Ralph Wiggum Posted December 23, 2017 Share Posted December 23, 2017 Models have made sizeable changes with the evolution of the Christmas Eve night/Christmas morning threat. Looks like a Miller B with one piece riding N into SW PA and a secondary low forming off the coast as opposed to just a wave developing along the boundary out over the Gulf Stream. This presents some challenges as most Miller Bs bring 1) a jump to the coast with an area in between left high and dry 2) more waa out ahead and 3) tying in with #2 a race to get cold air wrapped in before moisture and new lp move past our latitude.In any event, looks like it will come down to how quickly secondary can take over, where the jump to the coast takes place, and how much moisture is left once the column is cooled. Tightrope walking essentially. 3k NAM is interesting in that it develops a death band of snow as system pulls out with embedded thunder. Might be a hi res NAM blip so we will have to watch future runs for this feature. It does drop a quick 2-4" in parts of Upper Bucks Co in just an hour or 2 early Christmas morning. Link to comment Share on other sites More sharing options...
Ralph Wiggum Posted December 23, 2017 Share Posted December 23, 2017 Rgem is colder at 2m has most of SE PA very close to freezing with decent CAD signature at surface. Also colder at 850 but getting freeze line there moving NW last few frames of the run. In any event as I keep saying, really fragile setup. Not a prolific snow threat obviously but would be cool to whiten the ground for the holiday. Link to comment Share on other sites More sharing options...
Birds~69 Posted December 23, 2017 Share Posted December 23, 2017 Watching 6abc this morning and their snow map for Christmas morning seems pretty accurate and a good guess IMO. Even though I'm barely in the "coating" range, I'm hoping the over-achieving thing continues and I end up with a little more (.5") Link to comment Share on other sites More sharing options...
Ralph Wiggum Posted December 23, 2017 Share Posted December 23, 2017 3k NAM @ 6Z has that very narrow death band showing up again as the system pulls away to the NE. Still seems like a suspect feature but this is a few consecutive runs with this feature and actually looks more pronounced with each run. Other guidance hint at a banding feature swinging thru also. With the waa and miller b transfer depiction now hurting our chance for snow as the precip moves in, this feature might be our "Christmas Miracle" in disguise that it actually verifies could drop a quick coating-1" in parts of the forum to whiten the ground as the system pulls away. Link to comment Share on other sites More sharing options...
ChescoWx Posted December 23, 2017 Author Share Posted December 23, 2017 6z NAM has some snow on the ground west of the Delaware river with a 2 inches across Northern LNS/Chesco into Montco and N Bucks... Link to comment Share on other sites More sharing options...
ChescoWx Posted December 23, 2017 Author Share Posted December 23, 2017 For SE PA I think the 12z NAM is close to reality....with a white Christmas (not saying very white but a coating to an inch from the mason-dixon line north and west of 476 (Blue Route)...with elevations in Northern Chester County above 600ft having the best shot at 1" or so. Link to comment Share on other sites More sharing options...
Birds~69 Posted December 23, 2017 Share Posted December 23, 2017 Practically dark outside...low clouds, fog, mist/rain...you name it. Outdoor Christmas lights on....47F. Link to comment Share on other sites More sharing options...
RedSky Posted December 23, 2017 Share Posted December 23, 2017 My front yard north looks like the best chance for 1" or more of snow Christmas morning it's that close Link to comment Share on other sites More sharing options...
Newman Posted December 23, 2017 Share Posted December 23, 2017 What I would take to have the 18z NAM be right. 3-5" in my backyard verbatim. Setting my bar at only 1 inch though and see how it goes... Link to comment Share on other sites More sharing options...
geeter1 Posted December 24, 2017 Share Posted December 24, 2017 WWA just issued for Allentown. Snow, sleet, and freezing rain tonight. Total accumulations 1 to 3 inches. I'll take it and run.......... Merry Christmas Everyone Link to comment Share on other sites More sharing options...
Newman Posted December 24, 2017 Share Posted December 24, 2017 Mount Holly Snow Map Have a Merry Christmas everyone! Link to comment Share on other sites More sharing options...
LizardMafia Posted December 24, 2017 Share Posted December 24, 2017 Looks like about 3" here in Saylorsburg. Link to comment Share on other sites More sharing options...
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