First Warn Weather Forecast

Issued: Thursday, April 3, 2025 | 8:00 AM CDT
Coverage Area: Central Missouri, Southeast Missouri, St. Louis Metro, and Southern Illinois

CURRENT WEATHER EMERGENCY: MULTI-DAY FLOODING AND SCATTERED SEVERE STORMS

A prolonged and increasingly dangerous weather pattern remains in place across the region. Heavy rainfall from previous days has primed the soil for rapid runoff. A Flood Watch remains in effect through Saturday night for the entire region. Scattered severe storms, multiple rounds of heavy rainfall, and a looming catastrophic flood threat continue to be the primary concerns, particularly for Southeast Missouri and Southern Illinois.

Unlike previous single-day events, this is a multi-day, layered crisis involving the interaction of surface boundaries, deep Gulf moisture, a high-amplitude upper trough, and strong wind shear aloft. Repeated rainfall over saturated ground will lead to dangerous flash flooding and rising river levels, with additional threats from damaging winds, large hail, and tornadoes in a narrow corridor of instability.

PRIMARY HAZARDS THROUGH SATURDAY NIGHT

• Rainfall Totals (Storm Event): 8 to 12 inches widespread, with isolated totals up to 14 inches

• Flash Flooding: Increasingly likely with each round of rain; 2 to 4 inches per hour possible in embedded cells

• River Flooding: Major to historic flooding likely on the St. Francis, Black, Meramec, Kaskaskia, and Big Muddy rivers

• Scattered Severe Storms (Friday into Friday night): Large hail, damaging winds, and isolated tornadoes, especially in Southeast Missouri

• Isolated Strong Tornado Risk: Focused Friday afternoon and evening southeast of a line from Van Buren to Cape Girardeau

• Localized Infrastructure Failure: Washed-out roads, impassable low-water crossings, overwhelmed urban drainage systems

DETAILED SHORT-TERM OUTLOOK

THURSDAY – APRIL 3

Periods of rain will continue throughout the day. While instability remains limited for much of the region, a few strong to severe storms may develop late this afternoon and evening, especially in far Southeast Missouri and far Southern Illinois. Any storm that can become surface-based could pose a hail or damaging wind threat, but the greater concern is heavy rainfall in areas that have already received 3 to 5 inches.

Forecast rainfall today: 1 to 2.5 inches, with locally higher amounts possible where storms train or repeatedly redevelop. With the ground fully saturated, flash flooding is likely in poor drainage areas, low-lying roadways, and along creeks and streams.

FRIDAY – APRIL 4

Friday presents a complex and volatile severe weather setup, but storm coverage will be scattered—not widespread. That said, the storms that do form will occur in a highly favorable environment for severe weather, especially across Southeast Missouri and parts of Southern Illinois.

Forecast soundings show MLCAPE values between 1500–2500 J/kg, 0–6 km shear of 50–65 knots, and STP values exceeding 5 in select areas near Poplar Bluff, Van Buren, and the Bootheel region. While coverage will be isolated to scattered, any mature supercell will have the potential to produce very large hail and isolated tornadoes, one or two of which could be strong (EF2+).

The concern is that storm mode may be messy—with storm splitting, clustering, and possible merging. This will limit the total number of discrete cells, but enhance the potential for localized flooding and severe weather from individual storm cells.

The rainfall on Friday will vary widely depending on storm tracks. Most areas will see 1 to 3 inches, but locations hit by multiple storms may receive over 4 inches by Friday night. This will further saturate already-soaked basins and increase the threat for overnight flash flooding.

FRIDAY NIGHT – APRIL 4

Storms may continue into the late evening and early overnight hours, particularly across Southeast Missouri and the Missouri Bootheel. The low-level jet intensifies overnight, and any lingering instability could maintain elevated or semi-surface-based storms capable of large hail and damaging wind gusts.

Flash flooding will be a growing concern as runoff increases. Storms may also begin to align with the upper-level flow, allowing for training thunderstorms, particularly near the Kaskaskia and Big Muddy River basins in Southern Illinois.

Confidence is increasing that the combination of rainfall Friday and Friday night may tip some areas into a catastrophic flood scenario, especially near the Ozark Foothills and southeastern lowlands.

SATURDAY – APRIL 5

Saturday will bring the final wave of storms and rainfall, as the upper-level low begins to eject eastward. Model guidance continues to show a swath of 2 to 5 additional inches of rain impacting much of Southeast Missouri, the lower St. Louis Metro area, and Southern Illinois, especially along and south of the I-70 corridor.

Although the severe threat will be lower than Friday, there is enough instability—especially across the southern third of the region—to support isolated damaging winds or a tornado. However, the primary threat is flooding, especially from saturated soils, failing levees, and river overflows.

By late Saturday night, the storm system will finally exit the region, but the flood crisis will continue well into next week.

EXTENDED OUTLOOK: SUNDAY – SATURDAY

SUNDAY – APRIL 6
Showers end early. Skies begin to clear from west to east. However, rivers will still be rising, and major flood impacts will continue. Travel should be limited to essential needs in areas south of I-70 due to water-covered roads and residual hazards. Highs near 60.

MONDAY – APRIL 7
Cold air filters in behind the front. Morning lows will fall into the upper 20s to low 30s, especially in rural areas. A hard freeze is expected in Central and Southeast Missouri and much of Southern Illinois. Sunny skies prevail with highs in the low 50s.

TUESDAY – APRIL 8
Another clear and cold morning. Widespread frost/freeze possible with lows near 30. Continued dry with highs in the mid-50s. This period offers the first real opportunity for cleanup in flood-impacted zones.

WEDNESDAY – APRIL 9
A weak upper-level disturbance may bring scattered light showers, but totals appear minimal. Highs rise into the upper 50s to low 60s. Flooding continues along larger river systems.

THURSDAY – APRIL 10
Mostly sunny and milder. Highs rebound to the mid-60s, with improving ground conditions. Rivers may remain elevated, but no new significant rain is expected.

FRIDAY – APRIL 11
Partly cloudy with a slight chance of light rain late in the day. Temperatures continue trending warmer, with highs in the upper 60s to near 70 degrees.

SATURDAY – APRIL 12
A pleasant, mild day with increasing sunshine and highs near 70 degrees. The region will finally experience a full day of dry, stable weather, aiding recovery efforts.

FINAL REMARKS AND KEY MESSAGES

• This is a long-duration, high-impact flood and severe weather event. Each round of rain adds to the total impact.

• Storms Friday will be scattered—not widespread—but may be intense. Conditions are supportive of isolated strong tornadoes in Southeast Missouri.

• Catastrophic flash flooding is possible Friday night into Saturday.

• Major rivers will remain in flood well into next week. Travel in rural and flood-prone areas may be disrupted for days.

• Freezing temperatures are likely Monday and Tuesday morning, which may damage early season vegetation.

• Stay alert to rapidly changing conditions. River forecasts will continue to evolve based on actual rainfall.

This is not a typical spring weather event. This is a layered, evolving emergency with compounding threats from flooding and severe storms. Public safety agencies and residents should continue to monitor updates and be ready to act swiftly. Preparedness, awareness, and caution over the next 72 hours will save lives.

Stay tuned to First Warn Weather for real-time updates, alerts, and detailed storm tracking.

First Warn Severe Weather and Catastrophic Flooding Threat Statement

Issued: Thursday, April 3, 2025 |8:30 AM CDT
Coverage Area: Central Missouri, Southeast Missouri, St. Louis Metro, and Southern Illinois
Prepared by: First Warn Weather Team

OVERVIEW

A multi-day, multi-hazard high-impact weather event is currently affecting the region and will continue through Saturday night, with serious implications for life, safety, infrastructure, agriculture, and emergency management operations. This is a layered weather crisis, marked by scattered but intense severe thunderstorms, extremely heavy rainfall, and the growing likelihood of catastrophic flash and river flooding.

What distinguishes this event is not the storm coverage, but the storm efficiency—storms are forming in a highly saturated, thermodynamically rich environment, with abnormally high precipitable water (PWAT) values, deep warm cloud layers, and favorable kinematic support for training convection and supercell development, particularly Friday into Saturday.

The combined impacts of back-to-back rainfall episodes, escalating runoff, and compromised drainage will lead to compound flooding risks across both rural and urban areas, including locations with little or no history of flooding. The threat extends well beyond the end of rainfall—with major river flooding likely persisting into next week.

SYNOPTIC SETUP & METEOROLOGICAL INSIGHT

A broad, positively tilted upper-level trough continues to dig across the Four Corners region and Southern Plains, gradually evolving into a negatively tilted wave by Saturday. A persistent 40–60 kt low-level jet, originating from the western Gulf of Mexico, is maintaining a conveyor belt of deep-layer moisture transport into the mid-Mississippi and Ohio River Valleys.

As of Thursday morning, precipitable water values exceed 1.7 inches, which is near the 99th percentile climatologically for early April. This moisture is being lifted over a quasi-stationary surface front stretching from northern Texas through the Mid-South into the lower Ohio Valley. The position of this boundary will fluctuate, acting as a focal point for overrunning convection, mesoscale convective development, and occasional surface-based supercells, particularly when it briefly lifts northward Friday evening.

Warm air advection and embedded shortwave impulses—driven by jet streaks rotating around the base of the longwave trough—will support episodic rounds of thunderstorms, many of which will be elevated and high-precipitation in nature. These storms will be highly efficient rain producers due to weak mid-level lapse rates, deep saturated profiles, and training along convergence zones.

Model guidance, including the HRRR, ECMWF, GFS, and HREF, continues to signal localized rainfall rates of 2–4 inches per hour, particularly from late Friday afternoon through early Saturday morning. Ensemble output supports storm-total rainfall of 8 to 12 inches, with some guidance suggesting localized totals exceeding 14 inches across Southeast Missouri and southwest Illinois.

HAZARDS AND IMPACTS

1. Scattered Severe Thunderstorms (Today–Saturday)

• Today (Thursday): Instability remains modest north of the boundary, but surface-based convection is possible in far Southeast Missouri and Southern Illinois, especially near and south of the Bootheel. Expect isolated large hail and damaging winds, and possibly a brief tornado in the most unstable areas.

• Friday: Despite scattered coverage, storms will occur in an extremely volatile environment—particularly across Southeast Missouri into southwest Illinois. Soundings near Poplar Bluff and Sikeston show:

  • MLCAPE: 1800–2500 J/kg

  • 0–6 km shear: 50–65 kt

  • 0–1 km SRH: 250–400 m²/s²

  • Effective STP: 4–6

These values indicate an environment capable of supporting isolated strong tornadoes, giant hail, and severe wind gusts, especially if semi-discrete or embedded supercells develop late Friday afternoon and evening. While storms will be scattered in nature, any storm that forms will have access to prime thermodynamic and shear parameters for rapid intensification.

• Friday Night into Saturday Morning: As the boundary lifts north briefly and low-level shear intensifies, elevated and semi-surface-based storms will continue to pose a severe hail and damaging wind threat, with a non-zero tornado risk in Southeast Missouri and the lower Wabash Valley.

• Saturday: The cold front pushes east slowly. Instability remains modest, but embedded thunderstorms in a broader convective shield may still produce gusty winds and isolated brief tornadoes in the southern counties, especially before midday.

2. Catastrophic Flash Flooding and River Flooding

This is the primary and most consequential hazard through the weekend.

• Storm-total rainfall of 8 to 12 inches is expected across Southeast Missouri, East-Central Missouri, and Southern Illinois, with localized totals potentially exceeding 14 inches in training zones.

• Flash Flood Guidance (FFG) values are already low—some areas will exceed 1-hr or 3-hr thresholds within the first hour of Friday night rainfall.

• Urban and rural areas alike will experience:

  • Rapid water rise in low-lying streets, ditches, and creeks

  • Submersion of rural highways, county roads, and low-water crossings

  • Inundation of farmlands and property, especially in the Ozark Foothills, the Black River Basin, and the Big Muddy and Kaskaskia Rivers

• Major river flooding is likely by late weekend and early next week along:

  • St. Francis River – from Wappapello Lake to Arkansas

  • Black River – south of Clearwater Dam

  • Big Muddy River – affecting parts of Jackson and Perry Counties (IL)

  • Kaskaskia River – impacting Washington, Randolph, and Clinton Counties (IL)

  • Meramec River – especially near Pacific and Valley Park in the St. Louis Metro

KEY MESSAGES TO THE PUBLIC

• This is not a one-day storm. This is a multi-day, evolving disaster.

• Storms Friday and Friday night will be scattered—but dangerous. Some may be tornadic, especially in Southeast Missouri.

• Rainfall totals of 8 to 12 inches, with isolated 14+ inch amounts, will result in catastrophic flooding.

• Stay off roads during heavy rain and avoid all flooded areas. Turn around—don’t drown.

• Major rivers will remain in flood into early next week. Do not let your guard down once rain stops.

• Have multiple ways to receive warnings, especially overnight. Weather radios, wireless alerts, and local news are essential.

• Be prepared to evacuate. Know your flood risk and community alert systems.

NEXT STATEMENT & ACTION ITEMS

Anoterh update to this Threat Statement will be issued by Thursday evening, or earlier if changes in mesoscale or convective trends warrant it. Continue to monitor NWS updates, local emergency management announcements, and First Warn live briefings for the most timely, detailed coverage.

Prepared by:
Dr. Nick Palisch
First Warn Weather
www.firstwarnwx.com