Saturday, November 26, 2011

Colder Weather On The Way ! Pattern Change On Target for Dec 5th - 15th Time Frame !

Forecast Issued:
Saturday AM

Hi Folks,
It's time for an update on the Pattern Change and some thoughts for Early December, as we officially start the 2011-2012 Winter Season. As many of you know from my last post, back on Nov 13th, my best estimate for a Pattern change here in the East, was for Dec 5th - 15th, this looks to be on target and big changes are on the way !

For the last 4-6 weeks We've experienced near to above normal temps for the most part over the central and eastern US, while out west and in AK, they've experienced a -PNA which placed a trough and much colder weather out there. With this pattern, We've seen the PNA mainly Negative, while the AO and NAO have been near neutral to positive, which allowed more ridging here in the East, resulting in our Mild pattern.

As we head into this upcoming week, the gradual changes to a new pattern will begin, so enjoy the mild temps this weekend, because the 60's are about to become a thing of the past.
We start the workweek with some unsettled weather and temps in the mid to upper 50's, with some showers on Monday and periods of rain on Tuesday. A strong cold front will cross the region Tuesday night, ushering in seasonably cold air from Wednesday through Friday across the Delaware Valley region. During this time our temps fall to the mid and upper 40's for Highs, and the upper 20's to mid 30's for our low temps. This is average cold for the first few days of December, but this will feel quite chilly, after our mild stretch of weather over the past week or so.

During next weekend a stronger cold front and trough will deliver even colder air which will carry over into the following week (Dec 5th-9th) with below normal temperatures. During this time we can expect Highs mainly in the lower 40's and lows in the 20's. I would not be surprised if a day or two we stay in the upper 30's. Though we should be mainly dry and cold, a couple features will work into the picture and we could actually see some wintry precip between the 5th and 8th. There are some indications that a weak system could develop to our SW near the Tenn Valley, and move NE to the M/A coast. Also a clipper threat is possible. With cold air in place and High Pressure to our north, a rain/snow mix or even some wet snow can't be ruled out. I'll have more details on this potential as we get closer to that time frame. For now, I'll call it, a potential for some wet snow or mixed precip, between the 5th - 8th of Dec.

Through mid-month, I see the colder pattern continuing for the East, especially the G/L's, Midwest, and much of the NE. So overall I see the first half of December being slightly below normal to below normal with temps, and the potential for a minor snow event or two with this new pattern.

This is a Pattern change/Pattern flip, heading into the first half of December ! A huge PNA Ridge develops out west and both the NAO and AO are heading to near Neutral and slightly negative during the next 7 to 14 days. This along with the PNA heading Positive, will get the pattern change underway here in the Eastern US.

So to sum it all up, much colder weather is on the way, especially between the 5th and 15th of this month. 1 or 2 minor snow events can't be ruled out during this time frame, so winter is arriving on schedule for the Delaware Valley. I've noticed many have been quite nervous over the past few weeks, with this winter season being colder and snowy. Well I'm not, and my winter call stands firm, as I'm still quite confident it'll all work out !

Expect more frequent updates to my blog, as we enter the 2011-2012 Winter Season. Also check me out on twitter for quick updates each day. I have these tweets embedded on the top right of this blog, or just follow me on twitter. Once again, I post often and frequently on the Horizon weather Forum, so check me out there as well.

Take Care,

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