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Normally today I would be spending a considerable amount of time talking about the year that was with all sorts of stats etc…but we have bigger fish to fry heading into the holiday weekend. A 2 part system that will leave some snow lovers frustrated…others thrilled…and all very cold by the time the tomorrow afternoon is winding down.

This will come to us in a couple of parts and when you wake up in the morning there may not be a lot on the ground really…likely no snow locally and some will think…well “they” were wrong again. Things will evolve as the AM moves along…then a lull in the afternoon for awhile and then I think the key to getting extra snow…the 2nd part…a band of light snow that may last for a few hours…but because the atmosphere will be frigid…the snow may accumulate more efficiently into the overnight tomorrow. That I think is the key to getting the 1-5″ forecast from south to north through the Metro area.

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Forecast:

Today: Increasing clouds breezy and mild with highs in the mid-upper 50s

Tonight: Lowering clouds…with some light patches of freezing mist/drizzle and sleet developing after 12AM. There may be some slick areas by daybreak. Perhaps not widespread though. Something to pay attention too for changing road conditions though. Temperatures will be at their highest at 12AM (near 32°) and then drop from there to the low 20s at daybreak.

Saturday (Happy New Year): Winter Weather Advisory for the Metro. Temperatures keep falling to the single digits in the later afternoon. Sub-zero wind chills are likely in the afternoon as well. Sleet will convert to some snow (perhaps moderate to heavy N/W of the I-35 corridor area after 9AM. Then there should be a lull or two in the mid afternoon before the next round comes through later in the afternoon/evening. Total snow 1-5″ from south Metro to north Metro. Higher amounts in Northern MO (4-8″)

Sunday: Bright but bitterly cold. Lows near 0° IF we clear out fast enough before daybreak…colder NW of KC…perhaps -5 to -10° in spots.

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Discussion:

So I’ll start with good news for anti-snow readers. This snow should melt pretty well by Monday and Tuesday as temperatures warm back up into the 40s (some upside) on Tuesday and the overall pattern will be one of rapid ups and downs as another arctic shot of air comes in Wednesday and Thursday next week…maybe some snow with that as well.

Onto the matter at hand. As I’ve written about all week…the crux of the forecast is how two separate systems affecting the area. System one is the wave that was giving southern CA record rains yesterday in the LA area.

Pretty impressive for southern CA…and this has been an impressive December for rain and mountain snows out there as well…breaking all sorts of records. That system will eject and move quickly through the area tomorrow morning into early afternoon.

You can see it in the SW USA…on the water vapor loop via Rutgers.

This wave will weaken though…and one of the many keys to the forecast is how strong will this be…as it comes into the area tomorrow. It’s coming from the sub-tropics…so it’s not a “cold” system. This means that there will be above freezing air aloft with it’s arrival and that’s the key to use getting a bunch of sleet as opposed to snow for awhile in the morning tomorrow.

The AM NAM model continues to show a layer of above 32° air through 10AM or so above 5,000 feet. That’s a killer for snow to make it to the surface. The flakes melt and then either refreeze into ice pellets or remain liquid and we get freezing rain. That warm “nose” of air needs to be wiped out before we can talk about accumulating snow.

IF it wipes out earlier…there is upside to the snow forecast that we have…especially N/W of I-35 and N of I 70.

I’m basing my forecast through mid afternoon on this layer holding tough while we have a lot of “lift” to the atmosphere. So we’re wasting system #1 because we’re getting a LOT of sleet as opposed to a LOT of snow. IF this wasn’t the case…we’ have a 4-9″ snowstorm in the Metro.

So this is a major issue for a big snow in KC…as is I’m hoping we end up with about 1/10″+ of liquid after 10AM into the mid afternoon…which should create 1″ of snow….perhaps a bit more…mostly from the Metro north and west to the northern Metro. Areas S/E will continue to struggle. The NAM model isn’t too wonderful for snow lovers.

The morning HRRR model is a bit more bullish on the liquid…which then would be converted to snow. I’ve specified the time frame of 11AM>5PM below with an approximate sleet/snow transition line in black. West of that line most of that “liquid” is snow.

So you can see how we can get 1-3″ from this…perhaps more IF this is correct. Especially for areas north of I-70 and it’s the reason why I wanted to bring in a 3-5″ contour for areas north of the 435 Loop on the northside of the Metro (roughly)

Farther SE…the struggle is real for snow into the early afternoon…then the wave is gone. Hence the reasoning that areas SE of KC will have more slick roads from icier conditions as opposed to the sleet and snow in the KC immediate area.

Then there should be a pretty decent lull or lulls in anything accumulating into the mid-late afternoon hours before the 2nd part of the storm heads into the deepening and more snow friendly atmosphere above the area later in the day.

This 2nd piece will be the key to getting another 1-2″. IF it’s happening then we get a 1-5″ snow in the region from south to north in the KC area…IF we don’t get that 2nd shot…if it’s weaker or more broken up on radar then we’ll be more in the 1-3″ range from south Metro to north Metro.

Let me show you the “liquid” amount possible in the 2nd evening wave…

HRRR model from 6PM to 12AM Sunday.

Now take that liquid number…and we need to use a rough 15-20:1 ratio. Typically it’s about 10:1 but because the atmosphere is so cold…and cold air is more efficient in creating fluffier snowflakes…that tends to add up a bit faster.

So there is the way we get another 1/2″-2″ (high side) amount to the snow…the 2nd wave is the key to the 1-5″ forecast as you can see for the Metro from south to north. Areas on the southside that struggle for any snow accumulation on the 1st wave may get 1″ or so on the 2nd wave…while the north Metro gets a little something more for the 1st wave and a little something more on the 2nd wave and there is the 3-5″ potential.

Finally…as I get my way out of this…there is some data still has a decent snow event around these parts…the EURO last night came in with a band of heavier precip close by…the morning run of the GFS doesn’t though…it’s because of the way the 1st wave comes out and where it goes. Notice the subtle change…on the north and just north of the wave…there should be heavier precip.

Slide right…EURO model…more snow potential, esp N/W of I-35.
Slide left…GFS…a pinch farther north…a county or two…and that makes a BIG difference

Can ALL of this fizzle out and we get considerably less? Sure I guess…we should though get 1-2″ if nothing else up at KCI I think breaking the ice on the winter snow situation. Big picture through the next 10-14 days isn’t that thrilling for a big snowstorm either. (edit: there may be something noteworthy on Thursday and while not dissected completely…we may see some brutal cold here Wednesday into the weekend)

The issue with Sunday morning is how fast do the clouds clear out in the late overnight Saturday. IF slower we’ll be near 0-+5° around the Metro. IF faster…closer to 0°…maybe colder on the north side. For northern MO though where it clears out faster…0 to -10 seems reasonable!

Finally a note about the horrific fires yesterday in CO. The worst wildfires in they’re history destroying 100s of homes. This will be a billion dollar disaster…maybe multi billion with the price of housing these days.

Fueled by terrible and persistent drought conditions in eastern CO…no moisture for months…I believe only 1.6″ of moisture since August 1st in Boulder…no snow (only 1″” through yesterday) and wind gusts to 115 MPH with 75 MPH gusts for about 6 hours…it was a set-up that was feared.

It appears a transformer may have fallen…triggering a small fire…but because of the tinder dry conditions of the grass…it spread quickly and there weren’t nearly enough firefighters that could put things out. Some of the videos were horrific in how fast things were spreading. Folks barely had enough time to get a few of their things. People went in for a 1-2 hour lunch unaware of what was developing upwind from them and walked out to an apocalypse of smoke and fire with mandatory evacuations.

Just tragic.

Our sister station did an amazing job covering this…as I’m sure the other stations did as well.

Just sad…

One of the amazing things was seeing how the winds coming off the mountains were affecting the fire/smoke…creating “waves” of ascending smoke…and descending smoke in the pictures

I’ll post a special weather update blog in the morning tomorrow. Let’s see how things come together near or after daybreak in the morning. Roads should be deteriorating as the morning moves along.

Joe