On the morning of July 21st, a cluster of showers and thunderstorms containing heavy rainfall developed over the Twin Cities metropolitan area along a slow-moving surface frontal boundary. Rainfall rates neared two inches per hour which caused urban flash flooding in downtown St.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MPX wrote it up.
On the morning of July 21st, a cluster of showers and thunderstorms containing heavy rainfall developed over the Twin Cities metropolitan area along a slow-moving surface frontal boundary. Rainfall rates neared two inches per hour which caused urban flash flooding in downtown St. Paul at the intersection of I-35E and Shepard Rd. A car was left stranded with all lanes of traffic underwater.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Twin Cities, MN wrote its last area forecast discussion before the first event at Jul 21, 5:52 AM CST, 3 hours 54 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 652 AM CDT Sun Jul 21 2024 .KEY MESSAGES... - Scattered showers and thunderstorms each afternoon through Tuesday will be slow-moving and sub-severe. - Isolated pockets of heavy rain possible in any slow-moving storms, but widespread heavy rain and flooding threat is low. && .DISCUSSION... Issued at 346 AM CDT Sun Jul 21 2024 Aside from a few showers over western Wisconsin, current temps ranged in the 60s with calm winds at most observation sites. Despite tranquil conditions, degraded visibilities across parts of MN/WI are indicative of developed fog. Additional fog is expected to spread prior to sunrise with coverage being a bit more broader as compared to the last two mornings. Visibilities at times could become less than 1 mile before mixing out later this morning. An upper low continues to dance north of Lake Superior with a surface boundary draped across NE MN. This boundary is progged to slowly track to the south as its parent upper-level low moves at snail's pace to the south-southeast. This means another day of isolated showers and storms are possible. Isolated morning showers should be confined to western Wisconsin before additional development occurs from surface boundary interactions. Latest CAM solutions showing isolated showers/storms firing ~21z from Alexandria southeast towards Red Wing. A washout is not expected today however considering the moisture profile and lack of winds, storms could be slow moving and produce locally heavy rainfall. Storm organization will lack once again today due poor deep-layer shear thus, severe weather is not expected. Otherwise, partly sunny conditions with highs around the 80 deg mark. Monday will be similar to today's forecast as the surface boundary becomes quasi-stationary. More chances for isolated showers and storms are expected to develop by Monday afternoon as an upper- level wave ejects off of the parent upper-level low just off to its east. By Tuesday a cold front will sweep across eastern MN and western WI. Total rainfall accumulations continue to range between a few tenths to near a half inch. Depending on where the strongest rain falls a few local spots could observe an inch if not more. After Tuesday's frontal passage, the pattern becomes less active with temperatures slowly creeping their way back into the upper 80s by next weekend. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 645 AM CDT Sun Jul 21 2024 Early morning convection in far western MN (impacting AXN) and in western WI (impacting mainly EAU) has at least halted any fog formation but is resulting in TSRA at the start of this period. With respect to the fog, that has pretty much stayed away from the terminals so other than a brief 5-6sm mention at the start, ground fog is not affecting the MPX terminals this morning. Still looking for additional periods of convection later this afternoon at all sites, but the overall duration may end up being longer than the current PROB30's indicate (though the actual thunderstorms moving across a terminal at any given time would be rather short-lived and intermittent). May well have MVFR conditions with any TSRA this afternoon, possibly IFR visibility in any heavy rain. Conditions will improve to VFR later this evening but additional fog looks likely for early Monday morning. KMSP...Both convection and fog have stayed away from MSP this morning so have initialized with VFR conditions. Still looking for at least -SHRA to move into the area by early this afternoon with a window in the mid-to-late afternoon hours for TSRA. The timing for TSRA may be earlier than the 18z-22z window, and conditions may be dropped briefly to IFR levels. VFR conditions are likely this evening into the early morning hours, but ground fog does look likely overnight through sunrise Monday morning. /OUTLOOK FOR KMSP/ TUE...VFR, chc -TSRA/MVFR. Wind NW 5-10kts. WED...VFR. Wind NE 5-10kts. THU...VFR. Wind SE 5-10kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && DISCUSSION...Dunleavy AVIATION...JPC
Hazardous Weather Outlook National Weather Service Twin Cities/Chanhassen MN 357 AM CDT Sun Jul 21 2024 MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028- 220900- Douglas-Todd-Morrison-Mille Lacs-Kanabec-Stevens-Pope-Stearns- Benton-Sherburne-Isanti-Chisago-Lac Qui Parle-Swift-Chippewa- Kandiyohi-Meeker-Wright-Hennepin-Anoka-Ramsey-Washington- Yellow Medicine-Renville-McLeod-Sibley-Carver-Scott-Dakota- Redwood-Brown-Nicollet-Le Sueur-Rice-Goodhue-Watonwan-Blue Earth- Waseca-Steele-Martin-Faribault-Freeborn-Polk-Barron-Rusk- St. Croix-Pierce-Dunn-Pepin-Eau Claire- 357 AM CDT Sun Jul 21 2024 This Hazardous Weather Outlook is for portions of central and southern Minnesota, and west central Wisconsin. .DAY ONE...Today and Tonight. Scattered thunderstorms can be expected this afternoon. No severe weather is expected. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Scattered thunderstorms can be expected Monday through Tuesday, mainly during the afternoon and evening hours. No severe weather is expected. .SPOTTER INFORMATION STATEMENT... SKYWARN spotter activation will not be needed.
Special Weather Statement National Weather Service Twin Cities/Chanhassen MN 812 AM CDT Sun Jul 21 2024 WIC035-211445- Eau Claire- 812 AM CDT Sun Jul 21 2024 ...URBAN AND SMALL STREAM FLOODING EXPECTED... Thunderstorms with heavy rain will cause minor flooding in the following counties... Eau Claire... * Until 945 AM CDT. * At 812 AM CDT, Doppler radar and automated rain gauges indicated heavy rain due to thunderstorms. This will cause urban and small stream flooding. Overflow of water will result in minor flooding of poor drainage locations in the area. 1 to 2 inches of rain have fallen. * Some locations that will experience minor flooding include... Eau Claire, Altoona, and Seymour. PRECAUTIONARY/PREPAREDNESS ACTIONS... Turn around, don't drown when encountering flooded roads. Most flood deaths occur in vehicles. && LAT...LON 4475 9165 4486 9165 4486 9146 4474 9146 CTG
Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
959 AM CDT Sun Jul 21 2024
MNC053-123-211630-
Hennepin-Ramsey-
959 AM CDT Sun Jul 21 2024
...URBAN FLOODING EXPECTED...
Thunderstorms with heavy rain will cause minor flooding in the
following counties...
Hennepin...Ramsey...
* Until 1130 AM CDT.
* At 959 AM CDT, trained weather spotters reported minor flooding
occurring near Minneapolis and Robbinsdale. This will cause urban
flooding. Overflow of water will result in minor flooding of poor
drainage locations. Up to one inch of rain has already fallen.
* Some locations that will experience minor flooding include...
Minneapolis, St. Paul, Bloomington, Plymouth, Eden Prairie,
Minnetonka, Edina, St. Louis Park, Maplewood, Richfield, Roseville,
and Brooklyn Center.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.
&&
LAT...LON 4504 9328 4505 9309 4492 9310 4492 9313
4487 9320 4485 9320 4482 9324 4485 9348
4506 9342
CTGThe Minneapolis radar (KMPX), 34 km away, was scanning. The volume nearest the first event began at 15:47 UTC.
1 flash flood. Local standard time, as filed.
A MNDOT traffic camera showed the intersection of I-35E and Shepard Rd flooded, with one car stranded in the flood water due to heavy rainfall. Other cars were using the freeway entrance ramp to get around the flooded roadway since the regular traffic lanes were all under water.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2024Every state in 2024This day in weather historyWarnings in Minnesota, July 2024
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1205377.