NATIONAL STORM SUMMARY

SEPTEMBER 2023

Aug. 27-Sep. 2: Just after daybreak on August 30, Idalia became the first major hurricane in modern history to make landfall in the Big Bend of Florida. While moving ashore at 7:45 am EDT, Category 3 Idalia was packing maximum sustained winds near 125 mph and had a central barometric pressure of 949 millibars (28.02 inches). Most of the major damage caused by Hurricane Idalia was related to a record storm surge along the Gulf Coast, from the point of landfall (near Keaton Beach, FL) southward to Tampa Bay. However, damage also occurred along a narrow swath of (Continued from front cover) hurricane-force winds (74 mph or greater) extending from north-central Florida into southeastern Georgia. Additionally, Idalia produced heavy rain, totaling 4 to 8 inches or more, although freshwater flooding was limited by antecedent dryness.

A late-season monsoon surge in the West contributed to locally heavy showers, with mixed impacts. For example, Northwestern showers aided wildfire containment efforts and boosted topsoil moisture, while Southwestern downpours sparked local flooding and debris flows.

. Idalia’s rain was an exception to an overarching dry pattern. In Valdosta, GA, where 7.04 inches fell on the 30th, it was the wettest August day and the wettest day at any time of year since September 6, 2000, when 7.10 inches fell. Also on August 30, daily-record totals associated with Idalia included 5.81 inches in Alma, GA; 4.81 inches in North Myrtle Beach, SC; and 3.59 inches in Lumberton, NC. East of Idalia’s path, southerly winds were clocked (on the 30th) to 70 mph in Sarasota-Bradenton, FL, and 67 mph in Brunswick, GA. Elsewhere in Georgia, Valdosta clocked a northeasterly gust to 67 mph. Meanwhile, Florida crest (storm-surge) records set by Category 1 Hurricane Hermine on September 2, 2016, were broken on Cedar Key and along the lower reaches of the Steinhatchee River. A storm-surge record (from March 13, 1993) was broken at Clearwater Beach, FL. Even on the Atlantic Coast, Charleston, SC, reported its fifth-highest water level on record, just 3.29 feet below Hurricane Hugo’s high-water mark on September 22, 1989. Farther north, a cold front—which helped to steer Idalia’s remnants out to sea— produced its own area of locally heavy showers. Crossville, TN, netted 3.24 inches on August 29, followed the next day by daily-record amounts in West Virginia locations such as Elkins (2.24 inches) and Clarksburg (1.67 inches). Rain fell in the Northeast through August 30, when daily-record amounts reached 1.91 inches in Caribou, ME, and 1.62 inches in Montpelier, VT. Late in the week, downpours dotted the West, as moisture surged northward in advance of a cold front. St. George, UT, received 3.47 inches of rain in a 48- hour period from August 31 – September 2. Rain reached into the Pacific Northwest, where daily-record totals in Oregon for August 31 included 0.72 inch in McMinnville and 0.55 inch in Portland. August 31 featured the month’s first measurable rain (0.34 inch) in Dallesport, WA—the first time a daily amount topped one-tenth of an inch in that location since April 20. In early September, rainfall totals of 1 to 3 inches or more deluged parts of the southern Great Basin and the Desert Southwest, leading to flash flooding. Officially, Las Vegas, NV, tallied a daily-record sum of 0.88 inch on September 1. The following day, a total of 1.67 inches in Yuma, AZ, marked the wettest day in that location since January 21, 2010, when 1.95 inches fell. During the first 8 months of the year, Yuma’s rainfall had totaled just 0.59 inch (33 percent of normal). Elsewhere in Arizona, however, Phoenix completed its driest summer on record, with rainfall totaling just 0.12 inch (previously, 0.23 inch in June-August 1924).

3-9: As the week began, locally heavy showers shifted northeastward from the Great Basin and Intermountain West. A few days later, rain reached the upper Great Lakes region. During the second half of the week, showers and thunderstorms were mostly focused along a slow-moving cold front, which eventually reached the Atlantic Coast.

Dry weather prevailed in most other areas, including the Far West and the nation’s southern tier as far east as the Rio Grande Valley. Showers also bypassed large sections of the Midwest, helping to push summer crops toward maturity during a spell of late-season warmth. In fact, near- or above-normal temperatures encompassed much of the central and eastern U.S., with two notable areas experiencing unusually hot weather. First, the Northeast experienced a heat wave, with weekly temperatures averaging 10 to 15°F above normal. A separate area, covering the south-central U.S., also had several locations where readings averaged at least 10°F above normal. In contrast, weekly temperatures averaged as much as 5°F below normal in the Far West, especially near the California-Nevada border. Early-September heat across the upper Midwest hastened summer crop maturation and resulted in several monthly record high temperatures. On September 3, monthly records were established in locations such as Wausau, WI (99°F), and Duluth, MN (97°F). Triple-digit temperatures were reported on the 3rd as far north as Brainerd, MN (102°F), where the still-intact monthly record of 103°F was set on September 10, 1931. Triple-digit, daily-record highs were attained on the 3rd in Midwestern locations such as Huron, SD (103°F), and Norfolk, NE (101°F). With highs of 102, 103, and 102°F from September 2-4, Huron noted 3 consecutive September days with 100- degree heat for the first time since September 9-11, 1931. Meanwhile in Texas, September began with a run of 9 consecutive days with tripledigit heat in locations such as Abilene and San Angelo. In Abilene, a September record was tied with a high of 107°F on the 5th; that mark was broken with a reading of 108°F on the 8th. Elsewhere in Texas, other monthly record highs established on September 8 included 112°F in Wichita Falls (previously, 111°F on September 4, 2000); 107°F in Lubbock (previously, 105°F on September 19, 1930); and 106°F in El Paso (previously, 104°F on September 1, 1982). In fact, El Paso tied its original record on September 6, followed by a reading of 105°F on September 7. With El Paso recording highs of 100°F or greater on 8 of the first 9 days of the month, that city’s record for triple-digit days in September (previously, 4 days in 1959 and 1978) was doubled. Multiple monthly records highs were noted on September 7 in Texas’ northern panhandle, with temperatures reaching 108°F in Borger, 105°F in Amarillo, and 104°F in Dalhart. In neighboring states, monthly record highs included 106°F (on September 7) in Roswell, NM, and 111°F (on September 8) in Lawton, OK. The former record in Lawton, 110°F, had been set on September 2, 1939, and September 4, 2000. Meanwhile in the mid-Atlantic, Virginia’s Dulles Airport tied a monthly record with highs of 99°F on September 3, 4, and 5, followed by a reading of 100°F on September 6. Previously, Dulles Airport had reached 99°F only on September 2, 1980, and September 10 and 11, 1983. Farther south, Baton Rouge, LA, attained 100°F on September 6 and 7, that city’s 31st and 32nd days this year with tripledigit heat (previously, 21 days in 1921). Similarly, Phoenix, AZ, closed the week on September 8-9 with daily record highs of 110 and 114°F, respectively. That marked the 53rd and 54th days this year in Phoenix with a high temperature of 110°F or greater, surpassing 53 such days in 2020. As the week began, heavy rain lingered in the Great Basin.

In Nevada, daily-record totals for September 3 reached 1.00 inch in Winnemucca; 0.43 inch in Elko; and 0.34 inch in Reno. The following day, September 4, was the seventh-wettest day on record in Worland, WY, where 1.39 inches fell. Rainfall on the 4th also topped an inch (1.01 inches) at Montana State University in Bozeman. As showers swept eastward, high winds raked parts of the northern Plains and upper Midwest. In South Dakota, peak gusts on September 4 were clocked to 71 mph in Buffalo and 69 mph at Ellsworth Air Force Base. On the night of September 4-5, winds reached 77 mph in Grand Forks, ND, and 76 mph in North Platte, NE. Heavy rain reached the upper Great Lakes region on September 5, when daily-record totals included 2.77 inches in Duluth, MN, and 1.74 inches in Ashland, WI. Traverse City, MI, notched a daily-record sum (2.48 inches) on September 6. During the second half of the week, locally heavy showers dotted the East. In Vermont, record-setting totals for September 7 reached 1.19 inches in Burlington and 1.03 inches in Montpelier. Beckley, WV, collected a daily-record sum (1.82 inches) on September 8. Additional Eastern daily-record amounts on September 9 reached 4.41 inches in Blacksburg, VA, and 1.70 inches in Columbia, SC. For Blacksburg, it was the wettest September day on record (previously, 4.39 inches on September 29, 2015), as well as the second-wettest day during any month, with the standard remaining 4.48 inches on August 14, 1940.

10-16: Early in the week, heavy showers drenched parts of the East. Record-setting rainfall totals for September 10 reached 2.26 inches in Trenton, NJ, and 2.09 inches in Greensboro, NC. Another daily-record sum occurred in Greensboro on September 12, when 2.24 inches fell. Early-week rain also fell in the nation’s midsection, where daily-record amounts in Nebraska for the 10th included 1.21 inches in Chadron and 0.84 inch in Alliance. The following day, Pueblo, CO, netted 1.02 inches, a record for September 11. By the 12th, rain began to shift southward, with San Angelo, TX (2.27 inches), experiencing its wettest day since August 17, 2021, when 2.62 inches fell. Elsewhere in Texas, other daily-record totals included 2.02 inches (on the 14th) in Victoria and 3.09 inches (on the 15th) in Laredo. As rain spread into the southern Rockies and beyond, Albuquerque, NM, collected a daily-record sum (0.73 inch on September 13)—the wettest day in that location since August 22, 2022. Farther east, ongoing showers led to daily-record amounts in locations such as Tampa, FL (2.30 inches on September 15), and Augusta, GA (2.08 inches on September 13). In southern Florida, Miami measured 4.40 inches on the 16th, a record for the date, as a cold front slowed and stalled. At week’s end, Post-Tropical Cyclone Lee, a former hurricane, reached the Canadian Maritimes on the afternoon of the 16th, with estimated sustained winds near 70 mph and a central barometric pressure of 28.58 inches, or 968 millibars. On the day of landfall, Lee’s broadening wind field resulted a gust to 52 mph as far west as Worcester, MA, as the center of the storm passed some 215 miles east of Nantucket. In Maine, gusts on the 16th were clocked to 56 mph in Bangor, along with 1.86 inches of rain; 54 mph in Houlton, along with 1.91 inches; 52 mph in Augusta; and 50 mph in Millinocket.

17-23: Just before daybreak on Saturday, September 23, northbound Tropical Storm Ophelia made landfall near Emerald Isle, NC, packing sustained winds near 70 mph. Less than 18 hours after moving ashore, Ophelia had lost most of its tropical characteristics and was re-classified as a post-tropical cyclone. Still, the short-lived tropical cyclone, which was first named on Friday afternoon, produced as much as 4 to 8 inches of rain in the middle Atlantic coastal plain, as well as widespread wind gusts from 50 to 70 mph.

Earlier in the week, wet weather (rainfall locally totaling 1 to 2 inches or more) had lingered in New England, shortly after the remnants of Hurricane Lee had soaked eastern Maine. Farther west, a slow-moving storm system resulted in heavy showers and locally severe thunderstorms in the nation’s mid-section, especially across the northern Plains and upper Midwest. A secondary area of heavy rain was focused across the southeastern Plains and neighboring areas.

As the week began, the cold front that helped to sweep Hurricane Lee away from the Atlantic Coast produced some heavy showers. Elkins, WV, netted a daily-record sum (1.88 inches) for September 17. The following day, record-setting totals for the 18th included 2.29 inches in Portland, ME, and 1.34 inches in Islip, NY. Farther south, tropical moisture began to amass, mainly east of Florida. Still, Vero Beach, FL, collected a daily-record total of 2.40 inches on September 19. Potential Tropical Cyclone Sixteen—later Ophelia— was first classified on September 21, while centered about 450 miles south of Cape Hatteras, NC. September 22 featured a daily-record rainfall of 2.92 inches in Elizabeth City, NC, along with a northeasterly wind gust to 49 mph. North Carolina totals for the 22nd that were not daily records included 3.52 inches on Cape Hatteras and 3.23 inches in New Bern. The 2-day (September 22- 23) total in New Bern climbed to 4.86 inches, with a northeasterly gust to 55 mph reported on the latter date. Other peak gusts associated with Ophelia included 72 mph at Cape Lookout, NC; 68 mph at Oregon Inlet, NC; 67 mph at Beaufort, NC; 64 mph in Lewes, DE; and 61 mph at Cape Henry, VA. By September 23, daily-record rainfall totals extended to locations such as Atlantic City, NJ (3.67 inches); Georgetown, DE (3.31 inches); Salisbury, MD (2.83 inches); and Richmond, VA (2.76 inches). Farther west, significant precipitation fell during the second half of the week from the northern Rockies into the upper Midwest. The event generally kicked off on September 21, with daily-record totals in Valentine, NE (1.68 inches), and Havre, MT (0.50 inch). Elsewhere on the 21st, West Yellowstone, MT, experienced its wettest September day of the century to date, with 1.20 inches (previously, 1.08 inches on September 1, 2012). Similarly, the 22nd was the wettest September day of the 21st century in Buffalo, WY, where 2.05 inches fell (previously, 1.29 inches on September 24, 2016). Meanwhile in Montana, daily-record amounts for September 22 reached 1.60 inches in Miles City; 1.26 inches in Helena; and 1.02 inches in Lewistown. A day later, Sisseton, SD, measured a daily-record total (2.78 inches on September 23). Farther south, downpours dotted eastern Oklahoma and environs, leading to localized totals of 4 to 8 inches or more. From September 19-23, Muskogee, OK, reported 4.07 inches.

24-30: Early in the week, the remnants of Tropical Storm Ophelia produced rain from the middle Atlantic Coast to southern New England. Even after Ophelia’s dissipation, persistent easterly flow led to low clouds and showers along the Atlantic Seaboard, with rain lingering in some areas. Eventually, another round of heavy rain (locally 2 to 8 inches or more) pushed ashore, resulting in extensive flooding in New York City and environs. Meanwhile, unsettled weather from the Northwest into the upper Midwest contrasted with dry weather in most other areas of the country.

On September 24, rain associated with the remnants of Ophelia resulted in daily-record totals in Pennsylvania locations such as Scranton (2.51 inches) and Mt. Pocono (2.40 inches). A separate area of heavy rain near Lake Superior produced some flooding in Duluth, MN, where a dailyrecord sum of 3.02 inches occurred on the 24th. That marked the wettest September day in Duluth since September 7, 1991, when 3.57 inches fell. By September 25, rain arrived along the northern Pacific Coast, where daily-record amounts topped an inch in Crescent City, CA (2.11 inches), and North Bend, OR (1.69 inches). Meanwhile, a small area of heavy rain near the southern Atlantic Coast produced 6.14 inches of rain on September 26 in Brunswick, GA—the highest daily sum in that location since September 11, 2017, when Hurricane Irma delivered 6.25 inches (as part of a 2-day total of 11.64 inches). On September 29, torrential rain erupted across the mid-Atlantic and southern New England, catapulting New York’s JFK Airport to its wettest day on record. JFK’s daily sum of 8.05 inches eclipsed the standard established on August 14, 2011, when 7.80 inches fell. The wettest September day at JFK had been September 12, 1960, when rainfall totaled 5.83 inches. Elsewhere, record-setting rainfall totals for September 29 reached 5.48 inches at New York’s Central Park; 4.10 inches at New York’s LaGuardia Airport; and 4.07 inches in Hartford, CT. Both JFK and LaGuardia Airports completed their wettest September on record, with respective monthly totals of 13.01 and 12.76 inches. Finally, another round of Western storminess produced daily-record totals for the 29th in Oregon locations such as Medford (1.25 inches) and Roseburg (0.96 inch). The last day of September featured daily-record amounts in Tonopah, NV (1.04 inches), and Bishop, CA (0.35 inch). Farther east, however, the Mississippi River at Caruthersville, MO, fell to a stage of -1.84 feet on September 26, edging by 0.02 foot the record low set on October 16, 2022. Farther downstream, the minimum stage of -10.64 feet in Memphis, TN, on September 28 was just 0.17 foot higher than last year’s record low level, set on October 21.

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