A severe thunderstorm as it rolled into Carthage Illinois back on June 28, 2018; high, straight-line winds hit shortly after this photo was captured. / Photo credit: Amanda Bolte
Weather report round-up; 6:00pm Friday, July 20, 2018 — In many of the cases here, as is typical of many severe weather events, reports have come in well after the storm came through — I’m listing the times when the storm actually would have come through on Thursday, July 19, 2018; not necessarily when the report was received. Tornado details take time since a National Weather Service crew must investigate the scene and survey the damage.
6:07pm — 4.9 miles north of Keosauqua, Van Buren County, Iowa: a tornado of EF-1 rating (winds of 86-110 miles per hour) damaged a small farm outbuilding, traveled though a corn field and grove of trees, and ended with destroying a large, historic stone barn
6:09pm — 1.2 miles northeast of Keosauqua, Van Buren County, Iowa: a tornado (separate tornado from the one listed above) of EF-1 rating (winds of 86-110 miles per hour) destroyed several large farm outbuildings, pieces of farm equipment, and corn crops
6:30pm — 3 miles west of Indian Lake Park, Van Buren County, Iowa: 3 outbuildings down on a property
6:34pm — Farmington, Van Buren County, Iowa: numerous large oak trees down in town; roof of a building peeled back
6:34pm — Anson, Clark County, Missouri: large trees down, several feet in diameter, near Missouri Highway 81 and County V intersection
6:38pm — Keosauqua, Van Buren County, Iowa: estimated at least 1.00” (quarter-sized) hail and 60-mile-per-hour winds; considerable damage to buildings at the fairgrounds; gas pumps blown over; building damaged at a county facility near the fairgrounds
6:39pm — Croton, Lee County, Iowa: numerous trees down
6:43pm — Donnellson, Lee County, Iowa: numerous trees and power lines down in town
6:50pm — near Kahoka, Clark County, Missouri: estimated 60-mile-per-hour winds
6:50pm — Francisville, Clark County, Missouri: power lines and tree braches down
6:54pm — Argyle, Lee County, Iowa: at least 1.00” (quarter-sized) hail
6:58pm — Memphis, Clark County, Missouri: around 1.00” (quarter-sized) hail
7:18pm — Warsaw, Hancock County, Illinois: numerous trees down in town; at least 1.00” (quarter-sized) hail
7:19pm — Keokuk, Lee County, Iowa: power outages and trees down; at least 1.00” (quarter-sized) hail
7:27pm — Gorin, Clark County, Missouri: 1.75” (golf-ball-sized) hail reported by Gorin Fire Department and Clark County, Missouri Dispatch / 911 Call Center
7:38pm — Alexandria, Clark County, Missouri: trees down as reported by law enforcement
7:40pm Thursday, July 19, 2018 update
Aside from a newly-formed, small storm in Clark County, Missouri and extreme southern Lee County in Iowa, the severe weather threat has ended in our area. A wind gust of 50 to 60 miles per hour and very isolated quarter-sized hail will be possible with the remaining thunderstorm area. The storm is moving through a rain-cooled air mass from the severe weather that came through earlier — so it is quite unlikely to produce enduring severe weather or affect more than isolated spots. The overall ongoing region of severe storminess will next head throughout the Quincy, Illinois area.
6:00pm Thursday, July 19, 2018 update
A severe storm that has been producing tornadoes and large hail throughout the afternoon is getting set to roll southeastward through Van Buren County in Iowa. This includes Keosauqua. The storm may then affect other parts of our area. Tune in to The New Mix 107.3 FM and 101.7 The Bull FM for any updates. After this storm comes through, the severe weather threat will almost completely diminish — but this one storm has had a history of being a whopper.
From earlier, 1:43pm Thursday, July 19, 2018
Weather this afternoon and evening could turn severe. Damaging straight-line winds, large hail, and even a tornado or two could develop over Southeast Iowa, West Central Illinois, and Northeast Missouri. In addition, some storms may produce localized heavy rainfall.
Some computer models hint at thunderstorms forming here in the 3:00pm to 5:00pm range while others are as late as 7:00pm to 10:00pm. Most models show the thunderstorms as being of the scattered variety and not too extreme.
Temperature-wise, most of us ought to see around 80 for a high.
Details on what’s happening
The setup suggesting that severe weather is possible includes a low pressure area dropping southeastward from Western Minnesota. This low pressure area has an occluded front (the pinkish purple line extending south from the red ‘L’) – that’s where the cold front (blue line) has come in underneath and actually lifted the warm front (red line) through the atmosphere. This scenario is created with aging low pressure areas since cold fronts often move around twice as quickly as warm fronts – the cold front eventually catches up to the warm front.
Surrounding the area where the pinkish purple, blue, and red lines all meet is a unique opportunity, a possibility, for severe weather – including supercells, the small, localized variety of storms known for large hail and tornadoes.
The cloudiness and rain from the 11 o’clock hour this morning certainly reduced our instability (a good thing). The occluded weather feature will be arriving during or shortly after peak heating from the sun though, so the way things play out will depend on how much and for how long we get sun into the early and mid afternoon as well as some other factors. Stay with The New Mix 107.3 and 101.7 The Bull for the latest.