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September in November: Mild Autumn Continues for Much of U.S.

By: Bob Henson 4:52 PM GMT on November 01, 2016

The tenacious pattern that’s delayed the first frosts and freezes this autumn as far north as the Upper Midwest remains in place for much of the U.S. as we kick off November. Most of the Mid-Atlantic and Northeast has had a few quick shots of cold weather (Baltimore had its first freeze on October 26, a few days earlier than average), but many other parts of the nation have been uncommonly free of autumn’s frosty grasp. Denver has yet to see its first snowflake, making this second autumn in a row it has gotten to October 31 without any snow. This is also the first time the city has experienced three snowless Octobers in a row in records going back to 1872 (although there was a trace of snow in September 2014). There was plenty of snow in Minneapolis 25 years ago today, when the city was still in the throes of its infamous Halloween Blizzard of 1991 (here’s a nice photo gallery from the Minneapolis Star-Tribune). On November 4, 1991, the airport low reached –3°F, the earliest below-zero reading in city history. The contrast with this year couldn’t be much more stark. The Twin Cities have yet to dip below 36°F anytime this fall, and readings there should stay near or above 40°F for at least the next week. The latest freeze on record for Minneapolis occurred on Nov. 7, 1900.

Monday was the warmest Halloween on record for a wide swath of U.S. cities, as noted by weather.com’s Chris Dolce, including Atlanta, GA (86°F); Huntsville, AL (88°F); Amarillo, TX (87°F); and Colorado Springs, CO (80°F). A number of locations across the South and Midwest could set all-time heat records for November on Tuesday and/or Wednesday. For example, Louisville, KY, has a shot on both days at matching or beating its all-time November high of 84°F (set Nov. 17, 1958). Records in Louisville go back to 1872.

This past month has a shot of beating 1963 for the warmest October in U.S. recordkeeping, though it’ll be a few days before we know for sure.

Figure 1. Temperature anomalies (departures from average) for October 1 - 30, 2016. Virtually the entire nation was above average for the month, except for the soggy Pacific Coast from northern California through most of Washington. Image credit: NOAA/NWS Climate Prediction Center.

Still wet to to the northwest, dry to the southeast
October delivered a bountiful crop of moisture to the United States, but that water was distributed very unevenly. From Washington to northern California, the U.S. Pacific Coast was slammed by a series of powerful Pacific storms that gave two state capitals (Olympia, WA, and Salem, OR) their wettest Octobers on record. The relentlessly strong Pacific jet pushed enough moisture to eastern Washington and western Idaho to produce even more impressive records there. Spokane saw not only its wettest October but its wettest single month on record, with 6.23” beating the 5.85” notched in November 1897. The city saw 22 days with measurable precipitation, besting the monthly record of 20 days recorded in October 1947, plus 4 more days with a trace of rainfall. At higher altitudes, the strong Pacific flow led to record-high monthly precipitation at dozens of mountain stations (see Figure 2). Further southeast, a few high-altitude spots in Utah, Wyoming, and Colorado reported their lowest October totals on record.

All-time wettest Octobers
Seattle, WA: 10.05” (old record 8.96”, 2003; records began in 1894)
Spokane, WA: 6.23” (old record 5.41”, 1947; records began in 1881)
Olympia, WA: 12.43” (old record 10.72”, 2003; records began in 1948)
Vancouver, WA: 8.22” (old record 7.37”, 1997; records began in 1892)
Priest River, ID: 9.26” (old record 8.31”, 1947; records began in 1898)
Salem, OR: 11.25” (old record 11.17”, 1947; records began in 1892)

Figure 2. Mountain precipitation for the water year to date (October 1-31, 2016) shows the wettest totals on record for stations in dark blue, with the driest totals on record for stations in dark red. Periods of record vary by location but are typically several decades long. Image credit: USDA/NRCS National Water and Climate Center.

Figure 3. The weekly U.S. Drought Monitor report that tracked conditions through October 25, 2016, showed patches of D4 drought (exceptional), the most dire category, over parts of northeast Alabama, northwest Georgia, and far southeast Tennessee. Much of the South is now experiencing both short- and long-term drought impacts (black circle). Image credit: National Drought Mitigation Center

Message from the Southeast: please send water
While heavy rains and snows plastered the Northwest, drought conditions intensified across the Southeast. Much of Alabama and Georgia was lucky to see even 0.25” of rain, and many locations got far less. According to the weekly U.S. Drought Monitor issued on October 27, two of Georgia’s nine climate divisions and one of Alabama’s eight divisions saw their driest 60-day periods on record.

All-time driest Octobers, or extremely close
Tuscaloosa, AL: 0.00” (old record a trace, 1904; records began in 1900)
Rome, GA: trace (tied with 1938 and 1963; records began in 1893)
Birmingham, AL: trace (record remains 0.00”, 1924; records began in 1895)

There is a glimmer of hope in the medium-range forecast for the Southeast, as part of an upper-level trough may break off and dip into the region to bring rain next week. However, that scenario could easily change. In the longer term, NOAA’s Seasonal Drought Outlook is calling for drought to persist (and possibly worsen) through January 31, 2017, from the Arkatex region across to western North Carolina, including most of Mississippi and Alabama. With a weak La Niña expected, NOAA is projecting drier-than-average conditions over the Southeast through the upcoming winter and into spring 2017. La Niña tends to favor an active storm track across the northern U.S. with drier conditions across the Sunbelt.

Figure 4. In this Wednesday, Oct. 26, 2016 photo, an abandoned boat sits in the remains of a dried-out pond in Dawson, Alabama. Some of the South’s most beautiful mountains and valleys are filling with desperation as a worsening drought kills crops, threatens cattle, and sinks lakes to their lowest levels in years. The very worst conditions are in the mountains of northern Alabama and Georgia. Image credit: AP Photo/Brynn Anderson.

An ecological and political crisis deepens
On October 18, Alabama’s Office of Water Resources placed roughly the northeast half of the state under a drought emergency, which urges large users of water to implement conservation plans. Streamflows across northern Alabama are at or near record lows. Despite the drought’s severity, there are no state restrictions on water usage. “There’s a complete lack of a water plan in Alabama, and if you look at the history of water management in state, we always freak out in droughts,” Mitch Reid, director of the nonprofit Alabama Rivers Alliance, told the Huffington Post. One report issued in September found that Alabama was the weakest of the Southeastern states in its water management practices.

The current situation is the latest in an escalating series of drought-related crises affecting the Southeast, where rising populations have come up against an increasingly uncertain water supply. While the average amount of summer rainfall across the Southeast hasn’t changed in recent decades, the year-to-year variability has significantly increased. The comprehensive global modeling (CMIP5) associated with the most recent Intergovernmental Panel on Climate Change assessment shows that this variability in Southeast summer rainfall is likely to increase even further as this century unfolds, according to a 2013 study in Geophysical Research Letters led by Laifang Li (Duke University). “Overall, the ensemble of CMIP5 models suggest that the increase in [greenhouse gas] concentrations will likely enhance SE U.S. summer precipitation variability and result in more frequent occurrence of both dry and wet extremes in the future,” wrote Li and colleagues.

Recent droughts have also intensified the stakes in courtrooms, where the seemingly endless “tri-state water dispute” has pitted Georgia, Alabama, and Florida against each other since an initial lawsuit was filed back in 1990. In a nutshell, Florida is accusing metropolitan Atlanta and the state of Georgia of taking more than its fair share of southward-flowing water from the Chattahoochee and Flint rivers. Alabama is siding with Florida in the latest salvo, a trial that began on Monday at a federal courthouse in (of all places) Portland, Maine. Observers are calling this trial a potential milestone in the ongoing battle. This article from the Gainesville (FL) Times has a handy chronology of the 26-year-old saga.

We’ll be back with a new post by Wednesday afternoon.

Bob Henson

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