Sunday, December 8, 2013

Winter Storm Warning extended east, Maybe no school tomorrow?

Part one of today's storm was an overachiever, bringing more snow that expected to the area. Totals in the immediate DC metro ranged from 4 inches in the west to 1 inch to the south and east. Farther north and west, the totals were more impressive, with 7 inches in Frederick MD


Temperatures also stayed lower than expected today. this indicates that the ridging from the high pressure was stronger than expected and that the freezing precipitation will last longer. In response to the lower temperatures, The National Weather Service extended the Winter storm warning out to DC and PGCo.

The NWS also increased projected freezing rain accumulations to include DC and points north and west to receive more than .25 inches of ice. The 18z NAM model, which has higher resolution than the other operational models, predicts that the freezing line will stay south and east of DC and through 6AM Monday. 

As the day progresses, easterly winds of the relatively warm ocean will erode the cold air and the freezing rain will turn to just cold rain. Highs on Monday will be near 40. Tuesday features another chance at snow as another storm swings by to the south with highs in the mid 30's. 

Will we have school on Monday?

Loudoun County, VA has canceled school, which indicates that Montgomery County may follow suit. Loudon county lies just across the river from MoCo so whatever happens there is likely to happen here. MCPS needs to make it's decision by 5AM Monday. According to the models, temps will be below freezing at 6AM Monday for all of the county so MCPS will have to either call a 2 hour delay or no school. In addition, a quarter inch or more of ice is not something to mess with. It is much more hazardous to drive in than snow or sleet because it just freezes into something like an ice rink. the ice also may weigh down branches, resulting in scattered power outages. remember that just because the southern part of the county is above freezing does not mean there will be school. The northern portion may still be affected by winter weather.

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