NATIONAL STORM SUMMARY

SEPTEMBER 2019

1-7: Hurricane Dorian threatened Florida’s east coast before veering northward, eventually grazing the Carolinas and making landfall on Cape Hatteras. The storm, a Category 1 shadow of the Category 5 hurricane that had devastated the northern Bahamas,
crossed Cape Hatteras on the morning of September 6 with maximum sustained winds of 90 mph, down from 185 mph on September 1. Rainfall totals of 4 to 8 inches or more and hurricane-force wind gusts (74 mph or greater) were generally confined to the
coastal Carolinas, although locally heavy showers and H tropical storm-force winds (39 to 73 mph) were observed across a broader coastal area of the middle and southern Atlantic States. A storm surge also occurred on September 6 at some coastal sites,
with water-level rises of more than 7 feet observed on the Pamlico Sound side of Cape Hatteras in a 2-hour period. The hurricane also skirted coastal New England.
For much of the week, spotty precipitation was primarily confined to the North. Pittsburgh, PA, opened the month with a daily-record rainfall of 3.38 inches on September 1. The following day in Minnesota, Rochester netted a daily-record sum of 1.69
inches. Wausau, WI, received a daily-record total (1.94 inches) on September 3. By September 4, tropical stormforce winds associated with Hurricane Dorian grazed parts of Florida’s east coast, with a gust to 70 mph reported on Cape Canaveral. On
September 5, a few hurricane-force gusts occurred in coastal South Carolina, with Fort Sumter recording 80 mph. Daily-record rainfall totals for September 5 reached 10.39 inches in North Myrtle Beach, SC, and 8.58 inches in Wilmington, NC. By the
morning of September 6, when Dorian crossed Cape Hatteras, winds gusted to 70 mph in Elizabeth City, NC, and on Cape Henry, VA. Elizabeth City also collected a daily-record rainfall (6.56 inches) for September 6. Elsewhere, late-week showers spread
from the Pacific Northwest to the northern Plains. Daily-record amounts included 0.48 inch (on September 5) in Redmond, OR; 0.62 inch (on September 6) in Glasgow, MT; and 2.32 inches (on September 7) in Williston, ND.

8-14: Abundant showers erupted in the vicinity of the frontal boundary, soaking much of the North. Rain was especially heavy across the northern Plains and upper Midwest, resulting in flooding. Significant precipitation also fell in the Pacific
Northwest. Several other areas, including the East, Southwest, and southern Plains, received widely scattered showers, while California, the Great Basin, and the Ohio Valley were mostly dry. Any rain that fell in the southcentral and southwestern U.S.
provided only limited and localized relief from the punishing effects of late-summer heat and dryness on rangeland, pastures.
Torrential rain across northern Plains and upper Midwest sparked major flooding, especially in South Dakota along the James and Big Sioux Rivers. Record crests were established on September 14 along the James River from Scotland to Yankton, SD.
Previous record crests in both locations had been established on June 23, 1984, and the new high-water marks (9.24 feet above flood stage in Scotland and at least 14.96 feet above flood stage in Yankton) topped the former standards by 1.79 and 2.62 feet,
respectively. Similarly, the Big Sioux River from near Brookings to Sioux Falls, SD, generally achieved its second-highest level on record, behind the April 1969 flood. Near Brookings, the river crested 5.39 feet above flood stage on September 13, less
than 5 inches shy of the 1969 high-water mark. At I-90 in Sioux Falls, SD, the Big Sioux River crested 6.91 feet above flood stage on September 13, less than a foot below the record (7.80 feet above flood stage) set on April 10, 1969. Meanwhile in
North Dakota, month-to-date rainfall in Williston through the 14th totaled 6.13 inches
(1,179 percent of normal). Williston’s former September rainfall record of 3.74 inches was set in 1959. Elsewhere, rainfall during the first 2 weeks of September totaled at least 4 inches in South Dakota locations such as Mitchell (7.60 inches, or
685 percent of normal); Sisseton (5.59 inches, or 513 percent); Sioux Falls (4.38 inches, or 324 percent); and Aberdeen (4.09 inches, or 390 percent). Mitchell also achieved its wettest September on record, surpassing 6.83 inches in 1986. With a 3.53-
inch total on September 11, Mitchell logged its wettest September day since 1950, when 4.35 inches fell on the 21st. Selected daily-record totals across the northern Plains and Midwest included 1.98 inches (on September 11) in Dubuque, IA; 1.58 inches (
on September 12) in Milwaukee, WI; and 1.11 inches (on September 8) in Helena, MT. Locally heavy showers extended to other areas, including the mid-South and Northeast. In the latter region, Buffalo, NY, netted a record-setting total (2.14 inches) for
September 11. In the Northwest, where multiple rounds of showers occurred, daily-record amounts reached 1.82 inches (on September 14) in Quillayute, WA; 1.51 inches (on September 9) in Astoria, OR; 1.07 inches (on September 11) in Worland, WY; 0.96 inch
(on September 10) in Salem, OR; and 0.77 inch (on September 9) in Kalispell, MT.

15-21: Tropical Storm Imelda delivered inundating rainfall (1 to 3 feet or more) across a relatively small geographic area, mainly in southeastern Texas. The bulk of Imelda’s rain fell after landfall, which occurred on September 17 near Freeport, TX.
Meanwhile, significant rain also fell across portions of the nation’s mid-section, including previously dry areas of the southern Plains. Precipitation also fell in the Northwest, especially west of the Cascades, but dry weather covered most other
parts of the country. Short-term dryness and record-setting high temperatures were particularly impressive in the Ohio Valley and interior Southeast, favoring early-autumn fieldwork but leading to pasture stress and topsoil moisture depletion.
Some of the heaviest rain associated with Imelda fell in southeastern Texas from September 17-20. During that 4-day period, Texas totals included 22.82 inches in Beaumont-Port Arthur; 17.46 inches in Galveston; 16.15 inches in Conroe; and 12.68 inches
in Houston. For all of those locations, the wettest calendar day during the event was September 19, when daily totals topped the 10inch mark in Beaumont-Port Arthur (11.63 inches) and Conroe (11.18 inches). Even wetter weather had occurred with
Hurricane Harvey just 2 years ago when daily totals had included 13.64 inches (on August 27) in Conroe and 26.03 inches (on August 29) in Beaumont-Port Arthur. During Imelda, unofficial totals topped 3 feet in several southeastern Texas locations,
including Taylors Bayou (43.39 inches), Mayhaw Bayou (42.76 inches), and Pevito Bayou (39.41 inches). Following Imelda’s deluge, near-record flooding was reported in several Texas locations, including Cow Bayou near Mauriceville and Pine Island Bayou
near Sour Lake. Cow Bayou rose 6.98 feet above flood stage on September 20, behind only 9.85 feet on August 30, 2017. Pine Island Bayou crested 10.70 feet above flood stage on September 21, behind 14.68 feet on August 30, 2017, and 12.50 feet on
October 20, 1994. Farther north, high water continued to work its way through parts of the Missouri Valley. In Niobrara, NE, the Missouri River crested 5.34 feet above flood stage on September 22. That marked the second-highest crest in that location,
behind 5.76 feet above flood stage on June 26, 2011, and exceeded the March 2019 crest by 2.42 feet. Elsewhere, annual precipitation records were broken—with more than 3 months left in the year—in locations such as Rochester, MN, and Kennebec, SD.
Previous annual records had been 43.94 inches (in 1990) and 30.25 inches (in 1915), respectively. In addition, September rainfall records have already been broken in many communities, including Williston, ND (7.42 inches; previously, 3.74 inches in 1959)
, and Green Bay, WI (8.28 inches; previously, 7.80 inches in 1965). On September 20, an extreme rainfall event in parts of North Dakota and northern Minnesota sparked local flooding. The NWS office in Grand Forks, ND, experienced its wettest September
day on record on the 20th, with a 4.73inch total. Previously, the wettest September day in that location had been September 4, 2016, when 3.73 inches fell. Farther south, scattered daily record totals in excess of 2 inches were reported on the Plains
in locations such as Childress, TX (3.46 inches on September 21), and Omaha, NE (2.79 inches on September 19). Meanwhile, pesky Northwestern showers led to several daily-record amounts, including 1.75 inches (on September 15) in Bellingham, WA; 1.08
inches (on September 20) in Livingston, MT; 1.03 inches (on September 18) in Omak, WA; and 1.02 inches (on September 19) in Elko, NV.

22-28: Heavy rain (locally 2 to 4 inches or more) fell from eastern sections of Kansas and Oklahoma into the Great Lakes region and northern New England. Heavy showers also affected parts of the Southwest, particularly southern Arizona, following subpar
monsoon rainfall. Late in the week, cooler air overspread the northern Plains and the Northwest, accompanied by increasingly stormy weather. By September 27-28, wind-driven snow developed across northern sections of the Rockies and High Plains,
stressing livestock and further delaying final small grain harvest efforts. Snow blanketed several other areas of the Northwest, while rain showers occurred as far south as northern California and the Great Basin.
Early-week showers soaked portions of the Great Lakes region. In Michigan, record-setting rainfall totals for September 22 included 2.04 inches in Traverse City and 1.93 inches in Gaylord. Meanwhile, outof-season showers arrived in the Southwest,
starting on September 23, when daily-record amounts reached 0.53 inch in Yuma, AZ, and 0.24 inch in Las Vegas, NV. The following day in Arizona, record-setting amounts for September 24 included 2.27 inches in Nogales and 1.52 inches in Douglas. Farther
east, torrential rainfall shifted into portions of the eastern Plains and mid-South, where Fayetteville, AR, netted a daily-record sum (4.57 inches) for September 24. In stark contrast, the streak without measurable rain in Lexington, KY, stretched to
34 days (August 28 – September 30) and counting—the second-longest dry spell on record in that location behind 37 days from August 22 – September 27, 1908. Records for September dryness were set in numerous Southeastern locations, including
Lexington (a trace; previously, 0.24 inch in 1959); Knoxville, TN (0.03 inch; previously, 0.19 inch in 2014); and Montgomery, AL (0.05 inch; previously, 0.12 inch in 1923). Meanwhile, Augusta, GA, followed its wettest August on record (12.92 inches)
with September rainfall totaling just 0.77 inch. In contrast, heavy Midwestern rainfall led to daily-record rainfall totals for September 27 in Illinois locations such as Peoria (3.14 inches), Rockford (2.92 inches), and Chicago (2.28 inches). Toward
week’s end, a winter-like storm unfolding across the northern High Plains delivered heavy snow. On September 28-29, Great Falls, MT, received 19.3 inches of snow—a monthly record. Previously, the snowiest September in Great Falls occurred in 1934,
with a 13.2-inch total. During the same 2-day period, Spokane, WA, received 3.3 inches, also a September record (previously, 1.4 inches in 1926). Missoula, MT, set a September snowfall record with 1.7 inches (previously, 1.5 inches in September 1934.
Stormy weather extended southward into Utah, where Trenton (2.55 inches on September 29) experienced its wettest day on record (previously, 2.40 inches on August 18, 1977).

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