September 2020 National Storm Summary

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James Munley

Oct 13, 2020, 7:35:45 PM10/13/20


1st-5th: Heavy rain developed or persisted across the southeastern Plains and the mid-South. Some flooding occurred in Arkansas and environs, mainly where the remnants of Hurricane Laura had dumped heavy rain the previous week. Locally heavy showers also extended eastward across the Tennessee Valley into the middle Atlantic States. Other areas receiving a few heavy showers included Florida’s peninsula and the upper Midwest.

Early-week thundershowers were heaviest in parts of Florida, where record-setting totals for August 30 included 3.15 inches in Tampa and 1.91 inches in Lakeland. Meanwhile, widespread showers and thunderstorms developed across the southern Plains and spread eastward. Lawton, OK, received 1.74 inches of rain, a record for the date, on August 30. The last day of August featured record-setting rainfall totals in Fort Smith, AR (2.45 inches), and Oklahoma City, OK (2.35 inches). Heavy, late-August showers peppered other areas, including the mid-Atlantic and upper Midwest, leading to record setting amounts for August 31 in Lynchburg, VA (2.59 inches), and Rochester, MN (2.01 inches). Across the southeastern Plains and mid-South, heavy rain persisted into early September. In fact, the 1st was the second-wettest September day on record in Fort Smith, AR, where 3.93 inches fell. (Fort Smith’s wettest September day was September 21, 2018, when 4.44 inches fell.) Elsewhere on September 1, daily-record totals included 4.14 inches in McAlester, OK, and 2.29 inches in Russellville, AR. In contrast, Havre, MT, completed its third-driest August on record, with a monthly total of 0.03 inch (3 percent of normal). Meanwhile in the Northeast, Hartford, CT, finished its driest June- August period on record, with 4.42 inches (previously, 4.75 inches in 1965). With a June-August sum of 6.16 inches, Caribou, ME, endured its second-driest summer, behind only 5.60 inches in 1995. In eastern Nebraska, it was the fourth-driest summer in Omaha and Norfolk, with June-August totals of 4.63 and 5.11 inches, respectively.

6-12: Excessive rain fell in some areas, including the mid-Atlantic coastal plain and parts of Texas, sparking local flooding. Late in the week, heavy showers associated with Tropical Storm Sally—later a hurricane—spread across Florida’s peninsula. Excessive rain fell in southern portions of the state, including the Florida Key. As the week began, heavy showers developed in advance of a strong cold front. Dubuque, IA, collected a daily-record total of 1.93 inches on September 6. The following day, record-setting amounts for September 7 totaled 1.57 inches in Columbus, OH, and 1.34 inches in Fort Wayne, IN. With a 1.06-inch total on September 7, Sheridan, WY, experienced its wettest day since May 27, 2019. Elsewhere in Wyoming, September 7-8 snowfall totaled 7.5 inches in Casper and 4.7 inches in Lander. Alamosa, CO, received an incredible 13.6 inches of snow from September 8-10, breaking a monthly record originally set when 10.0 inches fell on September 27- 28, 1936. Meanwhile, measurable rain fell each day from September 6-12 in Iowa locations such as Dubuque and Davenport, totaling 7.46 and 7.76 inches, respectively. During the same 7-day period, Moline, IL, received 5.97 inches. Farther south, heavy rain also erupted across central Texas, where Abilene measured a daily record sum of 3.80 inches on September 9. Abilene’s 3-day (September 9-11) rainfall reached 4.89 inches, with more than 10 inches reported in some nearby locations. Heavy rain also soaked portions of the middle and southern Atlantic States, where Orlando, FL, weathered 4.05 inches—a record for the date—on September 9. Record-breaking totals for September 10 included 3.97 inches in Atlantic City, NJ; 2.88 inches in Washington, DC; and 2.75 inches in Islip, NY. Tropical Storm Sally was named on September 12 after crossing the southern tip of Florida. On that date, Florida rainfall totals included 9.37 inches in Key West and 8.13 inches in Marathon. For both locations, it was the wettest September day on record; previous standards had been 7.47 inches on September 10, 1919, in Key West and 5.92 inches on September 28, 1953, in Marathon.

13-19: Category 2 Hurricane Sally made landfall on September 16 near Gulf Shores, AL, around 4:45 am CDT, with sustained winds near 105 mph. Torrential rainfall across southern Alabama and western Florida sparked major to record flooding, while wind-related damage and power outages were common. Once inland over the Southeast, Sally quickly weakened but continued to produce heavy rain, extending as far north as southern Virginia. Except in southern Alabama and western Florida, overall impacts from Sally were relatively minor. Relatively tranquil weather prevailed until Hurricane Sally arrived along the Gulf Coast. Around the time of landfall, an elevated observation platform at Fort Morgan, AL, measured a wind gust to 121 mph. A similar observation site on Dauphin Island, AL, clocked a wind gust to 104 mph. Naval Air Station Pensacola, FL, reported 92 mph, while the official observation site in Mobile, AL, registered 82 mph. Mobile escaped with a September 15-16 rainfall total of 3.38 inches, but much higher totals fell just to the east. Several unofficial observation sites in southern Alabama and western Florida received 10 to 20 inches, with isolated amounts approaching 30 inches. On September 16, the Shoal River near Mossy Head, FL, experienced a record crest 11.65 feet above flood stage. The previous record in that location, 10.73 feet above flood stage, had been set on June 9, 1989. Farther downstream, the Shoal River near Crestview, FL, crested on September 17 at 8.61 feet above flood stage, second only to the high-water mark (13.40 feet above flood stage) set on September 30, 1998. Big Coldwater Creek near Milton, FL, also achieved its second-highest crest (11.50 feet above flood stage), just 1.48 below the March 1990 record. As the remnants of Sally moved northeastward, daily-record amounts for September 17 topped 4 inches in Wilmington, NC (4.16 inches), and North Myrtle Beach, SC (4.12 inches). Other daily-record amounts for the 17th included 3.37 inches in Lynchburg, VA, and 3.00 inches in Greenville-Spartanburg, SC. Unrelated to Sally, a daily-record amount (1.24 inches) fell on September 17 in McAllen, TX. Meanwhile, much-needed rain in the Pacific Northwest, led to a daily-record sum of 1.14 inches in smoke-plagued Eugene, OR. The National Weather Service office in Seattle, WA, reported a record-setting total (1.35 inches) on September 19.

20-26: Tropical Storm Beta made landfall on September 21 about 10 pm CDT near Port O’Connor, TX, with sustained winds near 45 mph. Once inland, slow-moving Beta weakened and turned northeastward, crossing the Mississippi Delta before dissipating on September 25 over the Southeast. Nevertheless, heavy rainfall associated with Beta caused local flooding, especially along and near the middle and upper Texas coast.

Heavy rain associated with Tropical Storm Beta began to overspread the western Gulf Coast region on September 20. In Texas, Houston’s Hobby Airport netted a September 20-22 total of 12.24 inches. Farther east, September 21-24 rainfall topped 4 inches in locations such as Natchez, MS (5.35 inches); Monroe, LA (4.83 inches); and Texarkana, AR (4.13 inches). In Chattanooga, TN, a daily-record total of 3.91 inches occurred on September 24. Although Southeastern rainfall gradually diminished in intensity, daily-record amounts for September 25 reached 1.90 inches in Raleigh-Durham, NC, and 1.67 inches in Roanoke, VA. Meanwhile, much-needed precipitation developed in the Pacific Northwest, including western Washington, where daily-record amounts for September 23 reached 1.32 inches in Hoquiam; 1.23 inches in Olympia; and 1.08 inches in Seattle. Troutdale, OR, reported more than an inch of rain on September 18, 23, and 25—with totals of 1.13, 1.18, and 1.02 inches, respectively. Late-week precipitation spread as far inland as the northern Rockies; in Idaho, daily-record totals included 0.55 inch (on September 25) in Stanley and 0.54 inch (on September 26) in McCall. Elsewhere, significant rainfall was limited to southern Florida, where Fort Lauderdale netted a daily-record sum of 2.90 inches on September 26. In contrast, September 1-26 rainfall in Maine totaled just 0.10 inch (3 percent of normal) in Millinocket and 0.05 inch (2 percent) in Bangor; respective monthly records are 0.60 inch in 2014 and 0.64 inch in 1929.

27-30: Locally heavy showers dotted Florida, where Apalachicola was drenched with 7.95 inches on September 27. Later, record-setting Florida totals for October 1 included 4.33 inches in Fort Pierce and 3.58 inches in West Palm Beach. In late September, locally heavy showers swept from the mid-South into the Northeast. In Kentucky, daily-record amounts for September 28 reached 1.33 inches in Paducah and 1.27 inches in London. Two days later, Trenton, NJ, netted a record-setting amount (1.57 inches) for September 30. During the last 3 days of September, rainfall topped 2 inches in Northeastern locations such as Glens Falls, NY (2.52 inches); Montpelier, VT (3.47 inches); and Pittsfield, MA (4.18 inches). In Maine, however, September rainfall totaled less than an inch in Bangor (0.28 inch, or 7 percent of normal); Houlton (0.50 inch, or 15 percent); and Portland (0.68 inch, or 18 percent). Bangor and Houlton set September records for dryness; previous records had been 0.64 inch in 1929 and 0.66 inch in 1950, respectively. Mild weather in Alaska resulted in several daily records, including September 30 highs of 70°F in Sitka and 60°F in Anchorage. Most of the Alaskan mainland experienced dry weather, but locally heavy precipitation fell across the state’s southern tier. During the last 4 days of September, Sitka received rainfall totaling 1.62 inches.
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