Arctic Air Invades Alabama on Sunday

**No afternoon Weather Xtreme Video today; scroll down for the morning video**

BIG CHANGES AHEAD: Our warm and muggy December weather continues through tomorrow with a generally cloudy sky and the risk of a few showers. Showers will increase tomorrow night in advance of the Arctic front, and we will introduce the chance of thunderstorms as instability values will be sufficient for some thunder and lightning. There is no formal severe weather risk on the SPC Day 2 outlook, and for now it looks like severe weather parameters aren’t too impressive, with very little surface based CAPE showing up (less than 50 j/kg). But, you always have to watch any storms in December with this kind of low level airmass in place.

INTO THE DEEP FREEZE SUNDAY AND MONDAY: The 12Z models runs suggest the cold air will be in here by Sunday morning. Looks like temperatures will slide into the 30s by mid to late morning, possibly recovering into the low 40s by afternoon. The model MOS products won’t understand the shallow cold air; it will most likely be colder than they suggest. Looks like the rain will end during the pre-dawn hours Sunday, with a clearing sky by the midday hours.

We continue to forecast a hard freeze early Monday morning, with lows in the 17 to 22 degree range across North Alabama. Some of the cold spots over far North Alabama could be close to 15 by daybreak Sunday. Monday will be sunny but cold with a high in the low 40s.

NEXT WEEK: No doubt a warming trend begins Tuesday, but the 12Z GFS brings a different solution for mid-week. The model suggests rain showers breaking out Wednesday, but a strong ridge keeps the surface front from passing through the state easily, and now maintains Alabama in a mild and moist airmass Christmas Day, with clouds, rain at times, and afternoon temperatures in the mild 60s. We won’t make any major changes in our forecast just yet, but if the 00Z runs continue this idea, we will have to bring in a chance of rain on Christmas Day and increase temperatures. It is just hard getting cold air in here for any serious length of time with this kind of upper air pattern and NAO phase.

VOODOO LAND: Still good evidence of a colder pattern developing for the eastern U.S. as the New Year begins… but nailing down details now is impossible. Just be aware that the Polar Express could be paying us a more extended visit sometime in early 2009.

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Good to see my pals J.B. Elliott, Dr. Tim Coleman, and Brian Peters today at a WeatherBrains lunch. I appreciate their friendship, and we look forward to making the show better in 2009. Brian will have the Weather Xtreme video updates over the weekend, my next video will be posted by Monday morning at 7:00 a.m. Enjoy the weekend!

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