Major Arctic Outbreak Likely Late Next Week
Issued: 10:54 AM CST Friday January 26, 2007
Major Arctic Outbreak Expected in Early February
For the past 7-9 days, long-range models have been predicting a major Arctic outbreak for the first week of February. We've talked about this outbreak on our daily Storm Development Outlook and on the StormWatch Daily Briefing video. Our confidence in the Arctic outbreak continues to grow each day. Today we will spell out what we're confident in, what has a good chance of occurring, and what type of weather is possible with such an outbreak.
What We're Confident In:
The Polar jet stream will be diving southward across the U.S. next week, transporting very cold air southward across much of the U.S. during the first week of February. Although some very cold Canadian air will be plunging down the Plains states by late this weekend, the leading edge of the coldest Arctic air will move into the northern tier of states from Montana to Minnesota by next Thursday, February 1st. This Arctic front should reach the Gulf Coast by around the 3rd or 4th of February -- next weekend. Unlike the last Arctic outbreak, this front will likely contain much colder air and deeper cold air. This means that the southeast states will not likely escape some very cold temperatures. As for duration, we think that the cold air may remain in place through the second week of February, possibly longer. What this means for the northern Gulf of Mexico is a prolonged period of strong north and northeasterly winds with rough seas beginning late next week.
What's Becoming More Likely:
Not only have the models consistently indicated the flow from the Arctic Circle to the central U.S., they've also been consistent in predicting that there will be a number of upper-level disturbances tracking across the Gulf Coast states once the cold air is in place. At the very least, this would mean clouds lingering behind the Arctic front, keeping high temperatures well below normal. But there is a very good chance that such a pattern would lead to some significant snowfall across north Texas, Oklahoma, and Arkansas by late next week into the first week of February. Perhaps as much as 6-12 inches of snow could fall across this region.
Variables:
1. We aren't yet confident just how cold it will eventually get across the central and southern U.S. with this outbreak, including the Gulf Coast.
2. We're also unsure about the southward extent of any freezing and frozen precipitation. It appears that this airmass may have a deeper sub-freezing layer than the previous Arctic front. That would mean a greater chance of snow and sleet, possibly down to the Gulf Coast. But our confidence that freezing/frozen precipitation will affect the southern parts of the Gulf Coast states is low.
3. Timing of any freezing/frozen precipitation events is uncertain. Such events will be driven by fast-moving small-scale weather features that may not be clearly evident until several days before any potential event.
What's Possible:
This cold outbreak could rival some of the major outbreaks in the 1980s that produced sub-freezing temperatures down to the Gulf coast for days at a time. In terms of cold, we think it's possible that low temperatures across the northern tier of states could reach -20F to -30F. The sub-zero temperatures could reach as far south as the Texas Panhandle east through central Oklahoma and Arkansas then northeast to the Mid Atlantic Coast. Across the Gulf Coast from Texas to the Florida Panhandle, low temperatures could reach the low 20s or even the upper teens, though 20s is more likely at first with the post-frontal cloud cover and potential post-frontal precipitation. Such an outbreak could produce sub-freezing high temperatures from the mid Texas coast to the Florida Panhandle by the 4th to 6th of February. But the above is just a possibility. Until the Arctic air is on the move southward, we won't be sure if the core of coldest air will move southward down the Plains or south! eastward across the Midwest.
As far as the chances of post-frontal precipitation, it's possible that disturbances moving across the well-established cold air could result in mixed freezing rain, sleet, and snow down to the Texas coast and east across coastal sections of Louisiana and Mississippi after the 3rd of February. With deeper cold air than the last outbreak, there may be a greater chance that more of the wintry precipitation may fall as snow down to the Gulf Coast. Again, we have very low confidence in a Gulf Coast ice storm, but the possibility is there.
Besides the Gulf Coast threat, such a flow pattern would favor the development of one or more major east coast snow storms - Nor'easters. Although none of the long-range models specifically shows any such storm development, it's quite possible that at least one and maybe two major snow storms will develop along the east U.S. Coast during the first week or two in February.
Meteorologist: Chris Hebert