Joe’s Weather Blog: A busy week of ice…rain and snow (MON-12/28)

Weather Blog

It’s been so dry for so long that this week may be eye-opening to a large extent. Moisture is a guarantee…some decent moisture is possible by the end of the week. What form that moisture takes on though is what is the toughest part of the forecast.

Things start getting bumpy tomorrow as a wave of frozen precipitation comes our way. It will take just about every form…including snow…sleet and freezing rain. The last two aspects are the majority I think. Things then will gradually convert to liquid from south to north as the afternoon moves along.

Tomorrow night will be wet and chilly.

Wednesday will be fine.

Then the end of the week will have more sleet and or snow. IF there is a more significant snow event this week…that would be it. The way the whole thing comes together though is unusual…sort of some VERY vague shades to the Christmas Eve blizzard back in 2009…but I don’t remember an upper level storm coming up from the south like this except for that one.

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Forecast:

Today: Variable clouds and cold. Really seasonable with highs in the upper 30s

Tonight: Cloudy but generally dry. There may be a few patches of flurries, especially on the KS side early AM Tuesday. Lows in the mid>upper 20s

Tomorrow: A winter mix gradually transitions to rain during the afternoon with slowly rising temperatures. Eventually well into the 30s (above freezing) later in the afternoon and night.

Wednesday: The moisture moves out before daybreak. Too fast by the time the colder air comes into the area. So no issues expected. Highs on Wednesday in the 30s

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Discussion:

So I’m not sure I want to rehash everything about tomorrow that I wrote about yesterday but here is a synopsis.

The upper level storm that is going to affect us will break up into 2 main pieces…one will go through the upper Midwest and the other will break off and move through central TX. This happens Tuesday through Thursday.

As this happens broad scale lift will be developing in the Plains region…on top of cold air that will be retreating northwards. That sets the stage for the potential of a light wintry mix to develop tomorrow morning at some point. It may be during the AM rush…or perhaps just afterwards. It will likely be light at first since there will be dry air that all this needs to overcome.

It should last for about 6 hours. Freezing rain will develop about 2-3 hours after the sleet arrives (if not earlier). Then we convert to rain between 2-5PM from south to north in the Metro it appears. Some slick roads are possible through the middle of the afternoon.

For areas farther north towards northern MO…there may be more significant icing happening up there…with a bit more snow at the onset of things. Travel will be impacted across northern MO perhaps moreso than the KC area and for longer it appears.

The hi-res NAM shows the outcome that I’m sort of looking for. It ends before daybreak on Wednesday before we can convert back to wintry weather.

For timing…12Z is 6AM…15Z is 9AM…18Z is Noon…21Z is 3PM…0Z is 6PM and 3Z is 9PM

While many don’t want the ice aspect of this…and there will be some…the moisture aspect is needed. Amounts should be at least 1/3″ to as much as 3/4″ on average in the area. So this, in the end will be needed moisture for us regardless of form.

Areas farther north and west should see over 1″ of moisture from this…including a bit more ice and snow potential.

The main reason why this part of the storm won’t be a snow event is that strong enough south winds above us will be sending temperatures into the lower 40s at around 5,000 feet or so. That melts whatever snowflakes fall. Initially the air below that will be below freezing so the melted snowflakes freeze up and we get sleet…then as that below freezing layer warms…a bit and thins out…then we get freezing rain. Eventually the below freezing layer of air is eliminated and we just get plain rain…that should happen during the mid afternoon hours.

Again travel would be impacted, especially on untreated roads and rural areas. So plan on extra time for scraping etc tomorrow.

Rain is likely though at ight…just liquid rain.

Nothing consequential on Wednesday and Thursday.

Then come Thursday night and Friday. Things get much more interesting for snow wanters in this time frame.

Let’s track the “other” piece of the system that has broken off in Texas. Notice where it goes…and the hard NNE turn it takes. That will be the key to this…because IF the turn is less “hard” and more towards St Louis…it might shunt the accumulating snow a bit farther eastwards. As is we’re sort of in the western side of this…so farther east won’t do us much for getting more snow locally.

So the EURO has this going through Central MO. That will work for snow locally. The GFS which initially had this about 150 miles farther east now has pulled back towards the west a bit and has this in the region as well

You would think it would be simple right…but it won’t be because of this one thing.

As the system pulls towards the NNE it will wrap in warmer air aloft again…killing snowflake production on Thursday night at least. Then as the wrap-around band solidifies…it chills the atmosphere down and voila we get snow to come together. This happens southwest to northeast.

Ensemble model use shows the potential of at least 1/4″ of moisture in the 24 hour period from Friday AM onwards. That would be mostly snow…so JUST by looking at that aspect…that would be a 2-4″ system locally.

With that said there is upside, especially towards northern MO.

This is by no means a simple thing to figure out. These types of systems get so wrapped up that drier air can wrap all the way around the upper level storm…cutting moisture levels in the snow growth areas of the atmosphere. That won’t be figured out till at least Thursday but that potential is something meteorologists should be paying attention too.

The snow jackpot happens IF the dry air doesn’t wrap into the area enough…and we end up in the core of the wraparound aspect of the system…there could be a path of over 6″ of snow locally.

Looking at the ensemble data though shows more members giving us under 1″ of snow than over 6″ of snow. This from the EURO model suite from earlier this morning.

The GFS suite from overnight is split…more bullish and less bullish for the heavier or not snows.

IF you want to break this down into probabilities…here are the two model suites. Looking at the chances of at least 1″ of snow…

EURO ensembles vs GFS ensembles probabilities for 1″ of snow

Now the 3″+ chances…

So there’s certainly something BUT the “weirdness” of the track of this one has me guarded right now.

The feature photo for today is from Glenna Oidtman…yesterday’s sunrise was amazing! (I slept through it ;) )

Joe

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