Winter Weather 

Posted: 9:30 am Friday, December 8th, 2017

By Kirk Mellish

As forecast precipitation started out as rain. In areas where the snow started earlier up to 5 inches expected in parts in the “warning area” in the pink below.

As usual we are right on the sharp dividing line between a lot of something and a lot of nothing for some, more something the closer to TN and AL you are and more nothing the closer to FL/SC you are.

With the rain-snow line aloft cutting roughly near and along I-85 give or take 20-40 miles North or South. So the farther North and West of the perimeter you are the better the chance of snow, also true heading Southwest toward Alabama where the cold air mass is deeper.

Rain showers will be push east during the day, mixed with and changing to snow in some areas. Precip will be on and off east and south sides. At times just rain and in some areas  all snow especially West and North.

Temps above freezing in most areas until after 3am Saturday, closer to midnight far North and West suburbs. But where it snows heavily the temp can dip to 32 or 31 this afternoon!. Back above freezing most areas of the metro after 10 am Saturday.

Most roads just wet or slushy at worse with whatever accumulates mostly grassy areas, trees bushes roof tops etc. However, this could change so stay tuned for forecast updates through the day AND our great team traffic reports!

I would be REMISS if I did not at least let you know that there ARE several computer projections of scary heavy snow accumulation and in more of the region. Forecasts as you know are never written in stone, we can be wrong so be aware there’s an outside chance this gets worse than expected.

Listen to my radio reports this morning for more info.

NCAR RAP MODEL MID-DAY FRIDAY:

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See how very much “on the line” the area around 285 is on the vertical forecast profile red line is temp near the 0C marker but above surface:

Screen Shot 2017-12-08 at 6.56.34 AM

 

NATIONAL WEATHER SERVICE BULLETINS:

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SURFACE WEATHER CHART THIS AM:

 

SURFACE WEATHER CHART EARLY EVENING:

95fndfd_init_2017120800

SURFACE WEATHER CHART MID-DAY SATURDAY:

98fndfd_init_2017120800

WPC PROBABILITY OF AT LEAST ONE INCH SNOW/SLEET:

Screen Shot 2017-12-08 at 9.36.30 AM

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PROBABILITY OF AT LEAST 4 INCHES OF SNOW:

Screen Shot 2017-12-08 at 9.37.22 AM

WPC AREA AT HIGHEST RISK OF SIGNIFICANT ACCUMULATION:

day1_psnow_gt_04

The models do not agree on how strong the upper-level disturbance in the jet stream becomes. IF it’s stronger we get more snow if its weak we get more rain.

WPC SYSTEM TOTAL SNOW/SLEET ACCUMULATION ESTIMATE:

Screen Shot 2017-12-08 at 7.52.49 AM

 

THE ESTIMATED RAIN SNOW LINE (red) OVER TIME:

NOON

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7PM

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10pm

Screen Shot 2017-12-08 at 7.50.42 AM

5AM SAT

Screen Shot 2017-12-08 at 7.51.30 AM

Follow me on Twitter @MellishMeterWSB.

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