1ST GUESS SNOW MAP FOR JAN 16–17 TENN VALLEY/ EAST COAST WINTER STORM
Because of the size of this event on Sunday, and Sunday night into Monday across so much of the eastern CONUS, we have taken the 1ST GUESS snowfall map and we have broken it up and enlarged it into northern and southern sections, so it is easier for you to see them in more detail. And we have also included the initial outlook for the start times of this event.
There is not much to change from our earlier statement made in the WNS / Weather Notification Statement. As with every winter storm, there are always uncertainties and variables and that is certainly the case with this particular event. As we talked about earlier, the global models ensembles (the GFS/ Canadian/ European) are somewhat to the right of the operational runs.
Back on Tuesday and Wednesday, this discrepancy and inconsistency between the regular operational Global models and their corresponding ensembles were quite significant. That is why there has been this concern or talk that the track of the main coastal LOW might shift to the east. However, during the last 24 hours that discrepancy has been reduced significantly. The operational Global models and their respective ensembles are in decent agreement. There is still some discrepancy, but it is not nearly as bad.
So the question or concern is this: Between now and Saturday night, is it possible that the coastal LOW is going shift 150 miles further to the east, given all the current and very consistent data? No — that is not going to happen.
But it is still possible that the track of the coastal LOW could shift 50 miles to the east. This would mean that the LOW, instead of tracking from Raleigh to Richmond, to DC/ BAL, to Allentown or Philadelphia, the LOW might shift closer to the coast and pass close to say Norfolk, the Delmarva and coastal New Jersey. If that were to happen, it would cause the snow amounts in Baltimore, Philadelphia, Washington, Fredericksburg, and Richmond to go up by several inches and there will be a lot more sleet and a lot less rain. It would also increase the chances of more snow in southern and eastern New England.
The two pieces of energy which are going to cause this big system to develop and possibly track inland, are just now entering western North America where the data fields for the computer models are much more refined. So if there is going to be a shift, it is going to occur sometime in the next 36 hours.
Our main area of uncertainty is the I-95 region from Baltimore and Washington DC to Richmond. We have kept the 6 inch close to these Metro areas but the confidence in the position of the 6-inch snow line is not high. If the coastal LOW tracks more Inland, that 6-inch snow will become a 3-inch snow line with a quicker changeover to rain.
What we are confident about is that western and southwestern portions of North Carolina, southwest Virginia, most of the Shenandoah Valley, the western half of Maryland, and much of central and eastern West Virginia, into central and western Pennsylvania will get a major snowstorm with amounts likely to be over 12 inches in several places.
With respect to the 10-inch snow Line which runs from Wilkes-Barre Scranton, to Harrisburg, to Winchester, to Charlottesville, to Lynchburg, and Smith Mountain Lake, a lot of this will depend on how much sleet gets involved in these areas and that is determined by the track of the coastal LOW .