A Tale of Two Seasons

There is a strong cold front draped across east central US at this time. It is very apparent. One side has winter with snow and ice. The other is more like early fall, with temps in the 50s and 60s. This is at 7 am. So quite the contrast. In between, there is quite a bit of rain.

However, I stated earlier, the trough is essentially splitting. One piece to our north and east, and the other to our south and west.  The second piece will bring a decent rainstorm to us Tue into early Wed. Somewhat cooler air behind it, but no arctic air in the foreseeable future.

The pattern for the next 10 days is one that is “classic” El Nino: Southern storminess, chilly south, mild north, cold air locked up in northern half of Canada, with westerly wind flow from Pacific to Atlantic. There are signs of things changing later in December. If you recall, a couple weeks ago, the models were showing the cold taking up residence in the central and eastern US. I thought they were too early, and the change would not occur until at least the middle of December.

Well, now the models are showing warm, warm, warm, but with daily major gyrations form big storm to no storm, to possible cold shot to no cold shot. It’s been a daily change, and every model has suffered from it. This typically means, they are struggling to figure out what is happening, and means that pattern is not set, and is likely changing. September, through early November is was pretty easy: Trough west, ridge east. But that is breaking down slowly. Signs of more ridging out west and more trough in the east are being seen. Again, I do not expect this change to really occur until at the earliest mid-December, but more likely late.

Be cautioned. I do not expect the change to be dramatic. I think it will go from mild/warm to seasonal, then cool, then cold by the time February arrives.  I have felt this since early fall, and see no reason to change now.
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Points of interest. According to NWS records, Harrisburg (at airport) in 2009 had a warm November with temps averaging close to 4 degrees above average. Less than 2” of precipitation was measured for the month too. That fall a more central (although much weaker) El Nino was occurring as well.  My point?  The winter of 2001-2010 is the winter of the famous “Snow-mageddon.” Baltimore, D.C., and Philly all set snowfall records that year. Thought you might find that interesting.  
 
My Weather Points for the Next 7 Days:

1. Seasonal: No big cold shots, and not big warm ups either. Most days in the 40s, a couple may get above 50, but our average highs are around 46-48 this time of year. So a pretty seasonal week.
2. Clouds: Cloudy Sat, Sun (late clearing), Tue and Wed.
3. Rain: Some showers possible Sat afternoon and night. Less than .20 if that. Could stay dry. Rain arrives early Tuesday and lasts on and off into very early Wed. A soaking rain with about .75” to 1”.
4. Rumors of Storms: Will need to watch the SE coast for a new storm to develop for Friday. This could try to move up the coast for Sat. I suspect it will stay off the coast, and at worst give us clouds at this time. The westerly flow is too fast to allow it to move due North up the coast.  
5. First 1” of Snow: No sign of it yet. At least 10 days away, probably longer.

 
Saturday: 54. Mostly cloudy. Chillier.  Chance shower late and at night.
Sunday: 48. Much colder. Mostly cloudy. Some partial sun in afternoon possible.   
Monday: 47. Mostly sunny. Seasonally cool.  
Tuesday: 47. Mostly cloudy. Rain arriving early. Temps steady or rising at night.
Wednesday: 55. Showers ending. Mostly cloudy then partly sunny. Milder.  
Thursday: 49. Mostly sunny. Seasonal.               
Friday: 51. Mostly sunny. Seasonally mild

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