Joe’s Weather Blog: Ice Storm Warning in effect (WED-2/6)
It’s slick in parts of the area today. Untreated surfaces and even some treated surfaces, especially bridges and overpasses, as well as the usual suspects are icy…and while NOT a lot is falling right now another wave will come at us tonight and extend into daybreak Thursday. That will be a combination of additional freezing rain…then potentially some sleet and backside snow that may accumulate as the arctic air barrels into the region. This spells perhaps big trouble for Thursday, especially during the 1st part of the day.
Tonight: Ice Storm Warning! Increasing areas of freezing rain. This will create bigger road issues Metro wide it appears. Then there should be a transition to sleet and then towards daybreak snow. Lows tonight in the lower 20s.
Thursday: The arctic air moves in around 4AM-7AM. This sends temperatures from the 20s to the teens. The atmosphere overall will turn colder and transition whatever ice we’re getting to a brief period of snow. Accumulations may range from a dusting to potentially 2″ in spots. The highest risk of 2″ may be north and west of KC…the lower risk would be south and east of KC. It will turn into a light powdery snow like what happened last week.
Friday: Frigid with AM lows near 0° and afternoon highs in the lower 20s.
We haven’t even gotten into the main part of the storm and IF it wasn’t for this “warm” layer of air above us that’s been “protecting” us from getting more snow…although the ice isn’t exactly a picnic out there either…we’d be sitting with about 2″ of snow for parts of the Metro right now with about a dusting to 1″ on the NW side of KC. So in a sense that “protective” layer of warm air isn’t helping at all because no one likes ice.
Well Mother Nature will take care of that protective layer around 4-7AM or so tomorrow morning (from north to south) and that’s when we see a ore formal change to snow (not for that long though).
The organizing last part or this multi day storm will come out of the Rockies tonight and move through the southern Plains and then up through central MO Thursday AM. The map below will auto-update
The cold air isn’t going anywhere. I knew it wouldn’t…I knew that the cold air would win the battle…that was my forecast from the past weekend and why my forecast was so much colder than many other sources. The only issue I didn’t know was to what extent the cold air would win the battle…and it is outperforming itself…hence all the ice.
When I said over the weekend that we might well stay below 32° all week in KC…I wasn’t kidding…and now we can’t even make 25° it appears.
So about tonight…well that’s a growing issue.
1st the surface map for the noon hour…
Fascinating to see the differences from Little Rock to Falls City, NE…from the 70s to the teens and that’s been the case for the entire history of this multi-day storm.
There were even some thunderstorms down towards the Lake Of The Ozarks last night.
So the surface storm will organize and since we still have this warm layer above us…see yesterday’s blog for a description of the image below
See how the red lines (temperatures as you go upwards) and the green lines (dew points as you go up) jut WAY to the right at the lower part of the atmosphere…and see that angled thin blue line that has a 0 on the right hand side (freezing line). Note how the jut to the right of the two lines ends up near 10°…that’s 50°F and that’s about 4-5000 feet above us right now, as it has been for a couple of days now.
Before daybreak tomorrow that “warm” layer gets wiped away.
This will be because the surface storm will be passing towards the south of the area AND the winds above us keeping us in the warm air upstairs will be passing by the area as well shifting the SW winds to the N and NW…this brings in the colder air above us.
This next map shows the temperatures (dashed lines) at around 4000-5000 feet or what we refer to as the 850 mb level.
The red dashed lines are above 0°C or above 32°F…the blue dashed lines are below 0° or 32°F. As I type this at 1PM the 0° line (32°F line) is in far SE Nebraska. Thursday AM that surges SEwards and it doesn’t have to get that far.
As we’ve seen though we can still get some snow grains from the bottom part of the atmosphere with this set up. My driveway is dusted white right now from yesterday’s evening weird snowfall that affected only parts of the Metro.
The “real” snow though can’t form till we eradicate this warm layer aloft.
So we have a messaging problem here…1) the duration of the freezing rain that will create the bigger headaches…and then the potential of backside snow…and then the falling temperatures and sub-zero wind chills. Try to get all that in a 3 minute weathercast. 5 minutes isn’t enough to time things out and the impacts of everything!
So let’s start with #1…and this is the great thing about the blog…no time limits.
The freezing mist/drizzle will continue into the evening with the associated problems that are still out there. Then we’ll start seeing more dramatic areas of freezing rain develop. This should happen after 9PM tonight. These areas of freezing rain will develop towards the SW of the KC Metro area and spread NEwards.
Here is radar from Pleasant Hill.
Now let’s move to the HRRR model and now that the shutdown is done (for now) I can repost this data that automatically updates for you.
The freezing rain will accumulate BUT don’t use the model forecasts of ice accumulation verbatim. Research shows this IS NOT the way to figure ice aggregation correctly on exposed surfaces. I’ve blogged about this every so often but my colleagues from Topeka have done an analysis of this and have come up with a different model that isn’t widely used by others (it’s used by me though) and it’s called the FRAM model.
This data is now being used by the NWS more and more…
So while the model data that many use shows 1/3″ to 1/2″ if ice accumulations research indicates that ice on power lines etc only accumulates at around 30-40% of that amount! In nutshell the gradual mist/drizzle that we’ve been getting actually accumulates more efficiently than the freezing rain that falls harder and steadier.
Here is a snippet of what I’m talking about.
IF you really want to get into this…there is a nice training video here about this stuff…it does get into the weeds a bit but there are nuggets of information that some of you may learn something from!
Anyway…the main icing will come from roughly 9PM to 5AM or so…here is data for 12AM-6AM
Add in a few hundredths of an inch before 12AM…and you get total accumulations around .15″ or so…
An Ice Storm Warning has been placed into effect for tonight into Thursday AM…
Still significant, especially for roads etc. My concern about that would be that we saw what happened yesterday on the southside with the roads after a 1 hour batch of freezing rain moved through that area…IF something like that happened in the Metro it would NOT be good overnight and into the morning rush.
Then we have the snow potential. Again a dusting to 2″ is possible especially from the Metro northwestwards. The timing on that would be sometime after 3-5AM…the window though is short.
Then the cold air and the winds. The arctic air moves in before daybreak..we drop into the teens tomorrow and the winds crank at 30+ MPH…there could be an issue IF there is ice on the power lines at that time. Power lines can handle a decent amount of ice with little wind. Once the winds get going…and the lines start moving more…then you can get more issues. It’s something to think about.
Friday morning should be near 0°.
We recover over the weekend..hopefully above 32° on Saturday.
There might be some light snow late Saturday night and early Sunday AM…iffy accumulations right now.
Our feature photo comes from @KTChasers down in JOCO, KS