A storm due to track northeastward from the Gulf of Mexico next week may break some of the winter weather drought occurring from the Northwest to the East.
Since the storm later next week will be ejected during a period of warmth, it will bring mostly rain to most places from the Tennessee Valley and the South to New England.
However, based on signals we have been seeing recently, the storm will cause cold air to empty southward from Canada onto the Plains and Midwest in its wake.
Many of the same signals also point toward sustained cold for the first time from the southern Canada Prairies to southeastern Canada and some of the northern U.S. beginning a short time after the storm's departure.
So essentially, the storm may get the ball rolling as it rolls into northeastern Canada, unlocking the gates.
According to Long Range Expert Paul Pastelok, "There is often a delay when these signals first appear and when the atmosphere reacts."
Where this cold temperature boundary stops will be critical for the storm track during the second half of January and perhaps beyond into February.
This appears to be the most valiant attempt this winter to set up a busy cross-country storm track from west to east.
This does not mean the pattern will drive frigid air and snow and ice deep into the South, but Central and Northern states would have multiple opportunities for snow or storms that bring a wintry mix.
There may be continuing problems with episodes of warmth in the west to east boundary zone, but there only has to be freezing temperatures at a critical layer in the atmosphere for snow and ice to occur during all or part of a storm.
Even though the default jet stream pattern may be a west to east (zonal) pattern, there seems to be more opportunity for cold air to slip underneath into the Northern states prior to the arrival of the storms.
Later in the month, the pattern could yield a little less warmth for the West and the opportunity for a few sizable storms to swing in from the Pacific. However, their moisture would dwindle moving into California.
At this time, we cannot give more detail than this.
There is a pattern change coming, but it will not be immediate.
As we said recently, even a shift toward normal winter weather will be quite a change for many folks, especially in the Northern states.
This story was originally published at 12:00 noon EST, Thursday, Jan. 5, 2012.
Temperatures will be a few degrees below average across the UK this weekend, but largely dry conditions are expected.
After no rain for almost a month, Santiago braces for rain early in the week. Cool air follows, spreading into Chile, Argentina and Uruguay mid-week.
There is a significant chance that Jimena will turn back toward Hawaii and threaten the islands during the second week of September.
An unusually strong push of cool air for early September will move southward along the Atlantic Seaboard into the Labor Day weekend before July-like heat returns by next week.
Steering winds could take Ignacio, as a remnant storm, into the southeastern arm of Alaska or British Columbia during the middle days of next week.
Strong thunderstorms will roll across the Upper Midwest while rain and strong winds roar through the Northwest this weekend.
Los Angeles, CA (1988)
110 degrees -- all-time September record.
Washington, DC (1939)
"Once in a hundred-year rainstorm" 4.40 inches in 2 hours at the Washington Zoo.
Minneapolis, MN (1941)
Tornado - 5 dead - $450,000 damage.