Discussion...
Overall not many changes were needed from our preliminary scenario map. Biggest overall change was backing off some with accumulations on the northern side. Most difficult aspect of the forecast was deciding on accumulation ranges. This storm will not produce the insane totals the one a few days ago did and generally accumulations over 20 inches will probably be more of an exception rather than rule. With that said, there is liable to be a lot of folks seeing about a foot plus with this storm.. which is still a big storm. Installed a 12-20 inch range from around DC through north central New Jersey, transitioning to a dashed 12-20 from NYC north, as it currently appears that the NYC area and northeastward is looking at more of an 8-14 inch type snowfall with some higher totals here and there. To remind folks, our dashed ranges are installed if we expect to see scattered totals that end up higher than the filled range in that area. In addition we installed a dashed 20-24" centered on Philly and surrounding areas, which is where models have been consistently throwing a QPF bullseye.
What this system "lacks" in snowfall accumulations compared to the last one will make up for it in sheer dynamics. This will be a much more powerful coastal storm and conditions in the I-95 corridor centered on Philly, but also New Jersey, Delaware, eastern MD, DC, and NYC/LI are going to be severe at the height of this storm with the winds it will generate. As the storm moves up and away from the coast, southern New England is probably going to see similar conditions
Further northwest, there is going to be a lot of 6-12 inch amounts across the southern 2/3rd of PA. Installed a dashed 10-20 inch range in the laurel highlands where a couple higher totals are likely to come in. Back in Ohio, looking at probably mainly 5-10 inches in the northern half of the state. Some question of whether a dry slot is going to cut into snow totals especially in southern Ohio, so decided to run with the 3-7 range there.
Things to watch for:
Three words, underdone forecast totals...
We feel that the region we have marked as ground zero is in good shape and covered well with our ranges, however my biggest area of concern is back across the rest of PA. As NWS State College had alluded to, coastal low development and associated mesoscale banding, etc is a big wildcard. Snow ratios is the other wildcard, high snow ratios could result in higher totals as well. Northern fringes are another area to watch, as a last minute northern trend could send advisories and possibly warnings another tier of counties or so north in the northeast.
Blizzard conditions:
I expect NWS offices, especially Mount Holly to issue blizzard warnings at some point today with the wind likely to be a major issue. Further west, it will get windy behind this storm. While it likely won't be really blizzard conditions, there is going to be about a 2-3 foot snowpack to drift around.. and there is liable to be significant problems on roadways with blowing and drifting.
..GLUNT.. 2/9/10
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