U.S. FALL FORECAST: Snowbirds heading south, read here
Tuesday, September 13, 2016, 9:03 PM - The summer of 2016 was dominated by widespread heat across the United States - particularly east of the Mississippi - as a return to classic summer weather brought a distinct change from the milder patterns of the previous few years.
Active weather was common in the Midwest, and torrential rains brought devastating flooding to parts of the Gulf Coast. The Northeast struggled with developing drought conditions, while California and parts of the West saw its extreme drought worsen.
As summer comes to an end, we take a look at the next three months to see what the fall season has in store. Will late summer weather linger well into the season? Or will we see crisp autumn air take hold early? And where do we expect to see the most active fall storm track? We have all the details below (and a preliminary look at our winter forecast as well) in The Weather Network’s 2016 Fall Forecast, which covers the months of September, October, and November.
Near to above normal temperatures are expected to dominate the fall season across the entire country. So you still have some time before you’ll need to put away the shorts and sunscreen. Regions east of the Mississippi and west of the Rockies are the most likely to see summer-like temperatures lingering well into the season, while the middle of the country should see more frequent periods of cooler weather as the season progresses, leading to overall temperatures near normal.
Of course it’s important to keep in mind that fall is a transitional season. Much like the spring, this is a time of year when big changes are par for the course. So there will certainly be exceptions to the overall pattern, and shots of cooler autumn weather will take hold from time to time even in regions that are largely above normal. We also can’t rule out an early taste of winter late in the season, as the potential for cold outbreaks should increase later in October and November.
After the record-breaking El Niño event that dominated the first half of 2016, the late summer and early fall has seen a return to near-neutral conditions in the equatorial Pacific. Whether these neutral conditions persist, or we move into a weak La Niña event as some guidance suggests, it appears that other factors beyond the El Niño cycle will dictate much of our weather pattern this fall. Water temperatures in the Gulf of Alaska and the north Atlantic, and atmospheric blocking patterns in the high northern latitudes will all contribute to the conditions we expect to see through the season.
The precipitation pattern we have forecast for this fall highlights the potential for typically active storm tracks through the heartland from the Plains and into the Great Lakes. This should lead to near normal precipitation for much of the centre of the country, and even above normal precipitation across the northern Plains.
Main Storm Track
With the main storm track shifted to the north and west, parts of the lower Mississippi Valley and Ohio Valley should see drier than normal weather this fall with more sunny days than normal. However, with the active tropical season expected to continue, there is the potential for a system or two to make landfall and bring a swath of excessive rain to parts of the region. As a result, places near the eastern seaboard have the best chance of seeing rainfall totals near normal despite extended periods of dry weather during the fall.
Along the west coast, we expect to see the primary Pacific storm track remain well to the north and into the Canadian province of British Columbia. So, while Washington and Oregon may see near normal amounts of rain this fall, we are forecasting the continuation of dry conditions across California and Nevada, leading to an expected worsening of already exceptional drought conditions. Elsewhere in the west, the pattern does favour a couple of surges of remnant tropical moisture into the Four Corners region, leading to near normal precipitation.
Peak of the Atlantic Hurricane Season
The early fall also brings the peak of the Atlantic hurricane season, which is expected to be remain more active than normal after many years of quiet tropical weather. Florida has already broken its over ten-year hurricane drought with the landfall of Hermine on September 2, 2016. The pattern this year continues to favour development in the western Atlantic as we move into the fall, which increases the chances of additional U.S. landfalls.
2016-2017 Winter Preview
Looking farther ahead to the end of fall and the beginning of winter, we expect that there will be a significant change in the pattern which would result in a winter that is rather different from the mild winter that we saw last year across much of the country. In fact, the pattern is expected to more closely resemble the winters of 2013-2014 and 2014-2015. A trough position roughly near Hudson Bay is expected to bring frequent and persistent outbreaks of arctic air to much of the central and eastern US. In this scenario much of the west would see milder conditions dominate the winter pattern.
One of the keys to our final winter forecast (which will be released on November 21, 2016) will be determining when the pattern change from the relatively warm fall to the colder winter pattern will occur. If the pattern change occurs in December, a much larger region of the central and eastern U.S. will see below normal temperatures for the winter as a whole and we would have to remove the Gulf Coast from the “above normal” category.
However, there are signs that we will see a “false start” to winter with an initial cold snap in November followed by a rather mild December. Regardless, we expect that the second half of winter will feature an extended period of classic winter weather for much of the central and eastern parts of the country.