Wednesday’s Winter Wallop

We are 48 hours away from yet another wintry headache across the Valley. From a forecasting standpoint, this one is somewhat “easier” than the system that shifted south on us 8 days ago. The storm track with this one is not exactly “locked in” yet but we have enough of a consensus among the various computer models that we can start giving you more detail than we could a few days ago.

Precipitation will arrive before sunrise Wednesday morning in the form of RAIN, or at least a mix of rain and wet snow. Roads will be wet pretty much everywhere until 9:00 on average (perhaps turning slick a bit earlier than that in northern Trumbull, and somewhat later from Route 30 south). Notice the projected temperatures locally at 8:00 Wednesday morning: gfs_t2m_b_ohio_21This shows readings still near freezing, and I could see where it is even a few degrees higher than this at 8:00. Especially from Route 30 south.

Then, a changeover to heavy, wet snow will occur from north to south. Travel conditions will likely deteriorate pretty quickly. It is March, the snow is falling during the day, the sun angle is much higher than a couple of months ago, and it will be very MILD right before this storm. It takes a HARD thump of snow at this time of the year under these conditions to get the roads to get slick quickly. But I do think that will happen.

The vertical velocity field early in the afternoon shows strong upward motion in the atmosphere around the region. Faster rising air=heavier precipitation rates: gfsvv

Snow will taper off very late in the afternoon and early in the evening. The afternoon/evening “rush” will be a mess.

How much snow?? A few forecasting challenges here.

1) Final snow totals will depend a lot on how quickly the changeover to snow occurs at the start of the storm Wednesday morning. The more moisture “wasted” on rain or a mix, the less snow accumulation. The changeover will happen last and the atmosphere will cool slowest from roughly Route 30 southward. So I think snow totals will be appreciably less in places such as East Liverpool and East Palestine compared to our far northern communities.

2) The snow-to-liquid ratios will be changing. At first, the ratios will be low, perhaps 7:1 (typical is 10:1). This means the snow will be wet and will not accumulate as efficiently AT FIRST. The ratios will quickly get higher though, perhaps 12:1 or so by the end of the afternoon. So it will take less liquid to produce more snow toward the end of the storm.

3) The storm will be strengthening as it pulls east of the Valley, leading to the possibility of some very hefty snow totals in northeastern Trumbull and northern Mercer counties. Especially in Mercer, heavy snow may persist well into the evening.

Here’s the SREF model for around the airport in southeastern Trumbull County: Screen Shot 2014-03-10 at 8Out of the 21 “members” of this model, each represented by a colored line, there is a range from about 0″ to 15″. Throwing out the extremes and focusing on where most of the lines are clustered, a reasonable range there is 5-8″. The mean, the dark black line, is about 6″ or so.

Other models, such as the GFS, European and Canadian generally jive with this idea (there are differences, yes, but they are not HUGE at this stage of the game).

We will put our “official” snow forecast out this afternoon. But I suspect it will look something like this: 2-4″ southeastern Columbiana, 4-8″ most everywhere else in viewing area, with perhaps an area of 8″+ in northeast Trumbull and northern Mercer. Stay tuned!!!

Thanks for reading!

Eric

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