stardate 202201.15 1610 est 1st Officer’s Log
For the second time this winter we have had to issue an adjustment to the LAST CALL SNOW FORECAST map because of changing weather situations in the last minute. The short-range high-resolution models from late last night into Saturday morning continue to show increasing amounts of warm air getting into the system faster than what the earlier models were detecting.
GFS / EURO 12Z SATURDAY RUN
12z Saturday short range
this data is screaming ice storm
There are two primary reasons for this. First, is the large cold Canadian HIGH pressure which is currently in New York state and is providing the colder temperatures and the north winds. But the HIGH is going to move rapidly off the New England coast on Sunday. When there is no large area of LOW pressure in southeastern Canada or a strong blocking pattern in Greenland, cold HIGH pressure systems that are centered in the Great Lakes/ northern New England/ southern Quebec Canada, will move off the New England coast at a fairly rapid pace. This results in the low-level winds becoming Northeast, then East, which of course brings in mild temperatures from the ocean.
In addition, the actual track of this particular Low-pressure area is so far inland, that it also is producing easterly winds. So, the combination of the East winds from the HIGH pressure area moving away from New England into the Northwest Atlantic, and the easterly winds generated by the surface LOW pressure area, is flooding the Middle Atlantic and New England regions with relatively milder Ocean air. The combination of both of these easterly winds is forcing in milder air along the East Coast from Georgia to Maine, and is why some of the short-range models are turning warmer and producing more sleet and freezing rain as opposed to snow.
The heavy rain currently in northeast Arkansas, Mississippi, and far western Tennessee will continue to spread westward during the next 6 to 12 hours. The rain will change to snow in most of Tennessee during the predawn hours of Sunday and it will begin as snow in far northeast corner of Georgia, and in the western North Carolina Foothills, and the mountains. Heavy sleet will develop across northwest third of South Carolina and central North Carolina including the Raleigh and Charlotte Metro areas by 4 am. These areas of sleet and snow will become heavy by 7 am, and the snow will be significant in central and eastern Tennessee and in northern Alabama during the day on Sunday.
SUNDAY MORNING -By 11 a.m. the snow will be spreading rapidly East and North into the rest of the Shenandoah Valley and much of central Virginia. It should reach Washington DC by 1 p.m. and Winchester Virginia by 2 pm.
Heavy freezing rain will be hammering northwest, 25% of South Carolina, including Greenville, Spartanburg and all of western North Carolina essentially west of Interstate 85. This will reduce the snowfall amounts in the mountains of western North Carolina.
SUNDAY AFTERNOON: Moderate to heavy snow will be falling from Roanoke to Winchester /Martinsburg and into Charlottesville and the northern half of the Virginia Piedmont between 1–7pm. The snow will continue to advance into western and central Maryland and most of Pennsylvania by sunset. Any sleet and /or freezing rain in central Virginia including the Richmond Metro Area will have gone over to plain rain by 6 or 7 pm, by 8 pm in Fredericksburg, and by 9–10 pm. in Washington DC metro area including Baltimore.
SUNDAY EVENING: It is in this time period where there is the biggest discrepancy in the models. The European and the GFS keep the primary precipitation snow in all of the Shenandoah Valley with some areas of sleet mixed in from Roanoke and Lexington to Winchester and Leesburg, and up into Frederick and Hagerstown, and the eastern panhandle of West Virginia. All of Pennsylvania except for the Philadelphia metro area is seeing moderate to heavy snow by Sunday evening. But the various short-range models have a lot more sleet in them and push to sleet area as far west as the Virginia -West Virginia border. This obviously would reduce the snow amounts but increase the icing significantly.
MONDAY PRE DAWN
As the LOW pressure area continues to push northwards in the early morning hours of Monday, the whole event will come to an end in North Carolina and Virginia well before dawn. Further north, the precipitation may begin as snow in Philly, New York City, Coastal Connecticut, and the southeast third of New England late Sunday night into early Monday morning. But the strong east and southeast winds will force everything to go over to rain rather quickly. The northern third of Connecticut as well as western and central New England will have significant snow accumulations but will also see mixing of sleet and freezing rain as the warmer air surges inland.
Finally, this is a tricky forecast as we stated previously and even now the short-range models are not in good agreement.
There is another event brewing for next weekend. This one does not have a piece of energy in the jet stream coming down from the upper Plains or the western Great Lakes to pull the coastal LOW inland (which is what is happening with this current system). We will look at that in more detail on Monday but it looks like a pretty good Mid-Atlantic storm at this point and with the Arctic air in place for most of this week, there is a decent chance of this next one being a moderate snow event for everybody.
