Excessive Rainfall and Potential Tropical Cyclone in the South; Severe Thunderstorms in the Midwest

Excessive rainfall may produce locally considerable flash flooding over parts of the northwestern Gulf Coast, lower Mississippi River Valley, and Deep South through Thursday. Potential Tropical Cyclone One is forecast to become a tropical storm (Arthur) as it moves along or just off the northwestern Gulf coast through Wednesday. An outbreak of severe weather is forecast in the Midwest Wednesday. Read More >

Overview

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0719 PM     TORNADO          1 NW FORT MADISON MUNIC 40.68N 91.35W
03/23/2021                   LEE                IA   NWS STORM SURVEY 

            A BRIEF TORNADO CAUSED ROOF/TREE DAMAGE AND 
            DESTROYED A SHED AT A RESIDENCE NORTH OF 
            TOWN. THE LEE COUNTY EM AND SHERIFF DEPT. 
            ASSISTED WITH THIS SURVEY.

Tornado
Radar
Environment

Tornadoes:

Tornado 1 - 3 NW FORT MADISON
LEE COUNTY

Date	3/23/2021
Time (Local)	7:19 - 7:20 PM CDT
EF Rating	EF-0
Est. Peak Winds	80 mph
Path Length	0.1 mi
Max Width	30 yards
Injuries/Deaths	0 / 0
Summary: A brief tornado caused roof and tree damage and destroyed a shed at a residence north of Fort Madison. The Lee County Sheriff's Department and Emergency Manager assisted NWS Quad Cities with the storm survey.

Track Map


Survey Photo: Pen City Current	Survey Photo: Pen City Current	Survey Photo: Pen City Current

Survey Photo: Pen City Current

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Radar

RADAR LOOP - Courtesy IEM

Environment

20210323 - SPC Event Review




Mesoscale Discussion 0239 NWS Storm Prediction Center Norman OK 1244 PM CDT Tue Mar 23 2021 Areas affected...Northern Missouri...southern Iowa...and far western Illinois Concerning...Severe potential...Watch unlikely Valid 231744Z - 231945Z Probability of Watch Issuance...20 percent SUMMARY...Isolated to scattered thunderstorm development is expected through the afternoon hours across northern Missouri and into portions of southern Iowa and far western Illinois. Damaging winds and hail will be the primary threats, though a tornado threat may evolve later this afternoon and evening. DISCUSSION...Visible satellite trends through the late morning and early afternoon have shown partial clearing within a mid-level dry slot on the eastern periphery of a stacked surface/upper-level low. This clearing has been sufficient for temperatures to warm into the low to mid 60s ahead of a surface trough/dryline. Despite a marginal influx of low-level moisture (dewpoints have climbed into the low/mid 50s), recent RAP mesoanalysis suggests around 500 J/kg MLCAPE is in place across central/northern MO. Deepening cumulus and a few lightning strikes support this idea and indicate buoyancy is sufficient to support at least transient updrafts. Instability should increase to some degree into the late afternoon as temperatures continue to warm. Recent analyses also reveal marginal, but sufficient, effective bulk wind shear orthogonal to the surface trough to support discrete, organized convection. As low-level lapse rates continue to steep via diurnal heating, a wind and hail threat should materialize. Given southeasterly surface flow within the narrow warm sector (per regional VWPs), a tornado or two will be possible with the more robust storms. Convection is most likely to develop across northern MO into southern IL this afternoon. There is some uncertainty regarding convective coverage further east into IL. However, this location may see the highest tornado potential later this afternoon and evening as an increase in the low-level jet augments effective SRH. A watch is not anticipated at this time, but conditions will continue to be monitored. ..Moore/Hart.. 03/23/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ILX...LSX...DVN...SGF...DMX...EAX...OAX...TOP... LAT...LON 38009235 38659336 39399432 39579526 40049569 40539550 40869480 41029345 41049208 40699104 40049074 39439049 38739024 38179082 37939162 38009235

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Excessive Rainfall and Potential Tropical Cyclone in the South; Severe Thunderstorms in the Midwest

Event Summary: March 23