Eastern Cold's Persistence is the Real Story
It seems like it's been really cold this winter in State College, Pennsylvania, home of AccuWeather HQ [Google Map].
But if you look at the monthly averages for December and January, they were -4.4 degrees and -1.1 degrees (so far). Although 4 degrees below normal is a fairly impressive departure from normal average temperature, those numbers (especially the one for January) don't seem to describe the cold. Here's a look at average departures for our area combining both months:
Now we're starting to see numbers between -5 and -8 that are very impressive between Pennsylvania and North Carolina, and the -11 in Johnstown, PA is especially notable. But still I'm not satisfied with this depiction. Blog reader Pete from New Hope, PA ran some interesting stats for Doylestown, PA (near Philadelphia) for 10-day periods during the last 10 years:
- Only 5 days have been above normal this meteorological winter (Dec. 1 - Feb. 28) - The first 40 days of winter were below normal; previously no 4 consecutive 10-day periods were.*
*This will probably end up being 50 / 5 10-day periods.
What he's saying is important because it speaks to the cold's persistence with no warm periods in between. This is something I was trying to explain to a new resident the other day -- it's not usually this consistently cold here in State College. We below average for the month and the season because the cold outbreaks keep coming. Here's a graph for Doylestown:
I've highlighted in blue the days on which the low or high temperature were below normal - a "colder than normal" day. As you can see, it's almost every day since December 1.
Going all the way to Wilmington, NC, you see a similar situation - the lion's share of the days have been colder than normal, and they have even set or tied their record lows twice.
And in Johnstown, which scored a -11.1 for the winter season so far, the graph is even more interesting. Notice the space between the green lines.
That would be the normal range for the temperature between morning and afternoon. Now look at the actual temperature lines - the space between them is much shorter in height. Let me highlight that for you:
The red area (this season) is much "shorter" than the green area, which is normal. This means that not only have the low temperatures been below normal, the high temperatures have been much below normal. Since afternoons are usually how people judge how a day feels, residents of Johnstown have surely been complaining about the cold weather this season, and with good reason.
So add up the persistence of the cold, and its inroads into areas that should be warm this time of year (Florida & the Caribbean, Mexico and the Southeast), and you can see why we are shivering this season.
