Joe’s Weather Blog: Snow System Early Thursday? (TUE-12/16)

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Good morning…the blog gets a bit more hectic when there are rumors of accumulating snow possible and that may be the case over the next 48 hours or so as a weak but potentially “strong enough” system moves nearby. I think I’ll try and get an update out at around 1PM this afternoon so check back in for that information. Snow may break out and with cold air in place, at least for awhile, plus the timing of the snow (late overnight WED into AM THU) increasing the chances of that snow sticking. It’s certainly NOT a slam dunk but the data is becoming more supportive of a sticking snow.

Forecast:

Rest of today: Hopefully some clearing in the PM hours. Blustery and certainly colder than yesterday with highs 30-35°

Tonight: Fair skies and cold with lighter winds. Lows near 20°

Wednesday: Variable clouds with temperatures near 35°

Discussion:

We haven’t had much snow to talk about so far this season, but there continue to be signs that the last half of the month may be a bit more active for our area for at least the chances of accumulating snow. There is the upcoming chance then lets really watch that Christmas to New Years period for not only the chances of more significant snow but also the outbreak of Arctic cold weather again that may be with us into at least early January.

We’ll get to the later part of that paragraph over the next 10 days…let’s deal with this weak system that could bring us some travel issues on Thursday morning.

There are actually two systems to watch. The 2nd one will likely pass harmlessly (for KC) south of the I-40 corridor on Friday.

The 1st system though is connected to a west coast disturbance that will be squirting out through the Plains later tomorrow into Thursday.

 

The system itself is near CA now and will be moving into the area tomorrow night into Thursday AM. It’s not a strong system by any stretch nor is it a very sharp system. It’ll also be in pieces as it moves through the area. So let’s be clear that there are concerns about how this plays out right from the start. If you’ve read the blog before, you know we hate these types of systems which are weak and at times unfocused over a broad area because where they can try to focus lift there is the potential of a 1-3″ swath of accumulating snow. Where the lift is unfocused, the snow production can be confined to flurries. Been there and done that.

So at this point I’m NOT jumping up and down about a lot of snow. With that said however one has to at least respect what the models are trying to day and also realize that part of the the process which can create the snow for this area is called “warm air advection”. A process that frankly the models sometimes have trouble figuring out in the 1st place.

The data overnight and into this morning all suggest that there is the potential for a 1-3″ swath of accumulating snow in the region later tomorrow night (near or after 12AM) into Thursday AM. The overnight NAM model suggested this…

ScreenHunter_01 Dec. 16 07.51

Notice the various areas of lighter blue on the image above…sort of hap hazard but indicative of the weak lift regime that will be creating the snow. Hence it wouldn’t take much for us to NOT get these totals (if the lift is even weaker).

What is making this forecast a lower confidence one from 48 hours out (then again so many snow forecasts are like this) is that the wave(s) in question are really weak and ill-defined. Let’s go up to about 18,000 feet or so and show you the conundrum by looking at the data.

CENTRAL_ETA_500_GPHTMPWNDVORT_60HR

Notice how there are at least 3 little pieces to the system. How those move and more importantly how much lift they generate will be the key to the snow amounts and who gets the accumulating snow. Would it shock me if the data today gave us very little snow because of this scenario…not at all.

The atmosphere will not exactly be loaded with moisture but it will have “enough” moisture to help the cause a little bit. So at least that’s not a big issue. Again my concern is whether there will be enough “left” to get things in motion.

So at this point let’s just watch the scenario play out…and be prepared for the potential of a dusting to 2+” system moving across the region. To be clear this doesn’t mean everybody will get 2-3″ (far from it at this point). That would be the upside I think to things. Most may end up in the lower range of this prediction. We’ll just watch it over the next 48 hours or so.

Again I’ve laid out my main concern with the lift and the broken up pieces as being the main culprits in forecasting higher totals.

(1PM Update):

The model data this after (especially the EURO) is somewhat more bullish with the precipitation totals…as a matter of fact taken as gospel, the EURO has the potential of 4″ snows in the KC region. Other model data, including the hi-res NAM isn’t quite as bullish with the totals…and are more of the dusting to 2″ (on the higher end for many) through the region.

Here is the liquid equivalent off the hi-res NAM model…notice the banding structure to the totals…makes exactly specifying who gets what somewhat problematic.

hires_t_precip_kc_20

Again this is the liquid equivalent. The ratios should be close to 12:1 or so.

Joe

 

 

 

 

 

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