Joe’s Weather Blog: It’s all about the timing of the switch (FRI-1/18)

Happy Friday…a lot happening in the weather world around KC tonight…and a reminder to give me a follow on twitter @fox4wx. I’ll be dropping in quick little updates on that platform. Then I should get another blog out before I get a few hours of sleep as the rain/snow line gets closer to KC this evening…because the accumulations are all about the timing of the transition. For northern MO where this happens faster…more snow is likely for areas south of KC which will be waiting longer for the changeover…odds favor lower amounts. Regardless all will have the winds and the tanking temperatures.

Another aspect of this, and this is also VERY important for the roads will be the flash freeze potential tomorrow morning. Temperatures will be crashing into the teens towards daybreak…so whatever moisture is out there will be freezing up too on the roads…so this is going to be a more messy road situation tomorrow morning.



  • Forecast:

Today: Cloudy skies with fog around this morning and rain developing as the day moves along. Temperatures in the 32-35° range.

Tonight: Rain to a wintry mix to heavy snow. The transition will take about 1-3 hours to spread from the north part of the Metro to the south part of the Metro. In my opinion the transition should be in the 7-9 PM hour on the north side and 8-10PM on the south side. Earlier switchover times means more snow potential. Accumulations will be in the 2-6″ range especially from KC northwards and in the 1-4″ range on the south side of KC. This will be a work in progress as the transition time is worked out. Later = less snow…earlier = a bit more snow. Winds increase to 30+ MPH gusts which means blowing and drifting and near blizzard conditions for several hours overnight.

Saturday: Snow ends before 9AM or so…the accumulating snow winds down towards daybreak. Windy and falling temperatures. Teens for highs with sub-zero wind chills. Some sunshine (!) possible later in the afternoon

Sunday: Partly cloudy and chilly but again not as brutal as it looked earlier in the week. Highs around 20°. Don’t forget about the eclipse later in the evening…although I’m concerned that clouds may block it out at times.



  • Discussion:

First an update on the current advisories and warnings out there. For KC, as of this writing a Winter Weather Advisory is in effect.

 

Winter storm warnings are in effect towards the NE of KC…snow amounts there may be more towards 4-8″ or so.

Winds are an issue with this storm unlike last weekend.

Here is the morning run of the HRRR model for wind gusts towards 1AM…

30+ MPH gusts locally with higher gusts SW of KC..perhaps overdone down there but still you get the point. The winds really get going overnight tonight.

Temperatures…check out a model forecast for 6AM Saturday…

Wind chills will be near to below 0° all day Saturday.

The storm now is taking shape…

It’s a developing area of low pressure in the western Plains. There are still issues with the exact track. Models that give us somewhat more snow has the surface low tracking along the MO/AR border while models that give us somewhat less snow have it more towards Little Rock, AR. Important! Farther north with that track…some bonus snow is possible.

The storm itself is starting to reveal itself aloft in western KC between Amarillo and Lubbock.

What that storm does…does it slow down today…does it get stronger…do other waves rotate around the storm…will help with the final results.

Radar…

 

Transition timing…looking at the higher res NAM model just out this morning…this seems somewhat reasonable to me.

1st map…6PM tonight. Still good to be getting around…wet but OK

Now 9PM…this is during the critical switch-over from north to south…it should be pouring down snow on the northern side of the Metro (at least). IF it’s also pouring down snow on the south side of KC too…then the south side will get over 4″ of snow.

Now 12AM…

So the model is trying to pick out these bands of heavier snows…it’s doing that from near Topeka towards Plattsburg towards Bethany.

The location of these “bands” is the determining factor to the heavier snow amounts. This can’t be picked out right now with accuracy. It’s just a matter of watching radar tonight.

Finally 3AM Saturday.

The heaviest may be winding down by there…and the temperatures will be tanking with gusting winds blowing and drifting everything around to some extent.

So how much? Well again I’m looking for the amount of moisture from roughly 9PM tonight to 9AM Saturday…really about 6AM but this is what I have to work with.

Roughly 1/4″ or so with upside north of the Downtown vicinity…where liquid totals may be 1/3rd to 1/2″ or so. The upside towards Cass and Johnson Co MO may be more of a combo of rain and snow there. IF it’s all snow there too…there will be upside to the end game regarding snow amounts.

The model is TRYING to pick out where the “bands” of heavier snow set up. This really could be anywhere and it could be on top of KC as well with a deeper storm pulling this band 1-2 counties farther south and I’m NOT discounting that at all at this point.

Snow ratios will start out lowish then increase after 12AM. So this makes it tricky too. Higher ratios, meaning more of a fluff factor to the snow means an easier accumulation BUT these higher ratios come in towards the time the snow starts to lighten up early Saturday. This one is a complicated one.

Snow accumulations…

Based on that map above…allowing for a couple of hours (at least) of extra fluff snow…I still think 2-6″ from south to north seems like a reasonable estimate for the snow totals in the KC Metro area. That area towards the NE of KC are certainly 4-8″ looking to me right now.

Temperatures for Sunday…

I think sub-zero lows are still VERY much on the table assuming clear skies. While the core of the high pressure will be farther up towards the Lakes region…the ridge axis extends down towards us. Assuming clear skies…light winds…and snowpack…I wouldn’t be surprised if some tank to -5° north of KC and close to 0 – +5° in the Metro. Afternoon highs will struggle…I’ll be somewhat more pessimistic than others and think closer to 22° or so. We should have a good amount of sunshine.

More on the eclipse tomorrow afternoon.

Another update later today or tonight. Our feature photo comes from ‎Harold Debbie Gibson

Joe

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