NATIONAL STORM SUMMARY

SEPTEMBER 2018

 

1-8: A slow-moving cold front, infused with moisture from the remnants of Tropical Storm Gordon, unleashed heavy, late-week rain from the Ohio Valley into the northern Mid-Atlantic region.  Even before Gordon became entangled with the front, multiple days of rain drenched areas from the southern Plains into the upper Midwest.  Lowland flooding occurred in several areas, but was most widespread in the upper Mississippi Valley.  Gordon made landfall late on September 4 about 30 miles east of Biloxi, MS, with maximum sustained winds near 70 mph, and later drifted across the Mississippi Delta as a tropical depression before turning northward and merging with the aforementioned cold front.  Wind impacts related to Gordon were generally minor and limited to the central Gulf Coast region, while heavy showers were scattered until the circulation merged with the front.  Relentless showers plagued the central and southern Plains and the Midwest.  In Nebraska, Lincoln netted a daily-record rainfall (2.42 inches) on September 2.  Iowa locations such as Waterloo (2.57 inches) and Des Moines (2.31) achieved daily-record totals for September 3 (Labor Day).  Concordia, KS, also measured a daily-record sum (2.97 inches) for September 3.  And, in Texas, daily-record amounts for the 3rd included 6.07 inches in San Antonio and 4.83 inches in Beaumont-Port Arthur.  It was San Antonio’s third wettest September day on record.  Similarly, Rochester, MN, experienced its fifth-wettest September day on the 4th, when 3.32 inches fell.  Other Midwestern daily-record totals for September 4 included 3.06 inches in Eau Claire, WI; 2.68 inches in Hastings, NE; and 2.65 inches in Sioux City, IA.  Meanwhile, Tropical Storm Gordon arrived in the central Gulf Coast region, dumping 11.46 inches of rain in Pensacola, FL, on September 45.  Greenwood, MS, noted 6.55 inches on September 5-6.  Peak wind gusts on the 4th were clocked to 57 mph in Mobile, AL; 52 mph in Pensacola; and 42 mph in Meridian, MS.  Late in the week, spotty downpours developed in the northern Mid-Atlantic region, while heavy rain soaked the Ohio and middle Mississippi Valleys.  On September 7, Philadelphia, PA, endured a daily-record sum of 4.54 inches, while daily-record amounts in Illinois reached 2.72 inches in Springfield and 2.65 inches in Quincy.  The 2-day (September 6-7) total in Quincy reached 4.86 inches.  On the 8th, daily-record amounts climbed to 3.92 inches in Cincinnati, OH, and 3.84 inches in Louisville, KY.  For Cincinnati, it was also the wettest September day on record, surpassing 3.76 inches on September 26, 2011.  For Louisville, it was the wettest September day since September 20, 2009, when 3.95 inches fell.

 

9-15: Hurricane Florence hammered the southern Mid-Atlantic region, making landfall around daybreak on September 14 near Wrightsville Beach, NC, as a Category 1 storm with sustained winds near 90 mph.  Initially, high winds, an impressive storm surge, and battering waves thrashed the coastal North Carolina, but the focus later turned to catastrophic freshwater flooding.  As Florence drifted inland and weakened, torrential rain spread toward the central and southern Appalachians, generating pockets of major flooding that submerged lowlands and damaged rural and municipal infrastructure.  Early-week rainfall associated with the remnants of Tropical Storm Gordon interacting with a cold front led to numerous daily-record totals from the Ohio Valley into the Northeast.  On September 9, Pittsburgh, PA, experienced its second-wettest September day (and second-wettest day during any month) on record, with a 3.73-inch total.  Pittsburgh’s wettest day remains September 17, 2004, when 5.95 inches fell.  Elsewhere, record-setting totals for September 9 reached 3.83 inches in Huntington, WV; 2.54 inches in Harrisburg, PA; 2.52 inches in Zanesville, OH; 2.33 inches in Wilmington, DE; and 2.23 inches in Baltimore, MD.  Lingering downpours on September 10 led to dailyrecord totals in locations such as Williamsport, PA (3.15 inches), and Binghamton, NY (2.70 inches).  In West Virginia, Bluefield netted consecutive daily-record totals (1.95 and 1.52 inches, respectively) on September 10-11.  Meanwhile, showers accompanied a surge of cool air into the Northwest, where daily-record totals reached 0.82 inch (on September 12) in Portland, OR, and 0.51 inch (on September 11) in Olympia, WA.  Farther south, persistently heavy rain fell in southern Texas, where Harlingen received 10.17 inches during the week.  More than half (6.25 inches) of Harlingen’s rain fell on September 12.  A day later, rain associated with Hurricane Florence began to overspread coastal North Carolina.  Cape Hatteras, NC, collected a daily-record sum of 4.26 inches on September 13, along with a peak wind gust to 67 mph.  Elsewhere in coastal North Carolina, Wilmington clocked a gust to 105 mph on the 14th, and received 18.52 inches of rain from September 13-15.  During the same 3-day period, 9.52 inches of rain fell in North Myrtle Beach, SC.  As Florence moved ashore on September 14, a crest record was set at the Beaufort Marine Lab, NC, where the water level exceeded the record set on October 15, 1954, and September 19, 1955, by a little over 4 inches.   The Trent River at Pollocksville, NC, climbed 5.45 feet above flood stage, second only to the Hurricane Floyd high-water mark (12.29 feet above flood stage) on September 19, 1999.  The water level at Johnny Mercer Pier in Wrightsville Beach, NC, reached its third-highest level, behind October 15, 1954, and September 6, 1996.

 

16-22: The interaction between a cold front and moisture associated with the remnants of Tropical Depression Nineteen-E contributed to heavy rainfall in the southcentral U.S.  Weekly rainfall totaled 4 to 8 inches or more across parts of the southeastern Plains, with a much larger area from the southern Rockies into the Tennessee Valley receiving heavy showers.   Heavy rain, locally in excess of 4 inches, also soaked parts of the upper Midwest. Finally, the sparked additional flooding in the southern Mid-Atlantic region before the storm finally accelerated northeastward.  However, runoff from historic rainfall totals (2 to 3 feet in a few locations) resulted in prolonged and historic river flooding in eastern North Carolina and southeastern South Carolina. Florence became an elongated area of low pressure on September 18, losing any remaining tropical characteristics while crossing the Northeast.  From September 13-18, rainfall totaled 23.20 inches in Wilmington, NC, exceeding that city’s event-total record of 22.54 inches, set from September 26-30, 2010.  Wilmington also achieved an annual precipitation record, with 86.40 inches, surpassing the 1877 standard of 83.65 inches.  Unofficial, stormtotal rainfall amounts of 2 to 3 feet were reported at a few locations in Horry County, SC, as well as Bladen, Brunswick, Carteret, Columbus, New Hanover, Onslow, Pender, and Robeson Counties in North Carolina.  Florence-driven rainfall reached nearly 36 inches near Elizabethtown in Bladen County, and at Lumberton in Robeson County.  A record crest was achieved on the Lumber River at Lumberton, where the river rose 9.21 feet above flood stage on September 17.  The highest water level since September 1945 was observed on the Cape Fear River at Elizabethtown, where the river crested 17.51 feet above flood stage on September 21.  Near Burgaw, NC, the Northeast Cape Fear River crested 15.57 feet above flood stage on September 19, surpassing the high-water mark (12.48 feet above flood stage) set in the aftermath of Hurricane Floyd on September 19, 1999.  The Trent River in Trenton, NC, which climbed 16.25 feet above flood stage on September 16, also topped a Floyd-fueled record (15.42 feet above flood stage on September 19, 1999).  The Pee Dee River at Cheraw, SC, rose 16.60 feet above flood stage on September 18, behind only 20.40 feet in September 1945 and 17.20 feet in August 1908.  Farther north, a Florence-related tornado outbreak struck southeastern Virginia on September 17.  In Chesterfield County, VA, a fatality occurred during an EF-2 tornado with winds of 115 to 125 mph—the nation’s first tornado-related death since July 10 and only the fifth of the year.  Downpours associated with Florence were prevalent in North Carolina on September 16, when daily-record totals reached 6.33 inches in Fayetteville; 4.60 inches in Greensboro; and 4.28 inches in Charlotte.  Fayetteville’s 3-day (September 14-16) rainfall reached 15.25 inches.  Florence’s last burst of heavy rain occurred in the Northeast on September 18, when daily-record amounts included 2.22 inches in Baltimore, MD, and 2.13 inches in Atlantic City, NJ.  Later, heavy showers developed across the upper Midwest.  In South Dakota, record-setting amounts for September 19 totaled 2.66 inches in Sioux Falls and 2.12 inches in Mitchell.  The following day, daily-record amounts reached 3.28 inches in Minneapolis-St. Paul, MN; 3.09 inches in Sioux Falls; and 2.72 inches in Grand Rapids, MI.  Sioux Falls’ 3-day (September 18-20) rainfall totaled 6.46 inches. In addition, as many as a dozen tornadoes were spotted on September 20 across southern Minnesota and neighboring areas, while wind gusts were clocked to 70 mph in Mankato, MN, and 56 mph in La Crosse, WI.  Crest records were set in several Iowa locations, including the Floyd River at Alton (9.96 feet above flood stage on September 20; previously, 7.19 feet on May 23, 2013) and the Little Sioux River at Linn Grove (5.91 feet above flood stage on September 22; previously, 4.91 feet on June 18, 2014).  Linn Grove had narrowly escaped a record flood just 3 months ago on June 24, when the river rose 4.62 feet above flood stage.  Finally, late-week downpours struck parts of the South, following the development of Tropical Depression Nineteen-E on September 19 and subsequent landfall in northwestern Mexico.  Record-setting amounts for September 21 topped 2 inches in locations such as Wichita Falls, TX (2.84 inches); Russellville, AR (2.54 inches); and Oklahoma City, OK  (2.28 inches).  September 22 featured a daily-record rainfall of 3.83 inches in Shreveport, LA.  San Antonio, TX, received 1.86 inches on September 22, boosting its monthly total to a September-record 16.82 inches (previously, 15.78 inches in 1946).

 A hint of cool weather in the Northwest contrasted with late-season warmth in most other areas.  Northwestern daily-record lows dipped to 28°F (on September 16) in Klamath Falls, OR, and 23°F (on September 17) in Alturas, CA.  Meanwhile in Colorado, Pueblo reported highs of 95°F or greater on 10 consecutive days from September 10-19, along with four daily-record highs in a row (97, 98, 97, and 98°F) during the last 4 days of the streak.  Similarly, New Orleans, LA, reached or exceeded the 95-degree mark each day from September 14-19, including a pair of daily-record highs of 98°F on the 16th and 17th.  Daily-record highs also attained or topped the 95-degree mark in many other locations, including Springfield, IL (95°F on September 18); Tupelo, MS (98°F on September 19); and McCook, NE (99°F on September 19).  On September 17-18, Macon, GA, collected a pair of daily-record highs (98 and 100°F, respectively).  Later, on September 20, daily-record highs soared to 97°F in Paducah, KY, and Nashville, TN, while a monthly record of 95°F was tied in Key West, FL.  Record-setting heat lingered in the Northeast through September 21, when highs reached 92°F in Rochester, NY, and 91°F in Erie, PA.

 

23-29: A series of cold fronts raced across the Plains and Midwest, generating widely scattered showers before plowing into deeper moisture and sparking heavier rain across the South and East.  Weekly rainfall totaled 2 to 4 inches or more in a broad area stretching from the western Gulf Coast region into southern New England. Repeated rain events pushed Southern and Eastern locations such as San Antonio, TX (16.86 inches); Crossville, TN (10.59 inches); and Bluefield, WV (10.25 inches), to September rainfall records.  Elsewhere in West Virginia, it was the wettest September and second-wettest month on record in Charleston (11.62 inches) and Huntington (10.41 inches).  Only July 1961, with 13.54 inches, was wetter in Charleston; only January 1937, with 12.07 inches, was wetter in Huntington.  Fittingly, Huntington netted a daily-record

total of 2.03 inches on September 23.  The following day, record-setting rainfall totals for September 24 included 3.41 inches in Chattanooga, TN, and 2.49 inches in Louisville, KY.  Daily-record amounts for September 25 reached 3.07 inches in Columbus, GA, and 1.97 inches in Bridgeport, CT.  Yet another deluge on September 27 resulted in daily-record amounts in several West Virginia locations, including Charleston (2.06 inches) and Beckley (1.87 inches).  Although heavy rain mostly bypassed the southern Mid-Atlantic States, some rivers continued to rise.  For example, record crests on the Waccamaw River—originally established in the wake of Hurricane Matthew in October 2016—were established on September 26-27 in South Carolina locations such as Conway, Bucksport, and Pawleys Island.  The new high-water mark in Conway, 10.16 feet above flood stage on September 26, vanquished the record by 3.29 feet.  In dramatic contrast, several records for lack of September precipitation were tied in Utah, where no rain fell at Tooele and Zion National Park.  Only a trace of rain fell in Salt Lake City, UT, tying a September record set in 1890, 1899, 1943, and 1951.

 

Jim G. Munley, jr.
http://www.jimmunleywx.com