather Advisory or nothing at all. That map will probably change. Everyone in north central Iowa and southeast Minnesota will have to deal with this.
Storm Tracker 6 Chief Meteorologist