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Posted: 11:36 a.m. Wednesday, Dec. 30, 2009
By Kirk Mellish
Severe cold wave or waves look to be on the way as the AO Arctic Oscillation tanks negative again and the Greenland block continues. Highlights of the pattern include: snow as far South as Dallas, Houston and Louisiana again. Snow flurries for North Georgia, outside chance of flurries in South Georgia. Cold enough for a snow storm in Dixie in the longer range IF a storm or storms form. Risk of a hard freeze deep into Florida with the Arctic front maybe as far south as the Yucatan Peninsula Mexico, Jamaica and Cuba. Risk to orange groves in Florida and gasoline refineries in Texas and Louisiana. This is all in the period from New Year's weekend through January 14th or so 2010. The AO has been negative often since the Summer and mainly negative for much of December. Since 1980 there have only been a few times when the AO has seen this kind of negative 3-month low.
The majority of numerical equations show a huge upper-level low pressure system locking in over SE Canada and the Great Lakes to New England while a huge high pressure system gets stuck over central Canada. This funnels the air mass flow South from the Arctic Ocean across extensive U.S. snow cover into the Southeast USA for much of the next 2 weeks. We could see the kind of cold not seen since December 2000. Some days could struggle to get much above the freezing level with night lows in the teens to 25. Some models and pattern analogs even hint at single digits by or before the 12th before any lasting January Thaw could give us a break.
It is too early for specific temp forecasts but the projected pattern should have you and authorities thinking about the safety of pets, the elderly, the poor and the homeless. As well as agriculture, fuel supplies, frozen pipes, and water and food for birds and other wildlife if we do get a multi-day period in the deep freeze. I do NOT see record cold YET but temperatures at least 10 degrees below normal for the first 5-10 days of the new year. This should easily be the coldest January since 2003 or 2004 with the tendency for below-normal temps if not every day then at least on average through January 20th. There is an OUTSIDE CHANCE this turns into the coldest January since the 1980s. Again, that is not a forecast at this point just something to monitor.
It also looks like our "active" pattern will continue with storm systems every 3-4 days or so and with all the cold air coming we will have to stay alert for any snow or ice threat or threats to come along. Nothing big is showing up YET but the pattern is one in which we will have to be on guard. As of this writing it only looks like snow flurries possible along and North of I-20 by Friday or Saturday and maybe again early next week.
The -AO and -NAO are a first step to "open the door" to a significant winter weather system in the Gulf Coast states and the Southeast states. But what is often also needed is a +PNA pattern a warm Western USA ridge. This has been lacking but some of the models are starting to suggest that West Coast into Mountains Ridge with a trough East of the MS River which means that a snow or ice threat is at least "on the table" in the period from Jan 7 to Jan 14th or so. Again do not mistake that as a FORECAST, it is NOT, just the pattern period to monitor as the models as of now show NO significant storms the next 10 days, so any winter precip AT THIS POINT anyway look more of the nuisance or curiosity type. The 30-60 day outlook for Georgia is for temps to average below-normal with precipitation above-normal on average for the period. The 90-day outlook is for below-normal temps on average with near-normal precipitation for the 90-day period on average. Stay tuned.
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