Good Saturday evening everyone. Snow has ended here in the Middle Atlantic States. There has been some significant snow in the middle atlantic region overnight and into early this morning. Part of the reason for the more significant snow is A. a very cold airmass, which increased the liquid snow ratios to 30;1 in places along the mason dixon line. Thus 1/4 inch of liquid equaled to 6-7 inches of very fluffy snow. This is a big concern as we head into this winter storm situation on Sunday, the high snow;liquid ratios. On a typical winter storm, we see 10;1 ratios. On this winter storm, 20;1 ratios are possible. That means 20 inches of snow would equal 1 inch of liquid. We gotta keep an eye on this.
In the meantime, snow amounts varied last night across Maryland and into eastern West Virginia. For example, here in Essex, MD 2 inches of snow fell bringing us up to 14 inches for the 2003-2004 winter season so far. 2.3 inches fell in Parkville, Maryland. However 6.5 inches fell in Manchester, Carroll County, MD. The highest total I could find was 7 inches in Martinsburg, West Virginia. These areas saw heavier amounts to begin with, but just 1/4 inch of liquid. That combined with a 30;1 ratio gives you these tremendous totals courtesy of this alberta clipper.
A brief respite has occurred this afternoon and evening. However more big problems are expected to occur as we head on through time. The latest model guidance is looking more ominous from the DC to Philly corridor. This precip combined with cold temps leads to very high snow to liquid ratios and huge amounts. The latest guidance is below.
18z GFS 30-42 hours
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_030s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_036s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_042s.gif
12z ETA 36-48 hours
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_036s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_042s.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_048s.gif
Snow should begin falling in the DC-Philly corridor most likely Sunday evening. Most of Sunday may turn out to be ok. However Sunday evening into Sunday night is when big problems begin. Supposing liquid ratios get up to 20:1, that means 20 inches of snow would equal 1 inch of liquid. The 12Z ETA is forecasting about 4 tenths to 1/2 inch of liquid to sweeze out from this. However the 18Z GFS shows over 1/2 inch of liquid sweezing out. The bottom line is 4-8 inches of snow maybe a conservative number, especially given the snow:liquid ratios. Local amounts in excess of 1 foot of snow seems more realistic at this stage of the game from DC to Philadelphia. Temps for most of the day Sunday will only be in the teens in the DC-Philadelphia corridor. Thus snow will tend to accumulate more quickly.
Further south into Virginia and North Carolina, snow will bew the initial precipitation type. However some mixed precipitation will likely occur with this. From Ashville to Hickory, NC, a light coating of snow will be followed by sleet accumulation of 1-2 inches and ice accreation from freezing rain of 1/4 to 1/2 inch thick. Richmond, VA on the other hand will see more snow out of this, thus 2-5 inches of snow there followed by sleet accumulation and possibly light freezing rain. Fredricksburg, VA could see 3-6 inches of snow, possibly higher amounts given the high ratios. Snow could even accumulate up to one inch on the Virginia coast including in Norfolk and Virginia Beach before changing over to rain down there.
Further west, icestorm warnings continue for Kansas City while a winter storm warning continues in effect for St Louis. The big story in these areas will be freezing rain accumulation of over 1/2 inch thick. As a result, travel could be impossible at times, and power outages are likely with the weight of the ice being the big problem, especially with trees and powerlines. Same can be said from Lexington, KY to Cincinnati, Ohio westward to the Paducah, Kentucky area. North of these icestorm areas will see several inches of snow. This will include Indianapolis, and Columbus, OH and likewise into Cleveland as well Saturday night into Sunday.
This situation must be watched carefully. In addition to the ice potential, we have to concern ourselves with DC-Philadelphia with high snow:liquid ratios combined with .45 to .75 inches of liquid could sweeze out over 8 inches of snow with some places exceeding 1 foot of snow. We'll keep ya posted on this storm throughout the night and into Sunday. Stay safe everyone.
Jim
Clipper snow amounts and weekend winter storm, a biggie!!!
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