Tuesday, December 27, 2005
Quiet Weather
Matt Ross @ 1:00 AM
Forecast
Today will be a very pleasant Winter day.
Sunny and breezy with highs in the upper 40s to around 50 degrees. Look for slightly warmer weather on Wednesday before some rain moves in Wednesday night and Thursday. This general pattern of above normal temperatures looks to continue for at least the next week or so. Enjoy a slight reprieve from the persistent cold of the last 3 weeks.
Amazing Sky in Fairfax County Yesterday courtesy of CapitalWeather.com Photographer, Kevin Ambrose.
What December Means for January and the Rest of Winter
Even though there are a few days left this month, we can reasonably draw several conclusions. First is that it will finish below normal temperature wise. Most likely around 3 degrees below normal, but at least 2 degrees below normal. Additionally, we will finish with right around 5" of snow for the month(4.8" officially at National Airport) as there is no realistic chance of snow before the end of the month. About 1/3 of all Decembers at National Airport(DCA) have averaged at least 2 degrees below normal as this month surely will. The January's following those cold December's averaged about 1 degree below normal. I would say this is at most marginally meaningful and most likely statistically insignificant. Regarding snow, about 25% of Decembers at DCA have had more than 4" of snow. The following January-April period averaged about 15" of snow versus our normal 13" average for that period. Again, not statistically significant in my opinion. So, at least with these 2 particular measures, climatology is not a useful correlative tool to help us determine the upcoming weather. As such, I think it is best to rely on a combination of the Winter Outlook we put out in October and useful medium range tools, such as models, indices, and pattern recognition. Both of these signs point to an above average January, or at least starting off that way. I will perhaps do a more in depth review of our December outlook next week, but while we certainly didn't nail it, there was enough correct to merit sticking with our overall ideas.
As January is our coldest month by a significant margin, there will still be chances for cold shots and snow. But I still think it has the best chance to finish above normal (with respect to temperature) of any winter month, and a 50-50 chance of finishing warmer than December in an absolute sense, even though it averages almost five degrees colder. No matter what happens, there will be plenty of interesting weather to keep us all occupied.
The system that brought us moderate to heavy rain on Christmas Day pounded Northern Maine(St. Agatha) yesterday with over 2 feet of snow. Courtesy of Will Horner.
Snow Lover's Crystal Ball 
Next Chance of Snow: Tuesday January 3rd - Fri January 6th Probability: 10%
Potential Impact:
Commentary: The big issue next week will be lack of cold air. Any snow on the East Coast will likely be confined to the Interior Northeast and New England. However, with a continuing moist and stormy pattern, there is enough uncertainty 7-10 days away to at least merit a 10% chance as we head into the 1st week of January.
Today will be a very pleasant Winter day.
Sunny and breezy with highs in the upper 40s to around 50 degrees. Look for slightly warmer weather on Wednesday before some rain moves in Wednesday night and Thursday. This general pattern of above normal temperatures looks to continue for at least the next week or so. Enjoy a slight reprieve from the persistent cold of the last 3 weeks.What December Means for January and the Rest of Winter
Even though there are a few days left this month, we can reasonably draw several conclusions. First is that it will finish below normal temperature wise. Most likely around 3 degrees below normal, but at least 2 degrees below normal. Additionally, we will finish with right around 5" of snow for the month(4.8" officially at National Airport) as there is no realistic chance of snow before the end of the month. About 1/3 of all Decembers at National Airport(DCA) have averaged at least 2 degrees below normal as this month surely will. The January's following those cold December's averaged about 1 degree below normal. I would say this is at most marginally meaningful and most likely statistically insignificant. Regarding snow, about 25% of Decembers at DCA have had more than 4" of snow. The following January-April period averaged about 15" of snow versus our normal 13" average for that period. Again, not statistically significant in my opinion. So, at least with these 2 particular measures, climatology is not a useful correlative tool to help us determine the upcoming weather. As such, I think it is best to rely on a combination of the Winter Outlook we put out in October and useful medium range tools, such as models, indices, and pattern recognition. Both of these signs point to an above average January, or at least starting off that way. I will perhaps do a more in depth review of our December outlook next week, but while we certainly didn't nail it, there was enough correct to merit sticking with our overall ideas.
As January is our coldest month by a significant margin, there will still be chances for cold shots and snow. But I still think it has the best chance to finish above normal (with respect to temperature) of any winter month, and a 50-50 chance of finishing warmer than December in an absolute sense, even though it averages almost five degrees colder. No matter what happens, there will be plenty of interesting weather to keep us all occupied.
Next Chance of Snow: Tuesday January 3rd - Fri January 6th Probability: 10%
Potential Impact:
Commentary: The big issue next week will be lack of cold air. Any snow on the East Coast will likely be confined to the Interior Northeast and New England. However, with a continuing moist and stormy pattern, there is enough uncertainty 7-10 days away to at least merit a 10% chance as we head into the 1st week of January.
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