From Tornado Potential To Blizzard Conditions

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3PM Update:

The 18Z NAM model run is coming out and is more bullish on the snowfall and continues to indicate that blizzard conditions will be possible tomorrow AM in the KC area. Snowfall is also a little greater…more on the order of a solid 1-3″ through the KC region. Timing hasn’t really changed but the model strongly suggests that an intensifying area of snow will be moving into and/or developing in the I-35 corridor around daybreak. This combined with surface winds of 25-35+ MPH would indicate an abysmal rush hour. In all honesty this may be a situation where we never really will know how much snow has fallen since it will blowing around so much in the area. The latest RAP model also clearly shows this developing band of moderate to potentially heavy snow moving through eastern KS. here is a forecast radar from the RAP model for 5AM Thursday showing the moderate snow moving into the area…

 

The Hi-Res NAM model is also showing an intensifying area of snow moving right into KC during rush hour. Should this data verify, rush hour would grind to a halt and numerous schools would be cancelled. The validity of the data is a concern because the storm will be intensifying nearby and pulling the snow/moisture from NW MO into the metro area. The surface wind fields will be through the roof on this storm. Again should the data be close to correct…rush hour will get worse and worse as the AM moves along.

Winter Weather Advisories are in effect for the region with Winter Storm Warnings for NW MO and NE KS. Snow there will be on the increase earlier in this process.

For your reference 23Z refers to 5PM CST.

I’m VERY concerned about how this will evolve tomorrow AM…for the anti-snow people, hope that the wrap around snows aren’t as impressive/heavy as what may occur.

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This storm will be fascinating to watch over the next 24-36 hours. Severe weather will be possible across parts of the south while blizzard conditions will be likely to the north of the KC area. The vast majority of our viewing area is from 36 highway southwards towards the Sedalia-Butler-Garnett region and that will be the main focus of the blog today but I’d be remiss if I at least didn’t talk about the other parts of the country so bear with me for a few minutes.

The storm doesn’t exactly look that impressive at this point, but over the next day to day and a half it will start looking much better in terms of it’s appearance on the satellite pictures. Take a look at the latest water vapor loop. This shows the atmospheric moisture a little better than just looking at the typical satellite showing only clouds. The storm itself is still located in the SW part of the country…look for the swirl towards the 4 Corners area. Notice as well the moisture fanning out ahead of the storm. That cloud cover is on top of us now and will slowly get thicker and lower as the lift from the developing storm moves towards out area this afternoon. We should see some rain develop later this afternoon into this evening. While rainfall amounts will be light (under 1/4″ for most) we’ll certainly take that moisture with open arms. Every bit helps.

This fanning out of the air, helping to create our clouds now, will be getting more pronounced across the southern part of the country where there will be more surface moisture. This should result in t-storms across parts of S MO through AR and LA. The SPC has highlighted this area for the potential of severe storms including maybe some tornados as well as this next graphic illustrates.

That’s one aspect of the storm, the next one is the blizzard aspect of this and that will be nasty across parts of the Midwest, perhaps as far south as northern MO in some cases. While I still expect about 3-5+” towards the IA border, when you factor in the winds if 30-45 MPH the blowing and drifting will be intense and driving conditions nearly impossible as you cross the border into IA where it will be worse. That combination makes it nearly impossible for road crews to handle the roads with any efficiency so beware that traveling up I-29/35 may be difficult at best tomorrow, especially through 12-3PM or so.

The reason why the surface winds will be cranking away is as our upper level storm comes through the region, the surface storm will rapidly intensify across MO and move NEwards. This process of intensification means that the winds will start to really howl as the surface storm sucks in the air around it so that by tomorrow @ 6AM the storm which will be near the MS River has intensified dramatically…

This will send the winds through the roof across many areas of the Midwest, so you add in some locally heavy snow, and the combination creates near to blizzard conditions. Here is what the folks up in the IA area are thinking for snowfall…

Let’s go a little farther westwards…and see what the folks in Omaha are thinking…

OK so that covers the headline of the blog…now let’s deal with the metro area. The biggest change in my thinking compared to yesterday is that this will evolve a bit slower than my thoughts from Tuesday. Now it appears the transition will occur between 1-4AM or so. In reality, we may get dry-slotted for a period of time tonight, before the wrap-around part of the storm (the one responsible for our snow) moves through. This part of the storm should encompass a lot of real estate through central and eastern KS and should hold together rather nicely as it moves through. The large area of wrap-around should counter the fact that the storm is still a bit dysfunctional through the atmosphere until it gets east of here. So the snow window, while still about 6 hours or so has been pushed to about 3AM-9AM.

This is NOT good news for the morning commute in the KC area which may be just awful. Should the wrap-around snow intensify a bit along the I-35 corridor which I’m expecting, this will create an absolute nightmare for the AM rush since the timing would coincide with everybody hitting the roadways. Remember during that time of the AM, it’s really not the amount of snow that can create massive headaches it’s the timing of the snow. All too many times we’ve seen 1″ of snow (or less) paralyze the roads…BE ALERT to the potential for tomorrow AM…and yes this would have the potential for cancelling some schools in the region (or delaying the start times at least).

As far as amounts go…I think widespread 1-2″ amounts are likely with some upside towards the N/NE of the immediate KC area, perhaps as close to us as Liberty to Smithville to Chillicothe. Areas farther S/SE of towards Sedalia and Clinton won’t see as much snow.

For the most part I think the NWS has this pretty correct, although I’m not as bullish for N MO as they are (I’m more on the low side of their forecast towards their accumulations for N MO from 36 highway northwards)…and regardless of all of this, with the wind blowing so much this will be nearly impossible to measure anyway but I think you get the point.

So let’s put this all together…for the rest of the day today, through 6PM…the clouds will thicken and lower. Some light RAIN showers/sprinkles will be possible later this afternoon. Temperatures in the 40s.

We should then have a period of RAIN with amounts under 1/3″ this evening before the rain diminishes for a few hours sometime between 9PM and Midnight. Temperatures in the 40s still.  As this occurs the backside of the storm, the one producing the snow will be moving through central and eastern KS heading this way. The transition should occur between 2-4AM or so, and there may be a period of moderate wind blown snow from 4AM-8AM. This will be the peak of the storm and when roads may get bad fast. Also be aware that any moisture on the roads will try and freeze up (especially untreated roads and elevated surfaces) and also be aware that since the roads will be pretty empty the treatments on them will work a bit slower since the cars won’t be helping the cause that much. Temperatures in this time frame will be dropping fast and by daybreak we should be close to 25-30° with howling NW winds of 25-35 MPH.

Here is the latest Hi-Res NAM model showing the banding features of the area of snow that will be around for about 6 hours or so that I think could be the wildcard in the snow forecast.

ScreenHunter_03 Dec. 19 08.49

This higher resolution model picks out the potential for these features better than the lower resolution models that I usually show you.

So what can happen for us to miss this event…well should that wrap-around band of snow NOT respond to the intensifying upper part of the storm and not get stronger as it approaches the I-35 corridor and be smaller in width and lighter in intensity…we’ll be more in the 1″ range for most of the metro area. This is still a somewhat dysfunctional storm system and there are some upper level tracks of the various features that I’m not thrilled with. Looking at a past storm that had a similar track (12/9/09) and with roughly the same intensity (maybe a bit stronger) that this should have…we saw about 2-4″of snow.

I should finally say that all these ideas are my own interpretation as far as the evolution of the storm goes.

Joe

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